研究者データベース

廣吉 直樹(ヒロヨシ ナオキ)
工学研究院 環境循環システム部門 資源循環工学分野
教授

基本情報

所属

  • 工学研究院 環境循環システム部門 資源循環工学分野

職名

  • 教授

学位

  • 博士(工学)(北海道大学)

J-Global ID

研究キーワード

  • 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   

研究分野

  • エネルギー / 地球資源工学、エネルギー学
  • ものづくり技術(機械・電気電子・化学工学) / 移動現象、単位操作

職歴

  • 2010年04月 - 現在 北海道大学 工学研究院 教授
  • 2007年04月 - 2010年03月 北海道大学 工学研究科 准教授
  • 2004年04月 - 2010年03月 北海道大学 工学研究科 助教授
  • 1997年 - 2001年 北海道大学大学院工学研究科 助手
  • 1997年 - 2001年 Instructor, Graduate School of Hokkaido University
  • 1993年 - 1997年 北海道大学 助手
  • 1993年 - 1997年 Instructor, Hokkaido University

学歴

  •         - 1991年   北海道大学   工学研究科   資源開発工学
  •         - 1991年   北海道大学
  •         - 1989年   北海道大学   工学部   資源開発工学
  •         - 1989年   北海道大学

所属学協会

  • 廃棄物資源循環学会   資源・素材学会   環境資源工学会   

研究活動情報

論文

  • 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年08月30日 
    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%).
  • Kosei Aikawa, Mayumi Ito, Atsuhiro Kusano, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi
    Minerals 12 6 723 - 723 2022年06月06日 
    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.
  • 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年04月 
    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.
  • Muhammad Bilal, Mayumi Ito, Riku Akishino, Xiangning Bu, Fawad Ul Hassan, Ilhwan Park, Sanghee Jeon, Kosei Aikawa, Naoki Hiroyoshi
    Minerals Engineering 180 2022年04月 
    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.
  • Kosei Aikawa, Mayumi Ito, Atsuhiro Kusano, Ilhwan Park, Tatsuya Oki, Tatsuru Takahashi, Hisatoshi Furuya, Naoki Hiroyoshi
    Metals 11 2 253 - 253 2021年02月02日 
    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.
  • 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 2020年12月
  • 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 2020年11月 
    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.
  • 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 2020年08月 [査読有り][通常論文]
  • Vothy Hornn, Mayumi Ito, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi
    Metals 10 7 912 - 912 2020年07月08日 [査読有り][通常論文]
     
    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.
  • Kosei Aikawa, Mayumi Ito, Tatsuya Segawa, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Naoki Hiroyoshi
    Minerals Engineering 152 106367 - 106367 2020年06月 [査読有り][通常論文]
  • Nguyen Thi Phuong Thao, Shushi Tsuji, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Mayumi Ito, Naoki Hiroyoshi
    Hydrometallurgy 194 105299 - 105299 2020年06月 [査読有り][通常論文]
  • Vothy Hornn, Mayumi Ito, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi
    Minerals 10 4 380 - 380 2020年04月23日 [査読有り][通常論文]
     
    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.
  • 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年04月20日 [査読有り][通常論文]
     
    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.
  • 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年 
    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.
  • Ilhwan Park, Carlito Baltazar Tabelin, Kensuke Seno, Sanghee Jeon, Hiroyuki Inano, Mayumi Ito, Naoki Hiroyoshi
    Heliyon 6 1 e03189 - e03189 2020年01月 [査読有り][通常論文]
  • Sanghee Jeon, Carlito Baltazar Tabelin, Ilhwan Park, Yoshito Nagata, Mayumi Ito, Naoki Hiroyoshi
    Hydrometallurgy 191 105214 - 105214 2020年01月 [査読有り][通常論文]
  • Tabelin Carlito Baltazar, Corpuz Ryan D, Iarashi Toshifumi, Villacorte-Tabelin Mylah, Ito Mayumi, Hiroyoshi Naoki
    CHEMOSPHERE 233 946 - 953 2019年10月 [査読有り][通常論文]
  • Park Ilhwan, Tabelin Carlito Baltazar, Jeon Sanghee, Li Xinlong, Seno Kensuke, Ito Mayumi, Hiroyoshi Naoki
    CHEMOSPHERE 219 588 - 606 2019年03月 [査読有り][通常論文]
  • Li Xinlong, Hiroyoshi Naoki, Tabelin Carlito Baltazar, Naruwa Kosuke, Harada Chie, Ito Mayumi
    CHEMOSPHERE 214 70 - 78 2019年01月 [査読有り][通常論文]
  • Seng Sophea, Tabelin Carlito Baltazar, Kojima Motoya, Hiroyoshi Naoki, Ito Mayumi
    MATERIALS TRANSACTIONS 60 2 277 - 286 2019年 [査読有り][通常論文]
  • Park Ilhwan, Tabelin Carlito, Inano Hiroyuki, Seno Kensuke, Higuchi Kazuki, Ito Mayumi, Hiroyoshi Naoki
    25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2019年 [査読有り][通常論文]
  • Seno Kensuke, Park Ilhwan, Tabelin Carlito, Magaribuchi Kagehiro, Ito Mayumi, Hiroyoshi Naoki
    25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2019年 [査読有り][通常論文]
  • Tabelin Carlito, Sasaki Asuka, Igarashi Toshifumi, Tomiyama Shingo, Villacorte-Tabelin Mylah, Ito Mayumi, Hiroyoshi Naoki
    25TH REGIONAL SYMPOSIUM ON CHEMICAL ENGINEERING (RSCE 2018) 268 2019年 [査読有り][通常論文]
  • 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 2019年 [査読有り][通常論文]
  • 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 2018年12月15日 [査読有り][通常論文]
  • Phengsaart Theerayut, Ito Mayumi, Hamaya Naoki, Tabelin Carlito Baltazar, Hiroyoshi Naoki
    MINERALS ENGINEERING 129 54 - 62 2018年12月 [査読有り][通常論文]
  • Jeon Sanghee, Tabelin Carlito Baltazar, Takahashi Hirotaka, Park Ilhwan, Ito Mayumi, Hiroyoshi Naoki
    WASTE MANAGEMENT 81 148 - 156 2018年11月 [査読有り][通常論文]
  • Park Ilhwan, Tabelin Carlito Baltazar, Seno Kensuke, Jeon Sanghee, Ito Mayumi, Hiroyoshi Naoki
    CHEMOSPHERE 209 1021  2018年10月 [査読有り][通常論文]
  • Ilhwan Park, Carlito Baltazar Tabelin, Kensuke Seno, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi
    Chemosphere 205 414 - 425 2018年08月01日 [査読有り][通常論文]
     
    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.
  • Inano Hiroyuki, Tomita Keiichi, Tada Tatsumi, Hiroyoshi Naoki
    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 126 8 595 - 601 2018年08月 [査読有り][通常論文]
  • Sanghee Jeon, Mayumi Ito, Carlito Baltazar Tabelin, Rongrit Pongsumrankul, Naho Kitajima, llhwan Park, Naoki Hiroyoshi
    Waste Management 77 195 - 202 2018年07月01日 [査読有り][通常論文]
     
    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.
  • Ilhwan Park, Carlito Baltazar Tabelin, Kagehiro Magaribuchi, Kensuke Seno, Mayumi Ito, Naoki Hiroyoshi
    Journal of Hazardous Materials 344 322 - 332 2018年02月15日 [査読有り][通常論文]
     
    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年 [査読無し][通常論文]
  • Carlito Baltazar Tabelin, Ryosuke Sasaki, Toshifumi Igarashi, Ilhwan Park, Shuichi Tamoto, Takahiko Arima, Mayumi Ito, Naoki Hiroyoshi
    CHEMOSPHERE 188 444 - 454 2017年12月 [査読有り][通常論文]
     
    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.
  • Carlito Baltazar Tabelin, Ryosuke Sasaki, Toshifumi Igarashi, Ilhwan Park, Shuichi Tamoto, Takahiko Arima, Mayumi Ito, Naoki Hiroyoshi
    CHEMOSPHERE 186 558 - 569 2017年11月 [査読有り][通常論文]
     
    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.
  • Carlito Baltazar Tabelin, Suchol Veerawattananun, Mayumi Ito, Naoki Hiroyoshi, Toshifumi Igarashi
    SCIENCE OF THE TOTAL ENVIRONMENT 581 126 - 135 2017年03月 [査読有り][通常論文]
     
    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.
  • Carlito Baltazar Tabelin, Suchol Veerawattananun, Mayumi Ito, Naoki Hiroyoshi, Toshifumi Igarashi
    SCIENCE OF THE TOTAL ENVIRONMENT 580 687 - 698 2017年02月 [査読有り][通常論文]
     
    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年 [査読無し][通常論文]
  • Peet Homchuen, Richard Diaz Alorro, Naoki Hiroyoshi, Ryo Sato, Hajime Kijitani, Mayumi Ito
    MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 37 4 246 - 254 2016年 [査読有り][通常論文]
     
    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.
  • Richard Diaz Alorro, Naoki Hiroyoshi, Hajime Kijitani, Mayumi Ito, Masami Tsunekawa
    MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 36 5 332 - 339 2015年09月 [査読有り][通常論文]
     
    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.
  • Shuichi Tamoto, Carlito Baltazar Tabelin, Toshifumi Igarashi, Mayumi Ito, Naoki Hiroyoshi
    JOURNAL OF CONTAMINANT HYDROLOGY 175 60 - 71 2015年04月 [査読有り][通常論文]
     
    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.
  • Sengpasith HoungAloune, Naoki Hiroyoshi, Mayumi Ito
    MINERALS ENGINEERING 74 51 - 59 2015年04月 [査読有り][通常論文]
     
    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年 [査読有り][通常論文]
  • Yoshitaka Nara, Ryo Nakabayashi, Megumi Maruyama, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko
    ENGINEERING GEOLOGY 179 41 - 49 2014年09月 [査読有り][通常論文]
     
    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.
  • Sengpasith HoungAloune, Takahiro Kawaai, Naoki Hiroyoshi, Mayumi Ito
    HYDROMETALLURGY 147 30 - 40 2014年08月 [査読有り][通常論文]
     
    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年 [査読無し][通常論文]
  • Flotation of anode slime in copper electro-refining
    M Ito, T Ikemoto, N Hiroyoshi
    12th Int. Symp. East Asian Recycling Technology 954 - 957 2013年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • ジグ選別における技術革新の歩みと先端的選別機への挑戦
    恒川昌美, 伊藤真由美, 広吉直樹
    Journal of MMIJ 129 284 - 289 2013年 [査読有り][通常論文]
  • 圧力およびレベルセンサーを用いたジグ選別における最適脈動条件の決定と微粒子選別への適用
    恒川昌美, 秋元淳希, 扇子渉, 越智大司, 広吉直樹, 伊藤真由美
    Journal of MMIJ 129 284 - 289 2013年 [査読有り][通常論文]
  • Advanced jig separation technology for resource recycling and mineral processing
    M Ito, N Hiroyoshi, M Tsunekawa
    The 5th Regional Conference on Geological Engineering 13 - 18 2013年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Masami Tsunekawa, Riki Kobayashi, Kunihiro Hori, Hideaki Okada, Naka Abe, Naoki Hiroyoshi, Mayumi Ito
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 114 27 - 29 2012年11月 [査読有り][通常論文]
     
    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.
  • Yoshitaka Nara, Kazuya Morimoto, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko, Philip M. Benson
    INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 49 18 2471 - 2481 2012年09月 [査読有り][通常論文]
     
    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.
  • Takashi Okada, Hiroyuki Inano, Naoki Hiroyoshi
    JOURNAL OF THE SOCIETY FOR INFORMATION DISPLAY 20 9 508 - 516 2012年09月 [査読有り][通常論文]
     
    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.
  • Kouki Kashiwaya, Takahiko Noumachi, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa
    POWDER TECHNOLOGY 226 147 - 156 2012年08月 [査読有り][通常論文]
     
    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.
  • Masami Tsunekawa, Mayumi Ito, Yoshiaki Nakamura, Yuta Sasaki, Tomoo Sakai, Naoki Hiroyoshi
    SEPARATION AND PURIFICATION TECHNOLOGY 89 94 - 97 2012年03月 [査読有り][通常論文]
     
    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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • Rani Kumari Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa
    MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 33 2 89 - 98 2012年 [査読有り][通常論文]
     
    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.
  • Yutaka Kuwayama, Mayumi Ito, Maiko Akatsuka, Naoki Hiroyoshi, Masami Tsunekawa
    JOURNAL OF MATERIAL CYCLES AND WASTE MANAGEMENT 13 2 156 - 163 2011年08月 [査読有り][通常論文]
     
    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.
  • Masami Tsunekawa, Mayumi Ito, Yuta Sasaki, Tomoo Sakai, Naoki Hiroyoshi
    JOURNAL OF HAZARDOUS MATERIALS 191 1-3 388 - 392 2011年07月 [査読有り][通常論文]
     
    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.
  • Rani Kumari Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa
    FUEL PROCESSING TECHNOLOGY 92 5 1032 - 1036 2011年05月 [査読有り][通常論文]
     
    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.
  • Yoshitaka Nara, Kazuya Morimoto, Tetsuro Yoneda, Naoki Hiroyoshi, Katsuhiko Kaneko
    INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 48 7-8 1130 - 1140 2011年04月 [査読有り][通常論文]
     
    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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • Takashi Okada, Hiroyuki Inano, Naoki Hiroyoshi
    IDW'11: PROCEEDINGS OF THE 18TH INTERNATIONAL DISPLAY WORKSHOPS, VOLS 1-3 617 - 620 2011年 [査読有り][通常論文]
     
    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.
  • Mayumi Ito, Kouki Kashiwaya, Naohiro Sumiya, Hisatoshi Furuya, Naoki Hiroyoshi, Masami Tsunekawa
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 97 1-4 92 - 95 2010年11月 [査読有り][通常論文]
     
    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.
  • Mayumi Ito, Masami Tsunekawa, Emi Ishida, Koki Kawai, Tatsuru Takahashi, Naka Abe, Naoki Hiroyoshi
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 97 1-4 96 - 99 2010年11月 [査読有り][通常論文]
     
    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.
  • Yoshitaka Nara, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko
    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 47 4 640 - 646 2010年06月 [査読有り][通常論文]
     
    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.
  • Kyoungkeun Yoo, Soo-kyung Kim, Jae-chun Lee, Mayumi Ito, Masami Tsunekawa, Naoki Hiroyoshi
    MINERALS ENGINEERING 23 6 471 - 477 2010年05月 [査読有り][通常論文]
     
    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.
  • 川﨑 了, 小潟 暁, 広吉直樹, 恒川昌美, 金子勝比古, 寺島 麗
    応用地質 51 1 10 - 18 一般社団法人 日本応用地質学会 2010年 [査読有り][通常論文]
     
    筆者らは, 土や岩の代表的なセメント物質である炭酸カルシウムまたはシリカを主成分とし, 微生物の代謝活動により土や岩の間隙や岩の割れ目を自然に閉塞させる新たな概念に基づくグラウト, すなわち, バイオグラウトを開発するための基礎的な研究を実施中である. 本論文では, 炭酸カルシウムを用いたバイオグラウト, すなわち, 炭酸カルシウム法に関して検討を実施した結果について報告する. 具体的には, 日本各地より採取した自然の土壌中に生息する微生物を用いて試験管による炭酸カルシウムの析出試験を行い, 試験時における温度の違いが炭酸カルシウム析出に与える影響について調査した. その結果, 温度5~35℃の低~中温域において, 土壌微生物により炭酸カルシウムが試験管内に析出することが示唆された. 一方, 試験に用いた土壌微生物の菌数測定および遺伝子解析を実施し, 試験前後の土壌中に含まれる微生物相の変化に関して, 生菌数, 最も出現頻度の高い菌の菌数およびその帰属分類群を用いることにより比較を行った. その結果, それらは主にPenicillium属およびAspergillus属の菌類であり, 有機栄養源を活発に代謝することにより菌数が増加したものと推定された.
  • 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年 [査読有り][通常論文]
  • Richard Diaz Alorro, Naoki Hiroyoshi, Hajime Kijitani, Mayumi Ito, Masami Tsunekawa
    MINERAL PROCESSING AND EXTRACTIVE METALLURGY REVIEW 31 4 201 - 213 2010年 [査読有り][通常論文]
     
    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.
  • Kunihiro Hori, Masami Tsunekawa, Masatsune Ueda, Naoki Hiroyoshi, Mayumi Ito, Hideaki Okada
    MATERIALS TRANSACTIONS 50 12 2844 - 2847 2009年12月 [査読有り][通常論文]
     
    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]
  • Mayumi Ito, Kouki Kashiwaya, Naohiro Sumiya, Naoki Hiroyoshi, Masami Tsunekawa
    SEPARATION AND PURIFICATION TECHNOLOGY 69 2 149 - 152 2009年09月 [査読有り][通常論文]
     
    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.
  • Kunihiro Hori, Masami Tsunekawa, Naoki Hiroyoshi, Mayumi Ito
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 92 3-4 103 - 108 2009年08月 [査読有り][通常論文]
     
    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.
  • Richard Diaz Alorro, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa
    HYDROMETALLURGY 97 1-2 8 - 14 2009年06月 [査読有り][通常論文]
     
    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.
  • 奈良 禎太, 高田 雅史, 五十嵐 敏文, 広吉 直樹, 金子 勝比古
    物理探査 62 1 163 - 171 物理探査学会 2009年03月 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • Yoshitaka Nara, Masafumi Takada, Toshifumi Igarashi, Naoki Hiroyoshi, Katsuhiko Kaneko
    EXPLORATION GEOPHYSICS 40 1 163 - 171 2009年 [査読有り][通常論文]
     
    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.
  • Masami Tsunekawa, Yugo Honma, Kyoungkeun Yoo, Naoki Hiroyoshi, Mayumi Ito
    MATERIALS TRANSACTIONS 50 1 171 - 176 2009年01月 [査読有り][通常論文]
     
    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]
  • Richard Diaz Alorro, Shinichi Mitani, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa
    MINERALS ENGINEERING 21 15 1094 - 1101 2008年12月 [査読有り][通常論文]
     
    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.
  • Rani Kumari Thakur Jha, Jacqueline Satur, Naoki Hiroyoshi, Mayumi Ito, Masami Tsunekawa
    MINERALS ENGINEERING 21 12-14 889 - 893 2008年11月 [査読有り][通常論文]
     
    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.
  • Mayurni Ito, Maiko Akatsuka, Yutaka Kuwayama, Kunihiro Hori, Naoki Hiroyoshi, Masami Tsunekawa
    MATERIALS TRANSACTIONS 49 10 2371 - 2376 2008年10月 [査読有り][通常論文]
     
    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]
  • 藤井 義明, 広吉 直樹, 原田 周作, 金子 勝比古
    工学教育 56 5 36 - 41 Japanese Society for Engineering Education 2008年09月20日 
    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,
  • 恒川 昌美, 広吉 直樹, 伊藤 真由美, 平島 剛
    工学教育 56 5 111 - 114 公益社団法人 日本工学教育協会 2008年09月20日 [査読無し][通常論文]
     
    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...
  • Masami Tsunekawa, Yuta Sasaki, Yoshiaki Nakamura, Mayumi Ito, Naoki Hiroyoshi, Kyoung Keun Yoo
    MATERIALS TRANSACTIONS 49 9 2119 - 2123 2008年09月 [査読有り][通常論文]
     
    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]
  • Mayumi Ito, Masami Tsunekawa, Eiji Yamaguchi, Kengo Sekimura, Kouki Kashiwaya, Kunihiro Hori, Naoki Hiroyoshi
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 87 3-4 100 - 105 2008年07月 [査読有り][通常論文]
     
    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.
  • Naoki Hiroyoshi, Hiroko Kitagawa, Masami Tsunekawa
    HYDROMETALLURGY 91 1-4 144 - 149 2008年03月 [査読有り][通常論文]
     
    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年 [査読無し][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • Jacqueline Satur, Naoki Hiroyoshi, Masami Tsunekawa, Mayumi Ito, Hideyuki Okamoto
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 83 3-4 116 - 124 2007年09月 [査読有り][通常論文]
     
    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.
  • Masami Tsunekawa, Mayumi Ito, Hisatoshi Furuya, Naoki Hiroyoshi
    MATERIALS TRANSACTIONS 48 5 1089 - 1094 2007年05月 [査読有り][通常論文]
     
    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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 川﨑 了, 村尾彰了, 広吉直樹, 恒川昌美, 金子勝比古
    応用地質 47 1 2 - 12 一般社団法人日本応用地質学会 2006年 [査読有り][通常論文]
     
    通常土壌には,1gあたり10^7〜10^9の微生物が含まれている.この非常に多くの微生物を,土や岩を対象とする工学の中でもとくに力学分野において利用することができれば,地球環境に配慮した新たな技術が開発されるものと期待される.筆者らは,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,微生物の代謝活動により土や岩の間隙や岩の割れ目を自然に閉塞させる新たな概念に基づくブラウト,すなわち,バイオグラウトを開発するための基礎的な室内試験を実施した.具体的には,市販のイースト菌および自然の土壌中に生息する微生物を用いて試験管による炭酸カルシウムの析出試験を行い,試験時の諸条件である温度,有機栄養源,緩衝溶液が炭酸カルシウムの析出に与える影響について検討した.また,バイオグラウトによる砂および粘土の透水特性の改良試験を実施し,バイオグラウト処理により両者の透水係数が処理前に比べて約1桁低下することを確認した.解決すべき残された課題は少なくないが,得られた試験結果より土壌微生物の代謝活動を利用したバイオグラウトによる地盤の物性改良およびバイオグラウトの開発に関して明るい見通しが得られた.
  • 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年 [査読有り][通常論文]
  • 恒川 昌美, 堀 邦紘, 広吉 直樹, 伊藤 真由美
    資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 121 10/11 467 - 473 社団法人 資源・素材学会 2005年11月25日 [査読無し][通常論文]
     
    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年 [査読無し][通常論文]
  • 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年 [査読有り][通常論文]
  • 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年 [査読有り][通常論文]
  • 岡本 秀征, 中山 良一, 黒岩 樹人, 広吉 直樹, 恒川 昌美
    資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 120 10 600 - 606 The Mining and Materials Processing Institute of Japan 2004年11月25日 
    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.
  • 伊藤 真由美, 恒川 昌美, 平島 剛, 広吉 直樹, 山田 龍一, 湯川 健太郎
    資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 117 12 961 - 966 社団法人 資源・素材学会 2001年12月25日 [査読無し][通常論文]
     
    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...
  • 広吉 直樹, 恒川 昌美
    資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 113 12 958 - 961 The Mining and Materials Processing Institute of Japan 1997年12月25日

書籍

  • 微生物資源工学(共著)
    コロナ社 1996年
  • Microbiology and Its Applications to Resources Engineering
    CORONA PUBLISHING CO. , LTD. 1996年

その他活動・業績

  • 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年
  • 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年
  • 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年
  • 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年
  • 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年
  • 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年
  • Sophea Seng, Carlito Baltazar Tabelin, Yuta Makino, Monyneath Chea, Theerayut Phengsaart, Ilhwan Park, Naoki Hiroyoshi, Mayumi Ito Minerals Engineering 143 2019年11月01日 [査読無し][通常論文]
     
    © 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.
  • Mayumi Ito, Ayumu Saito, Nana Murase, Theerayut Phengsaart, Shoko Kimura, Carlito Baltazar Tabelin, Naoki Hiroyoshi Minerals Engineering 141 2019年09月01日 [査読無し][通常論文]
     
    © 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).
  • 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年07月01日 [査読無し][通常論文]
     
    © 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.
  • Xinlong Li, Min Gao, Naoki Hiroyoshi, Carlito Baltazar Tabelin, Tetsuya Taketsugu, Mayumi Ito Minerals Engineering 138 226 -237 2019年07月01日 [査読無し][通常論文]
     
    © 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.
  • 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年
  • 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年
  • 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年01月01日 [査読無し][通常論文]
     
    © 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.
  • Jeon, M. Ito, R. Pongsumrankul, S. Tanaka, N. Kitajima, C. B. Tabelin, N. Hiroyoshi IMPC 2018 - 29th International Mineral Processing Congress 3790 -3798 2019年01月01日 [査読無し][通常論文]
     
    © 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.
  • 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年01月01日 [査読無し][通常論文]
     
    © 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Theerayut Phengsaart, Arisa Azuma, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Mayumi Ito 14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017 2017年01月01日 [査読無し][通常論文]
     
    © 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.
  • 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年01月01日 [査読無し][通常論文]
     
    ©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.
  • 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年01月01日 [査読無し][通常論文]
     
    ©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.
  • 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年01月01日 [査読無し][通常論文]
     
    © 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.
  • 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年06月23日
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • C. B. Tabelin, R. D. Corpuz, S. Veerawattananun, M. Ito, N. Hiroyoshi, T. Igarashi IMPC 2016 - 28th International Mineral Processing Congress 2016-September 2016年01月01日 [査読無し][通常論文]
     
    © 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年01月01日 [査読無し][通常論文]
     
    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.
  • 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年01月01日 [査読無し][通常論文]
     
    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.
  • 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年01月01日 [査読無し][通常論文]
     
    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.
  • 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年01月01日 [査読無し][通常論文]
     
    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.
  • 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年01月01日 [査読無し][通常論文]
     
    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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • C. B. Tabelin, T. Igarashi, M. Ito, N. Hiroyoshi ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 2554 -2560 2014年01月01日 [査読無し][通常論文]
     
    © 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.
  • 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年12月01日 [査読無し][通常論文]
     
    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.
  • 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年12月01日 [査読無し][通常論文]
     
    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.
  • 伊藤真由美, 竹内愛, 広吉直樹 資源・素材 2012 25 2012年09月11日 [査読無し][通常論文]
  • 伊藤真由美, 朝倉賢, 広吉直樹, 恒川昌美 資源・素材 2012 19 2012年09月11日 [査読無し][通常論文]
  • Yoshitaka Nara, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko Zairyo/Journal of the Society of Materials Science, Japan 61 (7) 662 -667 2012年07月 [査読無し][通常論文]
     
    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.
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Y. Nara, R. Nakabayashi, N. Hiroyoshi, T. Yoneda, K. Kaneko, S. Murata, T. Ishida Near Surface Geoscience 2012 2012年01月01日 [査読無し][通常論文]
     
    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.
  • Y. Nara, K. Kaneko, T. Yoneda, N. Hiroyoshi, K. Morimoto HARMONISING ROCK ENGINEERING AND THE ENVIRONMENT 757 -760 2012年 [査読無し][通常論文]
     
    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.
  • Yutaka Kuwayama, Mayumi Ito, Noki Hiroyoshi, Masami Tsunekawa JOURNAL OF MATERIAL CYCLES AND WASTE MANAGEMENT 13 (3) 240 -246 2011年10月 [査読無し][通常論文]
     
    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.
  • 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年09月26日 [査読無し][通常論文]
  • 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年09月26日 [査読無し][通常論文]
  • 広吉直樹, 大山史織, 伊藤真由美 資源・素材 2011 (2) 203 -204 2011年09月26日 [査読無し][通常論文]
  • 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年09月26日 [査読無し][通常論文]
  • 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年09月26日 [査読無し][通常論文]
  • 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年09月26日 [査読無し][通常論文]
  • 藤井 義明, 五十嵐 敏文, 廣吉 直樹 工学教育研究講演会講演論文集 23 (59) 538 -539 2011年08月22日
  • 伊藤 真由美, 広吉 直樹, 五十嵐 敏文 工学教育研究講演会講演論文集 23 (59) 620 -621 2011年08月22日 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年12月01日 [査読無し][通常論文]
     
    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.
  • R. Alorro, N. Hiroyoshi, M. Ito, M. Tsunekawa XXV International Mineral Processing Congress 2010, IMPC 2010 1 263 -271 2010年12月01日 [査読無し][通常論文]
     
    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.
  • M. Ito, M. Akatsuka, E. Ishida, K. Hori, N. Hiroyoshi, M. Tsunekawa XXV International Mineral Processing Congress 2010, IMPC 2010 2 843 -850 2010年12月01日 [査読無し][通常論文]
     
    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.
  • R. Jha, J. Satur, N. Hiroyoshi, M. Ito, M. Tsunekawa XXV International Mineral Processing Congress 2010, IMPC 2010 3 2025 -2033 2010年12月01日 [査読無し][通常論文]
     
    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.
  • 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年09月01日 [査読無し][通常論文]
  • 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年03月30日 [査読無し][通常論文]
  • 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年03月30日 [査読無し][通常論文]
  • 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年03月30日 [査読無し][通常論文]
  • 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年03月30日 [査読無し][通常論文]
  • 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年03月30日 [査読無し][通常論文]
  • Yoshitaka Nara, Toshifumi Igarashi, Naoki Hiroyoshi, Tetsuro Yoneda, Katsuhiko Kaneko Zairyo/Journal of the Society of Materials Science, Japan 59 (3) 180 -185 2010年03月 [査読無し][通常論文]
     
    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.
  • 伊藤真由美, 恒川昌美, 広吉直樹 資源・素材 2010 (1) 245 -246 2010年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年01月01日 [査読無し][通常論文]
     
    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.
  • Kyoungkeun Yoo, Naoki Hiroyoshi, Masami Tsunekawa Geosystem Engineering 13 (3) 91 -96 2010年 [査読無し][通常論文]
     
    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.
  • 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年12月01日 [査読無し][通常論文]
     
    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.
  • 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年03月26日 [査読無し][通常論文]
  • 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年03月26日 [査読無し][通常論文]
  • 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年03月26日 [査読無し][通常論文]
  • 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年03月26日 [査読無し][通常論文]
  • 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年03月26日 [査読無し][通常論文]
  • 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年03月26日 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 伊藤真由美, 恒川昌美, 広吉直樹 資源・素材 2009 (1) 235 -238 2009年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 恒川昌美, 秋元淳希, 広吉直樹, 伊藤真由美 資源・素材 2009 37 2009年 [査読無し][通常論文]
  • 伊藤真由美, 浜野孝俊, 広吉直樹, 恒川昌美 資源・素材 2009 31 2009年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 扇子渉, 恒川昌美, 広吉直樹, 伊藤真由美 資源・素材 2009 36 2009年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年12月01日 [査読無し][通常論文]
     
    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.
  • N. Hiroyoshi, M. Tsunekawa, H. Okamoto, R. Nakayama, S. Kuroiwa CANADIAN METALLURGICAL QUARTERLY 47 (3) 253 -258 2008年07月 [査読無し][通常論文]
     
    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.
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • N. Hiroyoshi, S. Kuroiwa, H. Miki, M. Tsunekawa, T. Hirajima HYDROMETALLURGY 87 (1-2) 1 -10 2007年06月 [査読無し][通常論文]
     
    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.
  • 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年03月29日
  • 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年03月29日
  • 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年03月29日
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 富岡 祐一, 広吉 直樹, 恒川 昌美 硫酸と工業 60 (2) 23 -28 2007年02月
  • 小林 元, 川崎 了, 広吉 直樹, 恒川 昌美, 金子 勝比古, 寺島 麗, 島田 俊介 研究発表会講演論文集 19 229 -230 2007年
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • SATUR Jacqueline, HIROYOSHI Naoki, ITO Mayumi, TSUNEKAWA Masami 春季大会講演集. I, 資源編 18 (2) 65 -66 2006年03月27日
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 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年03月27日 [査読無し][通常論文]
  • 富岡 祐一, 広吉 直樹, 恒川 昌美 J. of MMIJ 122 (6/7) 345 -352 2006年 [査読無し][通常論文]
     
    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 As2S3(am) by the reaction of the arsenic species and H2S generated by PbS.
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Masami Tsunekawa, Kunihiro Hori, Tsuyoshi Hirajima, Naoki Hiroyoshi, Masazumi Ito REWAS'04 - Global Symposium on Recycling, Waste Treatment and Clean Technology 1651 -1660 2005年12月01日 [査読無し][通常論文]
     
    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.
  • Kyoungkeun Yoo, Naoki Hiroyoshi, Masami Tsunekawa Proceedings - European Metallurgical Conference, EMC 2005 4 1751 -1765 2005年12月01日 [査読無し][通常論文]
     
    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.
  • MAA Zamani, N Hiroyoshi, M Tsunekawa, R Vaghar, M Oliazadeh HYDROMETALLURGY 80 (1-2) 23 -31 2005年11月 [査読無し][通常論文]
     
    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.
  • 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年07月14日 [査読無し][通常論文]
     
    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.
  • 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年04月 [査読無し][通常論文]
     
    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.
  • 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年03月28日
  • 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年03月28日
  • 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年03月28日
  • 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年03月28日
  • HIROYOSHI Naoki, SATUR Jacqueline, TSUNEKAWA Masami, OKAMOTO Hideyuki 春季大会講演集. I, 資源編 17 (2) 151 -152 2005年03月28日
  • 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年03月28日
  • 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年03月28日 [査読無し][通常論文]
  • 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年03月28日 [査読無し][通常論文]
  • 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年03月28日 [査読無し][通常論文]
  • 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年03月28日 [査読無し][通常論文]
  • 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年03月28日 [査読無し][通常論文]
  • 川崎 了, 村尾 彰了, 広吉 直樹, 恒川 昌美, 金子 勝比古 研究発表会講演論文集 17 221 -222 2005年
  • 富岡祐一, 広吉直樹, 久保泰政, 恒川昌美 資源と素材 121 (12) 597 -602 2005年 [査読無し][通常論文]
     
    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 K0.54(H3O)0.46Fe2.38(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 SO42- 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.
  • 富岡祐一, 広吉直樹, 恒川昌美 資源と素材 121 (8) 392 -398 2005年 [査読無し][通常論文]
     
    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.
  • 岡本 秀征, 中山 良一, 黒岩 樹人, 広吉 直樹, 恒川 昌美 資源と素材 121 (6) 246 -254 2005年 [査読無し][通常論文]
     
    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.
  • 山口英志, 恒川昌美, 広吉直樹, 伊藤真由美 資源・素材 2005 50 2005年 [査読無し][通常論文]
  • 伊藤真由美, 久保泰政, 広吉直樹, 恒川昌美 資源・素材 2005 66 2005年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Yuichi Tomioka, Naoki Hiroyoshi, Masami Tsunekawa Resources Processing 52 (3) 145 -150 2005年 [査読無し][通常論文]
     
    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.
  • Masami Tsunekawa, Kyoungkeun Yoo, Naoki Hiroyoshi, Mayumi Ito Resources Processing 52 (1) 32 -38 2005年 [査読無し][通常論文]
     
    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.
  • N Hiroyoshi, S Kuroiwa, H Miki, M Tsunekawa, T Hirajima HYDROMETALLURGY 74 (1-2) 103 -116 2004年08月 [査読無し][通常論文]
     
    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.
  • 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年03月29日
  • HIROYOSHI Naoki, SATUR Jacqueline, TSUNEKAWA Masami, OKAMOTO Hideyuki 春季大会講演集. I, 資源編 16 (2) 151 -152 2004年03月29日
  • 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年03月29日
  • 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年03月29日
  • 広吉 直樹, 恒川 昌美 春季大会講演集. I, 資源編 16 (2) 81 -82 2004年03月29日
  • 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年03月29日
  • 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年03月29日
  • 岡本秀征, 中山良一, 広吉直樹, 恒川昌美 資源と素材 120 (10/11) 592 -599 2004年 [査読無し][通常論文]
     
    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.
  • Kyoungkeun Yoo, Keiko Sasaki, Naoki Hiroyoshi, Masami Tsunekawa Materials Transactions 45 (7) 2422 -2428 2004年 [査読無し][通常論文]
     
    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.
  • Kyoungkeun Yoo, Keiko Sasaki, Naoki Hiroyoshi, Masami Tsunekawa, Tsuyoshi Hirajima Materials Transactions 45 (7) 2429 -2434 2004年 [査読無し][通常論文]
     
    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.
  • 恒川 昌美, 平島 剛, 広吉 直樹 工学・工業教育研究講演会講演論文集 15 453 -454 2003年09月04日
  • 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年03月27日
  • 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年03月27日
  • 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年03月27日
  • 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年11月08日 [査読無し][通常論文]
  • 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年03月28日
  • 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年03月28日
  • 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年03月28日
  • 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年03月28日
  • 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年03月28日
  • 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年03月28日
  • N Hiroyoshi, M Arai, H Miki, M Tsunekawa, T Hirajima HYDROMETALLURGY 63 (3) 257 -267 2002年03月 [査読無し][通常論文]
     
    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.
  • 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年09月24日
  • 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年09月24日
  • 広吉 直樹, 後藤 昌範, 恒川 昌美, 平島 剛 資源・素材 2001 32 -32 2001年09月24日
  • 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年09月24日
  • N Hiroyoshi, H Miki, T Hirajima, M Tsunekawa HYDROMETALLURGY 60 (3) 185 -197 2001年05月 [査読無し][通常論文]
     
    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.
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 恒川昌美, 堀江周, 広吉直樹, 平島剛 資源と素材 117 (4) 277 -281 2001年 [査読無し][通常論文]
     
    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.
  • 三木一, 広吉直樹, 平島剛, 恒川昌美 資源と素材 117 (3) 215 -220 2001年 [査読無し][通常論文]
     
    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.
  • 恒川 昌美, 堀江 周, 広吉 直樹, 平島 剛 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 117 (4) 277 -281 2001年 [査読無し][通常論文]
     
    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.
  • 三木 一, 広吉 直樹, 平島 剛, 恒川 昌美 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 117 (3) 215 -220 2001年 [査読無し][通常論文]
     
    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.
  • 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年10月10日
  • 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年10月10日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • Naoki Hiroyoshi, Hajime Miki, Tsuyoshi Hirajima, Masami Tsunekawa Hydrometallurgy 57 (1) 31 -38 2000年 [査読無し][通常論文]
     
    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.
  • N Hiroyoshi, M Hirota, T Hirajima, M Tsunekawa BIOTECHNOLOGY AND BIOENGINEERING 64 (4) 478 -483 1999年08月 [査読無し][通常論文]
     
    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.
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月29日 [査読無し][通常論文]
  • 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年03月25日
  • 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年03月25日
  • 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年03月25日 [査読無し][通常論文]
  • 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年03月25日 [査読無し][通常論文]
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日 [査読無し][通常論文]
  • 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年03月01日 [査読無し][通常論文]
  • 伊藤真由美, 恒川昌美, 平島剛, 広吉直樹, 湯川健太郎 資源と素材 115 (10) 737 -742 1999年 [査読無し][通常論文]
     
    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.
  • 広吉 直樹, 三木 一, 平島 剛, 恒川 昌美 資源と素材 115 (3) 172 -176 1999年 [査読無し][通常論文]
  • 伊藤 真由美, 恒川 昌美, 平島 剛, 広吉 直樹, 湯川 健太郎 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 115 (10) 737 -742 1999年 [査読無し][通常論文]
     
    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.
  • N Hiroyoshi, H Miki, T Hirajima, M Tsunekawa HYDROMETALLURGY OF COPPER 4 231 -243 1999年 [査読無し][通常論文]
     
    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.
  • 広吉 直樹, 三木 一, 平島 剛, 恒川 昌美 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 115 (3) 172 -176 1999年 [査読無し][通常論文]
     
    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.
  • 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年03月01日
  • 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年03月01日
  • 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年03月01日
  • 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年03月 [査読無し][通常論文]
  • 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年03月 [査読無し][通常論文]
  • 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年03月01日 [査読無し][通常論文]
  • 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年03月01日 [査読無し][通常論文]
  • 伊藤真由美, 湯川健太郎, 恒川昌美, 平島剛, 広吉直樹 資源・素材学会北海道支部春季講演会講演要旨集 1998 15 -16 1998年 [査読無し][通常論文]
  • 伊藤真由美, 山田龍一, 恒川昌美, 平島剛, 広吉直樹 資源・素材学会北海道支部春季講演会講演要旨集 1998 17 -18 1998年 [査読無し][通常論文]
  • 広吉直樹, 恒川昌美, 平島剛 資源処理技術 45 (4) 263 -268 1998年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • A New Method to Characterize the Flotation Performance of Fine Coal
    Proc. 13th Int. Coal Preparation Congress 1 397 -406 1998年 [査読無し][通常論文]
  • 広吉 直樹, 恒川 昌美, 平島 剛 資源処理技術 45 (4) 263 -268 1998年 [査読無し][通常論文]
  • 広吉 直樹, 前田 英人, 三木 一, 平島 剛, 恒川 昌美 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 114 (11) 795 -800 1998年 [査読無し][通常論文]
     
    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.
  • TSUNAKAWA M. Shigen to Sozai 114 (6) 421 -425 1998年 [査読無し][通常論文]
  • 広吉 直樹 静電気学会誌 21 (4) 166 -169 1997年07月31日
  • Enhancement in Bacterial Leaching of Chalcopyrite by Surfactant Addition
    Proceedings of the 20th International Mineral Processing Congress 4 546 -547 1997年 [査読無し][通常論文]
  • Naoki Hiroyoshi, Masahiko Hirota, Tsuyoshi Hirajima, Masami Tsunekawa Hydrometallurgy 47 (1) 37 -45 1997年 [査読無し][通常論文]
     
    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.
  • 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年10月21日 [査読無し][通常論文]
  • 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年03月29日
  • 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年03月29日
  • 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年03月29日 [査読無し][通常論文]
  • 恒川昌美, 今行忠, 平島剛, 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 1996 5 -6 1996年 [査読無し][通常論文]
  • 広吉 直樹, 伊藤 真由美, 恒川 昌美, 平島 剛 資源と素材 112 (3) 171 -175 1996年 [査読無し][通常論文]
  • Naoki HIROYOSHI, Mayumi ITO, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA J.Mining and Materials Processing Inst.Japan 112 (3) 171 -175 1996年 [査読無し][通常論文]
  • 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年03月28日
  • 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年03月28日 [査読無し][通常論文]
  • 広吉 直樹, 恒川 昌美, 平島 剛, 沢田 満 資源と素材 111 (1) 43 -47 1995年 [査読無し][通常論文]
  • 広吉 直樹, NAKAMURA Takeshi, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi, ITO Mayumi 資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 111 (13) 943 -948 1995年 [査読無し][通常論文]
  • Naoki HIROYOSHI, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA, Mitsuru SAWADA J. Mining and Materials Processing Inst. Japan 111 (1) 43 -47 1995年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • 資源と素材 109 (7) 558 -561 1993年 [査読無し][通常論文]
  • Experimental Methods for Bacterial Leaching of Sulfide Minerals
    J. Mining and Materials Process. Inst. Japan 109 (7) 558 -561 1993年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Naoki HIROYOSHI, Masami TSUNEKAWA, Tsuyoshi HIRAJIMA, Takakatsu TAKAMORI J. Mining and Materials Processing. Inst. Japan 108 (2) 129 -133 1992年 [査読無し][通常論文]
  • 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年 [査読無し][通常論文]
  • Dissolution Behavior of Zinc, Indium and Iron in Bacterial Leaching Process of Sphalerite Concentrate Containing Indium
    Hokkaido Geotechnics 2,14-18 1991年 [査読無し][通常論文]
  • 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 [査読無し][通常論文]

受賞

  • 2000年 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

共同研究・競争的資金等の研究課題

  • 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

教育活動情報

主要な担当授業

  • 共同資源工学特別演習
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 環境、鉱物・エネルギー資源、環境
  • 共同資源工学特別講義Ⅱ
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : Resources Production and Safety Engineering, Rock Mechanics and Mining Machinery and Mineral Processing, Recycling and Environmental Remediation.
  • 共同資源工学特別講義Ⅲ
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : Metallurgy, Environmental Protection
  • 大学院共通授業科目(一般科目):自然科学・応用科学
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
  • 金属製錬工学
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
  • 金属製錬工学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
  • 資源マネージメントⅠ
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : resources management, governance of natural resources, natural resources economics, economic management, human resources management, information management, risk management, socioenvironmental management, planning, implementation, monitoring and evaluation
  • 金属製錬工学特論
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
  • 資源循環システム実験Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 基本操作、物理計測、化学分析
  • 応用数学Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 常微分方程式 ラプラス変換 フーリエ解析 偏微分方程式
  • 資源循環システムⅠ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 地殻資源 資源探査 鉱山開発 採掘技術 未利用資源 都市鉱山 リサイクル 坑廃水処理 環境修復
  • 資源循環工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 地殻資源 資源探査 鉱山開発 採掘技術 未利用資源 都市鉱山 リサイクル 坑廃水処理 環境修復
  • 資源循環システム実験Ⅲ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 構造解析,物性評価,鉱物の利用,流体の分析,選別技術
  • 資源循環システム実験Ⅱ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : X線回折,岩石の構造,岩石の工学的性質,鉱物,地質図,地質巡検,偏光顕微鏡
  • 科学・技術の世界
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 資源、環境、気候変動、資源枯渇、持続的発展可能な社会
  • 粉体工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 粉体 物性 分離 資源 リサイクル
  • 資源工学概論
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 鉱物資源 鉱床 探査・開発技術 環境問題 未利用資源 リサイクル


Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.