Researcher Profile and Settings

Affiliation

• Faculty of Engineering　Sustainable Resources Engineering　Resources Engineering

Job Title

• Professor

Degree

• (BLANK)
• (BLANK)
• (BLANK)

J-Global ID

• 200901037657842418

Research Interests

• 粉体工学   資源リサイクル工学   鉱物処理工学   Powder Technology   Resources Recycling and Utilizatin   Mineral Processing   

Research Areas

• Energy / Earth resource engineering, energy science
• Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Transfer phenomena and unit operations

Educational Organization

•  Bachelor's degree program　School of Engineering
•  Master's degree program　Graduate School of Engineering
•  Doctoral (PhD) degree program　Graduate School of Engineering

Academic & Professional Experience

• 2010/04 - Today Hokkaido University
• 2007/04 - 2010/03 Hokkaido University
• 2004/04 - 2010/03 Hokkaido University
• 1997 - 2001 Hokkaido University Graduate School of Engineering
• 1997 - 2001 Instructor, Graduate School of Hokkaido University
• 1993 - 1997 Hokkaido University
• 1993 - 1997 Instructor, Hokkaido University

Education

•        - 1991  Hokkaido University
•        - 1991  Hokkaido University  Graduate School, Division of Engineering
•        - 1989  Hokkaido University  School of Engineering
•        - 1989  Hokkaido University  Faculty of Engineering

Association Memberships

• 廃棄物資源循環学会   資源・素材学会   環境資源工学会   

Research Activities

Published Papers

• Modified Diglycolamide Resin: Characterization and Potential Application for Rare Earth Element Recovery

  Junnile L. Romero, Carlito Baltazar Tabelin, Ilhwan Park, Richard D. Alorro, Joshua B. Zoleta, Leaniel C. Silva, Takahiko Arima, Toshifumi Igarashi, Takunda Mhandu, Mayumi Ito, Steffen Happel, Naoki Hiroyoshi, Vannie Joy T. Resabal

  Minerals 13 (10) 1330 - 1330 2023/10/14 

  Rare earth elements (REEs) are crucial for green energy applications due to their unique properties, but their extraction poses sustainability challenges because the global supply of REEs is concentrated in a few countries, particularly China, which produces 70% of the world’s REEs. To address this, the study investigated TK221, a modified extraction chromatographic resin featuring diglycolamide (DGA) and carbamoyl methyl phosphine oxide (CMPO), as a promising adsorbent for REE recovery. The elemental composition and functional groups of DGA and CMPO on the polystyrene-divinylbenzene (PS-DVB) support of TK221 were confirmed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of neodymium (Nd), yttrium (Y), cerium (Ce), and erbium (Er) followed the pseudo-second-order kinetic model and Langmuir isotherm, indicating monolayer chemisorption. Furthermore, iron (Fe) adsorption reached apparent equilibrium after 360 min, with consistent Fe adsorption observed at both 360 min and 1440 min. The inclusion of Fe in the study is due to its common presence as an impurity in most REE leachate solutions. The Fe adsorption isotherm results are better fitted with the Langmuir isotherm, implying chemisorption. Maximum adsorption capacities (qmax) of the resin were determined as follows: Nd (45.3 mg/g), Ce (43.1 mg/g), Er (35.1 mg/g), Y (15.6 mg/g), and Fe (12.3 mg/g). ATR-FTIR analysis after adsorption suggested that both C=O and P=O bands shifted from 1679 cm−1 to 1618 cm−1 and 1107 cm−1 to 1142 cm−1 for Y, and from 1679 cm−1 to 1607 cm−1 and 1107 cm−1 to 1135 cm−1 for Ce, implying possible coordination with REEs. These results suggest that TK221 has a huge potential as an alternative adsorbent for REE recovery, thus contributing to sustainable REE supply diversification.
• A novel recycling route for aluminum alloys: Synthesis of Fe/Al bimetallic materials and magnetic separation

  Ilhwan Park, Mayumi Ito, Sanghee Jeon, Carlito Baltazar Tabelin, Theerayut Phengsaart, Marthias Silwamba, Naoki Hiroyoshi

  Minerals Engineering 201 108202 - 108202 0892-6875 2023/10
• Functional modification of mussel adhesive protein to control solubility and adhesion property

  Anju Pilakka Veedu, Kazunori Nakashima, Hayahide Shiga, Takahiro Sato, Kasun Godigamuwa, Naoki Hiroyoshi, Satoru Kawasaki

  Journal of Bioscience and Bioengineering 136 (2) 87 - 93 1389-1723 2023/08
• A Pretreatment of Refractory Gold Ores Containing Sulfide Minerals to Improve Gold Leaching by Ammonium Thiosulfate: A Model Experiment Using Gold Powder and Arsenic-Bearing Sulfide Minerals

  Takunda Joseph Mhandu, Ilhwan Park, Sanghee Jeon, Sohta Hamatsu, Yogarajah Elakneswaran, Mayumi Ito, Naoki Hiroyoshi

  Metals 13 (8) 1357 - 1357 2023/07/28 

  The use of thiosulfate to extract gold from refractory ores is promising because of its non-toxicity and high selectivity. Sulfide minerals (i.e., pyrite, arsenopyrite, chalcopyrite), major gold carriers in refractory gold ores, however, hinder gold extraction due to the high consumption of a lixiviant. In this study, a new method to improve gold extraction from sulfide bearing gold ores is proposed based on the model experiments using a mixture of gold powder and arsenopyrite-bearing sulfide (HAsBS) ore. The effects of HAsBS ore on gold leaching in ammonium thiosulfate solutions were investigated, and it was found that gold extraction in the presence of HAsBS ore was suppressed because of the unwanted decomposition of thiosulfate on the surface of sulfide minerals. To improve gold extraction in the presence of the sulfide minerals, this study investigated the effects of the pretreatment of HAsBS ore using ammonium solutions containing cupric ions and confirmed that HAsBS ore was oxidized in the pretreatment and its surface was covered by the oxidation products. As a result, thiosulfate consumption was minimized in the subsequent gold leaching step using ammonium thiosulfate, resulting in an improvement in gold extraction from 10% to 79%.
• Selective Cementation of Gold Using an Iron Oxide and Zero-Valent Aluminum Galvanic System from Gold–Copper Ammoniacal Thiosulfate Solutions

  Joshua Zoleta, Sanghee Jeon, Akuru Kuze, Nako Okada, Ilhwan Park, Mayumi Ito, Yogarajah Elakneswaran, Naoki Hiroyoshi

  Metals 13 (7) 1289 - 1289 2023/07/18 

  Ammonium thiosulfate leaching is a promising alternative to the conventional cyanide method for extracting gold from ores. However, strategies for recovering gold from the leachate are less commercially used due to its low affinity to gold. The present study investigated the recovery of gold from the leachate using iron oxides (hematite, Fe2O3 or magnetite, Fe3O4). Cementation experiments were conducted by mixing 0.15 g of aluminum powder as an electron donor and 0.15 g of an electron mediator (activated carbon, hematite, or magnetite) in 10 mL of ammonium thiosulfate leachate containing 100 mg/L gold ions and 10 mM cupric ions for 24 h at 25 °C. The results of the solution analysis showed that when activated carbon (AC) was used, the gold was recovered together with copper (recoveries were 99.99% for gold and copper). However, selective gold recovery was observed when iron oxides were used, where the gold and copper recoveries were 89.7% and 21% for hematite and 85.9% and 15.4% for magnetite, respectively. An electrochemical experiment was also conducted to determine the galvanic interaction between the electron donor and electron mediator in a conventional electrochemical setup (hematite/magnetite–Al as the working electrode, Pt as the counter electrode, Ag/AgCl as the reference electrode) in a gold–thiosulfate medium. Cyclic voltammetry showed a gold reduction “shoulder-like” peak at −1.0 V using hematite/Al and magnetite/Al electrodes. Chronoamperometry was conducted and operated at a constant voltage (−1.0 V) determined during cyclic voltammetry and further analyzed using SEM-EDX. The results of the SEM-EDX analysis for the cementation products and electrochemical experiments confirmed that the gold was selectively deposited on the iron oxide surface as an electron mediator.
• Carrier Flotation Using Coarse Pyrite for Improving the Recovery of Finely Ground Chalcopyrite: Development of Post-Process of Carrier Flotation to Separate Finely Ground Chalcopyrite Particles from Coarse Pyrite Particles

  Muhammad Bilal, Ilhwan Park, Mayumi Ito, Fawad Ul Hassan, Kosei Aikawa, Sanghee Jeon, Naoki Hiroyoshi

  Minerals 13 (7) 916 - 916 2023/07/07 

  Carrier flotation is a technique that can recover fine particles by using coarse carrier particles during the flotation process. In heterogeneous carrier flotation, coarse mineral particles of different minerals are used as carriers to recover fine mineral particles. By using Cu2+-treated pyrite particles as carriers, fine chalcopyrite particles recovery could be improved. However, a disadvantage of this heterogeneous carrier flotation is that it requires a post-flotation separation process to improve the grade of the final Cu concentrate. This study tested mechanical and chemical treatments to detach finely ground chalcopyrite (D50~3.5 µm) particles from Cu2+-treated coarse pyrite particles (−125 + 106 µm) after flotation. The results showed that the ultrasonic treatment was not effective to detach chalcopyrite fines from Cu2+-treated pyrite particles. However, acid treatment was effective to detach chalcopyrite fines from coarse pyrite particles. At pH 2, approximately 96% of chalcopyrite fines were detached from coarse Cu2+-treated pyrite particles. The acid treatment of flotation froth (mixture of chalcopyrite fines and Cu2+-treated pyrite particles) decomposed the collector KAX (potassium amyl xanthate) and dissolved the Cu precipitates adsorbed on the pyrite surface. This weakened the hydrophobic attraction force between the chalcopyrite fines and coarse pyrite particles, thus promoting the detachment of chalcopyrite fines from Cu2+-treated coarse pyrite particles.
• Flotation of Copper Ores with High Cu/Zn Ratio: Effects of Pyrite on Cu/Zn Separation and an Efficient Method to Enhance Sphalerite Depression

  Kosei Aikawa, Mayumi Ito, Nodoka Orii, Sanghee Jeon, Ilhwan Park, Kazutoshi Haga, Taro Kamiya, Tatsuru Takahashi, Kazuya Sunada, Taisuke Sakakibara, Tatsuhiro Ono, Refilwe S. Magwaneng, Naoki Hiroyoshi

  Minerals 12 (9) 1103 - 1103 2022/08/30 

  Porphyry copper deposits are important sources of copper and typically processed by flotation to produce copper concentrates. As mining areas become deeper, the amounts of impurities, such as sphalerite, can be increased in copper ores, so the appropriate depression of sphalerite floatability should be achieved to obtain saleable copper concentrates. In this study, the flotation behaviors of chalcopyrite and sphalerite in model samples mimicking copper ores with high Cu/Zn ratios (i.e., the ratio of chalcopyrite/sphalerite = 13:1) were investigated with zinc sulfate as a depressant for sphalerite. In addition, the effect of pyrite—a major gangue mineral in copper ores—on the depression of sphalerite floatability with zinc sulfate was examined. When sphalerite and chalcopyrite coexisted, the floatability of the former was effectively depressed by zinc sulfate (Zn recovery: <12%), whereas the presence of pyrite promoted the release of Cu2+ due to the galvanic interaction with chalcopyrite, which resulted in the elimination of the effectiveness of zinc sulfate in depressing sphalerite floatability (Zn recovery: >90%). Despite the presence of much higher amounts of chalcopyrite and pyrite than sphalerite, the application of nitrogen (N2) gas limiting the galvanic interaction between pyrite and chalcopyrite by reducing the dissolved oxygen (DO) concentration in the system effectively depressed the floatability of sphalerite (Zn recovery: <30%).
• Development of a Sustainable Process for Complex Sulfide Ores Containing Anglesite: Effect of Anglesite on Sphalerite Floatability, Enhanced Depression of Sphalerite by Extracting Anglesite, and Recovery of Extracted Pb2+ as Zero-Valent Pb by Cementation Using Zero-Valent Fe

  Kosei Aikawa, Mayumi Ito, Atsuhiro Kusano, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi

  Minerals 12 (6) 723 - 723 2022/06/06 

  The presence of anglesite (PbSO4) in complex sulfide ores negatively affects the separation of Cu-Pb sulfides and sphalerite (ZnS) due to lead activation, and PbSO4 rejected to tailings dams contaminates the surrounding environment with lead. To address these problems, this study investigated the application of ethylene diamine tetra acetic acid (EDTA) pretreatment extracting PbSO4 to ZnS flotation and the recovery of the extracted Pb2+ as zero-valent Pb by cementation using zero-valent iron (ZVI). The application of EDTA pretreatment could extract ~99.8% of PbSO4, thus depressing ZnS floatability from 82% to 30%. In addition, cementation using ZVI could recover ~99.7% of Pb2+ from the leachate of EDTA pretreatment.
• Alkaline Leaching and Concurrent Cementation of Dissolved Pb and Zn from Zinc Plant Leach Residues

  Marthias Silwamba, Mayumi Ito, Naoki Hiroyoshi, Carlito Baltazar Tabelin, Ryota Hashizume, Tomoki Fukushima, Ilhwan Park, Sanghee Jeon, Toshifumi Igarashi, Tsutomu Sato, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka

  Minerals 12 (4) 2022/04 

  Zinc plant leach residues (ZPLRs), particularly those produced using old technologies, have both economic importance as secondary raw materials and have environmental impacts because they contain hazardous heavy metals that pose risks to human health and the environment. Therefore, the extraction and recovery of these metals from ZPLRs has both economic and environmental benefits. In this study, we investigated the removal of lead (Pb) and zinc (Zn) from ZPLRs by alkaline (NaOH) leaching and the concurrent cementation of dissolved Pb and Zn using aluminum (Al) metal powder. The effects of the leaching time, NaOH concentration, solid-to-liquid ratio (S/L), and dosage of Al metal powder on the extraction of Pb and Zn were investigated. Pb and Zn removal efficiencies increased with increasing NaOH concentrations and decreasing S/Ls. The Pb and Zn removal efficiencies were 62.2% and 27.1%, respectively, when 2.5 g/50 mL (S/L) of ZPLRs were leached in a 3 M NaOH solution for 30 min. The extraction of Pb and Zn could be attributed to the partitioning of these metals in relatively more mobile phases—water-soluble, exchangeable, and carbonate phases— in ZPLRs. Around 100% of dissolved Pb and less than 2% of dissolved Zn were cemented in leaching pulp when Al metal powder was added. Minerals in the solid residues, particularly iron oxides minerals, were found to suppress the cementation of extracted Zn in leaching pulp, and when they were removed by filtration, Zn was recovered by Al metal powder via cementation.
• Heterogenous carrier flotation technique for recovering finely ground chalcopyrite particles using coarse pyrite particles as a carrier

  Muhammad Bilal, Mayumi Ito, Riku Akishino, Xiangning Bu, Fawad Ul Hassan, Ilhwan Park, Sanghee Jeon, Kosei Aikawa, Naoki Hiroyoshi

  Minerals Engineering 180 0892-6875 2022/04 

  The recovery of fine mineral particles in flotation is limited owing to the low collision probability between the particles and air bubbles. The carrier flotation method can enhance fine particle recovery by attaching fines to coarse carrier particles. In this study, an attempt was made to improve the recovery of chalcopyrite fines using coarse pyrite particles as a carrier. Flotation experiments for finely ground chalcopyrite (D50 ∼ 3 µm) were conducted with and without coarse pyrite (–125+106 µm) using potassium amyl xanthate as a collector. The results showed that untreated pyrite did not act as an effective carrier and that the amount of fine chalcopyrite attached to pyrite was not significant; furthermore, Cu recovery into froth was around 65% both with and without pyrite. When pyrite was pre-treated with a CuSO4 solution, its carrier ability improved owing to a significant amount of fine chalcopyrite becoming attached to the Cu2+-activated pyrite particles and being recovered with pyrite into the froth (Cu recovery, >90%). Overall, the treatment of pyrite with CuSO4 improved its hydrophobicity, which improved its hydrophobic interactions with fine chalcopyrite particles. Thus, the Cu2+-treatment of pyrite promotes the attachment of fine chalcopyrite particles for their increased recovery from fines.
• A simple and efficient recovery technique for gold ions from ammonium thiosulfate medium by galvanic interactions of zero-valent aluminum and activated carbon: A parametric and mechanistic study of cementation

  S. Jeon, S. Bright, I. Park, C.B. Tabelin, M. Ito, N. Hiroyoshi

  Hydrometallurgy 208 2022/02 [Refereed]
  
• A Kinetic Study on Enhanced Cementation of Gold Ions by Galvanic Interactions between Aluminum (Al) as an Electron Donor and Activated Carbon (AC) as an Electron Mediator in Ammonium Thiosulfate System

  S. Jeon, S. Bright, I. Park, A. Kuze, M. Ito, N. Hiroyoshi

  Minerals 12 (1) 2022/01 [Refereed]
  
• Beneficiation of Low-Grade Rare Earth Ore from Khalzan Buregtei Deposit (Mongolia) by Magnetic Separation

  I. Park, Y. Kanazawa, N. Sato, P. Galtchandmani, M. K. Jha, C.B. Tabelin, S. Jeon, M. Ito, N. Hiroyoshi

  Minerals 11 (12) 2021/12 [Refereed]
  
• Addition of Fe3O4 as electron mediator for enhanced cementation of Cd2+ and Zn2+ on aluminum powder from sulfate solutions and magnetic separation to concentrate cemented metals from cementation products

  S. Choi, S Jeon, I. Park, M. Ito, N. Hiroyoshi

  Journal of Environmental Chemical Engineering 9 (6) 2021/12 [Refereed]
  
• Simultaneous extraction and recovery of lead using citrate and micro-scale zero-valent iron for decontamination of polluted shooting range soils

  Marthias Silwamba, Mayumi Ito, Carlito Baltazar Tabelin, Ilhwan Park, Sanghee Jeon, MasaoTakada, Yasushi Kubo, Naohiro Hokari, Masami Tsunekawa, Naoki Hiroyoshi

  Environmental Advances 5 2021/10 [Refereed]
  
• Repurposing of aluminum scrap into magnetic Al0/ZVI bimetallic materials: Two-stage mechanical-chemical synthesis and characterization of products

  C.B. Tabelin, V.J.T. Resabal, I. Park, M.G.B. Vilanueva, S. Choi, R. Ebio, P.J. Cabural, M.V. Tabelin, A. Orbecido, R.D. Alorro, S. Jeon, M. Ito, N. Hiroyoshi

  Journal of Cleaner Production 317 2021/10 [Refereed]
  
• A novel arsenic immobilization strategy via a two-step process: Arsenic concentration from dilute solution using schwertmannite and immobilization in Ca–Fe–AsO4 compounds

  I. Park, T. Ryota, T Yuto, C.B. Tabelin, T. Phengsaart, S. Jeon, M. Ito, N. Hiroyoshi

  Journal of Environmental Management 295 2021/10 [Refereed]
  
• Agglomeration-flotation of finely ground chalcopyrite using surfactant-stabilized oil emulsions: Effects of co-existing minerals and ions

  V. Horn, I. Park, M. Ito, H Shimada, T. Suto, C.B. Tabelin, S. Jeon, N. Hiroyoshi

  Minerals Engineering 171 2021/09 [Refereed]
  
• The Effects of Coexisting Copper, Iron, Cobalt, Nickel, and Zinc Ions on Gold Recovery by Enhanced Cementation via Galvanic Interactions between Zero-Valent Aluminum and Activated Carbon in Ammonium Thiosulfate Systems

  S. Jeon, S. Bright, I. Park, C.B. Tabelin, M. Ito, N. Hiroyoshi

  Metals 11 (9) 2021/08 [Refereed]
  
• Enhanced pyrite passivation by carrier-microencapsulation using Fe-catechol and Ti-catechol complexes

  X. Li, I. Park, C.B. Tabelin, K. Naruwa, T. Goda, C Harada, S. Jeon, M. Ito, N. Hiroyoshi

  Journal of Hazardous Materials 416 2021/08 [Refereed]
  
• Copper and critical metals production from porphyry ores and E-wastes: A review of resource availability, processing/recycling challenges, socio-environmental aspects, and sustainability issues

  C.B. Tabelin, I. Park, T. Phengsaart, S. Jeon, M.V. Tabelin, D. Alonzo, K. Yoo, M. Ito, N. Hiroyoshi

  Resources, Conservation and Recycling 170 2021/07 [Refereed]
  
• Development of a restraining wall and screw-extractor discharge system for continuous jig separation of mixed plastics

  T. Phengsaart, M. Ito, S. Kimura, A. Azuma, K. Hori, H. Tanno, S. Jeon, I. Park, C.B. Tabelin, N. Hiroyoshi

  Minerals Engineering 168 2021/07 [Refereed]
  
• Enhanced cementation of Cd2+, Co2+, Ni2+, and Zn2+ on Al from sulfate solutions by activated carbon addition

  S. Choi, S. Jeon, I. Park, C.B. Tabelin, M. I, N. Hiroyoshi

  Hydrometallurgy 201 2021/05 [Refereed]
  
• Suppression of arsenopyrite oxidation by microencapsulation using ferric-catecholate complexes and phosphate

  I. Park, K. Higuchi, C.B. Tabelin, S. Jeon, M. Ito, N. Hiroyoshi

  Chemosphere 269 2021/04 [Refereed]
  
• Effects of coarse chalcopyrite on flotation behavior of fine chalcopyrite

  M. Bilal, M. Ito, K. Koike, V. Hornn, F.U. Hassan, S. Jeon, I. Park, N. Hiroyoshi

  Minerals Engineering 163 2021/03 [Refereed]
  
• Flotation of Seafloor Massive Sulfide Ores: Combination of Surface Cleaning and Deactivation of Lead-Activated Sphalerite to Improve the Separation Efficiency of Chalcopyrite and Sphalerite

  Kosei Aikawa, Mayumi Ito, Atsuhiro Kusano, Ilhwan Park, Tatsuya Oki, Tatsuru Takahashi, Hisatoshi Furuya, Naoki Hiroyoshi

  Metals 11 (2) 253 - 253 2021/02/02 

  The purpose of this study is to propose the flotation procedure of seafloor massive sulfide (SMS) ores to separate chalcopyrite and galena as froth and sphalerite, pyrite, and other gangue minerals as tailings, which is currently facing difficulties due to the presence of water-soluble compounds. The obtained SMS ore sample contains CuFeS2, ZnS, FeS2, SiO2, and BaSO4 in addition to PbS and PbSO4 as Pb minerals. Soluble compounds releasing Pb, Zn2+, Pb2+, and Fe2+/3+ are also contained. When anglesite co-exists, lead activation of sphalerite occurred, and thus sphalerite was recovered together with chalcopyrite as froth. To remove soluble compounds (e.g., anglesite) that have detrimental effects on the separation efficiency of chalcopyrite and sphalerite, surface cleaning pretreatment using ethylene diamine tetra acetic acid (EDTA) was applied before flotation. Although most of anglesite were removed and the recovery of chalcopyrite was improved from 19% to 81% at 20 g/t potassium amyl xanthate (KAX) after EDTA washing, the floatability of sphalerite was not suppressed. When zinc sulfate was used as a depressant for sphalerite after EDTA washing, the separation efficiency of chalcopyrite and sphalerite was improved due to deactivation of lead-activated sphalerite by zinc sulfate. The proposed flotation procedure of SMS ores—a combination of surface cleaning with EDTA to remove anglesite and the depression of lead-activated sphalerite by using zinc sulfate—could achieve the highest separation efficiency of chalcopyrite and sphalerite; that is, at 200 g/t KAX, the recoveries of chalcopyrite and sphalerite were 86% and 17%, respectively.
• Enhanced Cementation of Co2+ and Ni2+ from Sulfate and Chloride Solutions Using Aluminum as an Electron Donor and Conductive Particles as an Electron Pathway

  S. Choi, S Jeon, I. Park, M. Ito, N. Hiroyoshi

  Metals 11 (2) 2021/02 [Refereed]
  
• Flotation Separation of Chalcopyrite and Molybdenite Assisted by Microencapsulation Using Ferrous and Phosphate Ions: Part I. Selective Coating Formation

  Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi

  Metals 10 (12) 2020/12 [Refereed]
  
• Solid-phase partitioning and release-retention mechanisms of copper, lead, zinc and arsenic in soils impacted by artisanal and small-scale gold mining (ASGM) activities

  Carlito Baltazar Tabelin, Marthias Silwamba, Florifern C. Paglinawan, Alissa Jane S. Mondejar, Ho Gia Duc, Vannie Joy Resabal, Einstine M. Opiso, Toshifumi Igarashi, Shingo Tomiyama, Mayumi Ito, Naoki Hiroyoshi, Mylah Villacorte-Tabelin

  Chemosphere 260 127574 - 127574 0045-6535 2020/12
• Acid mine drainage formation and arsenic mobility under strongly acidic conditions: Importance of soluble phases, iron oxyhydroxides/oxides and nature of oxidation layer on pyrite

  Carlito Baltazar Tabelin, Ryan D. Corpuz, Toshifumi Igarashi, Mylah Villacorte-Tabelin, Richard Diaz Alorro, Kyoungkeun Yoo, Simit Raval, Mayumi Ito, Naoki Hiroyoshi

  JOURNAL OF HAZARDOUS MATERIALS 399 0304-3894 2020/11 

  Acid mine drainage (AMD) formation and toxic arsenic (As) pollution are serious environmental problems encountered worldwide. In this study, we investigated the crucial roles played by common secondary mineral phases formed during the natural weathering of pyrite-bearing wastes soluble salts (melanterite, FeSO4 center dot 7H(2)0) and metal oxides (hematite, Fe2O3)-on AMD formation and As mobility under acidic conditions (pH 1.5-4) prevalent in historic tailings storage facilities, pyrite-bearing rock dumps and AMD-contaminated soils and sediments. Our results using a pyrite-rich natural geological material containing arsenopyrite (FeAsS) showed that melanterite and hematite both directly-by supplying H+ and/or oxidants (Fe3+)-and indirectly-via changes in the nature of oxidation layer formed on pyrite-influenced pyrite oxidation dynamics. Based on SEM-EDS, DRIFT spectroscopy and XPS results, the oxidation layer on pyrite was mainly composed of ferric arsenate and K-Jarosite when melanterite was abundant with/without hematite but changed to Fe-oxyhydroxide/oxide and scorodite when melanterite was low and hematite was present This study also observed the formation of a mechanically 'strong' coaling on pyrite that suppressed the mineral's oxidation. Finally, As mobility under acidic conditions was limited by its precipitation as ferric arsenate, scorodite, or a Fe/Al arsenate phase, including its strong adsorption to Fe-oxyhydroxides/oxides.
• Kinetic Analysis for Agglomeration-Flotation of Finely Ground Chalcopyrite: Comparison of First Order Kinetic Model and Experimental Results

  Vothy Hornn, Mayumi Ito, Ryosuke Yamazawa, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi

  61 (10) 2020/09 [Refereed]
  
• Detoxification of lead-bearing zinc plant leach residues from Kabwe, Zambia by coupled extraction-cementation method

  Marthias Silwamba, Mayumi Ito, Naoki Hiroyoshi, Carlito Baltazar Tabelin, Tomoki Fukushima, Ilhwan Park, Sanghee Jeon, Toshifumi Igarashi, Tsutomu Sato, Imasiku Nyambe, Meki Chirwa, Kawawa Banda, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka

  Journal of Environmental Chemical Engineering 8 (4) 104197 - 104197 2213-3437 2020/08 [Refereed][Not invited]
  
• Agglomeration–Flotation of Finely Ground Chalcopyrite Using Emulsified Oil Stabilized by Emulsifiers: Implications for Porphyry Copper Ore Flotation

  Vothy Hornn, Mayumi Ito, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi

  Metals 10 (7) 912 - 912 2020/07/08 [Refereed][Not invited]
   

  Flotation is the conventional method for processing porphyry copper deposits, one of the most economically important sources of copper (Cu) worldwide. The rapidly decreasing grade of this type of Cu ore in recent years, however, presents serious problems with fine particle recovery using conventional flotation circuits. This low recovery could be attributed to the low collision efficiency of fine particles and air bubbles during flotation. To improve collision efficiency and flotation recovery, agglomeration of finely ground chalcopyrite (CuFeS2) (D50 = 3.5 μm) using emulsified oil stabilized by emulsifiers was elucidated in this study. Specifically, the effects of various types of anionic (sodium dodecyl sulfate (SDS), potassium amyl xanthate (KAX)), cationic (dodecyl amine acetate (DAA)), and non-ionic (polysorbate 20 (Tween 20)) emulsifiers on emulsified oil stability and agglomeration–flotation efficiency were investigated. When emulsifiers were added, the average size of agglomerates increased, resulting in higher Cu recovery during flotation. This dramatic improvement in flotation efficiency could be attributed to the smaller oil droplet size in emulsified oil and their higher stability in the presence of emulsifiers. The utilization of emulsifiers during agglomeration–flotation not only lowered the required agitation strength for agglomeration but also shortened the agglomeration time, both of which made the process easier to incorporate in existing flotation circuits.
• Depression of lead-activated sphalerite by pyrite via galvanic interactions: Implications to the selective flotation of complex sulfide ores

  Kosei Aikawa, Mayumi Ito, Tatsuya Segawa, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Naoki Hiroyoshi

  Minerals Engineering 152 106367 - 106367 0892-6875 2020/06 [Refereed][Not invited]
  
• Redox potential-dependent chalcopyrite leaching in acidic ferric chloride solutions: Leaching experiments

  Nguyen Thi Phuong Thao, Shushi Tsuji, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Mayumi Ito, Naoki Hiroyoshi

  Hydrometallurgy 194 105299 - 105299 0304-386X 2020/06 [Refereed][Not invited]
  
• Agglomeration-Flotation of Finely Ground Chalcopyrite and Quartz: Effects of Agitation Strength during Agglomeration Using Emulsified Oil on Chalcopyrite

  Vothy Hornn, Mayumi Ito, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi

  Minerals 10 (4) 380 - 380 2020/04/23 [Refereed][Not invited]
   

  In flotation, the size of mineral particles is one of the most important parameters: when the size becomes fine, collision efficiency of the particles and air bubbles becomes low, causing low flotation recovery. To improve the collision efficiency and flotation kinetics, agglomeration using the emulsified oil of finely ground chalcopyrite (D50 = 3.5 μm) was carried out before flotation. In this study, the effects of agitation strength during agglomeration, kerosene dosage and potassium amyl xanthate (KAX) dosage on the flotation were investigated. Agglomeration using emulsified oil improved Cu recovery because the median diameter of agglomerate increased. With increasing agitation strength, KAX and kerosene dosages, Cu recovery was further increased. Agglomeration-flotation of a mixture containing chalcopyrite and quartz with 1:1 ratio (w/w, weight by weight) showed that Si recovery in froth was low and did not change with varying conditions (agitation strength, KAX and kerosene dosages); however, Cu recovery was significantly improved with increasing agitation strength, KAX and kerosene dosages, and thus the separation efficiency was improved.
• Recovery of Lead and Zinc from Zinc Plant Leach Residues by Concurrent Dissolution-Cementation Using Zero-Valent Aluminum in Chloride Medium

  Marthias Silwamba, Mayumi Ito, Naoki Hiroyoshi, Carlito Baltazar Tabelin, Ryota Hashizume, Tomoki Fukushima, Ilhwan Park, Sanghee Jeon, Toshifumi Igarashi, Tsutomu Sato, Meki Chirwa, Kawawa Banda, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka

  Metals 10 (4) 531 - 531 2020/04/20 [Refereed][Not invited]
   

  Zinc plant leach residues (ZPLRs) contain significant amounts of metal compounds of lead (Pb), zinc (Zn), iron (Fe), etc., hence, they are considered as a secondary source of metals. On the other hand, ZPLRs are regarded as hazardous materials because they contain heavy metals that pollute the environment. Resources and environmental concerns of ZPLRs were addressed in this study by removing/recovering Pb and Zn using a concurrent dissolution and cementation technique. To cement the dissolved Pb and Zn in leaching pulp, zero-valent aluminum (ZVAl) was added during ZPLRs leaching in the hydrochloric (HCl)–sodium chloride (NaCl) solution. The resulting cemented metals were agglomerated and separated by sieving. Lead removal increased with increasing both NaCl and HCl concentrations. However, when ZVAl was added, significant Pb removal was achieved at a low concentration. Zinc was not cemented out of the pulp using ZVAl and its recovery from ZPLRs was dependent on the HCl concentration only. By applying a concurrent dissolution and cementation technique, both Pb and Zn were removed using a low concentration of NaCl, and most importantly Pb—the most toxic metal in ZPLRs—was captured and separated before the solid-liquid separation, hence, eliminating the need for extensive washing of the generated residues to remove the inherent residual solution.
• Effects of galvanic interactions between lead-activated sphalerite and pyrite on flotation

  K. Aikawa, T. Segawa, S. Jeon, I. Park, C. B. Tabelin, N. Hiroyoshi, M. Ito

  15th International Symposium on East Asian Resources Recycling Technology, EARTH 2019 2020 

  Complex sulfide ores contain sphalerite and galena, and sometimes anglesite is also contained. In the flotation, sphalerite is activated by Pb2+ dissolved from anglesite; that is, Pb2+ makes PbS-like layer on sphalerite, resulting in the increase in the floatability of sphalerite. In this study, the floatability of lead-activated sphalerite in the presence of pyrite was investigated. Flotation results of lead-activated sphalerite showed that it was depressed when pyrite co-existed. To elucidate the mechanism of how pyrite depressed the floatability of lead-activated sphalerite, the effects of electrical connection between pyrite and lead-activated sphalerite were discussed. The results of agitating tests of PbS and pyrite suggested that the PbS dissolved due to the galvanic interaction between PbS and pyrite, thereby reducing the amounts of xanthate adsorbed on PbS.
• Carrier-microencapsulation of arsenopyrite using Al-catecholate complex: nature of oxidation products, effects on anodic and cathodic reactions, and coating stability under simulated weathering conditions

  Ilhwan Park, Carlito Baltazar Tabelin, Kensuke Seno, Sanghee Jeon, Hiroyuki Inano, Mayumi Ito, Naoki Hiroyoshi

  Heliyon 6 (1) e03189 - e03189 2405-8440 2020/01 [Refereed][Not invited]
  
• Ammonium thiosulfate extraction of gold from printed circuit boards (PCBs) of end-of-life mobile phones and its recovery from pregnant leach solution by cementation

  Sanghee Jeon, Carlito Baltazar Tabelin, Ilhwan Park, Yoshito Nagata, Mayumi Ito, Naoki Hiroyoshi

  Hydrometallurgy 191 105214 - 105214 0304-386X 2020/01 [Refereed][Not invited]
  
• Hematite-catalysed scorodite formation as a novel arsenic immobilisation strategy under ambient conditions

  Tabelin Carlito Baltazar, Corpuz Ryan D, Iarashi Toshifumi, Villacorte-Tabelin Mylah, Ito Mayumi, Hiroyoshi Naoki

  CHEMOSPHERE 233 946 - 953 0045-6535 2019/10 [Refereed][Not invited]
  
• A review of recent strategies for acid mine drainage prevention and mine tailings recycling

  Park Ilhwan, Tabelin Carlito Baltazar, Jeon Sanghee, Li Xinlong, Seno Kensuke, Ito Mayumi, Hiroyoshi Naoki

  CHEMOSPHERE 219 588 - 606 0045-6535 2019/03 [Refereed][Not invited]
  
• Suppressive effects of ferric-catecholate complexes on pyrite oxidation

  Li Xinlong, Hiroyoshi Naoki, Tabelin Carlito Baltazar, Naruwa Kosuke, Harada Chie, Ito Mayumi

  CHEMOSPHERE 214 70 - 78 0045-6535 2019/01 [Refereed][Not invited]
  
• Galvanic Microencapsulation (GME) Using Zero-Valent Aluminum and Zero-Valent Iron to Suppress Pyrite Oxidation

  Seng Sophea, Tabelin Carlito Baltazar, Kojima Motoya, Hiroyoshi Naoki, Ito Mayumi

  MATERIALS TRANSACTIONS 60 (2) 277 - 286 1345-9678 2019 [Refereed][Not invited]
  
• Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

  Park Ilhwan, Tabelin Carlito, Inano Hiroyuki, Seno Kensuke, Higuchi Kazuki, Ito Mayumi, Hiroyoshi Naoki

  25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2261-236X 2019 [Refereed][Not invited]
  
• Carrier-microencapsulation using Al-catecholate complex to suppress arsenopyrite oxidation: Evaluation of the coating stability under simulated weathering conditions

  Seno Kensuke, Park Ilhwan, Tabelin Carlito, Magaribuchi Kagehiro, Ito Mayumi, Hiroyoshi Naoki

  25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2261-236X 2019 [Refereed][Not invited]
  
• Prediction of acid mine drainage formation and zinc migration in the tailings dam of a closed mine, and possible countermeasures

  Tabelin Carlito, Sasaki Asuka, Igarashi Toshifumi, Tomiyama Shingo, Villacorte-Tabelin Mylah, Ito Mayumi, Hiroyoshi Naoki

  25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2261-236X 2019 [Refereed][Not invited]
  
• CeO2-dolomite as fire retardant additives on the conventional intumescent coating in steel substrate for improved performance

  Zoleta Joshua, Itao Gevelyn, Joy Resabal Vannie, Lubguban Arnold, Corpuz Ryan, Tabelin Carlito, Ito Mayumi, Hiroyoshi Naoki

  25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2261-236X 2019 [Refereed][Not invited]
  
• Arsenic, selenium, boron, lead, cadmium, copper, and zinc in naturally contaminated rocks: A review of their sources, modes of enrichment, mechanisms of release, and mitigation strategies

  Tabelin Carlito Baltazar, Igarashi Toshifumi, Villacorte-Tabelin Mylah, Park Ilhwan, Opiso Einstine M, Ito Mayumi, Hiroyoshi Naoki

  SCIENCE OF THE TOTAL ENVIRONMENT 645 1522 - 1553 0048-9697 2018/12/15 [Refereed][Not invited]
  
• Improvement of jig efficiency by shape separation, and a novel method to estimate the separation efficiency of metal wires in crushed electronic wastes using bending behavior and "entanglement factor"

  Phengsaart Theerayut, Ito Mayumi, Hamaya Naoki, Tabelin Carlito Baltazar, Hiroyoshi Naoki

  MINERALS ENGINEERING 129 54 - 62 0892-6875 2018/12 [Refereed][Not invited]
  
• Interference of coexisting copper and aluminum on the ammonium thiosulfate leaching of gold from printed circuit boards of waste mobile phones

  Jeon Sanghee, Tabelin Carlito Baltazar, Takahashi Hirotaka, Park Ilhwan, Ito Mayumi, Hiroyoshi Naoki

  WASTE MANAGEMENT 81 148 - 156 0956-053X 2018/11 [Refereed][Not invited]
  
• Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes (vol 205C, pg 414, 2018)

  Park Ilhwan, Tabelin Carlito Baltazar, Seno Kensuke, Jeon Sanghee, Ito Mayumi, Hiroyoshi Naoki

  CHEMOSPHERE 209 1021  0045-6535 2018/10 [Refereed][Not invited]
  
• Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes

  Ilhwan Park, Carlito Baltazar Tabelin, Kensuke Seno, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi

  Chemosphere 205 414 - 425 1879-1298 2018/08/01 [Refereed][Not invited]
   

  Pyrite (FeS2), the most common sulfide mineral in nature, plays an important role in the formation of acid mine drainage (AMD), one of the most serious environmental problems after the closure of mines and mineral processing operations. Likewise, arsenopyrite (FeAsS) is an important sulfide mineral because its dissolution releases toxic arsenic (As) into the environment. To mitigate the serious environmental problems caused by pyrite and arsenopyrite, this study investigated carrier-microencapsulation (CME) using Al-catecholate complexes, a technique that selectively forms protective coatings on the surfaces of sulfide minerals, by electrochemical techniques and batch leaching experiments coupled with surface sensitive characterization techniques. Cyclic voltammetry (CV) of Al-catecholate complexes (mono-, bis-, tris-catecholate) suggest that these three species could be oxidatively decomposed in this order: [Al(cat)3]3–→[Al(cat)2]–→[Al(cat)]+→Al3+, and these reactions were irreversible. Among these three species, [Al(cat)]+ was the most effective in suppressing pyrite and arsenopyrite oxidations because it requires less steps for complete decomposition than the other two complexes. Analyses of CME treated minerals by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicated that they were covered with Al-oxyhydroxide (γ–AlO(OH)), which became more extensive at higher [Al(cat)]+ concentrations. In addition, this coating was stable even at relatively high applied potentials that simulated surface oxidizing conditions. Based on these results, a detailed mechanism of Al-based CME is proposed: (1) adsorption of [Al(cat)]+ on the surface of mineral, (2) oxidative decomposition of [Al(cat)]+ and release of “free” Al3+, and (3) precipitation and formation of Al-oxyhydroxide coating.
• Lead generation and separation mechanisms from lead silicate glass by reduction-melting

  Inano Hiroyuki, Tomita Keiichi, Tada Tatsumi, Hiroyoshi Naoki

  JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 126 (8) 595 - 601 1882-0743 2018/08 [Refereed][Not invited]
  
• Gold recovery from shredder light fraction of E-waste recycling plant by flotation-ammonium thiosulfate leaching

  Sanghee Jeon, Mayumi Ito, Carlito Baltazar Tabelin, Rongrit Pongsumrankul, Naho Kitajima, llhwan Park, Naoki Hiroyoshi

  Waste Management 77 195 - 202 1879-2456 2018/07/01 [Refereed][Not invited]
   

  This paper describes the recovery of gold (Au) from shredder light fraction (SLF) of a recycling plant by flotation and leaching. SLF is typically sent to landfills as waste, but it still contains substantial amounts of Au, and other metals like Cu and Fe. The SLF sample used in this study contains 0.003% of Au, 12% of Cu, and 10% of Fe. Flotation results showed that over 99% of Au and 50% of combustibles were recovered in froth while most of the base metals were recovered in tailing. SEM-EDX of froth products indicates that Au floated via two mechanisms: (1) flotation of Au-plated plastic particles, and (2) agglomeration of fine Au particles together with plastic particles due to kerosene-induced hydrophobic-hydrophobic interactions followed by the flotation of these agglomerated particles. Combustibles in froth/tailing were analyzed by ATR-FTIR, and the results showed that plastics in the froth were mostly sulfonated polystyrene (PS) and acrylonitrile butadiene styrene (ABS) while those in tailing were polyurethane (PU) and polyethylene terephthalate (PET). Contact angle measurements of plastic particles suggest that PS and ABS are more hydrophobic than PU and PET. Most of the base metals in the tailing had either bent or twisted shapes because they were mostly made up of wires. In flotation, these large and heavy particles are unaffected by bubbles and simply sink. Leaching results using ammonium thiosulfate solutions showed that Au extraction increased from 33 to 51% after flotation.
• Suppression of the release of arsenic from arsenopyrite by carrier-microencapsulation using Ti-catechol complex

  Ilhwan Park, Carlito Baltazar Tabelin, Kagehiro Magaribuchi, Kensuke Seno, Mayumi Ito, Naoki Hiroyoshi

  Journal of Hazardous Materials 344 322 - 332 1873-3336 2018/02/15 [Refereed][Not invited]
   

  Arsenopyrite is the most common arsenic-bearing sulfide mineral in nature, and its weathering contributes to acid mine drainage (AMD) formation and the release of toxic arsenic (As). To mitigate this problem, carrier-microencapsulation (CME) using titanium (Ti)-catechol complex (i.e., Ti-based CME) was investigated to passivate arsenopyrite by forming a protective coating. Ti4+ ion dissolved in sulfuric acid and catechol were used to successfully synthesize Ti(IV) tris-catecholate complex, [Ti(Cat)3]2−, which was stable in the pH range of 5–12. Electrochemical studies on the redox properties of this complex indicate that its oxidative decomposition was a one-step, irreversible process. The leaching of As from arsenopyrite was suppressed by CME treatment using the synthesized Ti-catechol complex. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicate that this suppression was primarily due to the formation of an anatase (β-TiO2)-containing coating. Based on these results, a detailed 4-step mechanism to explain the decomposition of [Ti(Cat)3]2− and formation of TiO2 coating in Ti-based CME is proposed: (1) adsorption, (2) partial oxidation-intermediate formation, (3) non electrochemical dissociation, and (4) hydrolysis-precipitation.
• Magnetic separation of rare earth ore from from Khalzan Burgedei peralkaline rare earth deposit, Mongolia

  G. Purevdelger, M. Ito, N. Sato, C.B. Tabelin, N. Hiroyoshi, J. Sereenen

  Proc. of the 4th International Conference and Exhibition (Mineral Processing 2018) 21 - 23 2018 [Not refereed][Not invited]
  
• Simultaneous leaching of arsenite, arsenate, selenite and selenate, and their migration in tunnel-excavated sedimentary rocks: II. Kinetic and reactive transport modeling

  Carlito Baltazar Tabelin, Ryosuke Sasaki, Toshifumi Igarashi, Ilhwan Park, Shuichi Tamoto, Takahiko Arima, Mayumi Ito, Naoki Hiroyoshi

  CHEMOSPHERE 188 444 - 454 0045-6535 2017/12 [Refereed][Not invited]
   

  Predicting the fates of arsenic (As) and selenium (Se) in natural geologic media like rocks and soils necessitates the understanding of how their various oxyanionic species behave and migrate under dynamic conditions. In this study, geochemical factors and processes crucial in the leaching and transport of arsenite (As-III), arsenate (As-V), selenite (Se-IV) and selenate (Se-VI) in tunnel-excavated rocks of marine origin were investigated using microscopic/extraction techniques, column experiments, dissolution-precipitation kinetics and one-dimensional reactive transport modeling. The results showed that evaporite salts were important because aside from containing As and Se, they played crucial roles in the evolution of pH and concentrations of coexisting ions, both of which had strong effects on adsorption-desorption reactions of As and Se species with iron oxyhydroxide minerals/phases. The observed leaching trends of As-V, As-III, Se-IV and Se-VI were satisfactorily simulated by one-dimensional reactive transport models, which predict that preferential adsorptions of As-V and Se-IV were magnified by geochemical changes in the columns due to water flow. Moreover, our results showed that migrations of As-III, Se-IV and Se-VI could be predicted adequately by 1D solute transport with simple activity-K '(d) approach, but surface complexation was more reliable to simulate adsorption-desorption behavior of As-V. (C) 2017 Elsevier Ltd. All rights reserved.
• Simultaneous leaching of arsenite, arsenate, selenite and selenate, and their migration in tunnel-excavated sedimentary rocks: I. Column experiments under intermittent and unsaturated flow

  Carlito Baltazar Tabelin, Ryosuke Sasaki, Toshifumi Igarashi, Ilhwan Park, Shuichi Tamoto, Takahiko Arima, Mayumi Ito, Naoki Hiroyoshi

  CHEMOSPHERE 186 558 - 569 0045-6535 2017/11 [Refereed][Not invited]
   

  Rocks excavated in tunnel construction projects for roads and railways throughout Japan often leached out hazardous trace elements like arsenic (As) and selenium (Se) upon their exposure to the environment. In nature, the various oxyanionic species of As and Se not only coexist but also exhibit contrasting adsorption-desorption behaviors, so speciation is a crucial factor in their migration through natural geologic media. In this study, the leaching and transport of arsenite (As-III), arsenate (As-V), selenite (Sew) and selenate (Se-VI) in four tunnel-excavated rocks from the Cretaceous-Paleocene Yezo forearc basin were investigated using laboratory column experiments supplemented by batch leaching experiments. The single- and consecutive-batch leaching results revealed that As-III, As-V, Se-IV and Se-VI were released simultaneously, which could be attributed to the rapid dissolution of trace evaporite salts found in the rocks. Arsenic in the leachates was also predominated by As-V while Se-IV and Se-VI concentrations were nearly equal, which are both consistent with predictions of equilibrium Eh-pH diagrams. Under intermittent and unsaturated flow, however, periods when As-III and Se-VI predominated in the effluents were observed. Spatial distributions of As and Se species with depth at the end of the column experiments suggest that migrations of As-III, As-V and Se-IV were delayed, the extent of which depended on the rock. These results indicate that migration and speciation of As and Se in the rocks are controlled by preferential adsorption-desorption reactions, the effects of which were most probably magnified by changes in the pH and concentrations of coexisting ions due to intermittent and unsaturated flow. (C) 2017 Elsevier Ltd. All rights reserved.
• Pyrite oxidation in the presence of hematite and alumina: II. Effects on the cathodic and anodic half-cell reactions

  Carlito Baltazar Tabelin, Suchol Veerawattananun, Mayumi Ito, Naoki Hiroyoshi, Toshifumi Igarashi

  SCIENCE OF THE TOTAL ENVIRONMENT 581 126 - 135 0048-9697 2017/03 [Refereed][Not invited]
   

  The oxidative dissolution of pyrite is an important process in the redox recycling of iron (Fe) and is well-known for its role in the formation of acid mine drainage (AMD), which is considered as the most serious and widespread problem after the closure of mines and mineral processing operations. Because thiS process requires the movement of electrons, common metal oxides in nature that have either semiconducting (e.g., hematite) or insulating (e.g., alumina) properties may have strong effects on it. In this study, changes in the electrochemical behavior of pyrite in the presence of hematite and alumina were investigated. Results showed that the formation of surface bound species directly influenced the anodic and cathodic half-cell reactions as well as the transfer of electrons between these sites. Pyrite pretreated in the air became anodically more reactive than that pretreated in oxygenated water, but the type of oxidizing media had little effect on the cathodic half-cell reaction. The presence of hematite and alumina during pretreatment also had strong effects on the electrochemical properties of pyrite. Chronoamperometry measurements suggest that hematite and alumina enhanced the anodic half-cell reaction but suppressed the cathodic half-cell reaction of pyrite oxidation. Increased anodic half-cell reaction in the presence of hematite could be attributed to electron "bridging" and catalytic effects of this mineral. In contrast, the effects of alumina on the anodic half-cell reaction were indirect and could be explained by the formation of Fe3+-oxyhydroxide surface species during pretreatment. Suppression of the cathodic half-cell reaction by both minerals was attributed to their "protective" effect on cathodic sites. Our results also point to the cathodic half cell reaction as the rate determining-step of the overall oxidative dissolution process.
• Pyrite oxidation in the presence of hematite and alumina: I. Batch leaching experiments and kinetic modeling calculations

  Carlito Baltazar Tabelin, Suchol Veerawattananun, Mayumi Ito, Naoki Hiroyoshi, Toshifumi Igarashi

  SCIENCE OF THE TOTAL ENVIRONMENT 580 687 - 698 0048-9697 2017/02 [Refereed][Not invited]
   

  Pyrite is one of the most common and geochemically important sulfide minerals in nature because of its role in the redox recycling of iron (Fe). It is also the primary cause of acid mine drainage (AMD) that is considered as a serious and widespread problem facing the mining and mineral processing industries. In the environment, pyrite oxidation occurs in the presence of ubiquitous metal oxides, but the roles that they play in this process remain largely unknown. This study evaluates the effects of hematite (alpha-Fe2O3) and alumina (alpha-Al2O3) on pyrite oxidation by batch-reactor type experiments, surface-sensitive characterization of the oxidation layer and thermodynamic/kinetic modeling calculations. In the presence of hematite, dissolved sulfur (S) concentration dramatically decreased independent of the pH, and the formation of intermediate sulfoxy anionic species on the surface of pyrite was retarded. These results indicate that hematite minimized the overall extent of pyrite oxidation, but the kinetic model could not explain how this suppression occurred. In contrast, pyrite oxidation was enhanced in the alumina suspension as suggested by the higher dissolved S concentration and stronger infrared (IR) absorption bands of surface-bound oxidation products. Based On the kinetic model, alumina enhanced the oxidative dissolution of pyrite because of its strong acid buffering capacity, which increased the suspension pH. The higher pH values increased the oxidation of Fe2+ to Fe3+ by dissolved O-2 (DO) that enhanced the overall oxidative dissolution kinetics of pyrite. (C) 2016 Elsevier B.V. All rights reserved.
• Effects of pyrite and pyrrhotite on the flotation of lead-activated sphalerite

  Mayumi ITO, Tatusya SEGAWA, Yoji Minoura, Tsuyoshi Horiguchi, Carlito Baltazar Tabelin, Naoki HIROYOSHI

  the 28th International Mineral Processing Congress 2016 [Not refereed][Not invited]
  
• A Study on the Utilization of Magnetite for the Recovery of Platinum Group Metals from Chloride Solution

  Peet Homchuen, Richard Diaz Alorro, Naoki Hiroyoshi, Ryo Sato, Hajime Kijitani, Mayumi Ito

  MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 37 (4) 246 - 254 0882-7508 2016 [Refereed][Not invited]
   

  The recovery of platinum group metals (PGMs) from chloride solution using magnetite was investigated. The adsorption of platinum, palladium, and rhodium in chloride medium onto synthetic magnetite powders were studied at different pH conditions, contact time, sodium chloride concentrations, and initial Pt, Rh, and Pd concentrations. Platinum and palladium uptake by magnetite was at a maximum at pH 6-7, and pH 3-4 for rhodium after 24 h with 0.1 mol/dm(3) sodium chloride at an initial PGM concentration of 0.05 mol/m(3). A sorption mechanism for PGMs was discussed based on the results.
• Electrochemical Investigation of Gold Uptake From Chloride Solution by Magnetite

  Richard Diaz Alorro, Naoki Hiroyoshi, Hajime Kijitani, Mayumi Ito, Masami Tsunekawa

  MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 36 (5) 332 - 339 0882-7508 2015/09 [Refereed][Not invited]
   

  An electrochemical method (potential sweep method) was utilized to investigate the nature of the absorbed gold on magnetite and to determine the gold sorption mechanism. A magnetite electrode was prepared in the laboratory, made in contact with a gold chloride solution at different conditions, and was subjected to cyclic voltammetry. The cyclic voltammogram of the magnetite electrode pretreated in a gold chloride solution recorded an anodic current peak at around 1.0V (vs. Ag/AgCl), which corresponds to the current generated for the anodic dissolution of metallic gold in a chloride medium. The results of the electrochemical experiments suggest that gold chloride complexes are reduced to metallic gold on the surface of magnetite. A four-stage gold uptake mechanism was proposed: (i) the transport of [GRAPHICS] from the bulk solution to the magnetite surface, (ii) adsorption of [GRAPHICS] ions on magnetite surface by electrostatic attraction, (iii) electrochemical reduction of [GRAPHICS] to metallic Au, and (iv) the transport of soluble species to the solution phase. The electrochemical investigation also revealed that Fe3+ ions released from magnetite into the solution, suppressed the gold uptake at the acidic pH region.
• Short and long term release mechanisms of arsenic, selenium and boron from a tunnel-excavated sedimentary rock under in situ conditions

  Shuichi Tamoto, Carlito Baltazar Tabelin, Toshifumi Igarashi, Mayumi Ito, Naoki Hiroyoshi

  JOURNAL OF CONTAMINANT HYDROLOGY 175 60 - 71 0169-7722 2015/04 [Refereed][Not invited]
   

  Sedimentary rocks of marine origin excavated from tunnel construction projects usually contain background levels of hazardous trace elements, but when exposed to the environment, they generate leachates with concentrations of arsenic (As), selenium (Se) and boron (B) exceeding the WHO guideline for drinking water. In this study, the leaching of As, Se and B was evaluated under in situ conditions at various flow patterns, particle size distributions and column thicknesses. The results showed that these trace elements were leached out of the rock via short and long term mechanisms. In the short term, all three elements were rapidly and simultaneously released due to the dissolution of soluble evaporite salts formed from entrapped sea water of the Cretaceous. After their rapid release, however, these trace elements behaved differently as a result of their contrasting adsorption affinities onto minerals like clays and Feoxyhydroxides, which were further influenced by the pH, presence of coexisting ions and speciation of the trace elements. Selenium was quickly and easily transported out of the columns because it was mostly present as the very mobile selenate ion (Se[VI]). In comparison, the migration of As and B was hindered by adsorption reactions onto mineral phases of the rock Boron was initially the least mobile among the three because of its preferential adsorption onto clay minerals that was further enhanced by the slightly alkaline pH and high concentrations of Ca2+ and Na+. However, it was gradually re-mobilized in the latter part of the experiments because it was only weakly adsorbed via outer sphere complexation reactions. In the long term, the rock continued to release substantial amounts of As, Se and B via pyrite oxidation and adsorption/desorption reactions, which were regulated by the temperature and rainfall intensity/frequency on site. (C) 2015 Elsevier B.V. All rights reserved.
• Stability of As(V)-sorbed schwertmannite under porphyry copper mine conditions

  Sengpasith HoungAloune, Naoki Hiroyoshi, Mayumi Ito

  MINERALS ENGINEERING 74 51 - 59 0892-6875 2015/04 [Refereed][Not invited]
   

  Arsenic (As), a very poisonous inorganic pollutant is a major toxicant in tailings of porphyry copper deposits. Retention of As by Schwertmannite (a ferric-oxyhydroxysulfate mineral) has attracted much attention in recent years due to its strong binding affinity to toxic As species. The stability of As(V)-sorbed schwertmannite under copper mine waste conditions is not fully understood. The present study investigates the effect of Cu2+, Fe2+, pH, and ageing time on the stability of As(V)-sorbed schwertmannite (Sch-As). The results indicate that Cu2+ has no significant effect on the stability of Sch-As and that the As(V) incorporated in schwertmannite can retard or significantly inhibit Fe2+-catalyzed transformation of schwertmannite to goethite under acidic conditions (pH 3-4). The Sch-As aged at different pHs from 3 to 11 at 25 degrees C exhibits no mineralogical phase changes even after ageing for 120-days; however the concentration of As released from the solid phase appears to be strongly pH-dependent even after ageing for only 24 h. The release of As was negligible at pHs from 2 to 7, and there was considerableTelease of As at extremely acidic and alkaline conditions. This indicates that the release of As from Sch-As was controlled by environmental factors such as pH, Cu2+, and Fe2+ rather than time. (C)) 2015 Elsevier Ltd. All rights reserved.
• Effect of Fe(II) and Cu(II) on transformation of schwertmannite to goethite

  S. Houngaloune, N. Hiroyoshi, M. Ito

  International Journal of Chemical Engineering and Applications 6 (1) 32 - 37 2015 [Refereed][Not invited]
  
• Influences of electrolyte concentration on subcritical crack growth in sandstone in water

  Yoshitaka Nara, Ryo Nakabayashi, Megumi Maruyama, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko

  ENGINEERING GEOLOGY 179 41 - 49 0013-7952 2014/09 [Refereed][Not invited]
   

  Information on subcritical crack growth in rock is essential to ensure the long-term stability of structures in a rock mass. Subcritical crack growth in rock is known to be affected by its surrounding environment. In most cases, rock found underground is saturated by water. The underground water can be fresh water or salt water with variable electrolyte concentrations. However, the influence of electrolyte concentration on subcritical crack growth in rock has not been fully elucidated. In this study, subcritical crack growth in Berea sandstone and Shirahama sandstone was measured when saturated with distilled water and with sodium chloride solutions of differing concentrations. Crack velocity in Berea sandstone changed very little with different electrolyte concentrations. By contrast, in the Shirahama sandstone, crack velocity became lower with increased electrolyte concentrations up to 1.0 mol/l. With increasing electrolyte concentration, the width of the electric double layer on the surface of mineral grains decreased, which caused a decrease in the repulsive force acting on the crack surface, leading to a decrease in crack velocity up to concentrations of 1.0 mol/l. However, when the electrolyte concentration was higher than 1.0 mol/l, crack velocity increased due to the nucleation of microscopic defects on the boundary between clays and stiff mineral grains. Thus, electrolyte concentration affects subcritical crack growth by decreasing the width of the electric double layer and the condensation of clay minerals. (C) 2014 Elsevier B.V. All rights reserved.
• Study on schwertmannite production from copper heap leach solutions and its efficiency in arsenic removal from acidic sulfate solutions

  Sengpasith HoungAloune, Takahiro Kawaai, Naoki Hiroyoshi, Mayumi Ito

  HYDROMETALLURGY 147 30 - 40 0304-386X 2014/08 [Refereed][Not invited]
   

  Schwertmannite, a ferric oxyhydroxy sulfate mineral, has gained attention in recent years due to its high sorption capacity for toxic arsenic species. In porphyry copper mines, production of schwertmannite from heap leaching solutions may be possible because the solutions contain high concentrations of ferric and sulfate ions, which are components of schwertmannite. The present study investigates the effect of Cu2+ and Fe2+, coexisting ions in heap leaching solutions, on the synthesis of schwertmannite; as well as the efficiency of As(V) removal from acidic solutions by the synthesized products. Synthesis was carried out by neutralization of 50 mM Fe-2(SO4)(3) solutions at 65 degrees C (final pH: 3-4), and the synthesized products were characterized by XRD. The results indicated that Cu2+ does not affect the synthesis of schwertmannite, but that Fe2+ has a significant influence on the synthesis; transformation of intermediate schwertmannite to goethite occurred in the presence of Fe2+. Schwertmannite was produced in the presence of both Cu2+ and Fe2+, suggesting that Cu2+ inhibits the transformation of schwertmannite to goethite in the presence of Fe2+. To confirm this, the transformation of schwertmannite to goethite was investigated in solutions containing Fe2+ and Cu2+ at pH 3-4 and 65 degrees C. It was shown that a complete transformation to goethite occurred in 1 h in the presence of 100 mM Fe2+. However, 100 mM Cu2+ inhibited the transformation of schwertmannite to goethite in the presence of Fe2+. Batch sorption experiments were conducted to evaluate the As(V) sorption capacity of the synthesized products. The results showed that As(V) in acidic solutions (pH 3-4) can be removed effectively by synthesized schwertmannite with the maximum As(V) sorption capacity of 94-133 mg g(-1). A lower As(V) sorption capacity was observed in products containing goethite synthesized in the presence of Fe2+; here, the maximum As(V) sorption capacity was 58 mg g(-1). (C) 2014 Elsevier B.V. All rights reserved.
• Preparation of Fe/Al Composite for Metal Recovery

  M Ito, K Sukegawa, N Hiroyoshi

  12th Int. Symp. East Asian Recycling Technology 293 - 296 2013 [Not refereed][Not invited]
  
• Flotation of anode slime in copper electro-refining

  M Ito, T Ikemoto, N Hiroyoshi

  12th Int. Symp. East Asian Recycling Technology 954 - 957 2013 [Not refereed][Not invited]
  
• Separation of polyethylene and cross-linked polyethylene using a reverse hybrid jig

  M Ito, A Saito, N Murase, N Hamaya, M Takeuchi, N Hiroyoshi

  ASEAN++2013 2013 [Not refereed][Not invited]
  
• Application of reductive melting process of CRT glass for recovering valuable metals from PCB waste

  N Hiroyoshi, H Prin, Y Takaya, M Ito

  ASEAN++2013 2013 [Not refereed][Not invited]
  
• Technological development in jig separation and approaches to adovance in separation

  M Tsunekawa, M Ito, N Hiroyoshi

  Journal of MMIJ 129 284 - 289 2013 [Refereed][Not invited]
  
• A method for determining optimum water pulsation parameter in jig separatiin using pressure and level sensors and its application to separation of fine particles

  M Tusnekawa, J Akimoto, W Ogiko, S Ochi, N Hiroyoshi, M Ito

  Journal of MMIJ 129 284 - 289 2013 [Refereed][Not invited]
  
• Advanced jig separation technology for resource recycling and mineral processing

  Mayumi Ito, Naoki Hiroyoshi, Masami Tsunekawa

  Proc. of The 5th Regional Conference on Geological Engineering 13 - 18 2013 [Refereed][Not invited]
  
• SELECTIVE COMMINUTION AND MAGNETIC SEPARATION OF RARE-EARTH ORE FROM DONG PAO, VIETNAM

  M Ito, M Takamatsu, K Asakura, C Nisikawa, N Hiroyoshi, M Tsunekawa

  23rd World mining congress 775  2013 [Refereed][Not invited]
  
• STABILIZATION OF ARSENIC IN THE MINING AND METALLURGICAL INDUSTRIES? A REVIEW

  S Houngaloune, N Hiroyoshi, M Ito, F Masato

  23rd World mining congress 777  2013 [Refereed][Not invited]
  
• Coagulation flotation of anode slime in copper electro-refining

  M Ito, T Ikemoto, N Hiroyoshi

  Proc. of 3rd Joint seminar on Geo-environmental engineering & recycling 54  2013 [Not refereed][Not invited]
  
• Mineral processing of rare-earth ore from Kipawa, Canada

  M Ito, M Takamatsu, K Ono, N Hiroyoshi

  Proc. of 3rd Joint seminar on Geo-environmental engineering & recycling 70  2013 [Not refereed][Not invited]
  
• Recovery of the Platinum Group Metals from the Chloride Solution by Synthesized Magnetite and Slag Magnetite

  N Hiroyoshi, R Sato, P Homchuen, M Ito

  Proc. of 3rd Joint seminar on Geo-environmental engineering & recycling 19  2013 [Not refereed][Not invited]
  
• Preparation and Evaluation of Fe/Al composite for metal recovery

  M Ito, K Sukegawa, N Hiroyoshi

  Proc. of 3rd Joint seminar on Geo-environmental engineering & recycling 48  2013 [Not refereed][Not invited]
  
• Newly developed discharge device for jig separation of plastics to recover higher grade bottom layer product

  Masami Tsunekawa, Riki Kobayashi, Kunihiro Hori, Hideaki Okada, Naka Abe, Naoki Hiroyoshi, Mayumi Ito

  INTERNATIONAL JOURNAL OF MINERAL PROCESSING 114 27 - 29 0301-7516 2012/11 [Refereed][Not invited]
   

  The jig is efficient in separating relatively low density particles such as plastics; however conventional discharge devices attached to jigs cause mechanical disruption of the stratified layers at the outlet from the separation chamber, and decrease the grade of the recovered bottom layer product. A new device was developed for efficiently separating high grade bottom layer product, better than 99%, where particles of the bottom and top layers are recovered as overflow products by agitation with water pulsation. (C) 2012 Elsevier B.V. All rights reserved.
• Influence of relative humidity on fracture toughness of rock: Implications for subcritical crack growth

  Yoshitaka Nara, Kazuya Morimoto, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko, Philip M. Benson

  INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 49 (18) 2471 - 2481 0020-7683 2012/09 [Refereed][Not invited]
   

  Information relating to the fracture toughness of geomaterials is critical to our understanding of tensile fracturing, and in particular in geological and rock engineering projects that are subjected to elevated moisture levels. In this study, we conducted a comprehensive set of fracture toughness tests on a suite of key rock types in air under different relative humidities and at constant temperature in order to investigate the influence of relative humidity on fracture toughness. Three sandstones and two igneous rocks were chosen for this purpose. We show that the value of fracture toughness decreases with increasing relative humidity. In addition, we find that the decrease in fracture toughness was more significant when the expansive clay such as smectite was included in rock. Since smectite is prone to expanding in the presence of water, the strength and thus crack growth resistance decrease when relative humidity is high. Therefore, we interpret the decreasing fracture toughness upon the degradation of expansive clays with increasing water content. It was also shown that the decrease of the fracture toughness with increasing humidity is less significant than the concomitant decrease in the measured value of the subcritical stress intensity factor. This was likely as a result of stress corrosion having little influence on the fracture toughness. We conclude that crack growth in rock is affected by humidity, and that clay content is an important contributing factor to changes in fracture toughness and subcritical stress intensity factor. (c) 2012 Elsevier Ltd. All rights reserved.
• Recovery and immobilization of lead in cathode ray tube funnel glass by a combination of reductive and oxidative melting processes

  Takashi Okada, Hiroyuki Inano, Naoki Hiroyoshi

  JOURNAL OF THE SOCIETY FOR INFORMATION DISPLAY 20 (9) 508 - 516 1071-0922 2012/09 [Refereed][Not invited]
   

  Reductive melting treatment has been reported to be an effective method to recover lead from funnel glass in used cathode ray tubes, but a small amount of lead, a potential contaminant, remains in the treated glass. This paper applied a combination process of reductive and oxidative melting to the funnel glass to recover and immobilize lead in the glass. The funnel glass was melted in a lab-scale reactor changing the atmosphere, and the effects of the temperature and the Na2CO3 dosage on the efficiencies of the lead recovery and immobilization were investigated. In the reductive melting, the lead recovery was promoted by increasing the Na2CO3 dosage, however the lead extraction from the glass into water and hydrochloric acid was increased. Although the content of lead in the glass after the reductive melting was low, the lead extraction into water and the acid was larger than 0.01 mg-Pb/L-water and 150 mg-Pb/kg-glass, respectively (Japanese environmental criteria). The lead extraction was decreased by the oxidative melting with SiO2, Al2O3, MgO, and NaNO3. In the proposed method, metallic lead was recovered from the funnel glass with high lead recovery, and the lead remaining in the glass was immobilized to meet the Japanese environmental criteria.
• Effect of particle shape on hydrocyclone classification

  Kouki Kashiwaya, Takahiko Noumachi, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  POWDER TECHNOLOGY 226 147 - 156 0032-5910 2012/08 [Refereed][Not invited]
   

  Influence of particle shape on hydrocyclone classification was investigated. Classification tests using hydrocyclone and cyclosizer showed that coarse fractions of plate-like particles such as PTFE and glass flake used here were not necessarily recovered as underflow product, especially at relatively high inlet velocity. Settling velocity of the glass flake particles in centrifugal field was estimated using a centrifugal particle size analyzer, and it was revealed that differences in settling velocity between coarse and fine glass flake particles became smaller with increases in angular velocity. Moreover, settling test of glass plate in water or glycerin solution was conducted to know relationship between particle Reynolds number (Re) and settling velocity of the plate. At smaller Re condition, the glass plate settled straight and stably, and larger plate settled faster than smaller plate. However, oscillating motion of the plate occurred in the region of high Re, and settling velocities of the large plate became smaller than that of the small plate in such conditions. Drag coefficient (C) calculated based on the settling velocity of the glass plate is similar to that of glass spheres below Re of about 50, above which it became larger than that of glass sphere. Approximation formula of correlaton between Re and C suggests that the influence of the Re on C can be neglected in the region of high Re, and C increases with increases in the ratio of the particle diameter to thickness (D/T). The decrease of the difference in settling velocity recognized in the centrifugal settling test and the effect of the particle shape (D/T) on C at high Re region are considered to be able to affect the hydrocyclone classification. The misplacement of coarse plate-like particles in the hydrocyclone and cyclosizer tests could be ascribed to the particle shape effects. (C) 2012 Elsevier B.V. All rights reserved.
• Effect of water addition on centrifugal treatment to remove lead compounds from polyvinylchloride in electric wires and cables

  Masami Tsunekawa, Mayumi Ito, Yoshiaki Nakamura, Yuta Sasaki, Tomoo Sakai, Naoki Hiroyoshi

  SEPARATION AND PURIFICATION TECHNOLOGY 89 94 - 97 1383-5866 2012/03 [Refereed][Not invited]
   

  Recycling treatment of cable insulation resin generated from electric wires and cables was investigated. Here, PVC is the most common insulation resin and conventional insulation PVC contains a lead component, tribase, as a thermal stabilizer. To recycle this PVC as insulation resin, lead removal is necessary to be able to conform to RoHS. This paper proposes a solvent dissolution and centrifugation method and the effects of flocculants and water addition in the processes involved are described. (C) 2012 Elsevier B.V. All rights reserved.
• Mineral processing of deep-sea ores ”, The 4th Regional Conference on Geological Engineering

  M.Ito, S. Futakuchi, K. Asakura, N. Hiroyoshi

  The 4th Regional Conference on Geological Engineering“Research-based Education in Geological and Geo-resources Engineering for Sustainable Development in ASEAN Region 2012 [Refereed][Not invited]
  
• A Study on the Utilization of Magnetite for The Recovery of Platinum Group Metals from Chloride Solution

  P. Homchuen, M. Ito, N. Hiroyoshi

  The 4th Regional Conference on Geological Engineering“Research-based Education in Geological and Geo-resources Engineering for Sustainable Development in ASEAN Region 2012 [Refereed][Not invited]
  
• Plastic-plastic separation using advanced jig separation technology

  Mayumi Ito, Megumi Takeuchi, Naoki Hiroyoshi

  Proc of the 6th International Workshop and Conference on Earth Resources Technology 2012 [Refereed][Not invited]
  
• Hybrid jig separation of plastic particles-A case of a separation of Nylon and PVC-

  Mayumi Ito, Megumi Takeuchi, Naoki Hiroyoshi

  Proc. of Int. Symposium on earth science technology 2012 315 - 317 2012 [Refereed][Not invited]
  
• SUPPRESSION OF PYRITE OXIDATION BY CARRIER MICROENCAPSULATION USING SILICON AND CATECHOL

  Rani Kumari Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 33 (2) 89 - 98 0882-7508 2012 [Refereed][Not invited]
   

  Acid mine drainage (AMD) is formed from the natural oxidation of sulfide minerals such as pyrite and FeS2. Prevention of AMD is very important and several techniques are currently being investigated for the treatment and abatement of AMD. This paper proposes carrier-microencapsulation (CME) using Si-catechol complex -Si(cat)(3)(2-) -for preventing pyrite oxidation. In CME, the water soluble organic carrier, catechol, and metal ion, Si, make a complex, e.g., tris-catecholato complex of Si4+, which oxidatively decomposes on pyrite surface and forms a stable oxide or hydroxide, e.g., Si(OH)(4) or SiO2 layer on the pyrite surface as a protective coating against pyrite oxidation. To demonstrate the effect of CME using Si(cat)(3)(2-) on pyrite oxidation, shaking flask leaching experiments of pyrite without and with CME treatment were performed. Significant halt in pH drop was observed after the CME treatment of pyrite. The CME coating was found very effective even at low Si(cat)(3)(2-) concentration of 1 and 5 mol m(-3). The amount of Fe and S leached were lower from the pyrite with CME treatment than without CME treatment, indicating that CME using Si and catechol is effective in suppressing pyrite oxidation. The effect of pH and presence of microorganism were also evaluated. The CME coating was found very effective even in acidic pH range. The CME treatment suppressed pyrite oxidation even in the presence of iron oxidizing microorganism. Presence of Si and O on the residue pyrite surface in energy-dispersive X-ray spectroscopy analysis supported the sustainability of CME coating at acidic pH.
• Evaluation of entanglement properties of crushed automobile shredded residue and detachment of entrapped particles

  Yutaka Kuwayama, Mayumi Ito, Maiko Akatsuka, Naoki Hiroyoshi, Masami Tsunekawa

  JOURNAL OF MATERIAL CYCLES AND WASTE MANAGEMENT 13 (2) 156 - 163 1438-4957 2011/08 [Refereed][Not invited]
   

  Automobile shredded residue is a potential solid fuel when its metal and chlorine-containing parts have been removed. The authors have investigated physical separation of automobile shredded residue to obtain the components that may be used in solid fuel and found that agglomerates of entangling fiber-like components are formed during crushing, making removal of metals and chlorine-containing parts difficult. In this paper, a reattachment ratio, entrapment ratio, and disentanglement ratio are proposed to evaluate the entanglement properties of crushed automobile shredded residue. It is found that products smaller than 16 mm were not reattached easily in the sieving process, and an index based on entanglement properties proposed here is useful to predict suitable crushing conditions. Wet detachment of entrapped particles from agglomerates of entangling materials was also applied to separate particulate matter from crushed ASR.
• Removal of lead compounds from polyvinylchloride in electric wires and cables using cation-exchange resin

  Masami Tsunekawa, Mayumi Ito, Yuta Sasaki, Tomoo Sakai, Naoki Hiroyoshi

  JOURNAL OF HAZARDOUS MATERIALS 191 (1-3) 388 - 392 0304-3894 2011/07 [Refereed][Not invited]
   

  Recycling treatment of cable insulation resin generated from electric wires and cables was investigated. Conventional insulation PVC contains a lead component, tribase, as a thermal stabilizer and lead removal is necessary to recycle this PVC as insulation resin. This paper describes a solid surface adsorption method using ion exchange resin to remove the fine lead containing particles from PVC dissolved solution. Low lead concentration in the recovered PVC, complying with the requirements of RoHS, was achieved. (C) 2011 Elsevier B.V. All rights reserved.
• Suppression of floatability of pyrite in coal processing by carrier microencapsulation

  Rani Kumari Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  FUEL PROCESSING TECHNOLOGY 92 (5) 1032 - 1036 0378-3820 2011/05 [Refereed][Not invited]
   

  Carrier microencapsulation, CME. is a technique to form a thin layer of metal oxide or hydroxide on pyrite surface using a water soluble organic carrier combined with metal ions. The present study investigated the effect of CME using a tris-catecholato complex of Si(4+), Si(cat)(3)(2-) on pyrite-coal separation by dynamic bubble pick-up experiments and Hallimond tube flotation experiments using coal, pyrite. and a coal-pyrite mixture. The mineral samples were treated in 0-5 mol m(-3) Si(cat)(3)(2-) solutions at pH 4-9 at treatment times of 1-24 h. Dynamic bubble pick-up experiments showed that CME treatment converted the pyrite surface from hydrophobic to hydrophilic but did not affect coal's hydrophobic surface. The results of the Hallimond tube flotation experiments of a coal-pyrite mixture at pH 7-9 in the presence of kerosene as a collector showed that pyrite floatability was selectively suppressed after 1 h CME treatment with 0.5 mol (3) Si(cat)(3)(2-) while both coal and pyrite were floated without the treatment. Thus indicates that CME treatment is effective in suppressing pyrite floatability in coal-pyrite flotation. (C) 2011 Elsevier B.V. All rights reserved.
• Effects of humidity and temperature on subcritical crack growth in sandstone

  Yoshitaka Nara, Kazuya Morimoto, Tetsuro Yoneda, Naoki Hiroyoshi, Katsuhiko Kaneko

  INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 48 (7-8) 1130 - 1140 0020-7683 2011/04 [Refereed][Not invited]
   

  In order to ensure long-term stability of structures in a rock mass, the study of time-dependent fracturing is essential. The influences of the surrounding environmental conditions and rock fabric on subcritical crack growth in sedimentary rocks in air are yet to be clarified, while the nature of subcritical crack growth in igneous rocks has been studied well. In this study, the influences of temperature and relative humidity on subcritical crack growth in Berea sandstone, Shirahama sandstone and Kushiro sandstone were investigated in air. The load relaxation method of Double Torsion (DT) testing method was used to measure both crack velocity and stress intensity factor under a controlled temperature and relative humidity. Results show that the change of the crack velocity at a given stress intensity factor was unclear when the temperature increased under a constant relative humidity in air. On the other hand, we show that the crack velocity increased by several orders of magnitude when the relative humidity increased threefold or fourfold under a constant temperature at a given stress intensity factor. This increase is much larger than that expected from the conventional concept based on the theory of stress corrosion. It is therefore necessary to consider the additional mechanisms for subcritical crack growth in sandstone. The increase of the crack velocity was larger for sandstone which contained larger amount of clays. We conclude that subcritical crack growth in sandstone in air is affected remarkably by the relative humidity and the amount of clays in rock. (C) 2010 Elsevier Ltd. All rights reserved.
• Gold Recovery from Clolide Solution Using Copper Convertor Slag

  N. Hiroyoshi, H. Kijitani, R.D. Alorro, M. Ito, M. Tsunekawa

  Proceedings of 11th Int. Symp. East Asian Recycling Technology 442 - 445 2011 [Refereed][Not invited]
  
• Mineral Processing of Rare-Earth Ore from Dongpao

  M. Ito, C. Nishikawa, N. Hiroyoshi, M. Tsunekawa

  Proc of the 5th International Workshop and Conference on Earth Resources Technology 40 - 42 2011 [Refereed][Not invited]
  
• Recovery and immobilization of lead in cathode ray tube funnel glass by a combination of reductive and oxidative melting processes

  Takashi Okada, Hiroyuki Inano, Naoki Hiroyoshi

  IDW'11: PROCEEDINGS OF THE 18TH INTERNATIONAL DISPLAY WORKSHOPS, VOLS 1-3 617 - 620 1883-2490 2011 [Refereed][Not invited]
   

  Metallic lead was recovered from the funnel glass of cathode ray tubes with high lead removal rates by melting in a reductive atmosphere. The lead remaining in the glass was immobilized by melting in an oxidative atmosphere and was able to meet the Japanese criteria for recycle of the glass.
• Estimating the size distribution of anode and cathode activating agents in the crushed products of nickel metal hydride batteries from hybrid vehicles and its classification

  Mayumi Ito, Kouki Kashiwaya, Naohiro Sumiya, Hisatoshi Furuya, Naoki Hiroyoshi, Masami Tsunekawa

  INTERNATIONAL JOURNAL OF MINERAL PROCESSING 97 (1-4) 92 - 95 0301-7516 2010/11 [Refereed][Not invited]
   

  Nickel metal hydride batteries of hybrid vehicles contain Co and rare earth elements in the anode and cathode activating agents as well as in the main electrode component, Ni. The cathode electrodes comprise a porous Ni plate (cathode substrate) with nickel hydroxide as the cathode activating agent and the anode electrodes consist of a hydrogen storage alloy powder as the anode activating agent on a metal mesh substrate. A direct smelting method has been used to recover Ni from waste batteries, but the Co and rare earth elements are difficult to extract by this conventional method. To recycle Co and rare earth elements, physical pretreatment is necessary to separate the anode and cathode compounds before smelting. This study investigated the separation of anode and cathode activating agents in the <0.075 mm fraction of crushed nickel metal hydride batteries using a cyclone and the anode activating agent was concentrated in the underflow product. After crushing the waste batteries a mixture of cathode and anode activating agents is recovered as fines, and a simple and fast size distribution measurement method for each activating agent is desirable to evaluate the physical separation results and improve the separation efficiency. The results show that further size classification of the <0.075 mm fraction is effective to concentrate the anode activating agent for cylindrical type batteries. (C) 2010 Elsevier B.V. All rights reserved.
• Reverse jig separation of shredded floating plastics separation of polypropylene and high density polyethylene

  Mayumi Ito, Masami Tsunekawa, Emi Ishida, Koki Kawai, Tatsuru Takahashi, Naka Abe, Naoki Hiroyoshi

  INTERNATIONAL JOURNAL OF MINERAL PROCESSING 97 (1-4) 96 - 99 0301-7516 2010/11 [Refereed][Not invited]
   

  A desktop type batch reverse jig and prototype bench scale continuous reverse jig were designed by installing a top screen to the chamber of the RETAC jig. Shredded plastics of polypropylene (specific density 0.91) and high density polyethylene (specific density 0.96) were used for the tests and operating conditions were investigated using a desktop type batch jig. Waveform and screen design affected the separation results. Wettability control of feed sample is also important and 100% separation was achieved for the top and bottom layer products. The prototype bench scale continuous jig could obtain a high grade product, 99% pure as a bottom product. (C) 2010 Elsevier B.V. All rights reserved.
• Effects of relative humidity and temperature on subcritical crack growth in igneous rock

  Yoshitaka Nara, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko

  INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 47 (4) 640 - 646 1365-1609 2010/06 [Refereed][Not invited]
   

  Effects of relative humidity and temperature on subcritical crack growth in igneous rock have been investigated experimentally on samples of Kumamoto andesite and Oshima granite. Stress intensity factors and crack velocities were measured using the double-torsion technique, and all experiments were conducted in moist air. Our results show that in experiments conducted under the same relative humidity, crack velocity increased with increasing temperature, in agreement with previous studies. Our results also show that, in experiments conducted at the same temperature , crack velocity increased dramatically with increasing relative humidity. A three- to four fold increase in relative humidity resulted in an increase in crack velocity of between one and four orders of magnitude. Such an increase is larger than that predicted by classical stress corrosion theory. It is suggested that capillary condensation of water vapour close to crack tips of small aperture influences the rate of crack growth. It is concluded that relative humidity needs to be controlled to avoid time-dependent weakening and extend the life time of structures in a rock mass. (C) 2010 Elsevier Ltd. All rights reserved.
• Effect of chloride ions on leaching rate of chalcopyrite

  Kyoungkeun Yoo, Soo-kyung Kim, Jae-chun Lee, Mayumi Ito, Masami Tsunekawa, Naoki Hiroyoshi

  MINERALS ENGINEERING 23 (6) 471 - 477 0892-6875 2010/05 [Refereed][Not invited]
   

  The effect of chloride on chalcopyrite leaching has been investigated by performing batch leaching tests with three kinds of leaching solutions and using Hiroyoshi's model, which suggests that a zone of rapid leaching exists between the critical potential (E(c), equilibrium redox potential for the reduction of CuFeS(2) to Cu(2)S) and the oxidation potential (E(ox),, equilibrium redox potential for the oxidation of Cu(2)S). The results of the leaching tests show that the leaching rate in hydrochloric acid solution is the fastest and that the relationship between the Cu leaching rate and oxidation-reduction potential (ORP) follows Hiroyoshi's model. Thermodynamic calculations indicate that, with an increase in the chloride concentration, the concentration of cuprous ions increases as the chlorocuprate(I) complex ions are formed and the contribution of cuprous ions to the critical potential is greater than that of cupric ions, even though the concentration of cuprous ions is lower than that of cupric ions. This fact suggests that the formation of chlorocuprate(I) ions in a chloride solution may improve the chalcopyrite leaching rate by increasing the critical potential. (C) 2009 Elsevier Ltd. All rights reserved.
• Effect of temperature on precipitation of calcium carbonate using soil microorganisms

  Kawasaki, S, Ogata, S, Hiroyoshi, N, Tsunekawa, M, Kaneko, K, Terajima, R

  Journal of Japan Society of Engineering Geology 一般社団法人 日本応用地質学会 51 (1) 10 - 18 0286-7737 2010 [Refereed][Not invited]
   

  We have been performing fundamental laboratory tests in order to develop a novel conceptual grout, hereafter called biogrout. Hardened biogrout consists primarily of calcium carbonate or silica, typical cement elements in soil and rock. These compounds can fill the voids and cracks in soil and rock using microbial metabolism. This paper reports some test results for biogrout using calcium carbonate and discusses them. We performed a series of precipitation tests on calcium carbonate in test tubes using soil microorganisms sampled from various parts of Japan, examining the effect of temperature on the precipitation of calcium carbonate when testing. As a result, it was indicated that precipitation of calcium carbonate using soil microorganisms occurred at temperatures ranging from 5 to 35°C. Furthermore, we measured the number of soil microorganisms used in the tests and conducted gene analyses of them. The phases of soil microorganisms before testing were compared to those after testing by determining the number of living soil microorganisms, the highest relative frequency of soil microorganisms, and their attributive taxonomical groups. In consequence, it is possible that fungi such as the Penicillium and Aspergillus species frequently metabolized organic nutrition, and at the same time their number increased via their metabolism.
• Mineral processing of deep-sea hydrothermal deposit ores

  M. Ito, T. Takahashi, S. Futakuchi, N. Hiroyoshi, M. Tsunekawa

  Proc of the 4th International Workshop and Conference on Earth Resources Technology 2010 [Refereed][Not invited]
  
• On the Use of Magnetite for Gold Recovery From Chloride Solution

  Richard Diaz Alorro, Naoki Hiroyoshi, Hajime Kijitani, Mayumi Ito, Masami Tsunekawa

  MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 31 (4) 201 - 213 0882-7508 2010 [Refereed][Not invited]
   

  The sorption of gold chloride ([image omitted]) from chloride solution on synthetic and natural magnetite powders was investigated by batch sorption experiments. The effects of different parameters on the recovery were studied. The results showed that Gold (Au) uptake by magnetite was influenced by pH, contact time, chloride concentration, and initial Au concentration. Gold uptake by synthetic and natural magnetite was maximum at pH 6-7 with sorption amounts of 4.4mol/g and 5.0mol/g, respectively, after 24hr at an initial Au concentration of 0.05mol/m3. The Scanning Electron Microscopy-Energy Dispersive X-ray and Back Scattering Electron analyses of the magnetite particles after treatment confirmed the presence of Au precipitates on the magnetite (Fe3O4) surface.
• Development of a New Gravity Separator for Plastics -a Hybrid-Jig

  Kunihiro Hori, Masami Tsunekawa, Masatsune Ueda, Naoki Hiroyoshi, Mayumi Ito, Hideaki Okada

  MATERIALS TRANSACTIONS 50 (12) 2844 - 2847 1345-9678 2009/12 [Refereed][Not invited]
   

  The development of mechanical methods for plastic-plastic separation is important for recycling of scrapped plastics of office/home appliances and cars. This paper proposes a Hybrid-Jig as it new method for plastic-plastic separation. The Hybrid-Jig was developed based on jigging and flotation, where air bubbles are introduced into the particle bed during jigging to modify the apparent specific gravity of the particles by the attachment of air bubbles to the particles so that particles having different surface properties can be separated by jigging even if their specific gravities are similar. To demonstrate the performance of the Hybrid-Jig, a laboratory scale TACUB jig was modified to induce air bubbles through the screen under the particle bed. and separation experiments of plastic particle mixtures were carried out tinder various displacements and frequencies of water pulsation. Feed samples were particle mixtures of two plastics chosen from eight kinds of plastics (3 of polyvinyl chloride (PVC), 4 of polyethylene (PE), and 1 of polyethylene terephthalate (PET)). The particles were cylindrical of 2-3 mm length and diameter, and their specific gravities were 1.05-1.55. In normal jig operation (without air bubbles), plastic particles with similar specific gravities were difficult to separate, but they were easily separated by the Hybrid-Jig, when air bubbles adsorbed on the surface of the more hydrophobic plastics, and the plastic particles with air bubbles were recovered as top product due to the decrease in apparent specific gravity, Because the differences in the hydrophobicity of the plastics cause the selective bubble attachment, high grade plastic products over 99.9 mass% were recovered by the Hybrid-Jig even for plastic mixtures having the same specific gravity. [doi:10.2320/matertrans.M-M2009825]
• Anode activating agent recovery by magnetic separation from the < 0.075 mm fraction of crushed nickel metal hydride batteries from hybrid vehicles

  Mayumi Ito, Kouki Kashiwaya, Naohiro Sumiya, Naoki Hiroyoshi, Masami Tsunekawa

  SEPARATION AND PURIFICATION TECHNOLOGY 69 (2) 149 - 152 1383-5866 2009/09 [Refereed][Not invited]
   

  Nickel metal hydride batteries of hybrid vehicles contain rare metals such as Ni, Co, and rare-earth elements as electrode components. A direct smelting method has been used to recover Ni from waste batteries, but the Co and rare-earth elements are difficult to extract with this conventional method. To recycle Co and rare-earth elements, physical pretreatment is necessary to separate the anode and cathode compounds before smelting. This study investigated the magnetic separation of anode and cathode activating agents in the <0.075 mm fraction of crushed cylindrical and prismatic types batteries. In the cylindrical type anode activating agent concentrated in the non-magnetic product of the Davis tube tester, separated at low magnetic fields (0.1 T), while in the prismatic type anode activating agent concentrated in the magnetic product of high gradient magnetic separation. Microscope observations and results of the elemental analysis with energy dispersive X-ray spectroscopy showed that this separation behavior difference originates from differences in the cathode component manufacturing processes. An optimum physical treatment process using magnetic separation is proposed to recover the rare metal components. (C) 2009 Elsevier B.V. All rights reserved.
• Optimum water pulsation of jig separation for crushed plastic particles

  Kunihiro Hori, Masami Tsunekawa, Naoki Hiroyoshi, Mayumi Ito

  INTERNATIONAL JOURNAL OF MINERAL PROCESSING 92 (3-4) 103 - 108 0301-7516 2009/08 [Refereed][Not invited]
   

  Mechanical separation of different plastics should be established in planning and constructing a recycling plant for scrapped office and home appliances. The authors studied jig separation of small plastic particles (two types of burn-resistant polyethylene (PE) and polyvinyl chloride (PVC)) using a TACUB jig. The size of the particles was 0.5-3 mm and the specific gravities of the two PEs and PVC were about 1.1, 1.3 and 1.4, respectively. The jig separation experiments were carried out under various water pulsations, at which the amplitude, frequency, and pattern of pulsation were varied. Based on the observation of separation progress and water pulsation, it was found that the upstream velocity of the pulsation is a very important factor to form high grade PE and PVC product layers with high efficiency. Moderate fluidization of particle bed caused high separation performance. High-grade PE and PVC products over 99.8% were recovered under pulsations of small frequency and amplitude. The optimum separation condition was determined easily by measuring the fluidity of the plastic beds in the separation chamber. (C) 2009 Published by Elsevier B.V.
• Recovery of heavy metals from MSW molten fly ash by CIP method

  Richard Diaz Alorro, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  HYDROMETALLURGY 97 (1-2) 8 - 14 0304-386X 2009/06 [Refereed][Not invited]
   

  Molten fly ash (MFA), generated by the melting process of municipal solid waste incineration (MSWI) solid residues in Japan, contains considerable amounts of heavy metals such as Pb, Zn, Cu and Cd. Therefore, MFA is classified as a hazardous waste and needs treatment for detoxification or recovery of heavy metals as secondary sources. Carrier-in-Pulp (CIP) method, which is similar in principle with the Carbon-in-Pulp technology for gold recovery from ores, was proposed to recover these heavy metals from molten fly ash. Unlike the traditional Carbon-in-Pulp process, the carrier or adsorbent in the Carrier-in-Pulp method is not only limited to carbon; other materials such as Fe powder can also be used. Moreover, other physical separation techniques such as magnetic separation can also be employed to harvest the carrier from the leach pulp. The present study, which can be regarded as a batch mode Carbon-in-Pulp process, investigated the application of the CIP technique to recover heavy metals from MSW molten fly ash containing 10.2 wt.% Zn, 2.78 wt.% Pb, 0.14 wt.% Cu, and 0.12 wt.% Cd. Granular activated carbon (GAC) was utilized as an adsorbent in batch adsorption tests and experiments involving the CIP method using NaCl as lixiviant. The effects of activated carbon dosage, pH, NaCl concentration, and treatment time were determined. Adsorption tests showed that the competition of metal ions present in a multi-component system suppressed the adsorption of Pb, Zn, Cu and Cd on GAC but the suppression can be minimized by increasing the GAC dosage. Around 90-100% of Pb, Zn, Cu and Cd were extracted from MFA at various conditions. At the optimum conditions (5 kmol m(-3) NaCl, 10 g GAC, pH 5-6, and 3 h treatment time), GAC recovered 57% Zn, 40% Pb, 90% Cu, and 54% Cd. The leaching test confirmed that the extraction of Pb from the CIP-treated residue was below the standard. thus, satisfying the land-filling guidelines in Japan. (C) 2008 Elsevier B.V. All rights reserved.
• Subcritical crack growth in rocks in an aqueous environment

  NARA Yoshitaka, TAKADA Masafumi, IGARASHI Toshifumi, HIROYOSHI Naoki, KANEKO Katsuhiko

  Geophysical exploration 物理探査学会 62 (1) 163 - 171 0912-7984 2009/03 [Refereed][Not invited]
  
• Effect of temperature on rate of CaCO₃ precipitation for biogrouting process

  Ogata, S, Kawasaki, S, Hiroyoshi, N, Tsunekawa, M, Kaneko, K, Terajima, R

  Proceedings of 3rd International Workshop and Conference on Earth Resources Technology 12 - 17 2009 [Refereed][Not invited]
  
• 微生物代謝を利用したグラウトにおける炭酸カルシウム析出の温度依存性

  小潟 暁, 川﨑 了, 広吉直樹, 恒川昌美, 金子勝比古, 寺島 麗

  第38回岩盤力学に関するシンポジウム講演論文集 120 - 124 2009 [Not refereed][Not invited]
  
• Removal of Lead from PVC in Electric Wires and Cables

  M. Tsunekawa, J. Mimura, T. Sakai, Y. Nakamura, Y. Sasaki, M. Ito, N. Hiroyoshi

  Proceedings of EcoDesign2009 OS-3A-9  2009 [Refereed][Not invited]
  
• Physical Separation of Shredder Residue of Plastics used in Home Appliances -Gravity separation using advanced jig separation technology-

  M. Ito, M. Akatsuka, Y. Kuwayama, K. Hori, E. Ishida, N. Hiroyoshi, M. Tsunekawa

  Proceedings of EcoDesign2009 OS-3A-8  2009 [Refereed][Not invited]
  
• Physical Separation of Crushed Nickel-metal Hydride Battery Components for Recycling

  M. Ito, K. Kashiwaya, N. Sumiya, H. Furuya, N. Hiroyoshi, M. Tsunekawa

  Proceedings of EcoDesign2009 OS-3A-7  2009 [Refereed][Not invited]
  
• Characterization of ASR for Recovering Low Chloride Fuel and Metals by Physical Separation

  Y. Kuwayama, M. Ito, M. Akatsuka, N. Hiroyoshi, M. Tsunekawa

  Proceedings of 10th Int. Symp. East Asian Recycling Technology 636 - 639 2009 [Refereed][Not invited]
  
• Review of Treatment of Ocean-floor Resources -Recovery Methods for Rare Metals

  M. Ito, T. Takahashi, K. Sekimura, N. Hiroyoshi, Masami Tsunekawa

  Proceedings of 10th Int. Symp. East Asian Recycling Technology 302 - 305 2009 [Refereed][Not invited]
  
• Application of Electric Ddisintegration Method for Gold Containing Complex Waste Rocks of the Lepanto Mine

  M. Ito, T. Hamano, N. Hiroyoshi, M. Tsunekawa

  Proceedings of 10th Int. Symp. East Asian Recycling Technology 270 - 273 2009 [Refereed][Not invited]
  
• Wet Treatment of ASR to Obtain Solid Fuel - Removal of Unburnable Fine Particles Entrapped in the Agglomerates and Their Characte

  M. Ito, M. Akatsuka, Y. Kuwayama, N. Hiroyoshi, M. Tsunekawa

  Proceedings of 10th Int. Symp. East Asian Recycling Technology 640 - 643 2009 [Refereed][Not invited]
  
• A Hydrometallurgical Approach to Recover Metals from Primary and Secondary Sources

  Richard D. Alorro, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  Proceedings of 3rd International Workshop and Conference on Earth Resources Technology 187 - 196 2009 [Refereed][Not invited]
  
• Carrier Micro Encapsulation (CME) for Coal Preparation

  Rani Kumari, Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  Proceedings of 3rd International Workshop and Conference on Earth Resources Technology 197 - 203 2009 [Refereed][Not invited]
  
• Electrical disintegration of gold containing complex waste rocks of the Lepanto mine

  Mayumi Ito, Takatoshi Hamano, Naoki Hiroyoshi, Masami Tsunekawa

  Proceedings of 3rd International Workshop and Conference on Earth Resources Technology 204 - 211 2009 [Refereed][Not invited]
  
• Advanced jig separation of cobalt-rich ferromanganese ore

  Mayumi Ito, Tatsuru Takahashi, Kengo Sekimura, Kunihiro Hori, Naoki Hiroyoshi, Masami Tsunekawa

  Proceedings of 3rd International Workshop and Conference on Earth Resources Technology 212 - 217 2009 [Refereed][Not invited]
  
• Subcritical crack growth in rocks in an aqueous environment

  Yoshitaka Nara, Masafumi Takada, Toshifumi Igarashi, Naoki Hiroyoshi, Katsuhiko Kaneko

  EXPLORATION GEOPHYSICS 40 (1) 163 - 171 0812-3985 2009 [Refereed][Not invited]
   

  Subcritical crack growth is one of the main causes of time-dependent fracturing in rock. In the present study, we investigated subcritical crack growth in rock in distilled water ( pH = 5 7) and in an aqueous solution of sodium hydroxide (NaOHaq, pH = 12), comparing the results to those in air. We also investigated the effect of the pH in an aqueous environment. We used andesite and granite for all our tests. We determined the relationship between the crack velocity and the stress intensity factor using the double-torsion test under conditions of controlled temperature. We showed that crack velocities in water were higher than those in air, in agreement with other research results indicating that crack velocity increases in water. When we compared our results for NaOHaq with those for water, however, we found that the crack velocity at the same stress intensity factor did not change even though the pH of the surrounding environment was different. This result does not agree with the accepted understanding that hydroxide ions accelerate subcritical crack growth in rocks. We concluded that the pH at the crack tip influences subcritical crack growth, and not the bulk pH, which has little effect.
• Removal of Trace Impurity from Limestone Using Flotation Techniques

  Masami Tsunekawa, Yugo Honma, Kyoungkeun Yoo, Naoki Hiroyoshi, Mayumi Ito

  MATERIALS TRANSACTIONS 50 (1) 171 - 176 1345-9678 2009/01 [Refereed][Not invited]
   

  High grade limestone was obtained by removing trace impurities through reverse and carrier flotation techniques. A simple method for measuring the impurity content of limestone was developed by correlating the amount of impurities and the turbidity of suspensions of residue from limestone dissolved in 20% acetic acid. Impurity removal more than 50% with limestone recovery better than 85% was obtained under suitable conditions by both reverse flotation and carrier flotation using sodium oleate (NaOl) and dodecylammonium acetate (DAA) as collectors. Limestone containing more than 0.15 mass% impurity was used as the carrier. These results suggest that limestone treated by flotation can be used as high quality limestone in paper manufacturing. [doi:10.2320/matertrans.M-MRA2008839]
• Recovery of heavy metals from MSW molten fly ash by carrier-in-pulp method: Fe powder as carrier

  Richard Diaz Alorro, Shinichi Mitani, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  MINERALS ENGINEERING 21 (15) 1094 - 1101 0892-6875 2008/12 [Refereed][Not invited]
   

  Municipal solid waste (MSW) molten fly ash is classified as a hazardous waste because it contains considerable amount of heavy metals, which pose environmental concern due to their leaching potential in landfill environment. This study proposes carrier-in-pulp (CIP) method as a new hydrometallurgical route to extract and recover Pb, Zn, Cu, and Cd from molten fly ash before landfilling. In this method, a carrier material, which recovers the extracted metals, is added simultaneously with fly ash to a leaching solution and is harvested from the pulp by physical separation method, such as magnetic separation or sieving. To demonstrate the effect of the CIP method, shaking flask experiments were conducted under various conditions using NaCl solution, iron powder as carrier, and molten fly ash. More than 99 wt% Pb, Zn, and Cd, and 97 wt% Cu were extracted from the ash. However, only Pb and Cu were recovered (96.3 wt% Pb and 94.3 wt% Cu) by the iron powder through cementation, leaving behind Zn and Cd ions in the solution phase. The leaching test conducted on the treated fly ash residue revealed that the CIP method suppressed the solubilization of Pb to a value below the landfill disposal guideline. (C) 2008 Elsevier Ltd. All rights reserved.
• Carrier-microencapsulation using Si-catechol complex for suppressing pyrite floatability

  Rani Kumari Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa

  MINERALS ENGINEERING 21 (12-14) 889 - 893 0892-6875 2008/11 [Refereed][Not invited]
   

  Pyrite (FeS2) is a common sulfide mineral associated with valuable metal minerals and coal, and it is rejected as a gangue mineral using physical separation techniques such as froth flotation and discharged into tailing pond. In the flotation, pyrite is frequently entrapped in the froth due to its hydrophobic nature. Formation of acid mine drainage due to the air-oxidation of pyrite in the tailing pond is also a serious problem. The authors have proposed carrier-microencapsulation (CME) as a method for suppressing both the floatability and oxidation of pyrite. In this method, pyrite is coated with a thin layer of metal oxide or hydroxide using catechol solution as a carrier combined with metal ions. The layer converts the pyrite surface from hydrophobic to hydrophilic and acts as a protective coating against oxidation. The present study demonstrates the effect of CME using Si-catechol complex to suppress the pyrite floatability: The bubble pick-up experiments showed that attachment of pyrite particles to air bubble is suppressed by the CME treatment at pH 4-10, Si-catechol complex concentration over 0.5 mol m(-3) and treatment time within 2 min. The Hallimond tube flotation experiments showed that the pyrite floatability is suppressed by the CME treatment even in the presence of typical flotation collectors such as kerosene and xanthate. SEM-EDX analysis confirmed that Si present on the pyrite surface treated by Sicatechol complex, implying that SiO2 or Si(OH4) layer formed by the CME treatment convert the pyrite surface hydrophobic to hydrophilic. (C) 2008 Elsevier Ltd. All rights reserved.
• Immersion Behavior of Automobile Shredded Residue in Surfactant Solutions and Detachment of Particulate Matter

  Mayurni Ito, Maiko Akatsuka, Yutaka Kuwayama, Kunihiro Hori, Naoki Hiroyoshi, Masami Tsunekawa

  MATERIALS TRANSACTIONS 49 (10) 2371 - 2376 1345-9678 2008/10 [Refereed][Not invited]
   

  This study investigated the effect of the addition of wetting agents on automobile shredded residue (ASR) wettability, and found that the surfactants diisooctyl sodium sulfosuccinate (AOT) and sodium dodecyl sulfate (SDS) were effective to improve immersion of the ASR, due to their ability to reduce the solution surface tension and the contact angle of ASR. Urethane foam is a bulky compound in ASR and its immersion and wetting behavior showed similar changes as those of the ASR samples. With SDS the surface wettability of urethane was improved. The surfactant solutions were also effective in the detachment of the entrapped particles from the agglomerate of entangling fiber like materials. The effects of the surfactant concentrations on ASR wettability and the amount of detached particles are described. [doi: 10.2320/matertrans.M-MRA2008824]
• Attempts to Improve Education at Course of Sustainable Resources Engineering, Department of Socio-Environmental Engineering, Faculty of Engineering, Hokkaido University

  FUJII Yoshiaki, HIROYOSHI Naoki, HARADA Shusaku, KANEKO Katsuhiko

  Journal of Jsee Japanese Society for Engineering Education 56 (5) 36 - 41 1341-2167 2008/09/20 

  Department of Resources Engineering, Faculty of Engineering, Hokkaido University, which was renamed to Course of Sustainable Resources Engineering in 2005, was established in 1972 based on Department of Mining. Number of coal mines in Japan rapidly decreased at that time by the governmental policy and the department was not popular with students from the beginning. Students with very low GPA (Maximum GPA was 1.6 in 1981, for example) were distributed to the department and the department was filled with full of dull students. Teachers also lost eagerness for high quality education. A negative spiral was formed and the situation went worse and worse. As time goes, attempts were made to revolutionize the department. One is "Curriculum Petit Committee" . And the other is "Committee for Education System Improvement" . These two committees significantly improved the education in the department. As a result, the department was filled with full of vivid students, and teachers. For exampe, in 2007, students′ maximum, minimum and average GPA was 3.3, 2.0 and 2.5, respectively,
• Engineering Education for All University First Year Students Using Playing in the Sand and Blowing Soap Bubbles

  TSUNEKAWA Masami, HIROYOSHI Naoki, ITO Mayumi, HIRAJIMA Tsuyoshi

  Journal of JSEE 公益社団法人 日本工学教育協会 56 (5) 111 - 114 1341-2167 2008/09/20 [Not refereed][Not invited]
   

  Hokkaido University holds first year student seminars for promoting student ability in communication, presentation, design, and creativity. The authors have held this seminar to students of all faculties, where the research topics were determined by the students themselves from the phenomena or questions relating to children′s games such as playing in the sand and blowing soap bubbles. Then, they planned experimental procedures, discussed, summarized, and presented the results with minimal advice from teachers. After the student presentations the teachers introduced the techniques and equip...
• Dispersion-Flocculation Behavior of Fine Lead Particles in an Organic Solvent

  Masami Tsunekawa, Yuta Sasaki, Yoshiaki Nakamura, Mayumi Ito, Naoki Hiroyoshi, Kyoung Keun Yoo

  MATERIALS TRANSACTIONS 49 (9) 2119 - 2123 1345-9678 2008/09 [Refereed][Not invited]
   

  Methyl ethyl ketone (MEK) is a good solvent for polyvinyl chloride (PVC) and it has been proposed for use in PVC recycling. In the recycling process, fine particles of 3PbO.PbSO4.H2(O), used as a thermal stabilizer in PVC products, are dispersed and not dissolved in the solvent. To establish methods for removing of 3PbO.PbSO4.H2O particles from the solvent, factors affecting the dispersion-flocculation behavior of the particles in MEK were investigated. The zeta potential and particle distribution of 3PbO.PbSO4.H2O particles in MEK solutions containing known amounts of H2O were measured. Above 5 vol%H2O in MEK solutions, the zeta potential of 3PbO.PbSO4.H2O particles approached zero and the flocculation of particles was achieved. In addition, it was found that Pb2+ and Cl- affect the zeta potential of the particles. These results indicate that the dispersion-flocculation behavior of lead particles can be influenced by the concentration of H2O, Ph2+, and Cl- in MEK. [doi: 10.2320/matertrans.M-MRA2008822]
• Estimation of degree of liberation in a coarse crushed product of cobalt-rich ferromanganese crust/nodules and its gravity separation

  Mayumi Ito, Masami Tsunekawa, Eiji Yamaguchi, Kengo Sekimura, Kouki Kashiwaya, Kunihiro Hori, Naoki Hiroyoshi

  INTERNATIONAL JOURNAL OF MINERAL PROCESSING 87 (3-4) 100 - 105 0301-7516 2008/07 [Refereed][Not invited]
   

  Cobalt-rich ferromanganese crust and nodule ores from seamount areas contain volcanic and sedimentary rocks as substrate or nuclei. During mining operations, these rocks should be separated as unfavorable waste rocks with the ferromanganese minerals. The cobalt-rich ferromanganese crust and nodule ores require mineral processing to remove the substrate/nuclei rock before the smelting. Deep-sea manganese nodule ores in contrast contain vanishingly small rocks, and can be directly treated with a metallurgical process without mineral processing treatment. This study is a physical and chemical description of the ores for the purpose of mineral processing, and reports estimates of the degree of liberation in a coarse crushed product of ores and its gravity separation results. From the obtained results a process flow-sheet for the beneficiation of cobalt-rich ferromanganese crust and nodules is proposed. (c) 2008 Elsevier B.V. All rights reserved.
• Effect of solution composition on the optimum redox potential for chalcopyrite leaching in sulfuric acid solutions

  Naoki Hiroyoshi, Hiroko Kitagawa, Masami Tsunekawa

  HYDROMETALLURGY 91 (1-4) 144 - 149 0304-386X 2008/03 [Refereed][Not invited]
   

  The leaching rate of chalcopyrite (CuFeS2) by Fe3+ in H2SO4 solutions depends on the redox potential determined by the Fe3+/Fe2+ concentration ratio, and there is a maximum leaching rate at an optimum redox potential. The present study investigated the effects of solution composition on the optimum redox potential by electrochemical measurements using a CuFeS2 electrode and electrolyte solutions containing 0.01-1 kmol m(-3) of H2SO4, Fe2+, and Cu2+ at 298 K in nitrogen. Anodic-polarization curves of the CuFeS2 electrode showed that there was a current peak on the curves in the presence of Cu2+ and Fe corresponding to the maximum leaching rate. The redox potential of the peak increased markedly with increasing Cu2+ concentration, while it was little affected by the H2SO4 and Fe2+ concentrations. These results agree with the results of leaching experiments reported previously, and indicate that the optimum redox potential for chalcopyrite leaching is a function of the Cu2+ concentration. An empirical equation for the optimum redox potential for CuFeS2 leaching is proposed. (c) 2008 Elsevier B.V. All rights reserved.
• バイオグラウトにおける炭酸カルシウムの析出に及ぼす温度の影響

  川﨑 了, 小潟 暁, 広吉直樹, 恒川昌美, 金子勝比古, 寺島 麗

  地盤工学会北海道支部技術報告集 (48) 27 - 30 2008 [Not refereed][Not invited]
  
• Carrier-in-Pulp Method as a New Hydrometallurgical Route to Reject and Recover Heavy Metals from MSW Melting Fly Ash

  R. D. Alorro, S. Mitani, N. Hiroyoshi, M. Ito, M. Tsunekawa

  Proceedings of The 22nd International Conference on Solid Waste Technology and Management 270 - 276 2008 [Refereed][Not invited]
  
• Selective crushing of cobalt-rich ferromanganese ores and flotation of the fine size product

  M. Ito, K. Kashiwaya, E. Yamaguchi, K. Sekimura, T. Takahashi, N. Hiroyoshi, M. Tsunekawa

  Proceedings of The 2nd International Workshop and Conference on Earth Resources Technology 42 - 45 2008 [Refereed][Not invited]
  
• Optimization of Jig Separation with Fluidization of Particle Layer

  K. Hori, M. Tsunekawa, N. Hiroyoshi, M. Ito

  Proceedings of 24rd International Mineral Processing Congress 841 - 845 2008 [Refereed][Not invited]
  
• Rejection and recovery of heavy metals from MSW melting fly ash by carrier-in-pulp method

  R. D. Alorro, N. Hiroyoshi, S. Mitani, M. Ito

  Proceedings of 24rd International Mineral Processing Congress 3610 - 3617 2008 [Refereed][Not invited]
  
• Mineral processing of cobalt-rich ferromanganese crust and nodules

  M. Ito, M. Tsunekawa, K. Sekimura, E. Yamaguchi, K. Kashiwaya, K. Hori, N. Hiroyoshi

  Proceedings of 24rd International Mineral Processing Congress 806 - 812 2008 [Refereed][Not invited]
  
• Carrier-microencapsulation for preventing pyrite oxidation

  Jacqueline Satur, Naoki Hiroyoshi, Masami Tsunekawa, Mayumi Ito, Hideyuki Okamoto

  INTERNATIONAL JOURNAL OF MINERAL PROCESSING 83 (3-4) 116 - 124 0301-7516 2007/09 [Refereed][Not invited]
   

  The oxidation of pyrite causes the formation of acid mine drainage polluted by heavy metals. This paper proposes carrier-microencapsulation (CME) for preventing pyrite oxidation. In CME, an organic agent is used as an in-situ carrier for transporting Ti from Ti minerals to the pyrite surface through an aqueous phase. Then, the organic carrier is decomposed and Ti(OH)(4) or TiO2 film is formed on the pyrite surface as a protective coating against oxidation. To demonstrate the effect of CME on pyrite oxidation, shaking-flask leaching experiments of ground pyrite were performed at 298 K in air for 25 days, with or without anatase (TiO2) and catechol (1,24hydroxybenzene) as the organic carrier. The amounts of Fe and S extracted from the pyrite were lower with TiO2 and catechol than without TiO2 or catechol, indicating that CME using TiO2 and catechol is effective in suppressing pyrite oxidation. When TiO2 and catechol coexist, the Ti concentration in the solution phase increased initially and then decreased. SEM-EDX analysis of the CME-treated pyrite showed that Ti and 0 are present on the pyrite surface. Cyclic voltammogram of catechol showed that catechol was oxidized on pyrite electrode. These results indicate that Ti is extracted from TiO2 by catechol as a Ti-catechol complex and that the complex is adsorbed and oxidized on pyrite to form a Ti (OH)(4) or TiO2 coating suppressing pyrite oxidation. (c) 2007 Elsevier B.V. All rights reserved.
• The recovery of electrode compounds from waste nickel metal hydride batteries by physical separation techniques

  Masami Tsunekawa, Mayumi Ito, Hisatoshi Furuya, Naoki Hiroyoshi

  MATERIALS TRANSACTIONS 48 (5) 1089 - 1094 1345-9678 2007/05 [Refereed][Not invited]
   

  A recovery method for electrode compounds from waste nickel metal hydride batteries by physical separation using sizing and distance-variable magnetic separation was investigated. The electrodes are formed by bonding substances of substrate and fine activating agents. Fine particle separation causes increasing costs and decreasing separation efficiency, suggesting a treatment flow where the separation of the anodic compounds from the cathodic compounds is carried out first and then each compound is crushed again for the liberation of activating agents and substrate. There is no suitable magnetic separation equipment to separate ferromagnetic substances using the magnetic property differences in the substrate components and special equipment to achieve this was developed. Using this newly developed equipment resulted in good separation.
• Carrier-Microencapsulation using Si-Catechol Complex for Suppressing Pyrite Floatability

  R .K .T. Jha, J. Satur, N. Hiroyoshi, M. Ito, M. Tsunekawa

  Proceedings of MEI's Intern. Flotation '07 Conf 1 - 14 2007 [Refereed][Not invited]
  
• Development of Wet Recycling Process for Automobile Shredded Residue - Effect of Surfactants on the Wettability of Autmobile Shredded Residue

  M. Ito, M. Akatsuka, Y. Kuwayama, K. Hori, N.Hiroyoshi, M. Tsunekawa

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 237  2007 [Refereed][Not invited]
  
• Dispersion-Floccuration Behavior of Fine Pb Powder in Organic Solvent

  M. Tsunekawa, Y. Sasaki, Y. Nakamura, M. Ito, N. Hiroyoshi, K. K. Yoo

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 503  2007 [Refereed][Not invited]
  
• Physical Separation of Anode and Cathod Activating Agents from Waste Nickel Metal Hydride Batteries

  M. Ito, K. Kashiwaya, N. Sumiya, H. Furuya, N.Hiroyoshi, M. Tsunekawa

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 439  2007 [Refereed][Not invited]
  
• Classification of Fine Hydrophobic Particles Using Hydrocyclone

  K. Kashiwaya, T. Noumachi, M. Ito, N.Hiroyoshi, M. Tsunekawa

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 503  2007 [Refereed][Not invited]
  
• New Washing Method of Lead Contaminated Soil

  M. Ito, N. Hokari, M. Takada, N.Hiroyoshi, M. Tsunekawa

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 576  2007 [Refereed][Not invited]
  
• Development of a New Gravity Concentration Machinery - a Hybrid Jig

  K. Hori, M. Tsunekawa, N.Hiroyoshi, M. Ito

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 466  2007 [Refereed][Not invited]
  
• Development of Wet Recycling Process for Automobile Shredded Residue - Evaluation of Entanglement Properties of Automobile Shredded Residue Crushed Product

  M. Ito, Y. Kuwayama, M. Akatsuka, K. Hori, N.Hiroyoshi, M. Tsunekawa

  Proceedings of 9th Int. Symp. East Asian Recycling Technology 187  2007 [Refereed][Not invited]
  
• Mineral Processing of Cobalt-Rich Manganese Crust and Nodules - Establishment of treatment flow for removal of substrate rock from deep sea mined ore

  M. Ito, K. Kashiwaya, E. Yamaguchi, K. Sekimura, K. Hori, N. Hiroyoshi, M. Tsunekawa

  Proceedings of 37th Underwater Mining Institute 2007 [Refereed][Not invited]
  
• Carrier-Microencapsulation for Suppressing Flotability and Oxidation of Pyrite in Copper Mineral Processing

  J. Satur, N. Hiroyoshi, M. Ito, M. Tsune

  Proceedings of the 6th International Copper-Cobre Conference 3 - 9 2007 [Refereed][Not invited]
  
• Fundamental study on novel grout cementing due to microbial metabolism

  Kawasaki, S, Murao, A, Hiroyoshi, N, Tsunekawa, M, Kaneko, K

  Journal of Japan Society of Engineering Geology 一般社団法人日本応用地質学会 47 (1) 2 - 12 0286-7737 2006 [Refereed][Not invited]
   

  Natural soil contains approximately 10^7 to 10^9 microorganisms per gram. Considering this large number of microorganisms, it is expected that soil and rock engineering, especially the field of mechanics, may be able to develop a novel eco-friendly technology to improve the scalability of soil and rock. We performed fundamental laboratory tests in order to develop a novel conceptual grout, hereafter denoted as biogrout. Biogrout consists primarily of calcium carbonate, one of the typical cement elements in soil and rock. This compound can fill the voids and cracks in soil and rock using microbial metabolism. We performed separation tests on calcium carbonate in test tubes, examining the effects of several test conditions, including temperature, organic nutrition, and different buffering conditions, on the separation of calcium carbonate when challenged with commercially available dry yeast and microorganisms naturally living in soil. Furthermore, we examined the improvements in the sealability of sand and clay following biogrout improvement, confirming that coefficients of permeability of both soil types decreased by approximately one order of magnitude from those seen for normal soils. Although a number of problems will need to be addressed, these test results indicate that biogrout is a promising candidate to improve ground properties. The development of such a compound has been successful using microbial metabolism.
• The recovery of electrode materials from waste nickel metal hydride batteries in a hybrid vehicle

  Tsunekawa M, Furuya H, Hiroyoshi N, Ito M, Kitamura O, Ichimura R, Kikuta K

  Proceedings of 3rd Japan-Korea International Symposium of Resources Recycling and Materials Science 59 - 73 2006 [Refereed][Not invited]
  
• Technological Developments in Wet Gravity Separation Processes

  TSUNEKAWA Masami, HORI Kunihiro, HIROYOSHI Naoki, ITO Mayumi

  Shigen-to-Sozai 社団法人 資源・素材学会 121 (10/11) 467 - 473 0916-1740 2005/11/25 [Not refereed][Not invited]
   

  Gravity separation is one of the ancient technologies for mineral processing and is still in widespread use. In recent years, many kinds of machinery for wet gravity separation have been developed and applied to process fine particles and solid waste.<BR>The authors have reviewed newly developed machineries, in addition to the principle of wet gravity separation and conventional machineries. Most of them are conducted in gravitational fields or films of flowing water. The former harnesses the settling behavior of particles in water and the later the movement of particles in films of flowi...
• 微生物代謝により固化する新しいグラウトに関する基礎的検討

  村尾彰了, 川﨑 了, 広吉直樹, 恒川昌美, 金子勝比古

  第34回岩盤力学に関するシンポジウム講演論文集 417 - 422 2005 [Not refereed][Not invited]
  
• Upgrading of Crystalline Limestone by Carrier Flotation

  Tsunekawa M, Honma Y, Yoo K, Hiroyoshi N, Ito M

  Proceedings of 8th Int. Symp. East Asian Recycling Technology 221 - 224 2005 [Refereed][Not invited]
  
• The Recovery of Useful Materials from Scrapped Secondary Batteries by Physical Separation Techniques

  Tsunekawa M, Furuya H, Hiroyoshi N, Ito M, Kitamura O, Ichimura R, Kikuta K

  Proceedings of 8th Int. Symp. East Asian Recycling Technology 382 - 385 2005 [Refereed][Not invited]
  
• Catalytic Effect of Activated Carbon and Coal on Chalcopyrite Leaching in Sulfuric Acid Solutions

  OKAMOTO Hideyuki, NAKAYAMA Ryoichi, KUROIWA Shigeto, HIROYOSHI Naoki, TSUNEKAWA Masami

  Journal of MMIJ The Mining and Materials Processing Institute of Japan 120 (10) 600 - 606 0916-1740 2004/11/25 

  Activated carbon is known as a catalyst for chalcopyrite leaching in sulfuric acid solutions. This paper compares the effects of six different activated carbon samples on copper extraction from a chalcopyrite concentrate by shaking flask leaching experiments at 303 K under atmospheric conditions. Eight different coals were also evaluated as an alternative to activated carbon.
  Except for one activated carbon sample, activated carbon addition enhanced copper extraction. Increases in the weight ratio of activated carbon to the chalcopyrite concentrate caused increases in copper extraction.
  The effects of the coals on copper extraction were related to the rank of the coals: Low rank coals like brown coal, which have low fixed carbon contents and high contents of volatile matter, suppress copper extraction, and high rank coals, which contain more fixed carbon and less volatile matter, enhance copper extraction. High rank coals stored under atmospheric conditions over long periods (more than 7 months) suppressed copper extraction, implying that oxidation of the coal surface and its products cause the suppression in copper extraction.
  The experimental results are analyzed and discussed with a reaction model for the redox potential dependence of chalcopyrite leaching, which assumes the formation of intermediate Cu₂S by chalcopyrite reduction and a subsequent oxidation of the Cu₂S.
• Iron Dissolution Behavior from High Sulfur Refuse and Flotation of High Sulfur Coal in the Leachate of the Refuse

  ITO Mayumi, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi, HIROYOSHI Naoki, YAMADA Ryuichi, YUKAWA Kentaro

  Shigen-to-Sozai 社団法人 資源・素材学会 117 (12) 961 - 966 0916-1740 2001/12/25 [Not refereed][Not invited]
   

  The effects of inhibitors to iron-oxidizing bacteria (Thiobacillus ferrooxidans) on the dissolution of iron species from high sulfur coal refuse (5.75 db% S) were studied in acidic solutions with the bacteria, using sodium lauryl sulfate (SDS) and tannic acid as inhibitors. Flotation experiments of high sulfur coal (4.27 dafb% S) in leachates from the refuse were conducted to remove sulfur.<BR>Compared with tannic acid, SDS inhibited the iron-oxidizing activity of Thiobacillus ferrooxidans more and dissolution of pyrite in high sulfur coal refuse, but SDS did not prevent dissolution of solu...
• Recycling. Extraction and Recovery Techniques. Microbiological Treatment.

  広吉 直樹, 恒川 昌美

  Journal of MMIJ The Mining and Materials Processing Institute of Japan 113 (12) 958 - 961 0916-1740 1997/12/25

Books etc

• 微生物資源工学(共著)

  コロナ社 1996
• Microbiology and Its Applications to Resources Engineering

  CORONA PUBLISHING CO. , LTD. 1996

MISC

• Concurrent treatment combining extraction and cementation of anglesite for depression of sphalerite floatability

  相川公政, 伊藤真由美, 草野敦大, JEON Sanghee, PARK Ilhwan, 広吉直樹  資源・素材(Web)  2021-  2021
• Effects of pyrite on the floatability of lead-activated sphalerite in flotation

  相川公政, 瀬川達也, JEON Sanghee, PARK Ilhwan, TABELIN Carlito, TABELIN Carlito, 広吉直樹, 伊藤真由美  資源・素材学会春季大会(Web)  2020-  2020
• 鉛イオンで活性化された閃亜鉛鉱の浮遊性に及ぼす亜硫酸ナトリウムの影響

  草野敦大, 相川公政, JEON Sanghee, PARK Ilhwan, 広吉直樹, 伊藤真由美  資源・素材学会春季大会(Web)  2020-  2020
• 銅・亜鉛硫化鉱の浮選における閃亜鉛鉱の浮遊抑制

  折井のどか, 相川公政, JEON Sanghee, PARK Ilhwan, 広吉直樹, 伊藤真由美  資源・素材学会春季大会(Web)  2020-  2020
• Effects of several depressants on the floatability of sphalerite in the flotation of copper-zinc sulfides

  伊藤真由美, 折井のどか, 相川公政, JEON Sanghee, PARK Ilhwan, 広吉直樹, MAGWANENG Refilwe, 工藤賢太郎, 砂田和也, 高橋達  資源・素材(Web)  2020-  2020
• Effects of lead ion and sodium sulfite concentrations on sphalerite flotation

  伊藤真由美, 草野敦大, 相川公政, JEON Sanghee, PARK Ilhwan, 広吉直樹  資源・素材(Web)  2020-  2020
• Improvement of flotation and suppression of pyrite oxidation using phosphate-enhanced galvanic microencapsulation (GME) in a ball mill with steel ball media

  Sophea Seng, Carlito Baltazar Tabelin, Yuta Makino, Monyneath Chea, Theerayut Phengsaart, Ilhwan Park, Naoki Hiroyoshi, Mayumi Ito  Minerals Engineering  143-  2019/11/01  [Not refereed][Not invited]
   

  © 2019 Elsevier Ltd Acid mine drainage (AMD) is one of the biggest and most challenging environmental concerns of the mining and mineral processing industries. In our previous study, we reported a new and promising approach to passivate sulfide minerals and limit AMD formation called galvanic microencapsulation (GME), a technique that forms protective coatings via galvanic interactions between sulfide minerals (e.g., pyrite) and metal powders (e.g., zero-valent iron and aluminum). In this paper, the possible application of GME in a ball mill with steel ball media and phosphate to suppress pyrite floatability during coal cleaning and limit pyrite oxidation after disposal is proposed. The results showed that adding phosphate and maintaining sufficient oxygen supply during GME treatment in the ball mill passivated pyrite and suppressed its oxidation via the formation of protective iron phosphate coatings. Moreover, the iron phosphate coatings on pyrite made the mineral more hydrophilic, which improved the separation efficiency during coal flotation.
• Development of suitable product recovery systems of continuous hybrid jig for plastic-plastic separation

  Mayumi Ito, Ayumu Saito, Nana Murase, Theerayut Phengsaart, Shoko Kimura, Carlito Baltazar Tabelin, Naoki Hiroyoshi  Minerals Engineering  141-  2019/09/01  [Not refereed][Not invited]
   

  © 2019 Elsevier Ltd A modified jig called the hybrid jig was recently developed to separate mixed-plastics with similar specific gravities effectively using the concepts of bubble attachment, surface wettability and gravity separation. This method was effective in a batch-type jig setup, but when applied to a continuous-type jig setup, the efficiency of the process dramatically decreased. This drop in efficiency was attributed to the unintended negative effects of air bubbles on separation especially close to the screw-type extractor at the product end though this type of product recovery system was successfully applied to the RETAC and reverse jigs. To address this problem, a better product recovery system for continuous-type hybrid jig is proposed in this study, and the effects of air injection rate at different positions of the hybrid jig separation chamber were evaluated. The results showed that fluidization behavior of particles in the hybrid jig was influenced by not only water pulsation but also the rising motion of air bubbles. To improve the purity of heavy materials in the bottom layer products, two product recovery systems are proposed: (1) a screw-type extractor with one “separating” single-screen, and (2) a screw-type extractor with modified air injection and water pulsation (i.e., upward flow period was shortened).
• A physical separation scheme to improve ammonium thiosulfate leaching of gold by separation of base metals in crushed mobile phones

  Sanghee Jeon, Mayumi Ito, Carlito Baltazar Tabelin, Rongrit Pongsumrankul, Shinya Tanaka, Naho Kitajima, Ayumu Saito, Ilhwan Park, Naoki Hiroyoshi  Minerals Engineering  138-  168  -177  2019/07/01  [Not refereed][Not invited]
   

  © 2019 Elsevier Ltd As technology advances, consumers are looking to buy new phones. This phenomenon leads to decrease in life-cycle of mobile phones (ca. 2–3 years), resulting in increase of waste mobile phones. In waste mobile phones, it contains various components including display unit, battery, cases, and printed circuit boards (PCBs). PCBs alone contain variety of materials such as gold (Au), copper (Cu), and iron (Fe)as well as aluminum (Al)with plastics, which causes difficulty in recycling. The coexistence of Cu and Al in crushed mobile phones has been recently reported to cause very low Au extraction efficiency in ammonium thiosulfate medium due primarily to enhanced re-deposition of extracted Au ions via galvanically induced cementation. To limit this antagonistic effect of Cu and Al coexistence on Au extraction, Au-containing components were separated from Cu- and/or Al-bearing parts using a two-step crushing approach in tandem with various physical separation techniques (i.e. jig, hybrid jig, magnetic separation, flotation, and sink-float separation)that were applied on appropriate size fractions. The results showed that over 96% of PCBs, the primary Au-containing material in mobile phones, were recovered after jig separation. These concentrated PCBs were collected and further crushed to liberate Au-containing parts and then treated by diverse physical separation techniques such as magnetic separation, jig separation, hybrid jig separation, flotation, and sink-float separation depending on the crushed particle sizes. Ammonium thiosulfate leaching of the mixed Au-concentrated products from various physical pretreatment techniques showed that Au extraction improved by about 15-fold, indicating that the physical separation scheme proposed in this study is very promising.
• Suppression of pyrite oxidation by ferric-catecholate complexes: An electrochemical study

  Xinlong Li, Min Gao, Naoki Hiroyoshi, Carlito Baltazar Tabelin, Tetsuya Taketsugu, Mayumi Ito  Minerals Engineering  138-  226  -237  2019/07/01  [Not refereed][Not invited]
   

  © 2019 Elsevier Ltd Pyrite oxidation is the main cause of acid mine drainage (AMD) formation, a very serious environmental problem in numerous mining areas worldwide. To manage AMD, a promising approach called carrier-microencapsulation has been proposed to suppress pyrite oxidation via the formation of a protective coating on the mineral using redox sensitive catecholate complexes of Fe3+, Al3+, Si4+ and Ti4+. In this study, the mechanisms involved in the suppression of pyrite oxidation by Fe-based CME were investigated by conducting a series of electrochemical studies (i.e., linear sweep voltammetry (LSV), electrochemical impedance spectrometry (EIS), and chronoamperometry). The results of LSV showed that the sequential decomposition of Fe3+-catecholate complexes on pyrite (tris-catecholate → bis-catecholate → mono-catecholate → Fe3+) occurred at different electrode potentials that corresponded to HOMO energy levels of the three Fe3+-catecholate complexes. Moreover, the oxidative decomposition of Fe3+-catecholate complexes formed a passivating coating as illustrated by chronoamperometry and EIS results using a rotating disk platinum (Pt) electrode. With longer decomposition time and at higher anodic potentials, defects in the coat decreased, resulting in the formation of a more resistant and evenly distributed coating. A comparison between chronoamperometry results of coated and uncoated pyrite electrodes suggests that the coating formed by Fe3+-catecholate complexes suppressed both anodic and cathodic half-cell reactions of pyrite oxidation by limiting the diffusion of reactants and products between pyrite and bulk solution phase.
• 複雑硫化鉱浮選における閃亜鉛鉱の浮遊性低下のメカニズム

  相川公政, 瀬川達也, 得田敦博, TABELIN Carlito, 広吉直樹, 伊藤真由美  資源・素材学会春季大会(Web)  2019-  2019
• 鉛で活性化された閃亜鉛鉱の浮遊性に及ぼすガルバニック相互作用の影響

  伊藤真由美, 相川公政, 瀬川達也, JEON Sanghee, PARK Ilhwan, TABELIN Carlito, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2019-  2019
• Effects of physical separation as a pretreatment for ammonium thiosulfate leaching of gold from waste mobile phones

  S. Jeon, M. Ito, R. Pongsumrankul, S. Tanaka, N. Kitajima, C. B. Tabelin, N. Hiroyoshi  IMPC 2018 - 29th International Mineral Processing Congress  690  -698  2019/01/01  [Not refereed][Not invited]
   

  © IMPC 2018 - 29th International Mineral Processing Congress. All rights reserved. Gold (Au) extraction is inefficient when crushed waste mobile phones (WMPs) are directly leached by ammonium thiosulfate likely because of the cementation/precipitation of dissolved Au in the presence of base metals like copper (Cu), iron (Fe) and/or aluminum (Al). This study applied physical separation techniques to remove base metals as well as plastics and concentrate the Au containing fractions from WMPs prior to leaching. Coarse fraction of crushed WMP (+2-5.6 mm) was pretreated by jig and magnetic separation to remove plastics and base metals like Fe, Cu, and Al, while the fine fraction (-2 mm) was pretreated by flotation, and float and sink separation. The leaching results showed that Au extraction increased in both of the size fractions. In the coarse fraction, Au extraction increased by as much as 2-fold after pretreated (from 4 to 7%). Improvement of Au extraction in the fine fractions after pretreatments were even more dramatic. Au extraction increased from 4 to 61%. These results indicate that physical pretreatment to remove co-existing common metals and plastics is effective to improve Au extraction from WMPs.
• Effects of physical separation as a pretreatment for ammonium thiosulfate leaching of gold from waste mobile phones

  Jeon, M. Ito, R. Pongsumrankul, S. Tanaka, N. Kitajima, C. B. Tabelin, N. Hiroyoshi  IMPC 2018 - 29th International Mineral Processing Congress  3790  -3798  2019/01/01  [Not refereed][Not invited]
   

  © IMPC 2018 - 29th International Mineral Processing Congress. All rights reserved. Gold (Au) extraction is inefficient when crushed waste mobile phones (WMPs) are directly leached by ammonium thiosulfate likely because of the cementation/precipitation of dissolved Au in the presence of base metals like copper (Cu), iron (Fe) and/or aluminum (Al). This study applied physical separation techniques to remove base metals as well as plastics and concentrate the Au containing fractions from WMPs prior to leaching. Coarse fraction of crushed WMP (+2-5.6 mm) was pretreated by jig and magnetic separation to remove plastics and base metals like Fe, Cu, and Al, while the fine fraction (-2 mm) was pretreated by flotation, and float and sink separation. The leaching results showed that Au extraction increased in both of the size fractions. In the coarse fraction, Au extraction increased by as much as 2-fold after pretreated (from 4 to 7%). Improvement of Au extraction in the fine fractions after pretreatments were even more dramatic. Au extraction increased from 4 to 61%. These results indicate that physical pretreatment to remove co-existing common metals and plastics is effective to improve Au extraction from WMPs.
• Improvement of hybrid jig separation efficiency using wetting agents for the recycling of mixed-plastic wastes

  Mayumi Ito, Megumi Takeuchi, Ayumu Saito, Nana Murase, Theerayut Phengsaart, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Masami Tsunekawa  Journal of Material Cycles and Waste Management  2019/01/01  [Not refereed][Not invited]
   

  © 2019, Springer Japan KK, part of Springer Nature. We have developed the hybrid jig which combines the principles of jig separation and flotation. However, the selectivity of bubble attachment in water was poor because most plastics have inherently hydrophobic surfaces; so, development of surface modification techniques for plastic particles would expand the application of hybrid jig to the material recycling of plastics. In this study, hybrid jig separation of polypropylene using glass fiber and high impact polystyrene having similar specific gravities and surface wettability were investigated with three wetting agents [Di-2-ethylhexyl sodium sulfosuccinate (Aerosol OT, AOT), sodium lignin sulfonate, and tannic acid]. The results showed that the probability of bubble attachment was influenced by wetting agents because of their strong effects on the surface tension of solution and surface wettability of plastics. The results also suggest that wetting agents could be utilized to control the selectivity of bubble attachment and improve the hybrid jig separation efficiency. In addition, since the hybrid jig separation of polyvinyl chloride and polyamide (nylon-66) using AOT was imperfect, a two-step approach, composed of a pre-wetting step (first step) in a solution containing the wetting agent (AOT) and hybrid jig separation in water (second step), is proposed.
• The characterization of crushed printed circuit boards of waste mobile phone and recovery of gold components by hybrid-jig separation

  S. Jeon, M. Ito, S. Tanaka, N. Kitajima, C.B. Tabelin, N. Hiroyoshi  Proc. of the 17th Global Joint Seminar on Geo-environmental Engineering,  192  -197  2018  [Not refereed][Not invited]
  
• Suppression of the release of arsenic from arsenopyrite by titanium- and aluminum-based carrier-microencapsulation

  I. Park, C.B. Tabelin, K. Seno, K. Magaribuchi, M. Ito, N. Hiroyoshi  Proc. of the 17th Global Joint Seminar on Geo-environmental Engineering,  305  -311  2018  [Not refereed][Not invited]
  
• Comparison of electrochemical properties of various metal-catecholate complexes for carrier-microencapsulation

  X. Li, C. Harada, I. Park, N. Hiroyoshi, C.B. Tabelin, M. Ito  Proc. of the 17th Global Joint Seminar on Geo-environmental Engineering,  344  -348  2018  [Not refereed][Not invited]
  
• The roles of soluble phases in the release of geogenic arsenic and selenium from tunnel-excavated rocks of marine origin

  C.B. Tabelin, R. Sasaki, T. Igarashi, I. Park, S. Tamoto, T. Arima, M. Ito, N. Hiroyoshi  Proc. of the 17th Global Joint Seminar on Geo-environmental Engineering,  312  -319  2018  [Not refereed][Not invited]
  
• The effects of particle geometrical properties on the settling velocity of plastic particles in jig separation

  T. Phengsaart, A. Azuma, M. Ito, D. Kitayama, S. Kimura, C.B. Tabelin, N. Hiroyoshi  Mining in Asia International Symposium, Bandung, Indonesia  2018  [Not refereed][Not invited]
  
• Improvement of bottom product purity in a continuous jig using a restraining wall

  T. Phengsaart, M. Ito, A. Azuma, S. Kimura, K. Hori, H. Tanno, C.B. Tabelin, N. Hiroyoshi  Mining in Asia International Symposium, Bandung, Indonesia  2018  [Not refereed][Not invited]
  
• Effects of iron-catecholate complexes on pyrite oxidation.

  X. Li, N. Hiroyoshi, K. Naruwa, C. Harada, C.B. Tabelin, M. Ito  The 6th Joint Seminar on Geo-environment Engineering and Recycling (GER 2018)  2018  [Not refereed][Not invited]
  
• Recent advances in jig separation technologies for resources recycling

  T. Phengsaart, M. Ito, S. Jeon, A. Azuma, D. Kitayama, S. Kimura, C.B. Tabelin, N. Hiroyoshi  The 6th Joint Seminar on Geo-environment Engineering and Recycling (GER 2018)  2018  [Not refereed][Not invited]
  
• Characterization of zinc leaching residue in Kabwe area, Zambia.

  M. Silwamba, M. Ito, T. Fukushima, S. Takakuwa, K. Minatogawa, C.B. Tabelin, N. Hiroyoshi, M. Chirwa, K.E. Banda, I. Nyambe  Proc. of 2nd International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium, Lusaka, Zambia  2018  [Not refereed][Not invited]
  
• Decontamination of zinc leach plant residues: recovery of extracted lead in leach pulp by cementation on ZVI

  M. Silwamba, M. Ito, T. Fukushima, C.B. Tabelin, S. Takakuwa, N. Hiroyoshi, M. Chirwa, K.E. Banda, I. Nyambe  Proc. of 2nd International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium, Lusaka, Zambia  2018  [Not refereed][Not invited]
  
• he effects of geometrical properties of particles on recycling treatment by physical separation techniques: A review

  T. Phengsaart, M. Ito, N. Kitajima, A. Azuma, C.B. Tabelin, N. Hiroyoshi  Proceedings of the 10th AUN/SEED-net Regional Conference on Geo-Resource and Geological Engineering  446  -459  2017  [Not refereed][Not invited]
  
• Effects of metal ions on flotation of sulfide minerals

  M. Ito, A. Tokuda, T. Segawa, T Horiguchi, C.B. Tabelin, N. Hiroyoshi  Proceedings of International Symposium on Earth Resources and Management  2017  [Not refereed][Not invited]
  
• Electrochemical studies of chalcopyrite dissolution in acidic chloride solutions

  T.T. Nguyen, S. Tsuji, C.B. Tabelin, M. Ito, N. Hiroyoshi  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  3  -6  2017  [Not refereed][Not invited]
  
• Distribution of different metals in gravity separation of printed circuit boards from mobile phones using jig separator and Knelson concentrator

  S. Tanaka, S. Jeon, N. Kitajima, C.B. Tabelin, N. Hiroyoshi, M. Ito  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  23  -28  2017  [Not refereed][Not invited]
  
• Carrier-microencapsulation using Al-catechol complex for suppressing arsenic release from arsenopyrite

  I. Park, K. Seno, K. Magaribuchi, C.B. Tabelin, M. Ito, N. Hiroyoshi  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  10  -15  2017  [Not refereed][Not invited]
  
• Redox properties of metal complexes with catechol and its derivatives

  X. Li, K. Naruwa, C.B. Tabelin, M. Ito, N. Hiroyoshi  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  4  -9  2017  [Not refereed][Not invited]
  
• Effects of mechanochemical treatment on the stability of arsenic-loaded schwertmannite

  Y. Takeuchi, N. Hiroyoshi, R.D. Alorro, M. Ito, C.B. Tabelin  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  16  -21  2017  [Not refereed][Not invited]
  
• Effects of zinc ions and their precipitates on flotation of sulfide minerals under alkaline condition

  A. Tokuda, M. Ito, T. Segawa, T. Horiguchi, C.B. Tabelin, N. Hiroyoshi  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  2  -4  2017  [Not refereed][Not invited]
  
• Enhanced passivation of pyrite in phosphate solution using ferric-catechol complex and zero-valent iron

  C.B. Tabelin, X. Li, S. Seng, M. Kojima, T. Igarashi, M. Ito, N. Hiroyoshi  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  8  -13  2017  [Not refereed][Not invited]
  
• Heterocoagulation anf galvanic interaction in mineral processing: A review.

  S. Seng, C.B. Tabelin, M. Kojima, Y. Kontani, M. Ito, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  32  2017  [Not refereed][Not invited]
  
• Recovery of gold ions from ammonium thiosulfate solution by aluminum and other conductive particles

  S. Jeon, T. H. Takahashi, R. Pongsumrankul, S. Tanaka, C.B. Tabelin, M. Ito, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  32  2017  [Not refereed][Not invited]
  
• Suppressive effects of aluminum-catechol complexes on the release of arsenic from arsenopyrite

  I. Park, K. Seno, K. Magaribuchi, C.B. Tabelin, M. Ito, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  31  2017  [Not refereed][Not invited]
  
• Characterization of zinc contaminated mine waste in Kabwe area, Zambia

  M. Ito, T. Fukushima, S. Takakuwa, K. Minatogawa, C.B. Tabelin, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  29  2017  [Not refereed][Not invited]
  
• Effects of additional organic functional groups on the redox properties of metal-catecholate complexes

  X. Li, K. Naruwa, C.B. Tabelin, M. Ito, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  28  2017  [Not refereed][Not invited]
  
• Effects of particle size and shape during jig separation

  T. Phengsaart, M. Ito, A. Azuma, C.B. Tabelin, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  27  2017  [Not refereed][Not invited]
  
• Advanced separation techniques for coarse size fraction of cesium-contaminated soil: Effects of soil particle morphology of soil washing.

  M. Ito, S. Takakuwa, K. Minatogawa, C.B. Tabelin, N. Hiroyoshi, Y. Tomida  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  26  2017  [Not refereed][Not invited]
  
• Gravity separation and its application in coal cleaning and resources recycling: A review

  T. Phengsaart, M. Ito, C.B. Tabelin, G.C. Eliseo, Y. Makino, A. Azuma, N. Hiroyoshi  Proceedings of Coal Mining and Utilization for Sustainable Development International Conference, Chiang Mai, Thailand  301  -308  2017  [Not refereed][Not invited]
  
• Development of gold recovery method from ammonium thiosulfate solution using aluminum and activated carbon

  S. Jeon, H. Takahashi, C.B. Tabelin, M. Ito, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology  608  -610  2017  [Not refereed][Not invited]
  
• Redox potential dependence of chalcopyrite leaching in ferric-chloride solution: Effects of temperature and solution composition

  N. Hiroyoshi, S. Tsuji, T.T. Nguyen, M. Ito, C.B. Tabelin  Proceedings of International Symposium on Earth Science and Technology  615  -618  2017  [Not refereed][Not invited]
  
• Effects of aluminum-catechol complexes on pyrite oxidation

  I. Park, C.B. Tabelin, K. Seno, K. Magaribuchi, M. Ito, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology  611  -614  2017  [Not refereed][Not invited]
  
• Suppression of pyrite oxidation using zero-valent iron powder

  S. Seng, C.B. Tabelin, M. Kojima, Y. Kontani, M. Ito, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology,  619  -622  2017  [Not refereed][Not invited]
  
• Synergistic effects of calcium ion and anionic flocculants on coal flotation

  M. Ito, Y. Makino, G.C. Eliseu, C.B. Tabelin, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology  623  -626  2017  [Not refereed][Not invited]
  
• Attachment of iron oxyhydroxides on pyrite and its effects on pyrite oxidation

  S. Seng, C.B. Tabelin, Y. Kontani, M. Kojima, M. Ito, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology  600  -604  2017  [Not refereed][Not invited]
  
• Characterization of rare earth ore from Khaldzan Burgedei Peralkaline Deposit and its beneficiation by magnetic separation

  M. Ito, P. Galtchandmani, N. Sato, C.B. Tabelin, T. Otake, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology  98  -199  2017  [Not refereed][Not invited]
  
• Effects of flatness ratio on the jig separation of crushed plastic particles

  Theerayut Phengsaart, Arisa Azuma, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Mayumi Ito  14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017  2017/01/01  [Not refereed][Not invited]
   

  © The Mining and Materials Processing Institute of Japan In resources recycling, separation of crushed plastics is an important issue. In this study, effects of shape of crushed plastic (flatness ratio: thickness/breadth of particles) on jig separation were investigated using crushed ABS plates (specific gravity, 1.03; thickness, 2 and 3 mm), and PS plates (specific gravity, 1.06; thickness, 2 and 3 mm). When crushed ABS plate with 2 mm thickness was used, particles with high flatness ratio (sphere-like particle) were recovered in the bottom layer and low flatness ratio particle (disk-like particle) were recovered in the top layer. This may be due to larger hydraulic drag force and slower settling velocity with disk-like particle. When mixture of disk-like ABS and PS or mixture of sphere-like ABS and PS was used, heavier PS was recovered in bottom layer and lighter ABS was recovered in top layer. When mixture of disk-like ABS and sphere-like PS or mixture of sphere-like ABS and disk-like PS was used, heavier PS was recovered in bottom layer and lighter ABS was recovered in top layer, indicating that specific gravity is more dominant factor to decide the stratification than shape. In comparison with the mixture of sphere-like ABS and disk-like PS, separation efficiency (sharpness index) was higher with mixture of disk-like ABS and sphere-like PS, may be due to the slowest settling velocity for disk-like, lighter ABS.
• Kinetic modeling of agglomeration-flotation of finely ground chalcopyrite

  Vothy Hornn, Ryosuke Yamazawa, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Imaizumi Yuji, Mayumi Ito  14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017  2017/01/01  [Not refereed][Not invited]
   

  ©The Mining and Materials Processing Institute of Japan Experimental results for flotation of finely ground chalcopyrite were compared with first order kinetic model. Batch flotation experiments were carried out with potassium xanthate as collector, using three ground samples having different size distribution. In the model, particle-bubble collision probability was considered as a function of size and velocity of mineral particle and bubble, and attachment and detachment probabilities were assumed to be 1 and 0, respectively. Flotation recovery was calculated from particle size distribution measured before flotation by laser diffraction and bubble size was assumed to be 1 mm. Particle size measured in ethanol as a dispersion medium was smaller than that measured in water (or flotation pulp), indicating that particles are naturally agglomerated in the flotation pulp. The results of model calculation fitted well with the experimental results (recovery – time curve) when size distribution measured in flotation pulp was used. Details of the application of the model to agglomeration-flotation are also discussed.
• A review of heterocoagulation and galvanic interaction of sulfide minerals

  Sophea Seng, Motoya Kojima, Kontani Yusuke, Carlito Baltazar Tabelin, Mayumi Ito, Naoki Hiroyoshi  14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017  2017/01/01  [Not refereed][Not invited]
   

  ©The Mining and Materials Processing Institute of Japan Heterocoagulation refers to the formation of colloidal particles with different properties in a suspension. The differentiation of particles could be based on composition, shape, size and surface potential or charge. Heterocoagulation plays an important role in minerals flotation. During the flotation the minerals that have different surface properties attached to one another forming new surface properties of the particle which lead to effect recovery of mineral. Galvanic interaction occurs when two metals with different rest potentials interact with one another. The metal with lower rest potential will act as an anode and is oxidized while another one with higher rest potential will become the cathode. Galvanic interaction is very important in ore processing. In flotation, galvanic interaction affects the flotability of the mineral due to the surface coating on mineral and the effect depends on many factors such as mineral/solution ratio. Moreover, in hydrometallurgy, the study of several leaching and bioleaching showed that galvanic interaction enhanced the leaching rate of metal recovery from different mineral and also affect the mechanism of sulfide dissolution. In this paper heterocoagulation and galvanic interaction of sulfide minerals is a reviewed from the researched that had been conducted over the past years.
• Synergistic effects of aluminum and other conductive particles on the cementation of gold ions from ammonium thiosulfate solutions

  Sanghee Jeon, Hirotaka Takahashi, Rongrit Ponsumrankul, Shinya Tanaka, Carlito Baltazar Tabelin, Mayumi Ito, Naoki Hiroyoshi  14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017  2017/01/01  [Not refereed][Not invited]
   

  © The Mining and Materials Processing Institute of Japan. Cementation (reductive deposition) of gold from 10ml of ammonium thiosulfate solution (1 M Na2S2O3, 0.5 M NH3, 0.25 M (NH4)2SO4, 10 mM CuSO4, pH 9.5-10) containing 100 ppm Au+ was done using Al powder as a reductant for 24 h at 25?, and the effects of the addition of other conductive particles (Cu, Fe, and activated carbon) were investigated. Gold was not deposited with solo addition of 0.15 g Al, Cu, Fe and activated carbon. When 0.15 g Cu or Fe were added together with 0.15 g of Al, 50 % of gold was deposited. When 0.15 g activated carbon was added with 0.15 g Al, gold deposition was over 99 %. These results indicate that gold cementation using Al as a reductant was promoted by the addition of Cu, Fe and activated carbon.
• Advanced soil washing of coarse size fraction containing cesium : Removal of vermiculite by magnetic separation

  伊藤 真由美, 湊川 和貴, Tabelin Carlito Baltazar, 広吉 直樹  地下水・土壌汚染とその防止対策に関する研究集会講演集  22-  389  -391  2016/06/23
• Recent Studies in Laboratory of Mineral Processing and Resources Recycling in Hokkaido University : Applications of Carrier Microencapsulation for Preventing Acid Mine Drainage Formation and Pyrite Flotation in Coal Cleaning

  広吉 直樹, 伊藤 真由美, Tabelin Carlito Baltazar  環境資源工学 = Resources processing : 資源処理技術  63-  (2)  61  -64  2016
• Electrochemical insights on pyrite dissolution in the presence of alumina

  S. Veerawattananun, D. Wiwattanadate, C.B. Tabelin, M. Ito, N. Hiroyoshi, T. Igarashi  the 9th International Conference on Earth Resources Technology  906  -917  2016  [Not refereed][Not invited]
  
• Suppression of arsenopyrite oxidation by carrier microencapsulation using Ti-catechol complex.

  I. Park, K. Magaribuchi, S. Veerawattananum, C.B. Tabelin, M. Ito, N. Hiroyoshi, T. Igarashi  the 9th International Conference on Earth Resources Technology,  918  -928  2016  [Not refereed][Not invited]
  
• Recovery methods for valuable metals from used printed circuit boards: A review.

  S. Jeon, M. Ito, Y. Nagata, N. Kitajima, S. Tanaka, R. Pongsumrankul, T. Yamamoto, C.B. Tabelin, N. Hiroyoshi  the 9th International Conference on Earth Resources Technology  564  -579  2016  [Not refereed][Not invited]
  
• A review of approaches to enhance sulfide-fines recovery by flotation

  V. Hornn, M. Ito, M. Kameya, T. Segawa, R. Yamazawa, C.B. Tabelin, N. Hiroyoshi  the 9th International Conference on Earth Resources Technology  461  -473  2016  [Not refereed][Not invited]
  
• Fundamental electrochemical studies of carrier micro-encapsulation on pyrite: The stability of metal-organic complexes

  S. Veerawattananun, D. Wiwattanadate, C.B. Tabelin, M. Ito, N. Hiroyoshi, T. Igarashi  Proceedings of the 15th Japan-Korea-France-Canada Joint Seminar on Geo-environmental Engineering,  141  -150  2016  [Not refereed][Not invited]
  
• The interplay between pyrite and hematite and its implications in acid mine drainage control

  C.B. Tabelin, S. Veerawattananum, M. Ito, N. Hiroyoshi, T. Igarashi  Proceedings of the 15th Japan-Korea-France-Canada Joint Seminar on Geo-environmental Engineering  141  -150  2016  [Not refereed][Not invited]
  
• Formation of schwertmannite-like and scorodite-like coatings on pyrite and its implications in acid mine drainage control

  C. B. Tabelin, R. D. Corpuz, S. Veerawattananun, M. Ito, N. Hiroyoshi, T. Igarashi  IMPC 2016 - 28th International Mineral Processing Congress  2016-September-  2016/01/01  [Not refereed][Not invited]
   

  © 2016 TAPPI Press. All rights reserved. Acid mine drainage (AMD), the very acidic and heavy metal-contaminated leachate generated when pyrite-bearing rocks are exposed to surface oxidizing conditions, is a serious environmental problem encountered after the closure of mines and mineral processing operations. In this study, we investigated the effects of soluble phases and metallic oxides, which are commonly found in strongly weathered pyritic wastes, on pyrite oxidation. Strongly weathered pyrite containing melanterite (FeSO4·7H2O) as the main soluble phase was obtained from Furikusa mine, Japan. The sample was washed using two methods to vary the relative amounts of melanterite in the sample. The effect of metallic oxides on pyrite oxidation was evaluated using ultrapure hematite suspensions. Our results showed that under acidic conditions, the effect of soluble salts on the oxidation of pyrite was stronger than hematite. More thorough washing of the sample resulted in the formation of an arsenic-bearing iron-oxyhydroxysulfate coating that minimized pyrite dissolution. This oxidized layer became relatively thicker and mechanically stronger when hematite was introduced after the more thorough removal of soluble salts. Characterization of this “coating” coupled with geochemical modeling suggest that it is most probably composed of two materials: schwertmannite and scorodite. Based on these results, a new approach to suppress pyrite oxidation by directly using iron-oxyhydroxysulfate as coating material is introduced.
• Sequestration of boron, arsenic and selenium leached from tunnel-excavated rocks through adsorption

  C.B. Tabelin, A. Hashimoto, T. Igarashi, M. Ito, N. Hiroyoshi  Proc. of the 14th Global Joint Seminar on Geo-environmental Engineering  5  2015  [Not refereed][Not invited]
  
• The effects of colloidal α-Fe2O3 on pyrite oxidative dissolution and their implications in the formation of acid mine drainage

  C.B. Tabelin, N. Hiroyoshi, M. Ito, T. Igarashi  Proc. of the 8th International Conference on Geological and Geo-resources Engineering and 7th Mineral Symposium  17  2015  [Not refereed][Not invited]
  
• The effects of ferric-catechol on pyrite oxidation,

  X. Li, S. Veerawattananun, C.B. Tabelin, N. Hiroyoshi, M. Ito  the 13th International Symposium on East Asian Resources Recycling Technology,  80  -87  2015  [Not refereed][Not invited]
  
• Acid Mine Drainage: Sources, environmental impacts and mitigation approaches

  C.B. Tabelin, M, Ito, N. Hiroyoshi, T. Igarashi  Proc. of the 2nd International Symposium Integrated Research and Education Center for Energy Conversion, Storage, Saving, and Transport Technologies,  13  -14  2015  [Not refereed][Not invited]
  
• Effects of water recirculation on the flotation of Kushiro and Mozambique Coals

  Mayumi Ito, Geraldo Conde Eliseu, Carlito Baltazar Tabelin, Naoki Hiroyoshi  EARTH 2015 - Proceedings of the 13th International Symposium on East Asian Resources Recycling Technology  88  -94  2015/01/01  [Not refereed][Not invited]
   

  Mozambique, a major exporter of coking and thermal coals, remains one of the world's most promising emerging coal supply sources because of its still untapped coal reserves. One of the coal mines located in the district of Moatize, Mozambique treats fine coal via flotation. However, the efficiency of the current operation is compromised due to the higher-than-optimum consumption of flotation reagents. To address this problem, it is imperative to first identify how factors like water quality, slime, and residual reagent concentrations affect the overall coal cleaning cycle. In this study, coal samples from Kushiro, Japan, and Moatize, Mozambique were first characterized to determine their chemical and mineralogical characteristics and sequential flotation experiments were carried out to evaluate the liberation properties. Flocculation tests of the coal and flotation in flocculant solution are also reported.
• Effect of copper wires on the recovery of valuable metals and plastics from crushed small home appliances by JIG separation

  Theerayut Phengsaart, Dawan Wiwattanadate, Mayumi Ito, Naoki Hamaya, Tabelin Carlito, Naoki Hiroyoshi  EARTH 2015 - Proceedings of the 13th International Symposium on East Asian Resources Recycling Technology  765  -770  2015/01/01  [Not refereed][Not invited]
   

  Jig separation, which separates particles based on differences in their densities, is one of the oldest and most widely used methods in mineral processing especially for coal cleaning, because of its simplicity of operation, low cost, and high efficiency. In this study, RETAC jig (R&E, Co., Ltd.), which is a modified TACUB jig for plastic-plastic separation, was applied to recover valuable metals and plastics from crushed end-of-life small home appliances. The results show that the separation efficiency decreased in the presence of copper wires. This is due to the copper wires easily get entangled in the separation chamber during jig separation, and these entangled copper wires trap plastic and prevent their motion in the chamber. However, it is unclear which factors control this entanglement process of copper wires. Therefore, effects of factors like length and amount of copper wires was investigated by using model samples of plastics and copper wires mixture. The results showed that both the length and quantity of copper wires were important in the entanglement. The possibility of removing the copper wires by a pre-treatment before the jig separation to increase the separation efficiency and recovery is also reported.
• Recovery of valuable components from crushed mobile phones using JIG separation

  Mayumi Ito, Naho Kitajima, Ayumu Saito, Surang Khanchang, Carlito Baltazar Tabelin, Naoki Hiroyoshi  EARTH 2015 - Proceedings of the 13th International Symposium on East Asian Resources Recycling Technology  748  -753  2015/01/01  [Not refereed][Not invited]
   

  The amount of discarded mobile phones is rapidly increasing worldwide, and the disposal is fast becoming a serious concern in both developed and developing countries. Mobile phones not only contain valuable metals like gold and copper but also recyclable plastics like Acrylonitrile Butadiene Styrene (ABS) and polyamide (PA). Recently, mobile phones and other electronic waste have become considered as "urban ores" (waste containing economically recoverable valuable metals/materials). This makes it necessary to develop robust and inexpensive techniques to recover these valuable materials from discarded mobile phones. One promising technique is to use jig concentrators, which have been utilized in the mineral processing industry for more than a century, to separate gangue and valuable minerals based on differences in specific gravities. Plastics generally have specific gravities very close to each other, and so are relatively difficult to separate using conventional jig separation. The hybrid jig solves this problem by attaching air bubbles on hydrophobic plastic particles to make them relatively lighter than plastic particles without attached bubbles (hydrophilic plastics). In this study, valuable components of mobile phones were recovered using both conventional and hybrid jig separation. The jig separation tests were carried out with a water pulsation of 2 cm displacement and 30/min frequency for 3 min. The vertical distributions of Cu in the particle bed with conventional and hybrid jigs were compared.
• Novel method to recover gold from printed circuit boards using ammonium thiosulfate media

  Naoki Hiroyoshi, Yoshito Nagata, Mayumi Ito, Carlito Baltazar Tabelin  EARTH 2015 - Proceedings of the 13th International Symposium on East Asian Resources Recycling Technology  742  -747  2015/01/01  [Not refereed][Not invited]
   

  Printed circuit boards (PCBs) contain valuable metals such as gold (Au), silver (Ag) and copper (Cu). PCBs are regarded as high concentration Au ore. In previous study, the effects of oxidants (Cu2+, O2) and ligands (S2O32-, NH3) on the ammonium thiosulfate leaching was researched. The leaching experiments were performed by mixing 0.1g of ground PCB and 10 mL of prepared leachants with varying concentrations of Na2S2O3 (0-3 M), CuSO4, (0-10 mM), (NH4)2SO4 (2.5-250 mM), and NH4OH (5-500 mM). The leaching experiments were shaken at 298 K with durations ranging from 0 to 72 hunder alkaline conditions (pH 9-10). The optimum conditions for the ammonium thiosulfate leaching of Au from PCBs are as follows: 1 M of Na2S2O3, 10 mM of CuSO4and 1 M of total ammonium concentration and a treatment time of 24 h. Under these conditions, ca. 99% of Au was extracted from the PCB sample. In this study, recovering Au from pregnant solution was investigated.
• Bubble attachment on plastic particles during hybrid JIG separation: Measurements during water pulsation

  Mayumi Ito, Nana Murase, Ayumu Saito, Carlito Baltazar Tabelin, Naoki Hiroyoshi  EARTH 2015 - Proceedings of the 13th International Symposium on East Asian Resources Recycling Technology  754  -761  2015/01/01  [Not refereed][Not invited]
   

  Hybrid jigs can separate two plastics having similar specific gravities and air bubbles are selectively attached to one of the plastics after its surface has been rendered hydrophobic. Bub bles attached to the surface change the apparents pecific gravity of hydrophobic plastics (they become lighter), and one can be separated from the other. The apparent specific gravity is directly related to the volume of bubbles attached to the surface of an ingredient, and this parameter is critical in the efficient operation of hybrid jigs. This paper describes apparatus developed to estimate attached bubble volumes under pulsation and the results of three plastic-plastic pairs (Polyvinyl chloride (PVC)-Polyethylene terephthalate (PET), Polypropylene with glass fiber (PPGF)-High density polys tyrene (HDPS) and Polyethylene (PE)-Cross linked polyethylene (XLPE)). Relations between the results with this apparatus and the hybrid jig are also reported.
• Leachability of arsenic from tunnel-excavated rock under free- and controlled-flow conditions,

  C.B. Tabelin, T. Igarashi, M. Ito, N. Hiroyoshi  Proc. of the 13th Global Joint Seminar on Geo-Environmental Engineering,  31  -37  2014  [Not refereed][Not invited]
  
• Immobilization of arsenic by schwertmannite synthesized from copper heap leach solutions,

  S. Houngaloune, N. Hiroyoshi, M. Ito, M. Fujimura  Proc. of the 6th international seminar on process hydrometallurgy (Hydroprocess2014)  (3)  2014  [Not refereed][Not invited]
  
• The leaching and speciation behaviors of arsenic and selenium in tunnel-excavated rocks under flow-through conditions,

  C.B. Tabelin, R. Sasaki, T. Igarashi, S. Tamoto, M. Ito, N. Hiroyoshi  Proc. of the 3rd International Conference on Advances in Mining and Tunneling  573  -581  2014  [Not refereed][Not invited]
  
• Enhanced encapsulation of pyrite using colloidal “micro-seeds”: Visualization and attachment experiments,

  C.B. Tabelin, N. Hiroyoshi, M. Ito, T. Igarashi  Proc. of the 7th AUN/SEED-Net Geological Engineering Conference and the 2nd AUN/SEED-Net Natural Disaster Conference,  20  2014  [Not refereed][Not invited]
  
• Gold leaching from waste printed circuit boards by ammonium thiosulfate leaching

  N. Hiroyoshi, Y. Nagata, M. Ito, C.B. Tabelin  Proc. of the 8th International Conference on Earth Resources Technology,  19  -23  2014  [Not refereed][Not invited]
  
• Tunnel-excavated rock: An invisible threat to the environment

  C. B. Tabelin, T. Igarashi, M. Ito, N. Hiroyoshi  ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014  2554  -2560  2014/01/01  [Not refereed][Not invited]
   

  © 2014 by Japanese Committee for Rock Mechanics. Tunnel excavation techniques have advanced phenomenally in the past decades, resulting in the construction of longer and wider tunnels even in very remote locations as well as in difficult geologies and topographies (e.g., sea bed). Because of this, tunnels have increasingly become essential parts of many road and railway systems. Tunnel construction requires the excavation of huge amounts of rocks, which are usually recycled as road or railway embankment material. However, our recent studies have shown that some of these tunnel-excavated rocks actually pose significant threats when exposed to the environment because they release substantial amounts of hazardous trace elements. Many of these elements (e.g., arsenic, selenium, lead and cadmium) have adverse human-health effects when ingested via contaminated drinking water and food crops. Unfortunately, the leaching behavior as well as the factors and physico-chemical processes controlling the release of these toxic elements from tunnelexcavated rocks are still poorly understood. In addition, management of these voluminous rocks using traditional waste disposal facilities (e.g., special landfills) is impractical and unsustainable. This paper presents a comprehensive summary of our laboratory and in situ studies, which evaluated the leaching behaviors and release mechanisms of the most commonly encountered toxic elements in tunnelexcavated rocks. We also described several alternative mitigation approaches that could minimize the negative impacts of these rocks on the environment.
• Treatment of cobalt-rich ferromanganese ore

  M. Ito, K. Asakura, S. Futakuchi, N. Hiroyoshi  26th International Mineral Processing Congress, IMPC 2012: Innovative Processing for Sustainable Growth - Conference Proceedings  2242  -2252  2012/12/01  [Not refereed][Not invited]
   

  Cobalt-rich ferromanganese crust and nodule ores from seamount areas contain volcanic and sedimentary rocks as substrate or nuclei and these ores require mineral processing to remove the substrate/nuclei rock before smelting. This paper reviews the results of jig separation and air table treatment for the coarse fraction and flotation and hybrid jigging for the fine fraction. Using these techniques substrate/nuclei rock was removed from the cobalt-rich ferromanganese oxide components. The mineralogical properties and metallurgical treatment methods including hydrometallurgical treatment of low grade ore is also reviewed.
• Hybrid jig separation of plastic particles and surface modification of the plastics

  M. Ito, M. Takeuchi, E. Ishida, N. Hiroyoshi, M. Tsunekawa  26th International Mineral Processing Congress, IMPC 2012: Innovative Processing for Sustainable Growth - Conference Proceedings  2235  -2241  2012/12/01  [Not refereed][Not invited]
   

  The authors have developed the RETAC jig (a modified TACUB jig) and have reported that the RETAC jig can separate relatively low density particles such as plastics. To further improve the separation ability, a hybrid jig (a RETAC jig with an air bubbler under the particle bed), which can separate plastics having similar specific gravities by the differences in the wettabilities of the particles was developed. Surface modification of plastics with similar wettability enabling separation in the hybrid jig and the effects of wettability control of the plastics using reagents are reported.
• ハイブリッドジグ選別のためのプラスチックの表面改質

  伊藤真由美, 竹内愛, 広吉直樹  資源・素材  2012-  25  2012/09/11  [Not refereed][Not invited]
  
• 各種比重選別によるコバルトリッチクラストと脈石の分離

  伊藤真由美, 朝倉賢, 広吉直樹, 恒川昌美  資源・素材  2012-  19  2012/09/11  [Not refereed][Not invited]
  
• Subcritical crack growth of Shirahama sandstone in water with various electrolyte concentrations

  Yoshitaka Nara, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko  Zairyo/Journal of the Society of Materials Science, Japan  61-  (7)  662  -667  2012/07  [Not refereed][Not invited]
   

  Knowledge of subcritical crack growth is essential to ensure the long-term integrity of engineering structures in a rock mass. It has been found that subcritical crack growth in rock is affected by surrounding environmental conditions. In most cases, rock found underground is saturated by water. The underground water can be fresh water or salt water with different electrolyte concentrations. However, the influence of electrolyte concentration on subcritical crack growth has not been clarified. In this study, we have measured subcritical crack growth in Shirahama sandstone in distilled water and in sodium chloride solutions with various concentrations using the Double Torsion method. We show that the crack velocity was the highest in distilled water and the lowest in sodium chloride solution with a concentration of 1.0mol/l. This result indicates the retardation of subcritical crack growth in Shirahama sandstone in sodium chloride solutions of 1.0mol/l. With increasing the electrolyte concentration, the width of the electric double layer on the surface of a solid decreases, which causes the decrease of the repulsive force acting on the crack surface. This leads to the decrease of the crack velocity up to the concentration of 1.0mol/l. On the other hand, when the concentration is higher than 1.0mol/l, the crack velocity increased. This is probably caused by the nucleation of microscopic defects on the boundary between clays and solid mineral grains, such as quartz and feldspar. It can be concluded that electrolyte concentration affects subcritical crack growth by decreasing the width of the electric double layer and compacting clays. © 2012 The Society of Materials Science, Japan.
• 回分式ジグ選別過程の圧力計測に基づく解析

  広吉直樹, 河合孝樹, 武田良介, 伊藤真由美  資源・素材学会春季大会講演集  2012-  214  -215  2012  [Not refereed][Not invited]
  
• 選択的電析・磁化を用いたAl合金の選別技術の開発

  伊藤真由美, 中村啓一郎, ALORRO Richard Diaz, 広吉直樹  資源・素材学会春季大会講演集  2012-  45  -46  2012  [Not refereed][Not invited]
  
• ベトナム・ドンパオ鉱石中のレアアース鉱物の選択粉砕と磁選

  伊藤真由美, 高松慎, 朝倉賢, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2012-  45  -46  2012  [Not refereed][Not invited]
  
• PVC/Nylonのハイブリッドジグ選別~プラスチックの濡れ性に及ぼすAOT添加の影響~

  伊藤真由美, 竹内愛, 広吉直樹, 恒川昌美  資源・素材学会春季大会講演集  2012-  216  -217  2012  [Not refereed][Not invited]
  
• 銅電解スライム浮選に関しての基礎的研究

  伊藤真由美, 池本貴志, 朝倉賢, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2012-  43  -44  2012  [Not refereed][Not invited]
  
• ブラウン管ガラス熔融処理残渣からの鉛の溶出機構

  広吉直樹, 高谷佳寛, 岡田敬志, 伊藤真由美, 稲野浩行  資源・素材学会北海道支部春季講演会講演要旨集  2012-  49  -50  2012  [Not refereed][Not invited]
  
• 合成マグネタイトによる塩化物溶液からの白金族の回収

  広吉直樹, 佐藤遼, HOMCHUEN Peet, 雉子谷東, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2012-  41  -42  2012  [Not refereed][Not invited]
  
• 低品位銅鉱ヒープリーチング溶液からのシュベルトマナイト生成に関する基礎的研究

  広吉直樹, 河合崇泰, 伊藤真由美, 岡本秀征  資源・素材学会春季大会講演集  2012-  190  -191  2012  [Not refereed][Not invited]
  
• 金属回収のためのFe/Al複合粒子の調製

  伊藤真由美, 祐川香太, 小杉正人, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2012-  47  -48  2012  [Not refereed][Not invited]
  
• Subcritical crack growth in sandstone in water with various electrolyte concentrations

  Y. Nara, R. Nakabayashi, N. Hiroyoshi, T. Yoneda, K. Kaneko, S. Murata, T. Ishida  Near Surface Geoscience 2012  2012/01/01  [Not refereed][Not invited]
   

  In order to ensure the long-term integrity of structures in a rock mass such as the repositories of radioactive wastes in underground knowledge of subcritical crack growth is essential. The underground water can be fresh water or salt water with different electrolyte concentrations. However, the influence of electrolyte concentration on subcritical crack growth has not been clarified. In this study, we have measured subcritical crack growth in Berea sandstone and Shirahama sandstone in distilled water and in salt water (sodium chloride solution) with various concentrations. Specifically, we have investigated the influence of the electrolyte concentration on the relationship between the stress intensity factor and the crack velocity. It is found that the electrolyte concentration affects the relation between the stress intensity factor and the crack velocity for sandstone which contains smectite, and has little influence in sandstone which contains few clays. For the sandstone containing smectite, the crack velocity decreased and the stress intensity factor increased with increasing the electrolyte concentration because of the reduction of repulsive force on the surface of expansive clay at high electrolyte concentration. It is concluded that the rock containing expansive clay becomes more stable under salt water condition.
• Influence of humidity and rock fabric on subcritical crack growth in rock

  Y. Nara, K. Kaneko, T. Yoneda, N. Hiroyoshi, K. Morimoto  HARMONISING ROCK ENGINEERING AND THE ENVIRONMENT  757  -760  2012  [Not refereed][Not invited]
   

  The influences of relative humidity and rock fabric on subcritical crack growth in rock have been investigated on samples of Kumamoto andesite, Berea sandstone and Shirahama sandstone. Stress intensity factor and crack velocity were measured using the double-torsion technique, and all experiments were conducted in moist air at constant temperature. Our results show that crack velocity increased dramatically with increasing relative humidity. A three-to five-fold increase in relative humidity resulted in increases in crack velocity of between one and five orders of magnitude for Kumamoto andesite and Berea sandstone, and between nine and ten orders of magnitude for Shirahama sandstone. Such increases are much larger than those predicted by classical stress corrosion theory. The increase of the crack velocity was larger for rock which contained larger amount of clays. We conclude that subcritical crack growth in rock is affected remarkably by relative humidity and the amount of clays.
• Jig separation of crushed automobile shredded residue and its evaluation by float and sink analysis

  Yutaka Kuwayama, Mayumi Ito, Noki Hiroyoshi, Masami Tsunekawa  JOURNAL OF MATERIAL CYCLES AND WASTE MANAGEMENT  13-  (3)  240  -246  2011/10  [Not refereed][Not invited]
   

  Automobile shredded residue is a potential solid fuel when its metal and chloride-containing components have been removed. The authors have investigated physical separation of automobile shredded residue to isolate components that may be used as solid fuel and reported that agglomerates of entangling fiber-like material are formed during crushing. These agglomerates make removal of metals and chloride-containing components difficult, and the paper proposes a treatment flowchart consisting of separate treatments of the coarse size fraction containing entangling fiber-like components and the smaller size fraction containing particulate matter. This paper reports the treatment of the smaller size fraction treated with jigging to obtain a low-ash and low-chloride-content product. A new washability curve was developed based on float and sink analysis test results, and it was applied to estimate the gravity separation performance of treatments such as jigging and dense medium separation. The estimated results show good agreement with the experimental results of jig separation.
• ジグ内粒子運動の圧力計測に基づく解析

  広吉直樹, 河合孝樹, 武田良介, 伊藤真由美, 恒川昌美  資源・素材  2011-  (2)  197  -198  2011/09/26  [Not refereed][Not invited]
  
• 銅製錬スラグを用いた塩化物溶液からの金回収

  広吉直樹, 雉子谷東, ALORRO Richard Diaz, 伊藤真由美  資源・素材  2011-  (2)  135  -136  2011/09/26  [Not refereed][Not invited]
  
• 銅製錬所鉛澱物の鉛濃縮に関する研究

  広吉直樹, 大山史織, 伊藤真由美  資源・素材  2011-  (2)  203  -204  2011/09/26  [Not refereed][Not invited]
  
• Fe/Al複合粒子を用いた金属溶液からの金属回収

  伊藤真由美, 小杉正人, 祐川香太, 広吉直樹  資源・素材  2011-  (2)  141  -142  2011/09/26  [Not refereed][Not invited]
  
• ベトナム・ドンパオ鉱石中のレアアース鉱物の回収~粉砕・分級特性~

  恒川昌美, 西川千尋, 伊藤真由美, 広吉直樹, SATUR Jacqueline Vidal  資源・素材  2011-  (2)  137  -138  2011/09/26  [Not refereed][Not invited]
  
• 海底熱水鉱床鉱石中の閃亜鉛鉱の浮選挙動

  伊藤真由美, 二口修吏, 朝倉賢, 高橋達, 広吉直樹, 恒川昌美  資源・素材  2011-  (2)  139  -140  2011/09/26  [Not refereed][Not invited]
  
• 2-331 Faculty Development at Course of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University

  FUJII Yoshiaki, IGARASHI Toshifumi, HIROYOSHI Naoki  工学教育研究講演会講演論文集  23-  (59)  538  -539  2011/08/22
• 7-326 Internship Programs in the Course of Sustainable Resources Engineering, School of Engineering, Hokkaido University

  ITO Mayumi, HIROYOSHI Naoki, IGARASHI Toshifumi  工学教育研究講演会講演論文集  23-  (59)  620  -621  2011/08/22  [Not refereed][Not invited]
  
• ヒ素含有銅鉱石のヒープリーチングに関する基礎的研究

  広吉直樹, 河合崇泰, 伊藤正樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2011-  41  -42  2011  [Not refereed][Not invited]
  
• ベトナム・ドンパオ鉱石中のレアアース鉱物の回収~粉砕・分級特性~

  恒川昌美, 西川千尋, 伊藤真由美, 広吉直樹, SATUR Jacqueline Vidal  資源・素材学会春季大会講演集  2011 (CD-ROM)-  ROMBUNNO.2123  2011  [Not refereed][Not invited]
  
• 海底熱水鉱床鉱石の選鉱に関する基礎的研究~加温浮選とKnelson Concentratorを用いた銅・鉛・亜鉛鉱物の分離~

  伊藤真由美, 朝倉賢, 二口修吏, 高橋達, 広吉直樹, 恒川昌美  資源・素材学会北海道支部春季講演会講演要旨集  2011-  39  -40  2011  [Not refereed][Not invited]
  
• 海底熱水鉱床鉱石のジグによる比重選別

  伊藤真由美, 二口修吏, 朝倉賢, 高橋達, 広吉直樹  海洋工学シンポジウム(CD-ROM)  22nd-  ROMBUNNO.OES22-008  2011  [Not refereed][Not invited]
  
• ジグ内粒子運動の圧力計測に基づく解析

  広吉直樹, 河合孝樹, 武田良介, 伊藤真由美, 恒川昌美  資源・素材学会春季大会講演集  2011 (CD-ROM)-  ROMBUNNO.2103  2011  [Not refereed][Not invited]
  
• 銅製錬スラグを用いた塩化物溶液からの金回収

  広吉直樹, 雉子谷東, ALORRO Richard Diaz, 伊藤真由美  資源・素材学会春季大会講演集  2011 (CD-ROM)-  ROMBUNNO.2110  2011  [Not refereed][Not invited]
  
• ジグ内粒子運動の圧力損失に基づくセンシング

  広吉直樹, 河合孝樹, 武田良介, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2011-  33  -34  2011  [Not refereed][Not invited]
  
• 海底熱水鉱床鉱石中の閃亜鉛鉱の浮選挙動

  伊藤真由美, 二口修吏, 朝倉賢, 高橋達, 広吉直樹, 恒川昌美  資源・素材学会春季大会講演集  2011 (CD-ROM)-  ROMBUNNO.2121  2011  [Not refereed][Not invited]
  
• プラスチックのハイブリッドジグ選別に及ぼす濡れ性制御の影響~PVC/NylonとHDPS/PPGFの選別~

  伊藤真由美, 竹内愛, 石田絵美, 赤塚真依子, 広吉直樹, 恒川昌美  資源・素材学会北海道支部春季講演会講演要旨集  2011-  35  -36  2011  [Not refereed][Not invited]
  
• Al合金リサイクルのための選択的電析・磁化技術の開発~銅含有Al合金とその他のAlの選別~

  伊藤真由美, DIAZ ALORRO Richard, 中村啓一郎, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2011-  37  -38  2011  [Not refereed][Not invited]
  
• Temperature dependence of calcium carbonate precipitation for biogrout

  S. Ogata, S. Kawasaki, N. Hiroyoshi, M. Tsunekawa, K. Kaneko, R. Terajima  Rock Engineering in Difficult Ground Conditions - Soft Rocks and Karst - Proceedings of the Regional Symposium of the International Society for Rock Mechanics, EUROCK 2009  339  -344  2010/12/01  [Not refereed][Not invited]
   

  A series of fundamental laboratory tests was performed to develop a novel conceptual grout, that improves the sealability of soil and rock using microorganisms, hereafter denoted as biogrout. Biogrout, which includes calcium ions and glucose, is a material to produce the precipitation of calcium carbonate (CaCO 3), which plugs voids of rock and soil and, moreover, cracks of rock. In our previous studies, precipitation tests on CaCO 3 were carried out at 25°C. This paper especially focuses on evaluating the influence of the temperature on the precipitation of CaCO 3 to consider applications of biogrout in soils of various areas with varying climates. In laboratory tests, biogrout was added to soils from various areas in Japan under wide-ranging temperatures (5 to 35°C), and the results showed that the temperature highly affected the precipitation of CaCO 3 because of the temperature dependence of microbial metabolism. © 2010 Taylor & Francis Group, London.
• Recovery of precious metals from chloride solution by magnetite

  R. Alorro, N. Hiroyoshi, M. Ito, M. Tsunekawa  XXV International Mineral Processing Congress 2010, IMPC 2010  1-  263  -271  2010/12/01  [Not refereed][Not invited]
   

  The development of environmental-friendly lixiviants as alternatives to cyanide and the increasing recycling activities to recover precious metals from waste materials have prompted researchers to fi nd effi cient methods and alternative sorbents to recover precious metals, such as Au and Pt, from aqueous solutions. This study explored the use of magnetite (Fe3O4) as a sorbent to recover Au and Pt from chloride solutions. Magnetite is a semiconductor and has the capability of transferring electrons both within the solid state and across the solid-liquid interface and has the ability to reduce metal species on its surface. The sorption of AuCl4 - and PtCl62- from NaCl solution on commercial grade magnetite powder was investigated by batch-sorption experiments. The effects of pH, contact time, NaCl concentration and precious metal concentration on the recovery were studied. Sorption experiments revealed that magnetite exhibited selectivity towards other metals with the strongest affi nity for Au. Both Au and Pt recoveries showed similar pH dependence curves, with peaks at pH 6 - 7. At this pH range, a maximum of 4.4 μmol Au/g Fe3O4 and 3.0 μmol Pt/g Fe3O4 were recovered after 24 h at an initial metal concentration of 0.05 mol/m3. Increasing the initial precious metal concentration increased the Au and Pt uptake amount by magnetite. It was also observed that the recovery decreased with high NaCl concentrations. The SEM images of the magnetite particles after the treatment showed that gold, which was confi rmed by the EDX analysis, agglomerated and were deposited on Fe3O4 surface.
• Advanced Jig separation of shredded plastics

  M. Ito, M. Akatsuka, E. Ishida, K. Hori, N. Hiroyoshi, M. Tsunekawa  XXV International Mineral Processing Congress 2010, IMPC 2010  2-  843  -850  2010/12/01  [Not refereed][Not invited]
   

  The authors have reported that the RETAC jig is very useful in separating relatively low densityparticles such as plastics, and demonstrated that highly effi cient jig separation of plastic componentsin discarded offi ce machines is possible in pilot-scale tests. To further improve the separationeffi ciency, a hybrid jig (RETAC jig with air bubbler under the particle bed) which can separate plasticshaving similar specifi c gravities using differences in wettability produced by a pretreatment, and areverse jig (modifi ed RETAC jig for plastics lighter than water) were developed. This paper reviewsthe separation of shredded plastics using advanced jig separation technology (RETAC, hybrid andreverse jigs). Wettability control of the plastics for the advanced jig separation is also reported.
• Carrier micro encapsulation (CME) for suppressing pyrite floatability and oxidation in coal preparation

  R. Jha, J. Satur, N. Hiroyoshi, M. Ito, M. Tsunekawa  XXV International Mineral Processing Congress 2010, IMPC 2010  3-  2025  -2033  2010/12/01  [Not refereed][Not invited]
   

  On coal combustion, Pyrite, FeS2, in coal causes the emission of SO2; a major air pollutant and contributor in acid rain formation. Froth flotation has been applied for the removal of pyrite from coal, but the hydrophobic property of pyrite makes the removal of pyrite difficult. Formation of acid mine drainage due to pyrite oxidation in tailing dam is another important problem associated with pyrite. In the present paper, carrier-microencapsulation (CME) as a selective coating technique for pyrite using water-soluble organic carrier combined with metal ions is applied to suppress the pyrite floatability and its oxidation. Lab scale floatation experiments with Si4+or Ti4+as metal ion and catechol as organic carrier illustrates that formed coating converts the surface property of pyrite from hydrophobic to hydrophilic; therefore, pyrite floatability was successfully suppressed. After the CME treatment, the selective suppression for pyrite was observed in bubble pick up experiments, within wide range of slurry pH (4-10) with Si4+or Ti4+-catechol complex concentration (>0.5 mol m-3) in 2 - 60 min CME treatment time. Flotation experiments indicated that CME treatment suppresses pyrite floatability even in the presence of flotation collectors such as kerosene; with no significant suppression effect on coal floatability. The SEM-EDX analysis of CME treated pyrite confirms the formation of Si or Ti oxide/hydroxide thin layer on the surface. One month leaching experiments for pyrite showed that Si or Ti oxide/hydroxide layer acts as protective coating against pyrite oxidation, implying that CME treatment may be effective to suppress the formation of acid mine drainage due to pyrite oxidation in tailing pond.
• 混合プラスチックの湿式比重選別―RETAC JIGの原理と応用

  堀邦紘, 恒川昌美, 阿部中, 広吉直樹, 伊藤真由美, 岡田敦志, 丹野秀昭  高分子学会予稿集(CD-ROM)  59-  (2 Disk1)  ROMBUNNO.3Z03  2010/09/01  [Not refereed][Not invited]
  
• 複雑希土類鉱石中のバストネサイトの浮選分離(第2報)

  恒川昌美, 西川千尋, 伊藤真由美, 広吉直樹, SATUR Jacqueline Vidal  資源・素材学会春季大会講演集  (2)  53  -54  2010/03/30  [Not refereed][Not invited]
  
• 液晶パネルのリサイクルに関する基礎的研究

  恒川昌美, 朝比奈遼, 広吉直樹, 伊藤真由美, 浜野孝俊, 志村一美  資源・素材学会春季大会講演集  (2)  177  -178  2010/03/30  [Not refereed][Not invited]
  
• 硫化鉱物の浮遊性に及ぼすキャリアマイクロエンカプセレーションの効果

  広吉直樹, 川代晋太郎, JHA Rani, Kumari Thakur, 恒川昌美, 伊藤真由美  資源・素材学会春季大会講演集  (2)  51  -52  2010/03/30  [Not refereed][Not invited]
  
• 黄銅鉱浸出のためのマグネタイト利用に関する研究

  広吉直樹, 伊藤正樹, 竹原裕生, 恒川昌美, 伊藤真由美  資源・素材学会春季大会講演集  (1)  29  -30  2010/03/30  [Not refereed][Not invited]
  
• 電線被覆PVCからの鉛除去~三塩基性硫酸鉛と金属酸化物の凝集・分散~

  広吉直樹, 酒井智生, 三村隼生, 恒川昌美, 伊藤真由美  資源・素材学会春季大会講演集  (2)  179  -180  2010/03/30  [Not refereed][Not invited]
  
• Effect of surrounding environment on subcritical crack growth index and long-term strength for rock

  Yoshitaka Nara, Toshifumi Igarashi, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko  Zairyo/Journal of the Society of Materials Science, Japan  59-  (3)  180  -185  2010/03  [Not refereed][Not invited]
   

  Study of subcritical crack growth is important in estimating the long-term strength of rock and in ensuring the long-term stability of structures in a rock mass. The long-term strength is affected by the value of subcritical crack growth index (SCGI). However, the effect of environmental conditions on SCGI has not been clarified. In this study, we have estimated SCGI under various environmental conditions on a sample of Kumamoto andesite, using the Double-Torsion method. We show that the SCGI decreased when the temperature is higher in both air and water, the SCGI in water is smaller than that in air. When the relative humidity of the air increased, SCGI tended to be smaller and at 90 % relative humidity was close to the value in water. Under alkali conditions, the SCGI decreased slightly. Using the values of SCGI, the long-term strength was estimated and it is shown that the long-term strength decreased when SCGI was smaller. It is concluded that SCGI and the long-term strength is affected by the surrounding environment, specifically by the temperature and water. To ensure the long-term stability of rock, the control of the temperature and water migration is important. © 2010 The Society of Materials Science, Japan.
• 深海底鉱物資源開発のための選鉱法の確立

  伊藤真由美, 恒川昌美, 広吉直樹  資源・素材  2010-  (1)  245  -246  2010  [Not refereed][Not invited]
  
• リバースジグの選別性に及ぼす各種要因の検討

  恒川昌美, 河合孝樹, 石田絵美, 広吉直樹, 伊藤真由美, 阿部中  資源・素材学会北海道支部春季講演会講演要旨集  2010-  45  -46  2010  [Not refereed][Not invited]
  
• マグネタイトによる塩化物溶液からの金吸着

  広吉直樹, 雉子谷東, DIAZ ALORRO Richard, 恒川昌美, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2010-  41  -42  2010  [Not refereed][Not invited]
  
• メッキ廃水汚泥の安定性評価と資源化に関する研究

  恒川昌美, 大山史織, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2010-  27  -28  2010  [Not refereed][Not invited]
  
• カーシュレッダーダストからの低塩素分・低灰分可燃物の回収

  恒川昌美, 小杉正人, 桑山豊, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2010-  29  -30  2010  [Not refereed][Not invited]
  
• 海底熱水鉱床鉱石の選鉱

  伊藤真由美, 二口修吏, 高橋達, 広吉直樹, 恒川昌美  資源・素材学会北海道支部春季講演会講演要旨集  2010-  43  -44  2010  [Not refereed][Not invited]
  
• Effect of water on subcritical crack growth index and long-term strength for rock

  Y. Nara, T. Igarashi, N. Hiroyoshi, T. Yoneda, K. Kaneko  72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010  6-  4386  -4390  2010/01/01  [Not refereed][Not invited]
   

  Long-term stability is required for the structures in a rock mass. Especially, the estimation of long-term strength of rock is essential to consider the long-term stability. In this study, we investigated the time-dependent crack growth in rock. Specifically, subcritical crack growth in water and in air with different relative humidities was measured in order to investigate the effect of water on the value of subcritical crack growth index and the long-term strength for rock. It was shown that subcritical crack growth index in water was smaller than that in air. Additionally, subcritical crack growth index tended to be smaller when the relative humidity was higher. The long-term strength in water was smaller than that in air. In air, the long-term strength tended to be smaller when the relative humidity was higher. The long-term strength is larger when subcritical crack growth index is larger. For the long-term stability, it is thus important to achieve a condition where subcritical crack growth index becomes larger. It is concluded that retarding the migration of water into and through rock and keeping low humidity is important. © 2010, European Association of Geoscientists and Engineers.
• Removal of mn ions by biological co-precipitation of fe ions

  Kyoungkeun Yoo, Naoki Hiroyoshi, Masami Tsunekawa  Geosystem Engineering  13-  (3)  91  -96  2010  [Not refereed][Not invited]
   

  The behaviors of manganese ions during biological precipitation of iron ions by Acidithiobacillus ferrooxidans was investigated to remove the Mn ions from acid mine drainage. The effect of initial Fe2+ ion concentration with 900 g·m−3, 4500 g·m−3, and 9000 g·m−3 on the removal of Mn ions was examined by measuring pH, ORP, and the concentrations of Fe and Mn ions. In the experiments with the Fe2+ concentration with 4500 g·m−3 and 9000 g·m−3, pH increased and then decreased by the oxidation of Fe2+ and the precipitation of Fe ions. In all solutions, ORP increased to 630 mV, and Fe concentration decreased with Fe precipitation. Adding NaOH increased the amount of Fe precipitate and the Mn removal ratio in the early stage but there was no significant effect as the experiments were proceeded. © 2010 Taylor & Francis Group, LLC.
• Surface modification of shredder residue plastics for hybrid jig processing

  M. Ito, M. Akatsuka, Y. Kuwayama, K. Hori, N. Hiroyoshi, M. Tsunekawa  The Minerals, Metals and Materials Society - 3rd International Conference on Processing Materials for Properties 2008, PMP III  1-  315  -320  2009/12/01  [Not refereed][Not invited]
   

  The authors have reported that the RETAC jig (modified TACUB jig) is very useful in separating relatively low density particles such as plastics, and demonstrated that highly efficient jig separation of plastic components used in waste office machines could be possible in pilot-scale tests. To further improve the separation efficiency, a hybrid jig (RETAC jig with air bubbler under the particle bed), which can separate plastics having similar specific gravities using differences in wettability produced by a pretreatment was developed. This study describes the wettability control of plastics (PP, PE, PS, ABS, and PVC) of waste home appliances for hybrid jig separation. The effect of the surfactant solutions on the contact angle of the plastics is investigated and suitable surfactants and surfactant concentrations to separate plastics having similar specific gravities are determined.
• レパント金鉱山廃石の電気パルス粉砕処理特性

  伊藤真由美, 浜野孝俊, 広吉直樹, 恒川昌美  資源・素材学会春季大会講演集  (2)  83  -84  2009/03/26  [Not refereed][Not invited]
  
• 微粒子のジグ選別

  恒川昌美, 扇子渉, 堀邦紘, 小林利輝, 伊藤真由美, 広吉直樹  資源・素材学会春季大会講演集  (2)  169  -170  2009/03/26  [Not refereed][Not invited]
  
• 非水/水溶液界面への鉛含有微粒子の捕捉現象

  恒川昌美, 三村隼生, 酒井智生, 広吉直樹, 伊藤真由美  資源・素材学会春季大会講演集  (2)  115  -116  2009/03/26  [Not refereed][Not invited]
  
• 綿状物を含むASR粉砕産物中の不燃物,塩素の物理選別による除去

  桑山豊, 伊藤真由美, 赤塚真依子, 広吉直樹, 恒川昌美  資源・素材学会春季大会講演集  (2)  105  -106  2009/03/26  [Not refereed][Not invited]
  
• 圧力センサーを用いたジグ選別のモニタリング

  恒川昌美, 秋元淳希, 堀邦紘, 小林利輝, 広吉直樹, 伊藤真由美  資源・素材学会春季大会講演集  (2)  173  -174  2009/03/26  [Not refereed][Not invited]
  
• コバルトリッチクラストの細粒群のジグ選別

  伊藤真由美, 高橋達, 關村健吾, 広吉直樹, 恒川昌美  資源・素材学会春季大会講演集  (2)  85  -86  2009/03/26  [Not refereed][Not invited]
  
• 家電プラスチックのアドバンストジグ選別

  伊藤真由美, 赤塚真依子, 石田絵美, 高橋達, 桑山豊, 広吉直樹, 恒川昌美  資源・素材  2009-  38  2009  [Not refereed][Not invited]
  
• コバルトリッチクラストの選鉱法の確立

  伊藤真由美, 恒川昌美, 広吉直樹  資源・素材  2009-  (1)  235  -238  2009  [Not refereed][Not invited]
  
• 硫酸溶液中での黄銅鉱浸出に対するマグネタイトの影響

  広吉直樹, 伊藤正樹, 竹原裕生, 恒川昌美, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2009-  49  -50  2009  [Not refereed][Not invited]
  
• 複雑希土類鉱石の選鉱

  恒川昌美, 西川千尋, SATUR Jacqueline Vidal, 伊藤真由美, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2009-  47  -48  2009  [Not refereed][Not invited]
  
• コバルトリッチクラストの選鉱と希少金属の回収

  伊藤真由美, 高橋達, ALORRO Richard D, 關村健吾, 広吉直樹, 恒川昌美  資源・素材  2009-  32  2009  [Not refereed][Not invited]
  
• 電線被覆PVCからの鉛含有微粒子の除去

  広吉直樹, 酒井智生, 三村隼生, 恒川昌美, 伊藤真由美  資源・素材  2009-  41  2009  [Not refereed][Not invited]
  
• 各種センサーを用いたジグ選別特性の把握

  恒川昌美, 秋元淳希, 広吉直樹, 伊藤真由美  資源・素材  2009-  37  2009  [Not refereed][Not invited]
  
• Lepanto金鉱山廃石の電気パルス粉砕

  伊藤真由美, 浜野孝俊, 広吉直樹, 恒川昌美  資源・素材  2009-  31  2009  [Not refereed][Not invited]
  
• 複雑希土類鉱石中のバストネサイトの浮選分離

  恒川昌美, 西川千尋, VIDAL SATUR Jacqueline, 伊藤真由美, 広吉直樹  資源・素材  2009-  35  2009  [Not refereed][Not invited]
  
• 焼却灰の脱塩素特性に関する研究

  恒川昌美, 朝比奈遼, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2009-  55  -56  2009  [Not refereed][Not invited]
  
• 微粒子ジグ選別における諸要因の影響

  扇子渉, 恒川昌美, 広吉直樹, 伊藤真由美  資源・素材  2009-  36  2009  [Not refereed][Not invited]
  
• カテコール類似物質による酸化鉱物の選択的表面改質

  広吉直樹, 川代晋太郎, JHA Rani, Kumari Thakur, 恒川昌美, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2009-  51  -52  2009  [Not refereed][Not invited]
  
• 非水溶媒中に懸濁する鉛含有微粒子の固体表面への吸着除去

  広吉直樹, 酒井智生, 三村隼生, 恒川昌美, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2009-  53  -54  2009  [Not refereed][Not invited]
  
• Physical separation of crushed product of waste nickel-metal hydride batteries from hybrid vehicles

  M. Ito, M. Tsunekawa, K. Kashiwaya, N. Sumiya, H. Furuya, N. Hiroyoshi  Proceedings of the 2008 Global Symposium on Recycling, Waste Treatment and Clean Technology, REWAS 2008  3  -8  2008/12/01  [Not refereed][Not invited]
   

  The number of hybrid vehicles is increasing and this is causeing an increase in waste nickel-metal hydride batteries. The cathode activating agent of batteries is made of nickel hydroxide and the anode activating agent is an alloy of nickel and rare earth elements. Conventional rotary kiln methods cannot recover the rare earth elements, and hydrometallurgical treatment of crushed product consumes large volumes of agent. The physical separation of the anode alloy from the cathode hydroxide would make it possible to reuse the alloy. The authors have reported separation of anode and cathode components in the large size fractions using a newly developed dry magnetic separation method. Wet magnetic separation has been applied to the powder fraction and about 90% anode purity was achieved. This paper reviews experimental results from previous publications and proposes an integrated treatment process for crushed nickel-metal hydride batteries.
• Improved chalcopyrite leaching through optimization of redox potential

  N. Hiroyoshi, M. Tsunekawa, H. Okamoto, R. Nakayama, S. Kuroiwa  CANADIAN METALLURGICAL QUARTERLY  47-  (3)  253  -258  2008/07  [Not refereed][Not invited]
   

  In the leaching of chalcopyrite with sulphuric acid solutions, the copper extraction rate reaches a maximum at a given redox potential. This article reviews our studies on the determination of the optimum redox potential for chalcopyrite leaching. Shaking flask and column leaching experiments for a chalcopyrite concentrate were performed under various conditions and the results were analyzed using a normalized redox potential defined from a reaction model assuming the formation of an intermediate Cu2S from chalcopyrite. Factors, such as metal ion concentrations, solid/liquid ratio and the presence of iron-oxidizing bacteria, caused significant variations in the copper extraction versus time plots. However the copper extraction rate versus normalized redox potential plots were independent of the above factors and the copper extraction rate reached a maximum at the normalized redox potentials around 0.43. Converting the normalized redox potential to the solution redox potential gives the optimum redox potential for chalcopyrite leaching as a function of cupric and ferrous ion concentrations. This semi-empirical equation can be used to predict the optimum redox potential during leaching operation and is useful to design the redox-controlled heap leaching for chalcopyrite.
• コバルトリッチクラストの選鉱に関する基礎的研究 第二報

  恒川昌美, 伊藤真由美, 關村健吾, 山口英志, 高橋達, 柏谷公希, 広吉直樹  資源・素材学会春季大会講演集  (2)  197  -198  2008/03/27  [Not refereed][Not invited]
  
• ジグ選別における粒子の沈降挙動と選別パターン

  堀邦紘, 恒川昌美, 広吉直樹, 伊藤真由美  資源・素材学会春季大会講演集  (2)  109  -110  2008/03/27  [Not refereed][Not invited]
  
• 連続式網下気室型ジグ(RETAC Jig)選別の高度化に関する基礎的研究

  恒川昌美, 小林利輝, 堀邦紘, 岡田英明, 広吉直樹, 伊藤真由美  資源・素材学会春季大会講演集  (2)  107  -108  2008/03/27  [Not refereed][Not invited]
  
• 鉛汚染土壌からの鉛分リーチングおよび鉛濃縮に関する基礎的研究 第4報

  伊藤真由美, 高田政雄, 帆苅直弘, 恒川昌美, 広吉直樹  資源・素材学会春季大会講演集  (2)  189  -190  2008/03/27  [Not refereed][Not invited]
  
• 黄銅鉱のカラムリーチング

  広吉直樹, 竹原裕生, 桑澤毅成, 恒川昌美, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2008-  43  -44  2008  [Not refereed][Not invited]
  
• 非水/水溶液界面への微粒子の捕捉現象とそのメカニズム

  恒川昌美, 三村隼生, 佐々木勇太, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2008-  47  -48  2008  [Not refereed][Not invited]
  
• コバルトリッチクラスト・ノジュールと脈石のJIG選別~大型JIG処理試験と最適運転条件の検討~

  伊藤真由美, 高橋達, 關村健吾, 広吉直樹, 恒川昌美  資源・素材学会北海道支部春季講演会講演要旨集  2008-  45  -46  2008  [Not refereed][Not invited]
  
• 鉛汚染土壌からの鉛分の溶解およびセメンテーション~セメンテーションの検討~

  伊藤真由美, 高田政雄, 帆苅直弘, 恒川昌美, 広吉直樹  資源・素材  2008-  44  2008  [Not refereed][Not invited]
  
• ジグ選別プロセスにおける粒子流動化現象と最適条件

  恒川昌美, 秋元淳希, 堀邦紘, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2008-  7  -8  2008  [Not refereed][Not invited]
  
• 微粒子用ジグ選別機に関する基礎的研究

  恒川昌美, 扇子渉, 堀邦紘, 小林利輝, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2008-  5  -6  2008  [Not refereed][Not invited]
  
• 湿式サイクロンにおける微粒子の挙動に及ぼす粒子形状の影響

  柏谷公希, 能町聖彦, 伊藤真由美, 広吉直樹, 恒川昌美  資源・素材  2008-  32  2008  [Not refereed][Not invited]
  
• コバルトリッチクラストの選鉱に関する基礎的研究 第三報

  關村健吾, 恒川昌美, 伊藤真由美, 高橋達, 広吉直樹  資源・素材  2008-  17  2008  [Not refereed][Not invited]
  
• プラスチックの表面改質とハイブリットジグへの適用

  赤塚真依子, 伊藤真由美, SATUR Jacqueline, 桑山豊, 広吉直樹, 恒川昌美  資源・素材  2008-  34  2008  [Not refereed][Not invited]
  
• Effects of coexisting metal ions on the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions

  N. Hiroyoshi, S. Kuroiwa, H. Miki, M. Tsunekawa, T. Hirajima  HYDROMETALLURGY  87-  (1-2)  1  -10  2007/06  [Not refereed][Not invited]
   

  The leaching rate of chalcopyrite (CuFeS2) in H2SO4 solutions depends on the redox potential determined by the concentration ratio of Fe3+ to Fe2+, and the rate is higher at redox potentials below a critical value (critical potential). In actual leaching systems, different metal ions are released from coexisting minerals to the aqueous phase. The present study investigated the effects of coexisting metal ions on the critical potential of chalcopyrite leaching. Shaking-flask leaching experiments were carried out with 0. 1 g of ground chalcopyrite and 10 cm(3) of 0.1 kmol m(-3) H2SO4 containing 0.1 kmol m(-3) Fe2+ and 0.001 kmol m(-3) of the metal ions at 298 K in air. The initial redox potential was adjusted by adding Fe3+, and the amount of Cu extracted after 24 h was investigated as a function of the potential. The results indicate that the critical potential increases by the addition of Ag+ or Bi3+ but is not affected by Pd2+, Hg2+, Cd2+, Zn2+, Ni2+, Co2+, or Mn2+. The results were interpreted by a reaction model assuming the formation of intermediate CU2S due to the reduction of chalcopyrite and subsequent oxidation of the CU2S at potentials below the critical potential. Catalytic effects of metal ions on chalcopyrite leaching are also discussed based on the experimental results and the proposed model. (C) 2007 Published by Elsevier B.V.
• メタ珪酸ナトリウムを用いたバイオグラウト

  小林 元, 川崎 了, 広吉 直樹, 恒川 昌美, 金子 勝比古, 島田 俊介  春季大会講演集. I, 資源編  19-  (2)  73  -74  2007/03/29
• 水溶液中での岩石のサブクリティカルき裂進展に関する研究

  奈良 禎太, 高田 雅史, 五十嵐 敏文, 広吉 直樹, 金子 勝比古  春季大会講演集. I, 資源編  19-  (1)  47  -48  2007/03/29
• Recovery of Heavy Metals from MSW Melting Fly Ash by Carrier-in-Pulp Method

  ALORRO Richard D., HIROYOSHI Naoki, ITO Mayumi, TSUNEKAWA Masami  春季大会講演集. I, 資源編  19-  (2)  161  -162  2007/03/29
• 鉛汚染土壌からの鉛分リーチングおよび鉛濃縮に関する基礎的研究 第3報

  伊藤真由美, 帆苅直弘, 高田政雄, 恒川昌美, 広吉直樹  資源・素材学会春季大会講演集  (1)  KIKAKU.85-KIKAKU.86  2007/03/29  [Not refereed][Not invited]
  
• 鉛汚染土壌からの鉛分リーチングおよび鉛濃縮に関する基礎的研究 第3報

  伊藤 真由美, 帆苅 直弘, 高田 政雄, 恒川 昌美, 広吉 直樹  春季大会講演集. I, 資源編  19-  (2)  2007/03/29  [Not refereed][Not invited]
  
• カーシュレッダーダスト(ASR)の有価物湿式回収プロセスの開発 : 界面活性剤溶液中でのASR浸漬・解砕挙動

  伊藤 真由美, 赤塚 真依子, 桑山 豊, 堀 邦紘, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  19-  (2)  21  -22  2007/03/29  [Not refereed][Not invited]
  
• カーシュレッダーダスト(ASR)の有価物湿式回収プロセスの開発 : ASRのジグ選別における繊維状物質の挙動

  伊藤 真由美, 桑山 豊, 赤塚 真依子, 堀 邦鉱, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  19-  (2)  23  -24  2007/03/29  [Not refereed][Not invited]
  
• ハイブリッドジグ選別におけるプラスチック表面の濡れ性の影響

  恒川 昌美, 岡田 英明, 堀 邦紘, 越智 大司, 小林 利輝, 上田 将経, 広吉 直樹, 伊藤 真由美  春季大会講演集. I, 資源編  19-  (2)  25  -26  2007/03/29  [Not refereed][Not invited]
  
• プラスチック微粒子の湿式サイクロンによる分級

  柏谷 公希, 能町 聖彦, 伊藤 真由美, 山本 康彰, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  19-  (2)  29  -30  2007/03/29  [Not refereed][Not invited]
  
• 廃Ni-MH電池リサイクルプロセスにおける破砕微粉の物理選別

  伊藤 真由美, 角谷 直宏, 柏谷 公希, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  19-  (2)  31  -32  2007/03/29  [Not refereed][Not invited]
  
• 黄銅鉱浸出の電位制御による最適化

  桑澤 毅成, 恩田 真吾, 広吉 直樹, 恒川 昌美, 伊藤 真由美  春季大会講演集. I, 資源編  19-  (2)  45  -46  2007/03/29  [Not refereed][Not invited]
  
• 微量の水分を含む有機溶媒中での疎水性微粒子の分散・凝集

  恒川 昌美, 佐々木 勇太, 中村 孔亮, 伊藤 真由美, 広吉 直樹, YOO Kyoung Keun  春季大会講演集. I, 資源編  19-  (2)  51  -52  2007/03/29  [Not refereed][Not invited]
  
• JIGを用いたコバルトリッチクラストの選鉱

  恒川 昌美, 伊藤 真由美, 山口 英志, 關村 健吾, 柏谷 公希, 広吉 直樹  春季大会講演集. I, 資源編  19-  (2)  53  -54  2007/03/29  [Not refereed][Not invited]
  
• 硫化鉱物からのヒ素の溶出とその除去

  富岡 祐一, 広吉 直樹, 恒川 昌美  硫酸と工業  60-  (2)  23  -28  2007/02
• P42. Fundamental study on biogrout using sodium metasilicate

  KOBAYASHI Gen, KAWASAKI Satoru, HIROYOSHI Naoki, TSUNEKAWA Masami, KANEKO Katsuhiko, TERAJIMA Rei, SHIMADA Shunsuke  研究発表会講演論文集  19-  229  -230  2007
• 疎水性プラスチック微粒子の湿式サイクロンによる分級

  柏谷公希, 能町聖彦, 伊藤真由美, 山本康彰, 広吉直樹, 恒川昌美  資源・素材学会北海道支部春季講演会講演要旨集  2007-  47  -48  2007  [Not refereed][Not invited]
  
• Leaching&Cementation法による鉛汚染土壌の浄化~処理プロセスの検討~

  伊藤真由美, 高田政雄, 帆苅直弘, 広吉直樹, 恒川昌美  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM)  13th-  ROMBUNNO.S5-5  2007  [Not refereed][Not invited]
  
• カーシュレッダーダスト(ASR)の有価物湿式回収プロセスの開発~ASRの溶液浸漬性評価と浸漬機構の解明~

  伊藤真由美, 赤塚真依子, 桑山豊, 堀邦紘, 広吉直樹, 恒川昌美  資源・素材学会北海道支部春季講演会講演要旨集  2007-  49  -50  2007  [Not refereed][Not invited]
  
• Leaching&Cementation法による鉛汚染土壌の浄化~鉛の除去率に及ぼす各種因子の影響~

  伊藤真由美, 帆苅直弘, 高田政雄, 広吉直樹, 恒川昌美  地下水・土壌汚染とその防止対策に関する研究集会講演集(CD-ROM)  13th-  ROMBUNNO.S5-4  2007  [Not refereed][Not invited]
  
• 鉛汚染土壌からの鉛除去に関する研究~クエン酸による土中鉛浸出と鉄粉濃縮挙動の把握~

  伊藤真由美, 高田政雄, 帆苅直弘, 恒川昌美, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2007-  27  -28  2007  [Not refereed][Not invited]
  
• 連続式ジグのプラスチック選別特性~回分式ジグとの比較~

  恒川昌美, 小林利輝, 堀邦紘, 越智大司, 岡田英明, 広吉直樹, 伊藤真由美  資源・素材学会北海道支部春季講演会講演要旨集  2007-  45  -46  2007  [Not refereed][Not invited]
  
• 深海底鉱物資源の有効利用に関する研究~コバルトリッチクラストと基盤岩のJIG選別~

  恒川昌美, 伊藤真由美, 山口英志, 關村健吾, 柏谷公希, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2007-  43  -44  2007  [Not refereed][Not invited]
  
• Effects of Carrier-Microencapsulation on Surface Chemical Properties of Pyrite

  SATUR Jacqueline, HIROYOSHI Naoki, ITO Mayumi, TSUNEKAWA Masami  春季大会講演集. I, 資源編  18-  (2)  65  -66  2006/03/27
• ジグ選別における水の圧力損失と選別性の関係

  堀 邦紘, 恒川 昌美, 上田 将経, 越智 大司, 広吉 直樹, 伊藤 真由美, 伊藤 正澄  春季大会講演集. I, 資源編  18-  (2)  43  -44  2006/03/27  [Not refereed][Not invited]
  
• 気泡を利用したジグ選別の改良

  恒川 昌美, 上田 将経, 堀 邦紘, 越智 大司, 岡田 英明, 広吉 直樹, 伊藤 真由美, 伊藤 正澄  春季大会講演集. I, 資源編  18-  (2)  45  -46  2006/03/27  [Not refereed][Not invited]
  
• プラスチックのジグ選別における分離プロセスに関する一考察

  恒川 昌美, 越智 大司, 堀 邦紘, 上田 将経, 岡田 英明, 広吉 直樹, 伊藤 真由美, 伊藤 正澄  春季大会講演集. I, 資源編  18-  (2)  47  -48  2006/03/27  [Not refereed][Not invited]
  
• リーチングとセメンテーションによる都市ゴミ溶融飛灰からのPb除去・回収

  広吉 直樹, 三谷 慎一, 伊藤 真由美, 恒川 昌美  春季大会講演集. I, 資源編  18-  (2)  135  -136  2006/03/27  [Not refereed][Not invited]
  
• 鉛汚染土壌からの鉛分リーチングおよび鉛濃縮に関する基礎的研究 第2報

  伊藤 真由美, 久保 泰政, 帆苅 直弘, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  18-  (2)  179  -180  2006/03/27  [Not refereed][Not invited]
  
• Removal of Arsenic Ions in Sulfuric Acid Solutions by Sulfide Minerals

  TOMIOKA Yuichi, HIROYOSHI Naoki, TSUNEKAWA Masami  Journal of MMIJ  122-  (6/7)  345  -352  2006  [Not refereed][Not invited]
   

  Removal of arsenite and arsenate in sulfuric acid solutions were investigated with PbS, ZnS, FeS and CuS at 298K. Both arsenic species were removed by PbS, ZnS and FeS. Especially, PbS was most effective to remove arsenic species from the solutions. The removal of the arsenic species by PbS depends on the sulfuric acid concentration and is minimum at sulfuric acid concentrations around 0.01 kmol m^-3. Thermodynamic analysis of the experimental results and XRD and SEM-EDX analysis of the solid residue suggest that the removal of the arsenic species by PbS is due to both arsenic adsorption on PbS surface and precipitation of As₂S_3(am) by the reaction of the arsenic species and H₂S generated by PbS.
• 微量の水分を含む非水溶液中での微粒子の分散・凝集

  恒川昌美, 佐々木勇太, 中村孔亮, 伊藤真由美, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2006-  57  -58  2006  [Not refereed][Not invited]
  
• プラスチックのハイブリッドジグ選別のための表面物性評価

  恒川昌美, 岡田英明, 堀邦紘, 上田将経, 越智大司, 広吉直樹, 伊藤真由美, 伊藤正澄  資源・素材学会北海道支部春季講演会講演要旨集  2006-  55  -56  2006  [Not refereed][Not invited]
  
• ハイブリッド自動車用ニッケル水素電池からの湿式磁選法を用いた有価金属の回収

  恒川昌美, 角谷直宏, 伊藤真由美, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2006-  51  -52  2006  [Not refereed][Not invited]
  
• 鉛汚染土壌の新しい修復法に関する基礎的研究

  伊藤真由美, 帆苅直弘, 久保泰政, 恒川昌美, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2006-  11  -12  2006  [Not refereed][Not invited]
  
• 廃コンクリートの湿式選別リサイクルプロセスの開発~再生骨材の性状に及ぼす原コンクリートの影響~

  恒川昌美, 桑澤毅成, 伊藤真由美, 広吉直樹, 名和豊春, 西田法文, 田村幸保, 伊藤正澄  資源・素材学会北海道支部春季講演会講演要旨集  2006-  53  -54  2006  [Not refereed][Not invited]
  
• コバルトリッチクラストの選鉱に関する基礎的研究

  恒川昌美, 山口英志, 伊藤真由美, 広吉直樹, 柴崎洋志, 吉田友之  資源・素材  2006-  (C/D)  167  -168  2006  [Not refereed][Not invited]
  
• Application of jig separator to recycle plastics used in electrical appliances

  Masami Tsunekawa, Kunihiro Hori, Tsuyoshi Hirajima, Naoki Hiroyoshi, Masazumi Ito  REWAS'04 - Global Symposium on Recycling, Waste Treatment and Clean Technology  1651  -1660  2005/12/01  [Not refereed][Not invited]
   

  Development of mechanical separation of different plastics is essential in planning and constructing a recycling plant that processes scrapped office and home appliances. The authors have developed a plastic separator using a TACUB jig. Jig separation for plastics of smaller sizes (0.5-2 mm) but similar specific gravities was performed using polyvinyl chloride (PVC) and polyethylene (PE) from scrap electric wires. High-grade PE and PVC products over 99.8% were obtained under pulsation of smaller frequency and amplitude than that for coarser plastics. For the plastics from scrap copying machines containing polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PET), high grades (>99%) of each plastic were recovered in the two cells of the jig, where PET, is recovered from the first cell as a bottom product, and ABS and PS from the second cell as bottom and upper layer products, respectively. Their sizes ranged from 3.5-10mm and their specific gravities were 1.03, 1.22 and 1.71 for PS, ABS, and PET respectively. Based on the results, a recycling plant for processing scrap office and home appliances had been constructed.
• The removal of manganese ions using a sulfate-reducing bacteria bioreactor

  Kyoungkeun Yoo, Naoki Hiroyoshi, Masami Tsunekawa  Proceedings - European Metallurgical Conference, EMC 2005  4-  1751  -1765  2005/12/01  [Not refereed][Not invited]
   

  The optimum conditions for Mn2+ removal from AMD (acid mine drainages) was studied using a SRB (Sulfate-reducing bacteria) bioreactor. Chemical experiments with Na2S as S2- source were conducted to investigate the effects of pH, coexisting metal ions, and S 2- concentration on MnS formation from Mn2+ solutions. The amount of Mn removed from the Mn2+ solutions decreased with decreasing pH. The Zn2+ or Fe2+ coexisting in the solutions consumed S2- by forming ZnS or FeS, and this inhibited Mn removal by the formation of MnS. The high molar ratio of S2- concentration to Mn2+ was required to form manganese sulfides. Biological experiments using sulfate-reducing bacteria, Desulfovibrio desulfuricans (ATCC 7757), were carried out under the conditions of 37°C, pH 5-7, and without coexisting ions to investigate the effects of Mn2+ concentration on the activity of sulfate reducing bacteria in the modified ATCC 1249 mediums containing 100∼600 g·m-3 Mn2+. In the solution containing initial 100 and 200 g·m-3 of Mn 2+, Mn concentration decreased to less than 10 g·m -3, the maximum contaminant level (MCL) of environmental water quality in Japan. The precipitate formed during Mn removal in the SRB bioreactor was identified to be a metastable γ-manganese sulfide using an X-ray diffractometer and an X-ray fluorescence spectroscope.
• Bioleaching of Sarcheshmeh molybdenite concentrate for extraction of rhenium

  MAA Zamani, N Hiroyoshi, M Tsunekawa, R Vaghar, M Oliazadeh  HYDROMETALLURGY  80-  (1-2)  23  -31  2005/11  [Not refereed][Not invited]
   

  Bioleaehing of Sarcheshmeh (Iran) molybdenite concentrate using a native strain of Acidithiobacillus ferrooxidans for extraction of thenium was evaluated. Bioleaehing tests showed that rhenium was extracted from the molybdenite concentrate, but rhenium extraction was low. Maximum rhenium extraction was 7.3%, while molybdenum extraction was 0.54%. The native strain of the Acidithiobacillus ferrooxidans had been able to grow on media that contain up to 250 mg/L molybdenum by the addition of pyrite as an energy source, approximately three times more molybdenum than those that had been reported for Acidithiobacillus ferrooxidans. (c) 2005 Elsevier B.V. All rights reserved.
• 鉛汚染土壌からのクエン酸による鉛分リーチングおよび担体を用いた鉛濃縮・除去に関する基礎的研究

  伊藤真由美, 久保泰政, 広吉直樹, 恒川昌美  地球環境シンポジウム講演論文集  13th-  311  -315  2005/07/14  [Not refereed][Not invited]
   

  It is important to establish washing methods for contaminated soils by toxic metals such as lead in rifle shooting areas. In the lead-contaminated soils weathered after a long period, metal lead is extracted as ion, and is penetrated into the ground, depositing on the surface of soil particles or immersing into the pores of the particles mainly as a lead carbonate. Therefore it is difficult to remove lead from the weathered contaminated soils by conventional soil washing techniques such as sizing or gravity separation. In this study, a new method is proposed for removing lead from the contaminated soil. Lead components in the soil are extracted into the solution by sodium citrate as a chelating agent, and the extracted lead is precipitated on the surface of iron powder by redox reaction. Then the iron powder is recovered by physical separation techniques such as magnetic separation. Thermodynamic calculation showed that removal efficiency of lead was higher when leaching iron powder, sodium citrate, and lead carbonate simultaneously than when leaching first lead carbonate by sodium citrate and then adding iron powder to the lead citrate solution. This calculation result was supported by ICP and XRD results. The XRD pattern for the iron powder recovered by magnetic separation indicated that lead is present as solid form on the powder. The recovered powder would be used as a lead source in smelting process.
• Jig separation of plastics from scrapped copy machines

  M Tsunekawa, B Naoi, S Ogawa, K Hori, N Hiroyoshi, M Ito, T Hirajima  INTERNATIONAL JOURNAL OF MINERAL PROCESSING  76-  (1-2)  67  -74  2005/04  [Not refereed][Not invited]
   

  A TACLTB jig was applied to separate waste plastics [polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate (PET)] used in copy machine. The effect of water pulsation including amplitude and frequency on the separation performance was investigated for the feeds containing three plastics. Good results were obtained under suitable conditions. Grades of 99.8% PS, 99.3% ABS, and 98.6% PET were recovered as the products in the top, middle and bottom layers, respectively. Based on these results, a processing pilot plant for recycling of plastics from scrapped copy machines was constructed. Two cells of a TACLTB jig were used in the plant to separate the plastics containing PS, ABS and PET, where PET was recovered from the first cell as bottom layer product, and ABS and PS from the second cell as bottom and top layer products, respectively. A monitor and control system of the jig operation was developed. High recoveries of PET, ABS, and PS with high grades were achieved, and the Newton's efficiency of the first cell was 0.99. (c) 2004 Elsevier B.V All rights reserved.
• Acidithiobacillus thiooxidans による硫ヒ鉄鉱の溶解抑制

  富岡 祐一, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  17-  (2)  1  -2  2005/03/28
• 都市ごみ溶融飛灰からの金属回収のための湿式プロセス

  広吉 直樹, 岸本 直輝, 恒川 昌美, 野々山 裕貴, 三谷 慎一, 三嶋 弘次  春季大会講演集. I, 資源編  17-  (2)  185  -186  2005/03/28
• 都市ごみ溶融飛灰浸出液からの硫化法による金属回収

  広吉 直樹, 野々山 裕貴, 岸本 直輝, 三谷 慎一, 恒川 昌美, 三嶋 弘次  春季大会講演集. I, 資源編  17-  (2)  183  -184  2005/03/28
• 都市ごみ溶融飛灰の安定化に関する研究

  広吉 直樹, 三谷 慎一, 岸本 直輝, 野々山 裕貴, 恒川 昌美, 三嶋 弘次  春季大会講演集. I, 資源編  17-  (2)  181  -182  2005/03/28
• CARRIER-MICROENCAPSULATION FOR PREVENTING PYRITE OXIDATION (2^ Report) : Selective Adsorption of Ti-catechol complex on Pyrite over Silica

  HIROYOSHI Naoki, SATUR Jacqueline, TSUNEKAWA Masami, OKAMOTO Hideyuki  春季大会講演集. I, 資源編  17-  (2)  151  -152  2005/03/28
• 黄銅鉱浸出の最適電位に関する研究

  広吉 直樹, 北川 宏子, 恒川 昌美, 恩田 真吾  春季大会講演集. I, 資源編  17-  (2)  111  -112  2005/03/28
• キャリア浮選を用いた白色結晶質石灰石の高品位化

  恒川 昌美, 本間 佑吾, 柳 庚槿, 広吉 直樹, 伊藤 真由美  春季大会講演集. I, 資源編  17-  (2)  53  -54  2005/03/28  [Not refereed][Not invited]
  
• 低比重細粒破砕物のジグ選別における粒子流動性と最適分離条件

  恒川 昌美, 堀 邦紘, 上田 将経, 越智 大司, 広吉 直樹, 伊藤 真由美, 伊藤 正澄  春季大会講演集. I, 資源編  17-  (2)  55  -56  2005/03/28  [Not refereed][Not invited]
  
• プラスチックのジグ選別における粒子物性の影響

  恒川 昌美, 上田 将経, 堀 邦紘, 越智 大司, 広吉 直樹, 伊藤 真由美, 伊藤 正澄  春季大会講演集. I, 資源編  17-  (2)  57  -58  2005/03/28  [Not refereed][Not invited]
  
• 物理選別による廃2次電池中の有価物回収(第2報)

  恒川 昌美, 古谷 尚稔, 広吉 直樹, 伊藤 真由美, 北村 修, 市川 良二, 菊田 和幸  春季大会講演集. I, 資源編  17-  (2)  63  -64  2005/03/28  [Not refereed][Not invited]
  
• 再生粗骨材を用いたコンクリートの強度に及ぼす湿式選別条件の影響

  恒川 昌美, 上杉 浩平, 伊藤 真由美, 伊藤 正澄, 名和 豊春, 西田 法文, 広吉 直樹, 平島 剛  春季大会講演集. I, 資源編  17-  (2)  173  -174  2005/03/28  [Not refereed][Not invited]
  
• 63. Soil Improvement Tests on Sealability Using Biogrout

  Kawasaki Satoru, Murao Akira, Hiroyoshi Naoki, Tsunekawa Masami, Kaneko Katsuhiko  研究発表会講演論文集  17-  221  -222  2005
• Effect of Jarosite on the Removal of Arsenic ions in Sulfuric Acid Solution

  TOMIOKA Yuichi, HIROYOSHI Naoki, KUBO Yasumasa, TSUNEKAWA Masami  Shigen-to-Sozai  121-  (12)  597  -602  2005  [Not refereed][Not invited]
   

  Jarosite (KFe₃(SO₄)₂(OH)₆) is a secondary mineral in acidic polluted environments such as mine tailing dump, but few investigations have evaluated arsenic removal by jarosite.
  This study investigated the role of jarosite in arsenic removal using flask shaking experiments in diluted sulfuric acid solutions (pH1-3). Jarosite was synthesized and the chemical composition of the jarosite was K_0.54(H₃O)_0.46Fe_2.38(SO₄)₂(OH)₆. The shaking experiments found that As(V) was removed by the jarosite but As(III) was not removed. The mechanisms of As(V) removal were adsorption on the jarosite and co-precipitation with Fe(III) extracted from jarosite. The removal of As(V) from the liquid phase were increased with increasing pH, indicating that the adsorption of As(V) and SO₄^2- is competitive or that ionic As species (H₂AsO₄^-) is selectively adsorbed. The results suggest that jarosite is a sink for As(V) in acidic polluted environments.
• Effects of Solution Composition on Arsenic Extraction from Arsenopyrite-Study on Arsenopyrite Dissolution in Acidic Environments (1st report)-:-Study on Arsenopyrite Dissolution in Acidic Environments (1st report) -

  TOMIOKA Yuichi, HIROYOSHI Naoki, TSUNEKAWA Masami  Journal of MMIJ  121-  (8)  392  -398  2005  [Not refereed][Not invited]
   

  Weathering of arsenopyrite is a main cause of arsenic ions in acid mine drainage, and establishing the mechanism of arsenopyrite dissolution is important to design and develop methods for suppressing the dissolution. However, the factors affecting the oxidation state of arsenic formed by arsenopyrite dissolution are not established.
  This study investigated the effect of Fe(II) and Fe(III) concentrations as well as the presence of dissolved oxygen on the oxidation states of arsenic ions formed from arsenopyrite in sulfuric acid solutions by a shaking-flask method. Dissolved oxygen or Fe(III) was required as oxidant for dissolving arsenopyrite. When only Fe(III) was present as the oxidant, arsenic extracted from arsenopyrite was As(III). In the presence of dissolved oxygen, both As(III) and As(V) were formed and the concentrations of these ions were varied depending on the solution composition: As(V) was dominant when Fe(II) or Fe(III) were not added, and As(III) was dominant with high concentrations of Fe(III) and Fe(II). It was also found that under aerobic conditions arsenopyrite acts as a catalyst for the oxidation of As(III) to As(V), and that Fe(II) and Fe(III) inhibit the As(III) oxidation. Based on the results, the mechanism for arsenopyrite dissolution and the oxidation state of extracted arsenic are discussed.
• Normalized Redox Potential Used to Assess Chalcopyrite Column Leaching

  OKAMOTO Hideyuki, NAKAYAMA Ryoichi, KUROIWA Shigeto, HIROYOSHI Naoki, TSUNEKAWA Masami  Journal of MMIJ  121-  (6)  246  -254  2005  [Not refereed][Not invited]
   

  Column leaching experiments for two chalcopyrite concentrates agglomerated on supporting particles were performed with sulfuric acid solutions under various conditions. The results of the column leaching were compared to results of shaking flask leaching experiments reported previously.
  Factors such as solution composition, coexisting minerals like pyrite, and presence of iron-oxidizing bacteria affected chalcopyrite dissolution, causing a significant variation in the copper extraction fraction vs. time plots. However, copper extraction rate from unit surface area of chalcopyrite could be determined simply from the normalized redox potential proposed previously, a function of the ferric, ferrous and cupric ion concentrations. The copper extraction rate vs. normalized potential plot for the column leaching data fitted well with the plot obtained by shaking flask experiments, and the copper extraction rate has a maximum at normalized potentials of 0.4 to 0.5. These results suggest that the normalized potential could be used to assess and optimize chalcopyrite leaching with different methods and under various conditions.
• 低品位黒曜石の資源化

  山口英志, 恒川昌美, 広吉直樹, 伊藤真由美  資源・素材  2005-  50  2005  [Not refereed][Not invited]
  
• Leaching Cementation Separation~重金属汚染土壌の新しい修復法~

  伊藤真由美, 久保泰政, 広吉直樹, 恒川昌美  資源・素材  2005-  66  2005  [Not refereed][Not invited]
  
• ジグ選別におけるプラスチック粒子の分離挙動

  恒川昌美, 越智大司, 堀邦紘, 上田将経, 広吉直樹, 伊藤真由美, 伊藤正澄  資源・素材  2005-  55  2005  [Not refereed][Not invited]
  
• プラスチックのジグ選別における表面物性の影響

  恒川昌美, 上田将経, 堀邦紘, 越智大司, 広吉直樹, 伊藤真由美, 伊藤正澄  資源・素材  2005-  56  2005  [Not refereed][Not invited]
  
• プラスチックのジグ選別―最適分離条件と粒子の流動

  堀邦紘, 恒川昌美, 上田将経, 越智大司, 広吉直樹, 伊藤真由美, 伊藤正澄  資源・素材  2005-  57  2005  [Not refereed][Not invited]
  
• ジグ選別における粒子の分離挙動と選別性の簡易評価

  恒川昌美, 越智大司, 堀邦紘, 上田将経, 広吉直樹, 伊藤真由美, 伊藤正澄  資源・素材学会北海道支部春季講演会講演要旨集  2005-  61  -62  2005  [Not refereed][Not invited]
  
• Recent Topics on Environmental Contamination Caused by Minerals Containing Arsenic and its Remediation -Arsenic Dissolution and Stabilization in Mine Tailing Dumps-

  Yuichi Tomioka, Naoki Hiroyoshi, Masami Tsunekawa  Resources Processing  52-  (3)  145  -150  2005  [Not refereed][Not invited]
   

  Many contaminated lands and drainage with arsenic are caused by human activity in the world. In mine industry tailing dumps and old mined sites are main origin to generate acid mine drainage (AMD) containing arsenic. This review describes natural processes of the AMD generation and remediation based on the published 41 papers and reports. © 2005, The Resources Processing Society of Japan. All rights reserved.
• The Role of Mineral Processing Technology in a Society Based on Recycling

  Masami Tsunekawa, Kyoungkeun Yoo, Naoki Hiroyoshi, Mayumi Ito  Resources Processing  52-  (1)  32  -38  2005  [Not refereed][Not invited]
   

  Industrial systems and daily life in Japan are shifting to a society based on recycling to reduce energy and resource consumption. To establish a society based on recycling urban resource recovery centers (mines) are important as places to reduce waste volumes, reusing and recycling valuable materials with application of mineral processing technology. The authors have reviewed applications of mineral processing in urban mines, and recent developments in common separation methods, magnetic separation, gravity separation, flotation, and agglomeration in liquid. © 2005, The Resources Processing Society of Japan. All rights reserved.
• Synergistic effect of cupric and ferrous ions on active-passive behavior in anodic dissolution of chalcopyrite in sulfuric acid solutions

  N Hiroyoshi, S Kuroiwa, H Miki, M Tsunekawa, T Hirajima  HYDROMETALLURGY  74-  (1-2)  103  -116  2004/08  [Not refereed][Not invited]
   

  Copper extraction during the oxidative leaching of chalcopyrite (CuFeS2) by ferric ions or by dissolved oxygen in sulfuric acid solutions is known to be faster at low redox potentials but slower at potentials above a critical value. The present study shows that this phenomenon occurs only when cupric and ferrous ions coexist, based on electrochemical measurements. Using a chalcopyrite electrode prepared from an ore lump sample, effects of the addition of 0.1 kmol m(-3) cupric and ferrous ions on anodic polarization curves and AC impedance spectra were investigated in 0.1 kmol m(-3) sulfuric acid with stirring at 298 K in nitrogen. Without cupric and/or ferrous ions, the anodic current increased monotonically with increasing applied potential. When cupric and ferrous ions coexisted, active-passive behavior was observed, i.e., the current increased with increasing potential to reach a maximum and it suddenly decreased at a certain potential, whereby the current became less dependent on the potential. In the active region, i.e., at low potentials, the anodic current with coexisting cupric and ferrous ions was larger than that without these ions. These results agree well with the results of leaching experiments reported previously, and indicate that coexisting cupric and ferrous ions promote the anodic dissolution of chalcopyrite at low potentials. The analysis of the AC impedance spectra indicates that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth in the active region. To interpret the active-passive behavior of chalcopyrite, a reaction model, assuming the formation of intermediate Cu2S in the active region, is discussed based on the experimental results. (C) 2004 Elsevier B.V. All rights reserved.
• 石灰石中の微量不純物除去に関する研究

  恒川 昌美, 本間 佑吾, 広吉 直樹, 平島 剛  春季大会講演集. I, 資源編  16-  (2)  119  -120  2004/03/29
• CARRIER-MICROENCAPSULATION FOR PREVENTING PYRITE OXIDATION (1^ Report) : Suppressive Effect of TiO_2 and Catechol on Pyrite Oxidation

  HIROYOSHI Naoki, SATUR Jacqueline, TSUNEKAWA Masami, OKAMOTO Hideyuki  春季大会講演集. I, 資源編  16-  (2)  151  -152  2004/03/29
• 硫酸還元菌による Metastable γ-MnS の合成

  柳 庚槿, 笹木 圭子, 広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  16-  (2)  153  -154  2004/03/29
• 酸性環境における硫ヒ鉄鉱の溶解メカニズムに関する研究

  富岡 祐一, 広吉 直樹, 恒川 昌美, 笹木 圭子  春季大会講演集. I, 資源編  16-  (2)  65  -66  2004/03/29
• 硫酸酸性条件下での黄銅鉱アノード溶解に及ぼす液組成の影響

  広吉 直樹, 恒川 昌美  春季大会講演集. I, 資源編  16-  (2)  81  -82  2004/03/29
• ジグによる低比重細粒物質相互の比重選別

  恒川 昌美, 堀 邦紘, 広吉 直樹, 丸山 正浩, 伊藤 正澄  春季大会講演集. I, 資源編  16-  (2)  19  -20  2004/03/29
• 物理選別による廃2次電池中の有価物回収

  恒川 昌美, 古谷 尚稔, 広吉 直樹, 北村 修, 小島 和浩, 菊田 和幸  春季大会講演集. I, 資源編  16-  (2)  21  -22  2004/03/29
• Redox Potential Dependence and Optimum Potential of Chalcopyrite Leaching in Sulfuric Acid Solutions

  OKAMOTO Hideyuki, NAKAYAMA Ryoichi, HIROYOSHI Naoki, TSUNEKAWA Masami  Journal of MMIJ  120-  (10/11)  592  -599  2004  [Not refereed][Not invited]
   

  Leaching rate of chalcopyrite in sulfuric acid solutions depends on a solution redox potential, determined by a concentration ratio of ferric to ferrous ions, and it become maximum at a certain potential (an optimum potential) depending on leaching conditions. In this study, factors affecting the optimum potential were investigated.
  Shaking flask leaching experiments for two chalcopyrite concentrates were performed at 303 K under various pH values, pulp densities, and concentrations of ferrous and ferric ions with or without iron-oxidizing bacteria. The experimental results were analyzed based on a reaction model for the redox potential dependence of chalcopyrite leaching, which assumes the formation of an intermediate Cu2S from chalcopyrite. Plotting the leaching rate to a normalized potential in the model showed that the rate is controlled by the normalized potential and is independent of solution compositions, pulp densities, and iron-oxidizing bacteria when ferric ions do not precipitate. A maximum rate was achieved at a certain value of the normalized potential. Converting the normalized potential to the solution redox potential gives the optimum potential for chalcopyrite leaching as a function of cupric and ferrous ion concentrations. The optimum potential increases with increasing the cupric ion concentration and decreases with the ferrous ion concentration. Cupric ions affect stronger than ferrous ions on the optimum potential.
• Fundamental study on the removal of Mn2+ in acid mine drainage using sulfate reducing bacteria

  Kyoungkeun Yoo, Keiko Sasaki, Naoki Hiroyoshi, Masami Tsunekawa  Materials Transactions  45-  (7)  2422  -2428  2004  [Not refereed][Not invited]
   

  The optimum conditions for Mn2+ removal from acid mine drainage was studied by a SRB (sulfate reducing bacteria) bioreactor. Chemical experiments with Na2S as a S2- source were conducted to investigate the effects of pH, coexisting metal ions, and the components in a growth medium for SRB on MnS formation from Mn2+ solutions. The amount of Mn removed from the Mn2+ solutions decreased with decreasing pH. The Zn2+ or Fe2+ coexisting in the solutions consumed S2- by forming ZnS or FeS, and this inhibited Mn removal. Sodium citrate, a component of the growth medium for SRB, formed a complex with Mn2+ and suppressed MnS formation. Biological experiments using the SRB reactor were carried out at 37°C and it was confirmed that the Mn2+ concentration decreased to less than 10 g.m-3 from 100g.m-3 at neutral pHs (pH 5-7) after 100 hours when other metal ions and sodium citrate were absent. The formed precipitate was identified to be metastable γ-MnS with a band gap of about 3.8 eV by XRD, XRF, and UV-VIS.
• The effect of Mn2+ concentration on Mn removal by a sulfate reducing bacteria bioreactor

  Kyoungkeun Yoo, Keiko Sasaki, Naoki Hiroyoshi, Masami Tsunekawa, Tsuyoshi Hirajima  Materials Transactions  45-  (7)  2429  -2434  2004  [Not refereed][Not invited]
   

  In the design of sulfate reducing bacteria (SRB) bioreactors to remove metal ions from acid mine drainage, the tolerance of bacteria to metal ions is an important factor. The present study investigated the effects of Mn 2+ concentration on the growth and Mn removal activity of SRB in mediums containing 100-600 g.m-3 Mn2+. The Mn 2+ adsorbed on SRB cells and weakened the ability of bacterial sulfate reduction. However, the suppressive effect of Mn2+ on SRB growth can be disregarded, and 200 g.m-3 of Mn2+ in solution was removed, satisfying the requirement of the maximum contaminant level (MCL) of environmental water quality in Japan.
• Freshmen Seminar at University based on Children s Experience

  TSUNEKAWA Masami, HIRAJIMA Tsuyoshi, HIROYOSHI Naoki  工学・工業教育研究講演会講演論文集  15-  453  -454  2003/09/04
• Cu(II)とFe(II)を含む硫酸溶液中における黄銅鉱アノード溶解反応の速度論的検討

  広吉 直樹, 黒岩 樹人, 恒川 昌美, 平島 剛  春季大会講演集. I, 資源編  15-  (2)  114  -115  2003/03/27
• A. ferrooxidans による硫ヒ鉄鉱の溶解に及ぼす諸要因の影響

  富岡 祐一, 広吉 直樹, 恒川 昌美, 平島 剛, 笹木 圭子  春季大会講演集. I, 資源編  15-  (2)  171  -172  2003/03/27
• ジグによる低比重細粒物質相互の比重選別

  恒川 昌美, 堀 邦紘, 小川 真吾, 平島 剛, 広吉 直樹, 柳生 秀樹, 丸山 正浩, 伊藤 正澄  春季大会講演集. I, 資源編  15-  (2)  98  -99  2003/03/27
• アドバンスト・ミネラルプロセッシング技術の開発に関する調査研究

  平島剛, 広吉直樹, 恒川昌美, 大木達也, 伊藤真由美, 大和田秀二, 長岡亨  日本鉱業振興会助成研究成果報告書  2002-  65  -70  2002/11/08  [Not refereed][Not invited]
  
• 廃蛍光管からの希土類元素の再資源化とその有効利用に関する研究(第3報)

  平島 剛, 濱田 暢哉, 平井 宏尚, 恒川 昌美, 広吉 直樹, 笹木 圭子, 高橋 徹, 長野 伸泰  春季大会講演集. I, 資源編  14-  (2)  191  -192  2002/03/28
• OA機器リサイクルプラントにおけるプラスチック選別試験

  恒川 昌美, 小川 真吾, 直井 万隆, 平島 剛, 広吉 直樹, 尾谷 賢, 宮本 政博, 伊藤 正澄  春季大会講演集. I, 資源編  14-  (2)  206  -207  2002/03/28
• 黄銅鉱浸出に対する活性炭の触媒作用の機構

  三木 一, 広吉 直樹, 平島 剛, 恒川 昌美  春季大会講演集. I, 資源編  14-  (2)  69  -70  2002/03/28
• 黄銅鉱浸出における鉄沈殿共存の効果

  広吉 直樹, 黒岩 樹人, 平島 剛, 恒川 昌美  春季大会講演集. I, 資源編  14-  (2)  65  -66  2002/03/28
• Ammonical thiosulphate leaching : A friendly route for processing of refractory gold ore

  RATH Rajendra Kumar, HIROYOSHI Naoki, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi  春季大会講演集. I, 資源編  14-  (2)  67  -68  2002/03/28
• 硫酸溶液中における黄銅鉱アノード溶解反応のCu(II)-Fe(II)共存による活性化

  広吉 直樹, 三木 一, 平島 剛, 恒川 昌美  春季大会講演集. I, 資源編  14-  (2)  89  -90  2002/03/28
• A new reaction model for the catalytic effect of silver ions on chalcopyrite leaching in sulfuric acid solutions

  N Hiroyoshi, M Arai, H Miki, M Tsunekawa, T Hirajima  HYDROMETALLURGY  63-  (3)  257  -267  2002/03  [Not refereed][Not invited]
   

  Chalcopyrite leaching in sulfuric acid solutions depends on the redox potential determined by the concentration ratio of ferric to ferrous ions, and the leaching rate is higher at redox potentials below a critical value. Previously, the authors have proposed a reaction model to interpret this phenomenon. The present study applied the model to interpret the catalytic effect of silver ions on chalcopyrite leaching. The model assumes that at lower potentials, chalcopyrite leaching proceeds in two steps: first, chalcopyrite is reduced by ferrous ions to form Cu2S that is more rapidly leached; next, the intermediate CU2S is oxidized by ferric and/or dissolved oxygen to release cupric ions. During the chalcopyrite reduction, hydrogen sulfide is released to the liquid phase. Silver ions react with the hydrogen sulfide to form silver sulfide precipitate and decrease the concentration of hydrogen sulfide in the liquid phase, causing a rise in the critical potential of Cu2S formation and broadening of the potential range where rapid copper extraction takes place. To confirm the model, the redox potential dependence of chalcopyrite leaching was investigated in the presence of various concentrations of silver ions with 0.1 kmol in(-3) sulfuric acid containing known concentrations of ferrous and ferric ions at 298 K in air. The critical potential increased with increasing concentrations of silver ions. This agrees with the model proposed here but cannot be explained by the conventional model proposed by Miller et al. (C) 2002 Elsevier Science B.V. All rights reserved.
• 銅鉱リーチングに関する最近の研究動向とカザフスタンにおける選鉱廃さい資源化技術の開発

  広吉 直樹, 恒川 昌美, 平島 剛, 宮川 博, 星野 浩二, 神田 慶太, 土屋 春明  資源・素材  2001-  29  -32  2001/09/24
• ジグ選別を用いた廃OA機器リサイクルプラントの開発

  直井 万隆, 恒川 昌美, 平島 剛, 広吉 直樹, 田窪 徹雄, 尾谷 賢, 宮本 政博, 伊藤 正澄  資源・素材  2001-  18  -18  2001/09/24
• 都市ゴミ焼却飛灰のリーチング処理

  広吉 直樹, 後藤 昌範, 恒川 昌美, 平島 剛  資源・素材  2001-  32  -32  2001/09/24
• 物理選別による廃蛍光管からの希土類蛍光体回収

  平井 宏尚, 平島 剛, 恒川 昌美, 広吉 直樹, 中山 和久, 笹木 圭子, 高橋 徹, 長野 伸泰  資源・素材  2001-  27  -27  2001/09/24
• Enhancement of chalcopyrite leaching by ferrous ions in acidic ferric sulfate solutions

  N Hiroyoshi, H Miki, T Hirajima, M Tsunekawa  HYDROMETALLURGY  60-  (3)  185  -197  2001/05  [Not refereed][Not invited]
   

  The effects of ferrous ions on chalcopyrite oxidation with ferric ions in 0.1 mol dm(-3) sulfuric acid solutions were investigated by leaching experiments at 303 K in nitrogen. With high cupric ion concentrations, the chalcopyrite oxidation was enhanced by high concentrations of ferrous ions and copper extraction was mainly controlled by the concentration ratio of ferrous to ferric ions or the redox potential of solutions. Ferrous ions, however, suppressed the chalcopyrite oxidation when cupric ion concentrations were low. A reaction model, which involves chalcopyrite reduction to intermediate Cu2S by ferrous ions and oxidation of the Cu2S by ferric ions, was proposed to interpret the results. (C) 2001 Elsevier Science B.V. All rights reserved.
• 硫酸溶液中での黄銅鉱のサイクリックボルタモグラムに及ぼす各種金属イオンの影響 : 黄銅鉱浸出の電位依存性に関する研究(第2報)

  三木 一, 広吉 直樹, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  2001-  (2)  189  -190  2001/03/01
• 黄銅鉱浸出の臨界電位に及ぼす各種金属イオンの影響 : 黄銅鉱浸出の電位依存性に関する研究(第1報)

  広吉 直樹, 黒岩 樹人, 三木 一, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  2001-  (2)  187  -188  2001/03/01
• アンモニアリーチングによる都市ゴミ焼却灰中重金属の除去・回収

  広吉 直樹, 後藤 昌範, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  2001-  (2)  26  -27  2001/03/01
• 廃蛍光管からの希土類元素の再資源化とその有効利用に関する研究(第2報) : 湿式及び乾式選別による希土類蛍光体の回収

  平島 剛, 平井 宏尚, 中山 和久, 恒川 昌美, 広吉 直樹, 笹木 圭子, 高橋 徹, 長野 伸泰  一般発表(研究・業績発表)講演要旨集  2001-  (2)  10  -11  2001/03/01
• コピー機に用いられている各種プラスチックのジグによる選別

  恒川 昌美, 直井 万隆, 田窪 徹雄, 平島 剛, 広吉 直樹, 尾谷 賢, 宮本 政博, 伊藤 正澄  一般発表(研究・業績発表)講演要旨集  2001-  (2)  4  -5  2001/03/01
• Basic Study on Separation Characteristics of Permanent Magnetic Roll Separator

  TSUNEKAWA Masami, HORIE Syu, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi  Journal of MMIJ  117-  (4)  277  -281  2001  [Not refereed][Not invited]
   

  Magnetic separation experiments were carried out using a rare earth magnet type of magnetic roll separator and hematite, chalcopyrite and pyrite as feed material. The effects of feed sizes, their magnetic susceptibility and belt speed on the performance of the magnetic separator were investigated.
  The difference in magnetic susceptibility of the three minerals was a little, however the order of their values was hematite>chalcopyrite>pyrite. Irrespective of feed size and belt speed, hematite was recovered as magnetic product, and pyrite as non-magnetic product. Chalcopyrite was collected as non-magnetic product at high belt speed or with coarse feed size, but with decreasing belt speed and feed size its collecting region was shifted to magnetic product zone. Under a suitable condition chalcopyrite concentrate with 96.4% recovery and 85.0% grade was obtained from the mixture of three minerals.
  Based on the experimental results mentioned above, a mathematic model of particle movement in magnetic separation zone was derived, considering magnetic force, gravitation, centrifugal force, and frictional force and drag force. The movements under various conditions were calculated using the model, and the calculation results were in close agreement with the experimental results.
• Batch Leaching Behavior of Chalcopyrite in Acidic Ferric Sulfate Solutions : Relationship between solution redox potential and copper extraction

  MIKI Hajime, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi, TSUNEKAWA Masami  Journal of MMIJ  117-  (3)  215  -220  2001  [Not refereed][Not invited]
   

  Batch leaching behavior of ground chalcopyrite (median particle diameter 6 μ mm) was investigated anaerobically by a shaking flask method. The experiments used 0.1 mol dm^-3 sulfuric acid solutions containing 0.25 mol dm^-3 ferric ions and known concentrations of ferrous and cupric ions at 303 K. The initial pulp density of the chalcopyrite was 10 kg m^-3.
  When 1.00 mol dm^-3 of ferrous ions were added, copper extraction proceeded in three steps: (1) an induction period, (2) a leaching period, and (3) a stationary period. This extraction behavior can be interpreted by the following reaction model: in the induction period, copper is extracted slowly by the direct oxidation of chalcopyrite with ferric ions and the redox potential of the solution decreases due to the consumption of oxidant ferric ions. When the solution potential becomes lower than a critical potential, a leaching period, intermediate Cu₂S that is oxidized faster than chalcopyrite is formed by the reduction of chalcopyrite and copper extraction rate becomes high. When the solution potential decreases further, a stationary period, Cu₂S oxidation and copper extraction stop.
  Based on this reaction model, the effects of the initial pulp density and the initial concentrations of ferric, ferrous, and cupric ions on the leaching behavior were simulated numerically. As a result, it was predicted that the induction period could be eliminated by adding more than a critical amount of cupric ions with ferrous ions and that the stationary period can be eliminated by solution potential regulation during the leaching.
  The simulation agreed with the experimental results. When 1.00 mol dm^-3 ferrous ions and 0.05 mol dm^-3 cupric ions were added together, 56 % copper extraction was obtained after 9 days without an induction period, then extraction stopped. Further when the solution potential was regulated by the addition of ferric ions, 80 % of copper was extracted in two weeks. On the other hand, without the ferrous and cupric addition and the potential regulation, copper extraction was only 11 % even after 27 days.
• Basic Study on Separation Characteristics of Permanent Magnetic Roll Separator

  TSUNEKAWA Masami, HORIE Syu, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi  J. Mining and Material Processing Inst. Japan  117-  (4)  277  -281  2001  [Not refereed][Not invited]
   

  Magnetic separation experiments were carried out using a rare earth magnet type of magnetic roll separator and hematite, chalcopyrite and pyrite as feed material. The effects of feed sizes, their magnetic susceptibility and belt speed on the performance of the magnetic separator were investigated.
  The difference in magnetic susceptibility of the three minerals was a little, however the order of their values was hematite>chalcopyrite>pyrite. Irrespective of feed size and belt speed, hematite was recovered as magnetic product, and pyrite as non-magnetic product. Chalcopyrite was collected as non-magnetic product at high belt speed or with coarse feed size, but with decreasing belt speed and feed size its collecting region was shifted to magnetic product zone. Under a suitable condition chalcopyrite concentrate with 96.4% recovery and 85.0% grade was obtained from the mixture of three minerals.
  Based on the experimental results mentioned above, a mathematic model of particle movement in magnetic separation zone was derived, considering magnetic force, gravitation, centrifugal force, and frictional force and drag force. The movements under various conditions were calculated using the model, and the calculation results were in close agreement with the experimental results.
• Batch leaching Behavior of Chalcopyrite in Acidic Ferric Sulfate Solutions- Relationship between solution redox potential and copper extraction-

  MIKI Hajime, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi, TSUNEKAWA Masami  J. Mining an Material Processing Inst. Japan  117-  (3)  215  -220  2001  [Not refereed][Not invited]
   

  Batch leaching behavior of ground chalcopyrite (median particle diameter 6 μ mm) was investigated anaerobically by a shaking flask method. The experiments used 0.1 mol dm^-3 sulfuric acid solutions containing 0.25 mol dm^-3 ferric ions and known concentrations of ferrous and cupric ions at 303 K. The initial pulp density of the chalcopyrite was 10 kg m^-3.
  When 1.00 mol dm^-3 of ferrous ions were added, copper extraction proceeded in three steps: (1) an induction period, (2) a leaching period, and (3) a stationary period. This extraction behavior can be interpreted by the following reaction model: in the induction period, copper is extracted slowly by the direct oxidation of chalcopyrite with ferric ions and the redox potential of the solution decreases due to the consumption of oxidant ferric ions. When the solution potential becomes lower than a critical potential, a leaching period, intermediate Cu₂S that is oxidized faster than chalcopyrite is formed by the reduction of chalcopyrite and copper extraction rate becomes high. When the solution potential decreases further, a stationary period, Cu₂S oxidation and copper extraction stop.
  Based on this reaction model, the effects of the initial pulp density and the initial concentrations of ferric, ferrous, and cupric ions on the leaching behavior were simulated numerically. As a result, it was predicted that the induction period could be eliminated by adding more than a critical amount of cupric ions with ferrous ions and that the stationary period can be eliminated by solution potential regulation during the leaching.
  The simulation agreed with the experimental results. When 1.00 mol dm^-3 ferrous ions and 0.05 mol dm^-3 cupric ions were added together, 56 % copper extraction was obtained after 9 days without an induction period, then extraction stopped. Further when the solution potential was regulated by the addition of ferric ions, 80 % of copper was extracted in two weeks. On the other hand, without the ferrous and cupric addition and the potential regulation, copper extraction was only 11 % even after 27 days.
• 浮選による廃蛍光体からの希土類蛍光体の回収

  平島 剛, 中山 和久, 恒川 昌美, 広吉 直樹, 笹木 圭子, 高橋 徹, 長野 伸泰  廃棄物学会研究発表会講演論文集 = Proceedings of the Annual Conference of the Japan Society of Waste Management Experts  11-  (1)  495  -497  2000/10/10
• OA機器に使用されている各種プラスチックのジグによる選別

  恒川 昌美, 直井 万隆, 田窪 徹雄, 平島 剛, 広吉 直樹, 尾谷 賢, 宮本 政博, 伊藤 正澄  廃棄物学会研究発表会講演論文集 = Proceedings of the Annual Conference of the Japan Society of Waste Management Experts  11-  (1)  430  -432  2000/10/10
• 種々の物理選別における都市ゴミ焼却灰中の有価物の挙動

  恒川 昌美, 田窪 徹雄, 平島 剛, 広吉 直樹, 堀江 周  一般発表(研究・業績発表)講演要旨集  2000-  (2)  158  -159  2000/03/01
• 廃蛍光管からの希土類元素の再資源化とその有効利用に関する研究 -希土類蛍光体の回収-

  平島 剛, 中山 和久, 恒川 昌美, 広吉 直樹, 笹木 圭子, 高橋 徹, 長野 伸泰  一般発表(研究・業績発表)講演要旨集  2000-  (2)  169  -170  2000/03/01
• FE (II) による黄銅鉱浸出促進に関する研究 (第4報) -Cu (II) 添加と電位調節の効果-

  三木 一, 広吉 直樹, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  2000-  (2)  127  -128  2000/03/01
• 硫酸溶液中における黄銅鉱浸出の溶液電位依存性とAg (I) の触媒作用

  広吉 直樹, 荒井 政俊, 三木 一, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  2000-  (2)  129  -130  2000/03/01
• Sar Chesmeh 斑岩銅鉱山における金資源とその回収

  SALARI RAD M. M., 恒川 昌美, 岩瀬 広幸, 中山 和久, 平島 剛, 広吉 直樹, 米田 哲朗  一般発表(研究・業績発表)講演要旨集  2000-  (2)  133  -134  2000/03/01
• Model for ferrous-promoted chalcopyrite leaching

  Naoki Hiroyoshi, Hajime Miki, Tsuyoshi Hirajima, Masami Tsunekawa  Hydrometallurgy  57-  (1)  31  -38  2000  [Not refereed][Not invited]
   

  Oxidative leaching of chalcopyrite with dissolved oxygen and/or with ferric ions is promoted by high concentrations of ferrous ions in sulfuric acid solutions containing cupric ions. This paper proposes a reaction model to interpret this phenomenon and the thermodynamics of the leaching is discussed. The model considers the leaching to take place in two steps: (1) reduction of chalcopyrite to Cu2S by ferrous ions in the presence of cupric ions and (2) oxidation of the Cu2S to cupric ions and elemental sulfur by dissolved oxygen and/or by ferric ions. The intermediate Cu2S is more amenable to oxidation than chalcopyrite, causing enhanced copper extraction. The model predicts that the formation of intermediate Cu2S and ferrous-promoted chalcopyrite leaching occur when the redox potential of the solution is below a critical potential that is a function of the ferrous and cupric ion concentrations. To confirm this, flask-shaking leaching experiments were carried out with 0.1 mol dm-3 sulfuric acid solutions containing known concentrations of ferrous, ferric, and cupric ions at 303 K in air. The results agreed well with the predictions, i.e. copper extraction was enhanced at solution potentials below the critical potential predicted with the model.
• Inhibitory effect of iron-oxidizing bacteria on ferrous-promoted chalcopyrite leaching

  N Hiroyoshi, M Hirota, T Hirajima, M Tsunekawa  BIOTECHNOLOGY AND BIOENGINEERING  64-  (4)  478  -483  1999/08  [Not refereed][Not invited]
   

  It is generally accepted that iron-oxidizing bacteria, Thiobacillus ferrooxidans, enhance chalcopyrite leaching. However, this article details a case of the bacteria suppressing chalcopyrite leaching. Bacterial leaching experiments were performed with sulfuric acid solutions containing 0 or 0.04 mol/dm(3) ferrous sulfate. Without ferrous sulfate, the bacteria enhance copper extraction and oxidation of ferrous ions released from chalcopyrite. However, the bacteria suppressed chalcopyrite leaching when ferrous sulfate was added. This is mainly due to the bacterial consumption of ferrous ions which act as a promoter for chalcopyrite oxidation with dissolved oxygen. Coprecipitation of copper ions with jarosite formed by the bacterial ferrous oxidation also causes the bacterial suppression of copper extraction. (C) 1999 John Wiley & Sons, Inc.
• 高硫黄石炭ずり浸出水の水質制御に関する基礎的研究

  伊藤真由美, 山田龍一, 恒川昌美, 平島剛, 広吉直樹  資源・素材学会春季大会講演集  (2)  17  1999/03/29  [Not refereed][Not invited]
  
• 石炭の脱硫浮選に関する基礎的研究 (第3報)

  伊藤真由美, 湯川健太郎, 恒川昌美, 平島剛, 広吉直樹  資源・素材学会春季大会講演集  (2)  18  1999/03/29  [Not refereed][Not invited]
  
• 硫酸酸性溶液中での黄銅鉱浸出に及ぼす鉄(II)イオンの影響

  広吉 直樹, 前田 英人, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1997-  (1)  204  -204  1999/03/25
• バクテリアリーチングにおける鉄酸化細菌の役割に関する疑問-黄銅鉱の浸出実験結果に基づく考察-

  広吉 直樹, 恒川 昌美, 平島 剛, 廣田 雅彦  一般発表(研究・業績発表)講演要旨集  1997-  (1)  25  -25  1999/03/25
• 石炭浮選における脱灰性評価法

  恒川 昌美, 今 行忠, 平島 剛, 広吉 直樹, 伊藤 真由美  一般発表(研究・業績発表)講演要旨集  1997-  (1)  1999/03/25  [Not refereed][Not invited]
  
• 石炭の脱流浮選に関する基礎的研究

  伊藤 真由美, 恒川 昌美, 平島 剛, 広吉 直樹  一般発表(研究・業績発表)講演要旨集  1997-  (1)  1999/03/25  [Not refereed][Not invited]
  
• Fe(II)による黄銅鉱浸出促進に関する研究(第2報)-Fe(II)-Cu(II)混合溶液で前処理した黄銅鉱電極のアノード分極特性-

  広吉 直樹, 荒井 政俊, 三木 一, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  1999-  (2)  113  -113  1999/03/01
• Fe(II)による黄銅鉱進出促進に関する研究(第1報)-Fe(III)による黄銅鉱酸化に及ぼすFe(II)の影響とCu(II)の重要性-

  広吉 直樹, 三木 一, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  1999-  (2)  111  -112  1999/03/01
• Fe(II)による黄銅鉱浸出促進に関する研究(第3報)-進出促進を説明する反応モデルとその熱力学的成立条件-

  広吉 直樹, 三木 一, 平島 剛, 恒川 昌美  一般発表(研究・業績発表)講演要旨集  1999-  (2)  114  -115  1999/03/01
• Sar-Cheshmeh鉱石中の金の存在状態と選別プロセスにおけるその挙動

  ラド サラリ, 岩瀬 広幸, 恒川 昌美, 平島 剛, 広吉 直樹, 米田 哲朗  一般発表(研究・業績発表)講演要旨集  1999-  (2)  21  -22  1999/03/01
• 高硫黄石炭ずり浸出水の水質制御に関する基礎的研究

  伊藤 真由美, 山田 龍一, 恒川 昌美, 平島 剛, 広吉 直樹  一般発表(研究・業績発表)講演要旨集  1999-  (2)  1999/03/01  [Not refereed][Not invited]
  
• 石炭の脱硫浮選に関する基礎的研究(第3報)

  伊藤 真由美, 湯川 健太郎, 恒川 昌美, 平島 剛, 広吉 直樹  一般発表(研究・業績発表)講演要旨集  1999-  (2)  1999/03/01  [Not refereed][Not invited]
  
• Basic Study on Separation of Pyrite from Coal by Flotation Using Ferric Solution

  ITO Mayumi, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi, HIROYOSHI Naoki, YUKAWA Kentaro  Shigen-to-Sozai  115-  (10)  737  -742  1999  [Not refereed][Not invited]
   

  Flotation behavior of coal and pyrite was investigated by bubble pick-up tests and Hallimond tube flotation. Flotation recovery of coal and pyrite was high in the acidic region and decreased with increasing pH. In solutions containing iron species the recovery of pyrite decreased drastically at pHs where iron hydroxide was precipitated, but coal flotation was not influenced. Zeta potentials of pyrite and iron hydroxide precipitates were measured under various conditions and the formed precipitates were characterized by XRD, FTIR, and settling velocity measurements. The precipitates formed at the pH where depression of pyrite flotation occurred were very fine sized amorphous ferric hydroxides, which preferentially adhered on pyrite surfaces and rendered pyrite hydrophilic. Selective flotation of artificial high sulfur coal (mixture of coal and pyrite) was performed in the following three solutions containing ferric iron adjusted to pH 2.5 : a) prepared with ferric sulfate, b) prepared by oxidizing ferrous sulfate with iron-oxidizing bacteria (Thiobacillus ferrooxidans), and c) prepared by centrifuging the solution of b). In all solutions coal was selectively recovered as a froth product with high combustible recovery and high separation efficiency.
• 鉄((]G0002[))イオンを促進剤とする黄銅鉱浸出における鉄酸化細菌の生育抑制とその郊果

  広吉 直樹, 三木 一, 平島 剛, 恒川 昌美  資源と素材  115-  (3)  172  -176  1999  [Not refereed][Not invited]
  
• Basic Study on Sepatation of Pyrite from Coal by Flotation Using Ferric Solution

  ITO Mayumi, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi, HIROYOSHI Naoki, YUKAWA Kentaro  Shigen-to-Sozai  115-  (10)  737  -742  1999  [Not refereed][Not invited]
   

  Flotation behavior of coal and pyrite was investigated by bubble pick-up tests and Hallimond tube flotation. Flotation recovery of coal and pyrite was high in the acidic region and decreased with increasing pH. In solutions containing iron species the recovery of pyrite decreased drastically at pHs where iron hydroxide was precipitated, but coal flotation was not influenced. Zeta potentials of pyrite and iron hydroxide precipitates were measured under various conditions and the formed precipitates were characterized by XRD, FTIR, and settling velocity measurements. The precipitates formed at the pH where depression of pyrite flotation occurred were very fine sized amorphous ferric hydroxides, which preferentially adhered on pyrite surfaces and rendered pyrite hydrophilic. Selective flotation of artificial high sulfur coal (mixture of coal and pyrite) was performed in the following three solutions containing ferric iron adjusted to pH 2.5 : a) prepared with ferric sulfate, b) prepared by oxidizing ferrous sulfate with iron-oxidizing bacteria (Thiobacillus ferrooxidans), and c) prepared by centrifuging the solution of b). In all solutions coal was selectively recovered as a froth product with high combustible recovery and high separation efficiency.
• Ferrous promoted chalcopyrite leaching

  N Hiroyoshi, H Miki, T Hirajima, M Tsunekawa  HYDROMETALLURGY OF COPPER  4-  231  -243  1999  [Not refereed][Not invited]
   

  It is generally accepted that ferric ions are effective for leaching chalcopyrite as an oxidant and ferrous ions contribute to the leaching only as a source of the oxidant ferric ions. However, this paper shows that ferrous ions are more useful for leaching chalcopyrite than oxidant ferric ions in sulfuric acid solutions in air at ambient temperatures. Leaching experiments and dissolved oxygen consumption measurements were carried out with a very pure chalcopyrite and 0.001 - 1 mol dm(-3) sulfuric acid solutions containing 0 - 0.1 mol dm(-3) ferric or ferrous ions at 303 K. Chalcopyrite oxidation with dissolved oxygen was promoted by ferrous ions but suppressed by ferric ions. As a result, the amount of extracted copper was larger with ferrous ions than with ferric ions. Effects of Thiobacillus ferrooxidans on the ferrous promoted chalcopyrite leaching were also investigated and discussed based on the experimental data.
• Effects of Several Inhibitors to Thiobacillus ferrooxidans on Ferrous Promoted Chalcopyrite Leaching

  Naoki HIROYOSHI, Hajime MIKI, Tsuyoshi HIRAJIMA, Masami TSUNEKAWA  J. Mining and Material Processing Inst. Japan  115-  (3)  172  -176  1999  [Not refereed][Not invited]
   

  Ferrous ions enhance copper extraction from chalcopyrite in sulfuric acid solutions in air at ambient temperatures, because they promote chalcopyrite oxidation with dissolved oxygen. However iron-oxidizing bacteria such as Thiobacillus ferrooxidans rapidly consume ferrous ions, suppressing copper extraction. In this paper, three compounds were used to inhibit ferrous oxidation by T. ferrooxidans and their effects on ferrous promoted chalcopyrite leaching were investigated in the presence and absence of the bacteria. Sodium lauryl sulfate and tannic acid suppressed not only the bacterial ferrous oxidation but also the chalcopyrite oxidation with dissolved oxygen, resulting in a suppression of copper extraction. High concentrations of sulfuric acid (> 0.05 mol dm-3) suppressed the bacterial ferrous oxidation and promoted chalcopyrite oxidation with dissolved oxygen, causing enhanced copper extraction.
• 黄銅鉱浸出における鉄(III),鉄(II)イオンおよび鉄酸化細菌の役割 -鉄(II)イオンによる黄銅鉱酸素酸化浸出の促進と関連して-

  広吉 直樹, 恒川 昌美, 平島 剛  資源・素材  1998-  (3)  173  -176  1998/11
• レアアースロール磁選機の分離挙動に関する基礎的研究

  恒川 昌美, 堀江 周, 平島 剛, 広吉 直樹  一般発表(研究・業績発表)講演要旨集  1998-  (2)  95  -95  1998/03/01
• 鉄(II)イオンを促進剤とする黄銅鉱酸素酸化浸出における鉄酸化細菌の生育抑制とその効果

  広吉 直樹, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1998-  (2)  9  -9  1998/03/01
• 鉄(II)イオンを促進剤とする黄銅鉱酸素酸化浸出の過程における鉄(III)イオンの生成

  広吉 直樹, 三木 一, 前田 英人, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1998-  (2)  10  -10  1998/03/01
• 石炭の脱硫浮選に関する基礎的研究 (第2報)

  伊藤真由美, 恒川昌美, 平島剛, 広吉直樹  資源・素材学会春季大会講演集  21  1998/03  [Not refereed][Not invited]
  
• 微粉炭浮選における脱灰性の評価と鉱物質単体分離度の推定

  恒川昌美, 今行忠, 伊藤真由美, 平島剛, 広吉直樹  資源・素材学会春季大会講演集  22  1998/03  [Not refereed][Not invited]
  
• 石炭の脱硫浮選に関する基礎的研究(第2報)

  伊藤 真由美, 恒川 昌美, 平島 剛, 広吉 直樹  一般発表(研究・業績発表)講演要旨集  1998-  (2)  1998/03/01  [Not refereed][Not invited]
  
• 微粉炭浮選における脱灰性の評価と鉱物質単体分離度の推定

  恒川 昌美, 今 行忠, 伊藤 真由美, 平島 剛, 広吉 直樹  一般発表(研究・業績発表)講演要旨集  1998-  (2)  1998/03/01  [Not refereed][Not invited]
  
• Desulfurization flotation of imaginary high sulfur coal using the ferruginous solution.

  ITO MAYUMI, YUKAWA KENTARO, TSUNEKAWA MASAMI, HIRASHIMA TSUYOSHI, HIROYOSHI NAOKI  資源・素材学会北海道支部春季講演会講演要旨集  1998-  15  -16  1998  [Not refereed][Not invited]
  
• Basic research on property control of the leach from high sulfur coal.

  ITO MAYUMI, YAMADA RYUICHI, TSUNEKAWA MASAMI, HIRASHIMA TSUYOSHI, HIROYOSHI NAOKI  資源・素材学会北海道支部春季講演会講演要旨集  1998-  17  -18  1998  [Not refereed][Not invited]
  
• Leaching of Low Grade Copper Ore.

  HIROYOSHI Naoki, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi  Resources Processing  45-  (4)  263  -268  1998  [Not refereed][Not invited]
  
• 鉄((]G0002[))イオンを促進剤とする黄銅鉱浸出-浸出提程における鉄((]G0003[))イオンの生成とその影響-

  広吉 直樹, 前田 英人, 三木 一, 平島 剛, 恒川 昌美  資源と素材  114-  (11)  795  -800  1998  [Not refereed][Not invited]
  
• 微粒石炭浮選における脱灰性の評価と単体分離度の推定(共著)

  恒川昌美, 今行忠, 伊藤真由美, 平島剛, 広吉直樹  資源と素材  114-  (6)  421  -425  1998  [Not refereed][Not invited]
  
• A New Method to Characterize the Flotation Performance of Fine Coal

  Proc. 13th Int. Coal Preparation Congress  1-  397  -406  1998  [Not refereed][Not invited]
  
• Leaching of Low Grade Copper Ore

  HIROYOSHI Naoki, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi  RESOURCES PROCESSING  45-  (4)  263  -268  1998  [Not refereed][Not invited]
  
• Ferrous Promoted Chalcopyrite Leaching-Ferric formation and its effects on the leaching-

  Naoki HIROYOSHI, Hideto MAEDA, Hajime MIKI, Tsuyoshi HIRAJIMA, Masami TSUNEKAWA  J. Mining and Material Processing Inst. Japan  114-  (11)  795  -800  1998  [Not refereed][Not invited]
   

  This paper shows that ferrous ions are more useful for leaching chalcopyrite than oxidant ferric ions in sulfuric acid solutions in air at ambient temperatures. Leaching experiments and dissolved oxygen consumption measurements were carried out with a very pure chalcopyrite and 0.001 ∼ 1 mol dm-3 sulfuric acid containing 0 ∼ 0.1 mol dm-3 ferrous or ferric ions at 303 K. Chalcopyrite oxidation with dissolved oxygen was promoted by ferrous ions and was suppressed by ferric ions. As a result, the amount of extracted copper was higher with ferrous ions than with ferric ions in air. During the ferrous promoted chalcopyrite leaching, extracted copper ions catalyzed oxidation of ferrous ions to ferric ions which suppressed copper extraction. This result indicates that higher leaching rates can be achieved by reducing the ferric ions formed during the leaching.
• A Method to Characterize Flotation Performance of Fine Coal and Estimate its Liberation

  TSUNAKAWA M.  J. Mining and Material Processing Inst Japan  114-  (6)  421  -425  1998  [Not refereed][Not invited]
  
• Biotechnology for Waste Treatment and Recycling

  HIROYOSHI Naoki  Proceedings of the Institute of Electrostatics Japan  21-  (4)  166  -169  1997/07/31
• Enhancement in Bacterial Leaching of Chalcopyrite by Surfactant Addition

  Proceedings of the 20th International Mineral Processing Congress  4-  546  -547  1997  [Not refereed][Not invited]
  
• A case of ferrous sulfate addition enhancing chalcopyrite leaching

  Naoki Hiroyoshi, Masahiko Hirota, Tsuyoshi Hirajima, Masami Tsunekawa  Hydrometallurgy  47-  (1)  37  -45  1997  [Not refereed][Not invited]
   

  It is generally accepted that ferric ions as an oxidant are effective for leaching chalcopyrite but ferrous ions contribute to the leaching only as a source of ferric ions. However, this paper found that several chalcopyrite samples were more effectively leached in ferrous sulfate solution than in ferric sulfate solution. Chalcopyrite samples from four different sources were leached in 0.1 mol dm-3 sulfuric acid solution containing 0.1 mol dm-3 ferrous sulfate or ferric sulfate at 303 K in air for 168 h. Three samples were more effectively leached in the ferrous sulfate solution than in the ferric sulfate solution. Especially, with the sample from the Akenobe mines, Hyogo, Japan, the amount of copper extracted with ferrous sulfate was about five times larger than that with ferric sulfate. By using the Akenobe sample, leaching experiments and oxygen consumption measurements were carried out under various conditions. The amount of extracted copper increased markedly with increasing ferrous sulfate addition and decreasing pH. During the leaching experiments, most of the soluble iron was present in the ferrous form. By adding ferrous sulfate, proton consumption increased. The mole ratio of elemental sulfur to extracted copper was about 2. When the leach solution was purged with nitrogen, the amount of copper extracted was negligible even with ferrous sulfate. By adding ferrous sulfate, dissolved oxygen consumption on the sample surface increased. From these results, it was concluded that ferrous ions enhance the following reaction for the Akenobe sample: CuFeS2 + O2 + 4H+ = Cu2+ + Fe2+ + 2S0 + 2H2O. The importance of this effect in the bacterial leaching of chalcopyrite is discussed. © 1997 Elsevier Science B.V.
• Mineral Bioprocessingへの挑戦〜北大・鉱物処理工学研究室における最近の研究〜

  伊藤 真由美, 恒川 昌美, 平島 剛, 広吉 直樹, 笹木 圭子  資源・素材  1996-  (1)  1996/10/21  [Not refereed][Not invited]
  
• 黄銅鉱のバクテリアリ-チングに及ぼす菌体量の影響

  広吉 直樹, 廣田 雅彦, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1996-  (1)  227  -227  1996/03/29
• 界面活性剤添加による黄銅鉱のバクテリアリ-チングの浸出性改善-数種の界面活性剤の効果の比較-

  広吉 直樹, 西田 信一, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1996-  (1)  228  -228  1996/03/29
• 強酸性領域における黄鉄鉱の浮選挙動

  伊藤 真由美, 広吉 直樹, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1996-  (1)  1996/03/29  [Not refereed][Not invited]
  
• Feed grain size and limitative ash content in coal flotation.

  TSUNEKAWA MASAMI, KON YUKITADA, HIRAJIMA TSUYOSHI, ITO MAYUMI, HIROYOSHI NAOKI  資源・素材学会北海道支部春季講演会講演要旨集  1996-  5  -6  1996  [Not refereed][Not invited]
  
• Simple and Rapid Cell Growth Estimation Method for Thiobacillus ferrooxidans and the Growth Rate in the Presence of Polyoxyethylenes

  HIROYOSHI Naoki, ITO Mayumi, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi  Journal of the Mining and Materials Processing Institute of Japan  112-  (3)  171  -175  1996  [Not refereed][Not invited]
  
• Simple and Rapid Call Growth Estimation Method for Thlobacillus Ferrooxidans and the Growth Rate in the Presence of Polyoxyethylene

  Naoki HIROYOSHI, Mayumi ITO, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA  J.Mining and Materials Processing Inst.Japan  112-  (3)  171  -175  1996  [Not refereed][Not invited]
  
• ポリオキシエチレンソルビタンモノラウレートによる黄銅鉱のバクテリアリーチングの浸出性改善

  広吉 直樹, 中村 剛, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1995-  (1)  42  -42  1995/03/28
• 鉄酸化細菌の増殖挙動の簡便測定法とその応用 : ポリオキシエチレン化合物存在下での増殖挙動の把握

  広吉 直樹, 伊藤 真由美, 恒川 昌美, 平島 剛  一般発表(研究・業績発表)講演要旨集  1995-  (1)  1995/03/28  [Not refereed][Not invited]
  
• Thiobacillus ferrooxidans による黄銅鉱のバクテリアリーチングに及ぼすphosphatidylethanolamineの影響

  広吉 直樹, 恒川 昌美, 平島 剛, 沢田 満  資源と素材  111-  (1)  43  -47  1995  [Not refereed][Not invited]
  
• Enhancement in Bacterial Lerching of Chalcopyrite by Polyoxyethylene Sorbitan Monolaurate Addition

  Naoki HIROYOSHI, Takeshi NAKAMURA, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA, Mayumi ITO  J.Mining and Material Processing Iust.Japan  111-  (13)  943  -948  1995  [Not refereed][Not invited]
  
• Effects of Phosphatidylethanolamine on Bacterial Leaching of chalcopyrite by Thiobacillus ferroocidans

  Naoki HIROYOSHI, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA, Mitsuru SAWADA  J. Mining and Materials Processing Inst. Japan  111-  (1)  43  -47  1995  [Not refereed][Not invited]
  
• 鉄酸化細菌の簡便な増殖測定法

  広吉直樹, 伊藤真由美, 恒川昌美, 平島剛  資源・素材学会北海道支部春季講演会講演要旨集  1994-  3  -4  1994  [Not refereed][Not invited]
  
• 硫化鉱のバクテリアリーチングの基礎実験法

  資源と素材  109-  (7)  558  -561  1993  [Not refereed][Not invited]
  
• Experimental Methods for Bacterial Leaching of Sulfide Minerals

  J. Mining and Materials Process. Inst. Japan  109-  (7)  558  -561  1993  [Not refereed][Not invited]
  
• Thiobacillus ferrooxidans による黄銅鉱精鉱の微生物学的浸出に及ぼすりん脂質の影響-Phosphatidylglycerol の影響-

  広吉 直樹, 恒川 昌美, 平島 剛, 高森 隆勝  資源と素材  108-  (2)  129  -133  1992  [Not refereed][Not invited]
  
• Effects of Phospholipid Bacterial Leaching of Chalcopyrite Concentrate by Thiobacillus ferrooxidans-Effect of Phosphatidylglcerol-

  Naoki HIROYOSHI, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA, Takakatsu TAKAMORI  J. Mining and Materials Processing. Inst. Japan  108-  (2)  129  -133  1992  [Not refereed][Not invited]
  
• 亜鉛精鉱の微生物学的浸出とインジウムの浸出挙動

  北海道応用地学合同研究会論文集  2,14-18-  1991  [Not refereed][Not invited]
  
• Dissolution Behavior of Zinc, Indium and Iron in Bacterial Leaching Process of Sphalerite Concentrate Containing Indium

  Hokkaido Geotechnics  2,14-18-  1991  [Not refereed][Not invited]
  
• Comparison of the suppressive effect of ferric- and ferrous-catechol complexes on pyrite oxidation

  X. Li, N. Hiroyoshi, K. Naruwa, M. Ito, C.B. Tabelin  Proceedings of International Symposium on Earth Science and Technology  605  -607  [Not refereed][Not invited]
  

Awards & Honors

• 2000 資源・素材学会 第25回奨励賞
  
• (社)資源・素材学会 第32回論文賞
   硫酸溶液中での黄銅鉱浸出に対する活性炭と石炭の触媒作用 

  受賞者: 岡本秀征;中山良一;黒岩樹人;広吉直樹;恒川昌美

Research Grants & Projects

• New development on carrier micro-encapsulation for prevending acid mine drainage formation

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2020/03 

  Author : Hiroyoshi Naoki

   

  Carrier micro-encapsulation (CME) was studied as a new method to suppress oxidative dissolution of pyrite, causing the formation of acid mine drainage. A novel technique of CME using Fe or Al ions, which are easy to be obtained at mine site, was proposed and its suppressive effects on pyrite dissolution was confirmed based on electrochemical studies and surface analysis. When Ti and Fe-catecholate complexes coexisted, a high acid resistant protective coating was formed on pyrite surface, and it suppressed cathodic reduction of oxygen on the mineral surface and pyrite oxidation.
• Understanding of host minerals for radioactive cesium fixation and proposal for reasonable volume reduction of the contaminated soils

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2015/04 -2018/03 

  Author : Sato Tsutomu

   

  Detail observations for the contaminated soils particles collected from different areas in Fukushima prefecture,percentage of the contaminated particles was limited to be only 0.3%.The contaminated particles were categorized to agglomerated weathered biotite, complex of organic matter and weathered biotite and weathered biotite.From the observation,the weathered biotite would be dominant host of radioactive cesium in Fukushima prefecture and supported by adsorption experiments.From our observation,spherical glass particles (so called "Cs ball") were not detected. Therefore, we can conclude that the host of radioactive cesium is the weathered biotite in Fukushima prefecture.Our laboratory experiments showed that the weathered biotite can be collected by magnet.After ball milling crushing and ultra sonic dispersion for agglomerated weathered biotite and complex of organic matter and weathered biotite, the contaminated particles would be efficiently collected by magnetic cobbing machine.
• Development of environment-friendly preservation material with self-healing function

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2012/04 -2015/03 

  Author : KAWASAKI SATORU, HIROYOSHI Naoki, HATA Toshiro

   

  Self-healing and environment-friendly novel preservation materials for remains, relics, stone cultural heritages and others were developed by using the function of microorganisms living in nature. The preservation materials were primarily composed of calcium carbonate or calcium phosphate compounds which were typical cement substances in nature. In addition, mechanical properties of soils using the preservation materials and the population of microorganisms were investigated during the testing periods, and the validity of the newly developed preservation materials were evaluated. As a result, a possibility that they were effective as self-healing and environment-friendly preservation materials was obtained approximately.
• Selective recovery of precious metals from solution using magnetite

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2011/04 -2014/03 

  Author : HIROYOSHI Naoki, ITO Mayumi, FUKUSHIMA Masami

   

  A new method to recover precious metals like gold and platinum group metals selectively from the solutions containing common metal ions. Reduction potential of the precious metal ions are high and they are reduced and precipitated on magnetite surface, but reduction potential of common metals like copper and zinc are lower than that of magnetite and they are not reduced on magnetite surface. Magnetic separation can be used to recover precious metal loaded magnetite from the suspension of precious metal ores and scraps. It was confirmed that slag magnetite (a magnetic portion of crushed copper converter slag) can be used to recover precious metals.
• Self-sealability of fractures in rock and its application to fracture and strength control

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010/04 -2014/03 

  Author : KANEKO Katsuhiko, KAWASAKI Satoru, NARA Yoshitaka, ITO Mayumi, MUKUNOKI Toshifumi, HIROYOSHI Naoki, SAKAGUCHI Kiyotoshi, HARADA Syusaku

   

  A series of experimental studies on the sealability of fracture has been performed and its application to geotechnical engineering has been discussed. Firstly, analyzing the influence of environments on the sub-critical crack growth in rock, the mechanism of crack growth has been clarified. Secondarily, the self-sealing process of fracture in the rocklike material in water was investigated and the mechanism of self-sealing was clarified. Thirdly, the process of fracture propagation was analyzed numerically and a design method to control fracture propagation, i.e., crack orientation and so on. From these results, a method to estimate the long-term strength of rock has been proposed. Furthermore it is pointed out that the strength of rock can be controlled by controlling the environmental condition.
• Advanced jig separation technology for resource recycling and wettability control of plastics

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2011 -2013 

  Author : ITO Mayumi, HIROYOSHI Naoki

   

  Industrial systems and daily life in Japan are shifting to a society based on recycling to reduce energy and resource consumption and efficient separation technology of valuable component from used products is important. The authors have developed the RETAC jig (a modified TACUB jig) and the RETAC jig can separate relatively low density particles such as plastics. To further improve the separation ability, a hybrid jig (a RETAC jig with an air bubbler under the particle bed), which can separate plastics having similar specific gravities by the differences in the wettabilities of the particles was developed. Surface modification of plastics with similar wettability enabling separation in the hybrid jig and precise control of the wettability of plastic surfaces are investigated. Effect of bubble size on apparent density of particles was also investigated and recovery system of floating and suspending particles was developed.
• Proposal of environment-friendly preservation material using microbial function

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2009 -2011 

  Author : KAWASAKI Satoru, HIROYOSHI Naoki, HATA Toshiro

   

  An environment-friendly novel preservation material for remains, relics, stone cultural heritages, etc. was produced by using the function of microorganisms living in nature. The preservation material was primarily composed of silica which was one of the typical cement substances. In addition, mechanical properties of soils using the preservation material made and the numbers of microorganisms were investigated during the testing periods, and the validity of the newly developed preservation material was evaluated. As a result, a possibility that it was effective as an environment-friendly preservation material was obtained approximately.
• Application of carrier-microencapsulation for coal flotation to remove pyrite and to suppress acid mine drainage formation at tailing dam

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2008 -2010 

  Author : HIROYOSHI Naoki, TSUNEKAWA Masami, ITO Mayumi, IGARASHI Toshifumi, FUKUSHIMA Masami

   

  Pyrite associated with coal generates SOx causing acid rain during coal combustion. In coal preparation, pyrite is rejected as a gangue mineral using the physical separation technique such as froth flotation and wasted into tailing pond. In the froth flotation, pyrite is frequently entrapped in froth together with valuable mineral due to its hydrophobic nature. Formation of acid mine drainage due to the air-oxidation of pyrite in tailing pond is also a serious problem. In the present study, carrier-microencapsulation (CME) is proposed to suppress both the floatability and oxidation of pyrite in coal preparation.
• 分けるのは訳ないリサイクル用ハイパー比重選別機の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2009 -2009 

  Author : 恒川 昌美, 廣吉 直樹, 伊藤 真由美

   

  研究代表者および分担者らの研究室で開発した網下気室型湿式比重選別機(TACUB JIG)をベースにして,より選別効率の高い比重選別機の開発に取り組み,以下に述べる3タイプの新しい比重選別機を開発した。 1)TACUB JIGのフィード部および産物回収部に改良を加え,さらに制御法を工夫して,廃棄物の資源化・リサイクルに適した比重選別機(RETAC JIG)を開発し,種々のプラスチックを素材別に選別することを可能にした。 2)このRETAC JIGをベースにして,比重差が無くても濡れ性に差があれば比重選別できるHybrid JIGを開発した。この選別機では,気泡を導入して,より疎水性の粒子表面に微細気泡を選択的に付着させることで,その見かけ比重を小さくして,物質間に見かけ比重差を生じさせて,比重分離する。このJIGにより,比重の同じプラスチックの相互選別が可能になった。 3)水より軽い物質相互を分離するため,RETAC JIGの選別槽上部に天網を設置し,この天網の下にフィードして上下に脈動を与えることで,天網下部に比重別に産物を成層させて選別できるREVERSE JIGを開発した。 4)上述の新たに開発した3タイプの比重選別機をあわせてAdvanced JIGと総称し,本Advanced JIGを組み合わせることで廃家電リサイクルプラントから排出されるプラスチックを素材別に選別して,マテリアルリサイクルできることを実証した。 5)いずれのJIGでも,純度99%以上の産物を回収することができた。
• Development and evaluation of a novel preservation materialcementing due to microbial metabolism

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2006 -2008 

  Author : KAWASAKI Satoru, HIROYOSHI Naoki

   

  土や岩の代表的なセメント物質の1つである炭酸カルシウムを主成分とし, 自然の土の中に生息する微生物の代謝活動を利用した環境に優しく新しい遺構, 遺物, 石造文化財などの保存材料(強化材料, 接着剤, 補填材料など)を作製した。また, 作製した保存材料を使用した土の力学・水理学特性およびその使用前後における微生物の菌数と帰属分類群について調査し, 新たに作製した保存材料の有効性について評価を実施した。その結果, 保存材料として有効であるとの見通しが大略得られた。
• 有機・無機複合廃棄物のハイパー解砕・資源化技術の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2005 -2007 

  Author : 恒川 昌美, 廣吉 直樹, 伊藤 真由美, 米田 哲朗, 吉田 豊, 柳 庚槿

   

  循環型社会を構築していくうえで鍵を握るのは,都市域における廃棄物の資源化・リサイクル技術および環境保全技術の開発である。我々は,廃自動車や廃家電・OA機器類の資源化技術を開発してきている。この開発過程で,現状の処理プロセスでは解砕・破砕が主として減容化を目的に行われているため,その後の有価物選別・回収の段階で低い選別精度,回収率にとどまること,解砕・破砕時に発生するシュレッダーダストの軽比重物(例えばウレタンなど)に絡み込んでいる有価物が十分に回収できないことを見出した。そこで種々の有機・無機複合廃棄物を効率的に資源化・リサイクルする立場から,解砕・破砕,選別を合理的に行うための要素技術の開発研究に取り組んだ。 最終年度にあたる19年度は,下記のような検討を行い,有用な知見を得た。 1)二つの使用済み自動車のシュレーダーダストを対象に,破砕後に種々の風力分級をして,産物について化学分析,灰分測定,組成解析などを行った。その結果,サーマルリサイクルに適した,ウレタンなどの可燃分からなる産物を回収できるプロセスの条件を明らかにした。 2)ウレタン類に鉄・銅・アルミニウムなどの金属類,繊維などが絡まっている場合は,ある種の界面活性剤溶液に浸漬することで,有価金属類を分離回収できることを見出した。 3)17〜19年度の成果を踏まえ,各種有機・無機複合廃棄物に対する適切な破砕・解砕法と有価物回収法についてまとめた。
• Advanced Heap-leaching for Chalcopyrite

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2005 -2007 

  Author : HIROYOSHI Naoki, TSUNEKAWA Masami, YONEDA Tetsuro, ITO Mayumi

   

  Heap-leaching has become important in copper production: over 20% of copper in the world is now produced at open pit mines of porphyry copper deposits through this method. In this method, copper in low-grade oxide and secondary sulfide ores is extracted into sulfuric acid solutions, and the extracted copper is recovered by solvent-extraction and electro-winning methods. However, the leaching rate of chalcopyrite (CuFeS_2), a major copper mineral in the deepest parts of the deposits, is very slow, and the development of advanced heap-leaching methods for this mineral is an object for copper hydrometallurgy in the future. One factor affecting the leaching rate of chalcopyrite is the redox potential determined by the concentration ratio of Fe^<3+> to Fe^<2+> in the solution: the leaching rate increases when increasing the redox potential to reach a maximum at an optimum redox potential, and then decreases at higher redox potentials. This study investigated the effect of redox potential control on chalcopyrite leaching rates. Shaking flask leaching experiments and electrochemical experiments were carried out to clarify factors affecting the redox potential dependence of chalcopyrite leaching, and the results indicates that the optimum redox potential is a function of the cupric and ferrous ion concentrations. Based on the experimental results and theoretical considerations of the leaching mechanism, a computer simulation model was developed and the optimum leaching conditions for chalcopyrite were determined. The simulated results agree with the results of column leaching experiments using a chalcopyrite powder sample supported on inert silica host rocks: About 80% of copper was extracted from the chalcopyrite in 100 days when the chemical composition and redox potential of solution were controlled. This extraction rate is comparable to the rate in the conventional heap-leaching operation for secondary copper sulfides, indicating that the redox potential control established here is effective for chalcopyrite leaching.
• Development of Urban Mines as Urban Resource Recovery Centers to Utilize Solid Waste and Create a Holonic Path for a Sustainable Society

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2004 -2007 

  Author : TSUNEKAWA Masami, HIROYOSHI Naoki, ITO Mayumi, YONEDA Tetsuro, NAWA Toyoharu, HIRAJIMA Tsuyoshi

   

  Industrial systems and daily life in Japan are shifting to become recycling-based to reduce energy and resource consumption. To establish a society based on recycling, urban resource recovery centers (urban mines) are important as places to reduce waste volumes, reusing and recycling valuable materials with application of mineral processing technology. The authors have studied advanced mineral processing technology for urban mines, and have developed new processes as described below. Based on these results, the creation of a holonic path in a sustainable society is discussed and proposed. 1) A process for recycling of plastics and metals from scrapped copy machines was developed and a processing Pilot plant was constructed around the RETAC jig developed in our laboratory. 2) A process for recovering fine and high quality glass from waste fluorescent lamps was developed using RETAC jig. 3) A hybrid jig using the differences in specific gravity and surface affinity for water was developed for separating plastics with the same specific gravities. 4) A metal recovery process for incinerated municipal solid waste was developed using leaching and cementation-in-pulp methods. 5) A process for recovering electrode materials from waste nickel metal hydride batteries was developed using selective crushing at low temperature and with 3 stages magnetic separation. 6) A microencapsulation method to remediate soils contaminated with heavy metals was developed. 7) A process to recover heavy metals and to remediate soils contaminated with heavy metals was developed using a hybrid method combined with leaching, cementation and magnetic separation. 8) Sustainable societal systems linked with urban mines are discussed and proposed.
• キャリアマイクロエンカプセレーション 〜鉱山汚濁水発生防止のための新しい方法〜

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2005 -2006 

  Author : 廣吉 直樹, 恒川 昌美, 伊藤 真由美

   

  本研究では,鉱山酸性汚濁水の発生を防止する新しい方法としてキャリアマイクロエンカプセレーション(Carrier Micro Encapsulation, CME)を提案する.本法では,地殻中に存在するTiO_2などの鉱物中のTiを有機キャリアで水に可溶化して,汚染源となる黄鉄鉱FeS_2などの表面に吸着させた後,キャリアを分解して化学的に安定なTiO_2薄膜で汚染源を被覆し,水や空気から遮蔽する. 昨年度の結果に基づき,Tiとの錯体形成能力や酸化分解性に優れたカテコール(1,2-dihydroxybenzene, C_6H_4(OH)_2)をキャリアとして選択し,黄鉄鉱粉末(粒子径53〜75μm)の溶解に対するCMEの効果を振盪フラスコ法によるモデル実験で調べた.実験は天然Ti鉱物の代替物として試薬アナターゼ(TiO_2)5kg/Lを用いて,黄鉄鉱-溶液比0.6kg/L,温度25℃,大気下で行った。CMEを施した実験(カテコールとTiO_2を添加した実験)では,黄鉄鉱表面にTiO_2あるいはTi(OH)_2の被膜が形成され、対照実験(カテコールとTiO_2の双方あるいは一方を添加しなかった実験)に比べて黄鉄鉱の溶解量(硫酸とFeの溶出量)が少なくなり,pHの低下が緩和された.黄鉄鉱溶解に対するCMEの抑制作用は,カテコール添加濃度0.01kmol m^<-3>以上,pH4〜7の範囲で発現した.また,別の実験では,Ti-カテコール錯体は代表的な造岩鉱物である石英SiO_2には吸着せず,黄鉄鉱に選択的に吸着することが確認され,黄鉄鉱の周辺に石英などが共存してもCMEの効果は低下しないものと推定された.これらの結果は,CMEが鉱山の廃さい堆積場や掘削跡地に存在する黄鉄鉱の溶解を抑制し,酸性汚濁水の発生防止に役立つことを示唆している.
• 微生物代謝による固化する新しいグラウトの開発に関する基礎的研究

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2005 -2006 

  Author : 川崎 了, 広吉 直樹

   

  本研究の目的は,微生物代謝を利用した安価で環境に優しい新たなグラウト(以下,バイオグラウトと呼ぶ)を開発し,バイオグラウトの注入前後における地盤(土および岩)の水理学・力学特性について評価を行うことである。最終年度である平成18年度はセメント物質としてシリカを対象とし,(1)イースト菌およびエタノールを用いたシリカコロイドのゲル化試験,(2)シリカコロイドを主成分とするバイオグラウトにより改良した砂質地盤の透水試験,(3)メタ珪酸ナトリウム水溶液のゲル化試験を実施した。 得られた主な知見をまとめると,以下に示すとおりである。 (1)シリカコロイドにイースト菌とグルコースを添加すると,シリカコロイドはゲル化する。 (2)シリカコロイドに高濃度のエタノールを添加すると,シリカコロイドはゲル化する。 (3)イースト菌によるシリカコロイドのゲル化には,グルコースの微生物代謝産物(二酸化炭素およびエタノール)と菌体細胞の双方が関与している。 (4)シリカコロイドを主成分とするバイオグラウトを用いた豊浦砂の改良試験および改良の前後における豊浦砂の透水試験を実施した結果,改良後の透水係数が改良前よりも約1桁低下した。 (5)メタ珪酸ナトリウム水溶液を用いたゲル/ゾル/ゲル法によるゲル化試験を実施した。具体的には,塩酸による中和で生じたメタ珪酸ナトリウム水溶液のゲルを機械的に撹拝することでゾルにし,その直後にグルコースを添加することで再ゲル化を抑制し,さらにイースト菌を添加することにより微生物代謝によるゲルを生じさせることができた。 (6)メタ珪酸ナトリウム水溶液を用いた直接ゲル法によるゲル化試験を実施した。具体的には,高いpH領域においても,イースト菌およびグルコースを添加したメタ珪酸ナトリウム水溶液がゲル化することが確認された。 以上,2年間の研究により,バイオグラウトの技術開発に関して見通しが得られた。
• Quality Improvement of Pyrolysis Char Derived From Various Kind of Solid Waste for Recycling

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2005 -2006 

  Author : MATSUTO Toshihiko, TOJO Yasumasa, TSUNEKAWS Masami, HIROYOSHI Naoki, ITO Mayumi, KAKUTA Yoshitada

   

  In this study, sixteen kinds of char obtained from various sources including industrial waste were used for experiments. In order to use char as fuel, chlorine level should be reduced to avoid corrosion. Chlorine in char derived from MSW was characterized in terms of solubility. CO2 bubbling could reduce chorine to acceptable level for cement kiln use. Pulverization was proven to be ineffective in the dissolution of non water-soluble chlorine. Ash content is another fraction which should be lowered for fuel use of char. Ash rich fraction (r<125 um) was subjected to float-sink separation, froth flotation, and oil agglomeration methods. As a result, a lower combustible recovery rate was resulted to get a good quality of char with high heating values. For MSW-derived char, the targeted quality level (20000 kJ/kg heating value and 30% ash content) was attained using froth floatation or oil agglomeration. Results of the EDX/SEM analysis indicated that char particles were not segregated to single substances even after being milled for 1 h. Even in the case that char quality is not good enough for fuel use, carbonization was considered as a thermal pretreatment method before landfilling. Soluble organic carbon levels were fairly decreased by carbonization both in batch and column leaching tests. The release amount of heavy metals from carbonization residue decreased but its extent could be varied with the aerobic/or anaerobic condition, and which relys on the physical adsorption onto the surface or pore structure of carbonization residue.
• Production of Eco-Friendly Slurry Fuel from Biomass and Low Rank Coal Mixture by Hydrothermal Treatment

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2003 -2005 

  Author : HIRAJIMA Tsuyoshi, TSUNEKAWA Masami, HIROYOSHI Naoki, SASAKI Keiko, ITOI Ryuichi, NONAKA Moriyasu

   

  During circulative hydrothermal treatments of biomass and low rank coal, it is clarified that the blend of these materials reveals a discrepancy in TOCs between the theoretical and experimental values due certainly to the adsorbent effect of the coal. Therefore, coalffication and partial adsorption of extractives are expected by mixing up the biomass with the coal during hydrothermal treatment. TOC variation is predicable from an on-line monitoring of the absorbance intensity during the treatment. Effects of treatment temperature and mixing ratio on the fuel characterization of the solid phase of the treated material were studied by the batch and continuous treatments. The treatment at higher temperature affects more on degree of the upgrading for both the materials and the upgrading reaction of the mixture was independent and in parallel with each other. The fuel ratio decreased as the mixing ratio increased, however, the chemical compositions of C,H,N and 0,and the gross calorific value were almost identical on a dry ash-free basis, independent of the mixing ratio. The continuous test produced the solid phases having a gross calorific value similar to that for the batch test. In addition, it is worth mentioning that a five-hour run of the continuous treatment was conducted successfully. The characterization of the liquid phase clarified that reducing phenols such as 2,6-dimethoxyphenol, guaiacol and etc. as well as acetic acid and methanol were contained in the liquid phase. The liquid phase reduced Cr (VI) effectively to Cr (III) and the addition of slaked lime or quicklime to the reduced system removed almost all amount of Cr (III) as a precipitate. The amount of sludge decreased 1/2 - 1/3 as compared with the use of iron (I) sulfate as a reducer.
• 次世代銅生産技術としての鉱石中銅・金・銀の同時リーチング

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2002 -2003 

  Author : 廣吉 直樹

   

  従来の銅鉱石のリーチングでは,鉱石に含まれる金・銀は溶出されず,その回収法が確立していない。本研究では,チオ硫酸イオンとアンモニウムを含む浸出液を用いて銅(II)アンミン錯体を酸化剤として鉱石中の銅・金・銀を同時に酸化浸出する方法(チオ硫酸アンモニウム浸出)を検討した。 鉱石試料として5種類の黄銅鉱浮選精鉱を,浸出液として所定濃度のアンモニア,硫酸アンモニア,チオ硫酸ナトリウムを含む水溶液を用いてフラスコ振盪浸出実験を行ない,銅,金,銀の溶出に及ぼす時間(0〜144h),温度(25〜70℃),pH(5〜13),試薬濃度(チオ硫酸濃度;0〜1M,アンモニア濃;0〜4M,硫酸アンモニウム濃度0〜2M)の影響を調べた。銅の溶出量は時間の経過に伴い多くなるが,金と銀の溶出は24h程度で停止した。銅,金,銀いずれの溶出に関しても最適温度は40℃,最適pHは12〜13であった。高濃度のチオ硫酸ナトリウムは金と銀の溶出を促進するが,銅の溶出を妨げた。全アンモニア濃度(硫酸アンモニウムとして添加したアンモニウムイオンと分子態アンモニアの総和)の増加は金,銀,銅いずれの溶出も促進した。 銅浮選精鉱のチオ硫酸アンモニウム浸出の貴液からの金属の回収法として直接電解法を試みた。カソード電極に電圧を印加するとチオ硫酸イオンが還元されて硫化物イオンが発生し,浸出液中の銅,銀が硫化物としてほぼ完全に沈殿した。金も銅,銀と共に沈殿したが一部は溶液中に液中に残留した。
• Redox Controlled Chalcopyrite Leaching as a New Method for Copper Production

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2001 -2003 

  Author : TSUNEKAWA Masami, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi

   

  Heap leaching of low-grade copper ore, combined with solvent-extraction/electro-winning, has become important in copper production, because of its low capital and operation costs, operational simplicity However, the process has not been fully successful, due to the extremely slow leaching kinetics of a common copper source, chalcopyrite (CuFeS_2). Chalcopyrite leaching is a redox process and the control of the redox potential determined by the concentration ration of oxidant ferric ion to reductant ferrous ion has been proposed to improve the leaching rate. In this study, the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions and the factors affecting the potential dependence of the leaching were investigated to establish the redox controlled chalcopyrite leaching. Leaching and anodic-polarization experiments showed that coexistence of cupric and ferrous ions activate anodic dissolution of chalcopyrite, causing faster copper extraction at the potentials below a certain value (critical potential). The analysis of the AC impedance spectra for chalcopyrite electrode indicated that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth at low potentials. These results are explained by a reaction model assuming the formation of intermediate Cu_2S due to chalcopyrite reduction and the subsequent oxidation of the Cu_2S. The critical potential corresponds to the redox potential of the Cu_2S formation and the predicted values matched with the experimental results, and the optimum redox potential for chalcopyrite dissolution is a function of cupric and ferrous ion concentrations. Effects of catalysts like silver ions and activated carbon on chalcopyrite leaching were also explained based on the above model.
• Development of Advanced Mineral Processing, Material Recycling and Waste Water Treatment Technology for establishment of Urban Mines

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2001 -2003 

  Author : TUNEKAWA Masami, HIRAJIMA Tsuyoshi, HIROYOSHI Naoki, YONEDA Tetsuo, YOSHIDA Yutaka, SASAKI Keiko

   

  Industrial systems and daily life in Japan are shifting to a recycling-based society to reduce energy and resource consumption. To establish a society based on recycling urban resource recovery centers (mines) are important as places to reduce waste volumes, reusing and recycling valuable materials with application of mineral processing technology. The authors have studied applications of mineral processing in urban mines, and developed new methods and processes as described below. 1)A process for recycling of plastics and metals from scrapped copy machines was developed and the processing pilot plant was constructed using the TACUB jig developed in our laboratory. 2)A metal recovery process from melting plants of incinerated municipal-solid waste was developed using a leaching-sulfudization method. 3)A process recovering electrode materials from waste nickel metal hybrid batteries in a hybrid vehicle was developed using selective crushing at low temperature and 3 stages magnetic separation. 4)A process recovering fine and coarse aggregate and cement hydrate powder from waste concrete was developed using TACUB jig and multi-gravity separator. 5)An advanced process to treat wastewater containing manganese was developed using sulfur reducing bacteria. 6)A microencapsulation method to remediate soils contaminated by heavy metals was developed.
• Improvement of Energy Use Efficiency and Reduction of Environmental Load by Upgrading of Unused Low Rank Coal

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2000 -2002 

  Author : HIRAJIMA Tsuyoshi, SASAKI Keiko, HIROYOSHI Naoki, TSUNEKAWA Masami, FUKUSHIMA Masami

   

  Hot water drying (HWD) treatment was carried out at different temperatures such as 270, 300 and 330℃. With increasing temperature water content and carboxyl content of the both coals were decreased and their floatability became higher. Combustible matter recovery of the HWD treated coals by flotation was 20-30% higher than that of the raw coals and the ash content of the froth product was lower for the treated coals than the raw coals. Products containing 4.1-4.3% ash were also recovered by oil agglomeration of the fine HWD treated Beluga coals. Chemical coal cleaning method of the HMD treated coals with aqueous caustic process leads to a drastic decrease in ash content with a high recovery of combustible matter than that of raw coal. The ultra clean coal with 0.5% ash and 86% recovery of combustible matter was produced by a combination of three treatments such as the HWD, flotation and chemical cleaning. Liquid products produced in a HWD process were characterized by GC/MS, HPLC, GPC, TOC measurement and cyclic voltammetry. The ability of the liquid products to reduce Cr(VI) was investigated by analyzing solutions containing the liquids and Cr(VI), and by fluorescence spectrometry. With increasing treatment temperature TOC concentration of the liquid products became larger. The liquid product at 270℃ contained acetic acid, acetic acid-methyl ester and oligomer of mass weight 1600-3400. The liquid product at 300℃ and 330℃ contained catechol and phenol, and the latter product included more catechol groups. The reduction behavior of both liquids obtained above 300℃ was similar to that of catechol in cyclic voltammetry. All liquid products reduced the Cr(VI) to Cr(III), and their reduction ability became stronger with decreasing pH. For a solution containing high Cr(VI) concentration the liquid obtained at 330℃ successfully reduced Cr(VI) below the allowed level at pH 2. It was found by fluorescence spectroscopy that Cr(VI) was reduced to catechol groups in the liquid products.
• アンモニアリーチングによる焼却灰中重金属の除去・回収

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2000 -2001 

  Author : 広吉 直樹

   

  都市ごみ焼却灰は、1000〜10000ppm程度の重金属(Cu,Pb,Zn,Cdなど)を含んでおり、埋立地周辺の土壌・地下水汚染を引き起こす潜在的可能性を持つことから、重金属の除去・回収技術を確立することが望まれている。本研究では、焼却灰中重金属の除去・回収法としてアンモニアリーチング法を適用することを提案し、その実用化の可能性を検討した。昨年度は、浸出工程について検討し、硫酸アンモニウム溶液を浸出液に用いると、飛灰中のCu,ZnおよびCdがアンミン錯体として溶液中に溶出し、Pbが硫酸鉛として残渣中に安定化されることを明らかにした。本年度は、この結果を受けて、浸出液からのCu,ZnおよびCdの回収法と繰り返し使用に伴う浸出液の劣化について検討した。 模擬浸出液として所定濃度のCu(II),Zn(II)およびCd(II)を含むアンモニア-硫酸アンモニウム混合液を用い、硫化ナトリウムを沈殿剤とする重金属の回収実験を行った。いずれの金属も硫化ナトリウム添加により沈殿した。X線回折分析とX線蛍光分析の結果、沈殿物が金属硫化物であることが確認された。重金属の回収率は硫化ナトリウム添加量の増加につれて増大し、等量の硫化ナトリウムを添加すると98%以上となった。 飛灰の浸出ろ液に所定量の硫化ナトリウムを添加して重金属を沈殿回収し、このろ液を浸出液に用いて再び飛灰の浸出実験を行った。重金属の沈殿回収工程の際に等量以上の硫化ナトリウムを添加した場合、液中に過剰分の硫化物イオンが残留するため、2度目の浸出の際には飛灰からの重金属の浸出率が低下した。また、浸出液の硫酸アンモニウム濃度が低いと、液の繰り返しに伴ってpHが上昇し、浸出率の低下を招いた。したがって、浸出液の繰り返し利用に際しては、金属回収工程での過度の硫化ナトリウムの添加を避け、pHを調整する必要がある。
• 都市代謝システム構築のためのハイブリッド資源回収プロセス

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1999 -2001 

  Author : 恒川 昌美, 米田 哲朗, 広吉 直樹, 平島 剛

   

  人類が将来にわたり持続可能な発展を遂げていくためには,限りある資源を有効に活用し,環境と調和した生活や生産活動を営むことができる資源循環型社会を築くことが不可欠となる。都市における資源循環型システム,即ち都市代謝システムを構築するうえで,量的に多い焼却灰を含めた資源回収プロセスを確立する必要がある。本研究の目的は,廃OA機器および焼却灰を主な対象として適切な資源回収プロセスを検討し,将来の都市代謝システム構築に向けた基礎的知見を得ることにある。 本年度は,昨年度までの研究成果に基づき,廃コピー機リサイクルプラントの基本設計について検討した。また,都市ゴミ焼却飛灰中の重金属を各種リーチング法で除去・回収することを試みた。得られた主な知見は,以下のようである。 1)廃コピー機中の有価物を回収し,リサイクルするための適正なプロセスとして,次のようなものが提案される。 a)初めにプリント基板を手選別して製錬プロセスに送り,そこで有価物を回収する。 b)残りの部分は,圧縮,切断,衝撃作用を適切に組み合わせた解体・破砕プロセスで処理し,金属とプラスチックを剥離する。 c)上記の剥離した金属から,磁選機を用いて鉄を,水力分級機を用いて非鉄を回収する。 d)プラスチックについては,ジグ選別により成分別に分離,回収する。 2)都市ゴミ焼却飛灰については,次のようなことを明らかにした。 a)硫酸アンモニウム溶液で処理すると,銅,亜鉛,カドミウムは選択的に溶出し,鉛は残渣中に安定な形で残る。 b)チオ硫酸アンモニウム溶液で処理すると,銅,亜鉛,カドミウムとともに鉛も溶出する。 c)これらの溶出金属は,沈殿として回収できる。
• Refining and Utilization of Rare Earth Elements from Phosphors in Waste Fluorescent Lamp

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1999 -2001 

  Author : HIRAJIMA Tsuyoshi, SASAKI Keiko, HIROYOSHI Naoki, TSUNEKAWA Masami, NAGANO Nobuhiro, TAKAHASHI Touru

   

  The separation and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in fluorescent lamp waste. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by heavy media separation, hydro separation, pneumatic separation, gravity separation and flotation. Newly developed heavy media separation method showed highest separation efficiency, recovery and grade of rare earth phosphors and the pneumatic separation was the second result. After pneumatic separation of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth component was recovered by treatment processes such as hydroxide and oxalate precipitations. Yttrium and europium from phosphor sludge contained in fluorescent lamp waste were recovered effectively by three processes of pneumatic separation, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finallv about 65%, and its purity was 98.2%. It was also found that separation and recovery of rare earth elements from the leaching solution by multistage countercurrent extraction were possible. Synthesis method and sintering conditions have been examined to establish the synthesizing Y_20_3 : Eu^<3+> from phosphor sludge in processing waste fluorescent lamp. Y_20_3 : Eu^<3+> were synthesized by 1.5 mol/l sulfuric acid leaching, subsequent treatment processes such as hydroxide and oxalate precipitations, freeze-dry, and sintering in optimum condltions ; sintering temperature is 1200℃, sintering time is 40 hours, with addition of 1% barium borate as the flux. Y_20_3 : Eu^<3+> powder synthesized from phosphor sludge, was obtained well crystal structure of above 0.2 μm crystal size, and with 50% particle size in the range of 5-6 μm. It was found that Y_20_3 : Eu^<3+> powder synthesized from phosphor sludge by this work could be used substantially as a red rare earth phosphor.
• Gold Occurrence in Sulfide Ore Deposit and Process Mineralogy

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1999 -2001 

  Author : YONEDA Tetsuro, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi, TSUNEKAWA Masami

   

  The Sar Cheshmeh porphyry copper ores were studied as a case study for the sulfide ore deposits. Processed ore samples in addition to collected ore samples from outcrop and drilling core were examined in this study. The mineralogy of the samples suggests that the mineral assemblages in ores of SarCheshmeh depositare alike to those in the typical porphyry copper deposit. The average gold contents of the samples rontaining >0.25 % and >0.4 % Cu in the hypogene were determined as 58.2 and 64.4 ppb Au and in the supergene ores were 70.7 and 71.5 ppb Au, respectively. Based on the metal ratios the Sar Cheshmeh porphyry copper ore can be evaluated as "Mo-rich, relatively Au-poor type". The gold distribution in the mill products of the porphyry copper beneficiation plant demonstrates that only about 44 % of the gold is routinely recovered as the byproduct in the copper concentrate, and the remaining is lost to the tailings. The recovery of gold in the flotation circuit was controlled mainly by its degree of association with copper minerals and the recovery of pyrite. Gold was present in the ore and mill products in different modes of occurrence including "visible" ,"invisible" and encapsulated forms Though there was some gold in solid solution and/or colloidal size within the sulfide minerals, "visible" gold was the principal form of the gold. Based on these results, attempts were made to scavenge gold from the plant tailings by bulk sulfide flotation. Then bio-leaching of the bulk flotation concentrate with Thiobacillus ferrooxidans was conducted, followed by cyanidation. Using this process, about 61 % and 70% of gold recovery were obtained from the concentrates bio-leached for 1 and 2 weeks, respectively. The recovery was found to be higher than that by another leaching methods with cyanidation.
• Slow Crack Growth in Rock Mass

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1998 -1999 

  Author : NAKASHIMA Iwao, HIRASHIMA Tuyoshi, KANEKO Katsuhiko, TUNEKAWA Masami, HIROYOSHI Naoki, YONEDA Tetsuro

   

  In this research project, a series of experimental and analytical studies on the mineralogical and the chemical properties of weathered rock, micro-crack distribution and permeability of rock, and crack propagation in rock, have been performed to clarify the mechanism of the slow crack growth in rock mass. (1) A method to quantify the weathering of rock by using XFD and ATEM analyses was proposed and the mineralogical property of weathering rock was made clear. (2) A method to evaluate the three dimensional orientation distribution of micro-cracks in rock was developed. It is pointed out that the anisotropy of rock permeability can be estimated by analyzing crack orientation distribution. (3) A computer program to simulate the crack propagation in rock has been developed. Comparing the crack propagation processes in static and dynamic loading, a relation between the dynamic strength and the static one of rock is made clear. (4) A mechanism of the giant rock fall occurred at the entrance of Toyohama tunnel has been analyzed. Analyzing the mineralogical property of smectite in the rock, it is pointed out that the long time strength of the rock may be reduced by the existence of smectite. From these result a theoretical model for slow crack propagation in rock mass was proposed.
• Inhibition of Acid-Mine-Drainage Formation in Mine Environments and Remediation of Acid Contaminated Sites

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1997 -1999 

  Author : TSUNEKAWA Masami, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi

   

  Weathering of pyrite and chalcopyrite plays an important role in formation of acid mine drainage and releases toxic trace elements, such as Ni, Co, Zn and As from the minerals. In mine environments, and especially in aerobic environments, the pyrite and chalcopyrite weathering is accelerated by iron- and sulfur-oxidizing bacteria. This research was conducted on the weathering mechanism, inhibitor to the bacteria and remediation of acid contaminated sites. In acid solutions the preferential dissolution of iron took place resulting in the formation of a surface layer enriched with sulfur. Natural organic acid, such as tannic acids, wood vinegar, fulvic acids, and humic acids, suppressed microbially mediated dissolution of pyrite. It was caused by adsorption of natural organic acids on pyrite, inhibition of cell growth, as well as reduction and complexation of Fe(III) ions. Ferrous ions enhanced copper extraction in sulfuric acid solutions in air at ambient temperatures because they promoted chalcopyrite oxidation with dissolved oxygen. However iron-oxidizing bacteria consumed ferrous ions, suppressing copper extraction. Sodium lauryl sulfate and tannic acid suppressed not only the bacterial ferrous oxidation but also the chalcopyrite oxidation with dissolved oxygen, resulting in a suppression of copper extraction. Dissolution of iron from high sulfur coal refuse by iron-oxidizing bacteria was depressed in the presence of sodium lauryl sulfate, which inhibited cell growth. However, the refuse contained some soluble iron species that could release into drainage. For decreasing iron concentration of drainage addition of lime was effective.
• Application of Agglomeration in Liquid to Recycling and Waste Treatment Processes

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1995 -1997 

  Author : HIRAJIM Tsuyoshi, HIROYOSHI Naoki, TSUNEKAWA Masami

   

  Fine particles suspended in a liquid are agglomerated by addition of a second immiscible liquid (bridging liquid) which preferentially wets the particles under appropriate agitation conditions. Distinct noises are emitted when agglomerates impinge on the walls of the agglomeration vessel in the process of agglomeration in an organic liquid. In addition, the turbidity of the suspension changes from opaque to transparent during the progress of agglomeration. The technical feasibility of on-line monitoring of the agglomerate's diameter and recovery was demonstrated by measuring relative energy and laser attenuation. The effects of various operating variables on the oil agglomeration of electrostatic precipitator soot (EP soot), such as oil dosage, impeller speed, temperature of suspension, and time of agglomeration on yield and ash content of the products were studied in a laboratory batch agglomeration cell. The yield increases and the ashcontent of the agglomerates decreases with increasing oil dosage, impeller speed and time of agglomeration. From the results, it was concluded that a high energy consumption is required to recover low ash content agglomerates with high yields. Wet sieve analysis indicated that the ash content of EP soot increases with decreases in particle size. This was simulated using the equation derived from a model of petroleum coke combustion. X-ray diffraction patterns of the feed revealed that most peaks are consistent with metal compounds such as FeV_2O_4, Fe_2SiO_4, NiFe_2O_4, MgFeAlO_4, NiSO_4・2H_2o, and CaV_2O_6. Wet magnetic separation was conducted on the -400 mesh sample containing 53.8% ash. Semiquantitative study of the XRD results showed that in the magnetic fraction FeV_2O_4, Fe_2SiO_4, NiFe_2O_4, and MgFeAlO_4 contents increase and in the non-magnetic fraction CaSO_4・1/2H_2O content increase. In this report, the authors also reviewed recent progress in fundamental studies of agglomeration and its application ; especially, the main factors affecting the agglomeration, on-line monitoring systems and topics in industrial fields were described. Agglomeration in liquid is a promising method for mineral and material processing, fuel beneficiation, recycling and waste treatment.
• バクテリアリーチングの半導体光電気化学的研究

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1996 -1996 

  Author : 廣吉 直樹

   

  バクテリアリーチングの過程では、硫化鉱物表面の組成と半導体的性質が変化し、浸出速度にその影響が現れてくることが予想される。本研究の目的は、半導体光電気化学的手法により、バクテリアリーチングの過程における硫化鉱表面の半導体的性質の変化と浸出挙動の関係を明らかにすることである。本年度は、鉄酸化細菌を接種した硫酸鉄(II)溶液中に黄銅鉱電極を浸漬して電極電位の経時変化および光応答について調べ、つぎのような知見を得た。 1)黄銅鉱電極電位は、主として溶液の酸化還元電位により決定され、鉄酸化細菌の作用で鉄(II)イオンが鉄(III)イオンへ酸化されて溶液電位が上昇するのに伴い高くなる。しかし、溶液電位が約0.68Vvs.SHE以上になるとほとんど上昇しなくなった。 2)浸漬直後の黄銅鉱電極に光を照射すると、電極電位は負方向へ変化し、照射終了後、正方向へと変化した。このことは、鉱物内の電子のバンドのエネルギー準位が鉱物/溶液界面から鉱物内部に向かって低下していることを意味する。浸漬数時間後、黄銅鉱電極電位は、光照射と同時に瞬間的に正方向へ立ち上がった後、ゆるやかに下降し、照射終了後、正方向へ変化するようになった。光照射開始直後の立ち上がりは、溶液電位の上昇に伴い大きくなるが、溶液電位が約0.66Vvs.SHE以上になるとほとんど認められなくなった。以上のことから、黄銅鉱表面には内部とは異なる半導体層が形成され、溶液の酸化還元電位が0.66-0.68Vvs.SHE付近を境にその状態が変化するのではないかと推察される。
• Surface Modification of Coal With Carbon Dioxide and Its Application to Advanced Coal Cleaning

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1994 -1996 

  Author : TSUNEKAWA Masami, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi

   

  Four coals from different localities (Datong, Wandoan, Illinois and Shenmu) were used in this study. Immersion time measurements were carried out to assess wettability of coal surface using 100-200 mesh coals. Flotation tests were conducted by introducing air, nitrogen and carbon dioxide gases, respectively. After sparging the gases into coal slurries, the slurries were chemically analyzed. For flotation and chemical analysis fine coals (mean particle size : about 30mum) were used. Some of the coals were treated with 0.6kgf/cm^2 of carbon dioxide gas prior to the experiments. The collectors used were kerosene for Datong and Shenmu coal, and heavy oil A for the other coals. The hydrophobicity of four coals treated with carbon dioxide became slightly higher than that of untreated coal. When sparging carbon dioxide gas, the highest amounts of calcium and magnesium were dissolved from Datong and Wandoan coals and the amounts of bassanite and calcite in the coals were simultaneously decreased. By flotation with carbon dioxide, the maximum yield was obtained for the coals treated with carbon dioxide than the untreated coals. In the case of Shenmu coal containing calcite and dolomite, separation efficiency of combustibles from mineral matters became higher with decreasing pH. Fine grinding of four coals were investigated. The ground product with a mean size of 2mum was obtained at a suitable operating conditions for all coals. The wear loss of the grinding media and vessel depended strongly on the amount of the hard minerals disseminated in coal, such as quartz, pyrite and iron oxide.
• 微生物を利用する石炭浮選パルプの酸化還元電位の制御とその脱硫浮選への応用

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1995 -1995 

  Author : 広吉 直樹

   

  本研究は、鉄イオンを含んだ鉱廃水の酸化還元電位を鉄酸化細菌により調節し、この液を浮選用水として用いて石炭中に含まれる黄鉄鉱を分離するプロセスを開発することを目的としている。本年度は、鉄(II)イオンと鉄(III)イオンをそれぞれ所定の濃度で含む模擬浮選液中での黄鉄鉱(柵原鉱山産)の濡れ性について、種々の方法(バブルピックアップ法、ハリモンドチューブ法、マイクロフローテーションセル法)で検討し、以下のような知見を得た。 1.鉄イオン無添加の場合、黄鉄鉱はpH6以上の中・アルカリ性領域では親水性で気泡とあまり付着しないが、pH6以下の酸性領域では疎水性となり気泡とよく付着した。 2.鉄イオンの添加濃度が高くなるに従い、黄鉄鉱が気泡と付着し始めるpHはより酸性側へと移行した。また、溶液の酸化還元電位が高くなるに従い、すなわち、全溶存鉄イオンにしめる鉄(III)イオンの比率が高い場合ほど、黄鉄鉱が気泡と付着し始めるpHは低下した。このpHは、水酸化鉄(III)の沈殿が生成し始めるpHとよく一致し、黄鉄鉱は水酸化鉄(III)の付着により親水化されるものと考えられる。 3.水酸化鉄(III)が存在しない強酸性領域では、溶液の酸化還元電位が高くなるにつれ黄鉄鉱の疎水性は増した。これは、鉄(III)イオンにより黄鉄鉱が酸化され、元素硫黄が表面に生成してくるためと考えられる。
• Experimental Studies on Metal Extraction Improvement in Bacterial leaching

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1993 -1995 

  Author : TSUNEKAWA Masami, YOSHIDA Yutaka, HIROYOSHI Naoki, HIRAJIMA Tsuyoshi

   

  Bacterial leaching has the advantages of low energy consumption and operation costs over abiological conventional processes, and is now used commercially to recover copper from low-grade sulfide ore which would otherwise be waste. However, the leaching rate is generally slow and metal extraction is incomplete. To achieve higher leaching rates and metal recovery, it is important to establish the factors influencing leaching behavior. The authors have investigated the effects of extracellular phospholipids and polyoxyethylene sorbitan monolaurate on bacterial leaching of chalcopyrite by Thiobacillus ferrooxidans. Phosphatidylglycerol and phosphatidylethanolamine are main phospholipids detected in the cultures of iron-oxidizing bacteria. The former depressed chemical leaching of chalcopyrite with ferric sulfate and ferrous oxidation by T.ferrooxidans. The final copper extraction in bacterial leaching decreased with increasing phosphatidylglycerol addition. On the other hand, phosphatidylethanolamine accelerated slightly the chemical leaching and had no effect on the ferrous oxidation. The copper extraction in bacterial leaching was not affected by phosphatidylethanolamine. Polyoxyethylene sorbitan monolaurate is a nonionic surfactant. Without the surfactant, most cells of T.ferrooxidans adhered to chalcopyrite surfact and soluble iron was dominantly present in ferrous form. The surfactant depressed the cell adhesion to the mineral surface and number of cells in the liquid phase increased with increasing addition. When adding 20 to 50 g/m^3 of the surfactant, the cells in the liquid phase rapidly oxidized ferrous ions to ferric ions and chalcopyrite was chemically oxidzed by the ferric ions, as a result the amount of extracted copper increased markedly. However, the excessive addition depressed the bacterial ferrous oxidation and the chemical leaching of chalcopyrite with ferric ions, consequently copper extraction was decreased. Moreover, the authors have developed a simple and rapid cell growth estimation method for T.ferrooxidans.
• カラム浮選機のファジィ制御に関する研究

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1994 -1994 

  Author : 平島 剛, 広吉 直樹, 恒川 昌美

   

  本研究は、申請者らが開発したカラム浮選機用のファジィ制御プログラムを改良し、カラム浮選機の完全自動運転を可能にすることを目的に行った。得られた結果を要約すると次のようである。1.実験室用カラム浮選機を用い、空気流量の増加は、気泡径、気泡充満率を増大させ、液面レベルを上昇させることなどを確認した。2.豊羽鉱山選鉱場亜鉛精選系カラム浮選機(直径2.7m、高さ13.5m)で空気流量をステップ状に変化させた場合のフロス層厚さおよびフロス層内の亜鉛品位の変動について測定を行った。液面レベルは空気流量増加後、振幅約20cmで振動した後ほぼ一定の液面レベル(フロス層厚さ160cm)となった。亜鉛精鉱品位は、空気流量の増加により低下した。その変化は速く、5分後にはほぼ定状状態となった。これらの結果より、空気流量の変化に対する精鉱品位の応答は敏速であり、精鉱品位制御において、空気流量は有効な操作量であることが分かった。3.申請者らが先に開発したファジィ制御プログラムの問題点について現場担当者と検討を行った。比較的処理しやすい鉱石の場合には、空気流量を変化させて精鉱品位を制御する基本制御規則には問題がないことが分かった。しかし、処理しにくい鉱石の場合、原鉱および尾鉱中の亜鉛品位、液面レベルなどの情報をさらに加え、精鉱品位または液面レベルを空気流量変化により制御する必要があること、原鉱の性状によってはフロス層を安定に維持するため最高空気流量および最低空気流量を自動的に変化させる必要があることなどが明らかになった。それらについての経験則等を基に制御規則を追加しカラム浮選機の制御を行った結果、処理困難な鉱石の場合にも自動運転が可能であることが分かった。完全自動運転のためには、各種情報の整理、長期間の運転による新たな経験則の構築などが必要であるが、本研究で改良されたプログラムにより完全自動運転へ一歩前進することができた。
• 都市ゴミ焼却灰からの有価物回収
• バクテリアリーチングに関する研究
• Recovery of valuable materials from municipal waste incineration ash
• Study on Bacterial Leaching

Educational Activities

Teaching Experience