Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Engineering　Sustainable Resources Engineering　Resources Engineering

Affiliation (Master)

• Faculty of Engineering　Sustainable Resources Engineering　Resources Engineering

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Profile and Settings

Affiliation

• Hokkaido University, Faculty of Engineering, Division of Sustainable Resources Engineering, Associate Professor

Degree

• PhD（2019/03 Hokkaido University）

Profile and Settings

• Name (Japanese)

  Park

• Name (Kana)

  Ilhwan

• Name

  201901001106560155

Affiliation

• Hokkaido University, Faculty of Engineering, Division of Sustainable Resources Engineering, Associate Professor

Achievement

Research Interests

• Environmental Remediation   Resources Recycling   Extractive Metallurgy   Mineral Processing   

Research Areas

• Other / Other

Research Experience

• 2023/04 - Today Hokkaido University Division of Sustainable Resources Engineering, Faculty of Engineering Associate Professor
• 2019/04 - 2023/03 Hokkaido University Division of Sustainable Resources Engineering, Faculty of Engineering Assistant Professor

Education

• 2016/04 - 2019/03  Hokkaido University  Division of Sustainable Resources Engineering
• 2014/03 - 2016/02  Korea Maritime & Ocean University  Department of Ocean Energy & Resources Engineering
• 2008/03 - 2014/02  Korea Maritime & Ocean University  Department of Energy and Resources Engineering

Awards

• 2024/02 Hokkaido University Hokkaido University President's Award for Outstanding Research
   

  受賞者: Ilhwan Park
• 2023/03 The Mining and Materials Institute of Japan (MMIJ) Best Paper Award
   Kinetic Analysis for Agglomeration-Flotation of Finely Ground Chalcopyrite: Comparison of First Order Kinetic Model and Experimental Results 

  受賞者: Vothy Hornn;Mayumi Ito;Ryosuke Yamazawa;Hiromasa Shimada;Carlito Baltazar Tabelin;Sanghee Jeon;Ilhwan Park;Naoki Hiroyoshi
• 2022/03 Faculty of Engineering, Hokkaido University Young Faculty Award
   

  受賞者: Ilhwan Park
• 2018 17th Global Joint Seminar on Geo-Environmental Engineering, Japan Best Presentation Award (2nd place)
   Suppression of the release of arsenic from arsenopyrite by titanium- and aluminum-based carrier-microencapsulation 

  受賞者: Ilhwan Park
• 2017 1st International KAMPAI Symposium, Japan Best Presentation Award
   uppressive effects of aluminum-catechol complexes on the release of arsenic from arsenopyrite 

  受賞者: Ilhwan Park
• 2017 The Mining and Materials Processing Institute of Japan (MMIJ), Japan MMIJ Young Poster Award
   Carrier-microencapsulation using Al-catechol complex for suppressing arsenic release from arsenopyrite 

  受賞者: Ilhwan Park
• 2016 5th International Doctoral Symposium, Japan Best Presentation Award
   The Influence of Aluminum-Catechol Complexes on the Suppression of Arsenopyrite Oxidation 

  受賞者: Ilhwan Park
• 2016 9th AUN/SEED-Net Regional Conference on Geological and Geo-resources Engineering, Thailand Best Presentation Award
   Suppression of Arsenopyrite Oxidation by Carrier Microencapsulation using Titanium-Catechol Complex 

  受賞者: Ilhwan Park
• 2015 The Korean Institute of Metals and Materials, Korea Best Poster Presentation Award
   The Leaching Behavior of Cuprous Oxide Powder in Sulfuric Acid 

  受賞者: Ilhwan Park
• 2014/02 The Korean Institute of Resources Recycling, Korea The President's Award
   

  受賞者: Ilhwan Park
• 2013/12 Federation of Busan Science and Technology, Korea Busan Future Scientist Award (3rd place)
   The Selective Leaching of Nd from Waste Magnet using Mechanochemical Decomposition 

  受賞者: Ilhwan Park

Published Papers

• APiS (AI powered intelligence spectrum analyser): hyperspectral imaging machine learning analyser app for mineral processing

  Natsuo Okada, Narihiro Owada, Kaito Takizawa, Brian Bino Sinaice, Okhala Muacanhia, Angesom Gebretsadik, Shunki Tanaka, Kosei Aikawa, Ilhwan Park, Mayumi Ito, Yoko Ohtomo, Youhei Kawamura

  International Journal of Mining, Reclamation and Environment 1 - 27 1748-0930 2024/10/02
• Microencapsulation-based surface modification for improving flotation separation of Cu-Zn mixed sulfide minerals

  Ilhwan Park, Dai Uchida, Sanghee Jeon, Kosei Aikawa, Naoki Hiroyoshi, Mayumi Ito

  Minerals Engineering 213 108756 - 108756 0892-6875 2024/08
• Role of Semiconductive Property on Selective Cementation Mechanism of Iron Oxides to Gold in Galvanic Interaction with Zero-Valent Aluminum from Gold–Copper Ammoniacal Thiosulfate Solutions

  Joshua Zoleta, Kosei Aikawa, Nako Okada, Ilhwan Park, Mayumi Ito, Yogarajah Elakneswaran, Naoki Hiroyoshi

  Metals 14 (5) 550 - 550 2024/05/07 

  Iron oxides (hematite, Fe2O3, and magnetite, Fe3O4), previously used as electron mediators in the galvanic system with zero-valent aluminum (ZVAl), have been shown to recover Au upon cementation in Au–Cu ammoniacal thiosulfate media selectively, and this warrants further investigation. This research is focused on investigating the role of the semiconductive properties of metal oxides by performing a cementation experiment by mixing 0.15 g of electron mediators (Fe3O4, Fe2O3, TiO2 (anatase and rutile)) and 0.15 g of zero-valent aluminum powder as an electron donor in various electrochemical experiments. The results revealed that upon the cementation experiment, synthetic Fe2O3 and Fe3O4 were consistently able to selectively recover Au at around 90% and Cu at around 20%. Compared to activated carbon (AC), TiO2, in anatase and rutile forms, obtained selective recovery of gold, but the recovery was utterly insignificant compared to that of iron oxides, obtaining an average of 93% Au and 63% Cu recovery. The electrochemical and surface analysis supports the results obtained upon the cementation process, where TiO2, upon cyclic voltammetry (CV), obtained two reduction peaks centered at −1.0 V and −0.5 V assigned to reducing Au and Cu ions, respectively. Furthermore, various electrochemical impedance spectroscopic analyses revealed that the flat band potential obtained in the Mott–Schottky plot is around −1.0 V and −0.2 V for iron oxides and titanium oxides, respectively, suggesting that the electrons travel from semiconductor interface to electrolyte interface, and electrons are accessible only to Au ions in the electrolyte interface (reduction band edge around −1.0 V). The determination of this selective cementation mechanism is one of a kind. It has been proposed that the semiconductive properties of Fe2O3, Fe3O4, and, by configuring their relative energy band diagram, the travel of electrons from the iron oxide–electrolyte interface facilitate the selective cementation towards Au(S2O3)23+ ions in gold–copper ammoniacal thiosulfate solutions.
• Isolation and Characterization of Indigenous Ureolytic Bacteria from Mindanao, Philippines: Prospects for Microbially Induced Carbonate Precipitation (MICP)

  Kryzzyl M. Maulas, Charla S. Paredes, Carlito Baltazar Tabelin, Mark Anthony Jose, Einstine M. Opiso, Takahiko Arima, Ilhwan Park, Walubita Mufalo, Mayumi Ito, Toshifumi Igarashi, Theerayut Phengsaart, Edrhea Villas, Sheila L. Dagondon, Ephrime B. Metillo, Mylene M. Uy, Al James A. Manua, Mylah Villacorte-Tabelin

  Minerals 14 (4) 339 - 339 2024/03/26 

  Microbially induced carbonate precipitation (MICP), a widespread phenomenon in nature, is gaining attention as a low-carbon alternative to ordinary Portland cement (OPC) in geotechnical engineering and the construction industry for sustainable development. In the Philippines, however, very few works have been conducted to isolate and identify indigenous, urease-producing (ureolytic) bacteria suitable for MICP. In this study, we isolated seven, ureolytic and potentially useful bacteria for MICP from marine sediments in Iligan City. DNA barcoding using 16s rDNA identified six of them as Pseudomonas stutzeri, Pseudomonas pseudoalcaligenes, Bacillus paralicheniformis, Bacillus altitudinis, Bacillus aryabhattai, and Stutzerimonas stutzeri but the seventh was not identified since it was a bacterial consortium. Bio-cementation assay experiments showed negligible precipitation in the control (without bacteria) at pH 7, 8, and 9. However, precipitates were formed in all seven bacterial isolates, especially between pH 7 and 8 (0.7–4 g). Among the six identified bacterial species, more extensive precipitation (2.3–4 g) and higher final pH were observed in S. stutzeri, and B. aryabhattai, which indicate better urease production and decomposition, higher CO2 generation, and more favorable CaCO3 formation. Characterization of the precipitates by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR) confirmed the formation of three carbonate minerals: calcite, aragonite, and vaterite. Based on these results, all six identified indigenous, ureolytic bacterial species from Iligan City are suitable for MICP provided that the pH is controlled between 7 and 8. To the best of our knowledge, this is the first report of the urease-producing ability and potential for MICP of P. stutzeri, P. pseudoalcaligenes, S. stutzeri, and B. aryabhattai.
• A Mixed Media Approach Using Locally Available Neutralizing Materials for the Passive Treatment of Acid Mine Drainage

  Joshua Pascual Pocaan, Casey Oliver A. Turingan, Carlito Baltazar Tabelin, Joshua B. Zoleta, Takahiko Arima, Ilhwan Park, Mayumi Ito, Aileen H. Orbecido

  2024/01/05 

  Abstract Acid mine drainage (AMD)—the strongly acidic and highly polluted effluents from mine sites—are generally managed via active or passive treatment. Active treatment strategies are effective but requires continuous input of energy, chemicals and manpower making them unsustainable in the long term. Because of this, passive treatment is explored as a more sustainable alternative especially for abandoned and legacy mines. Recent studies of the authors have explored the use limestone and waste materials like low-grade ores (LGO), fly ash (FA), and concrete wastes for AMD treatment and found that although these materials generated alkalinity individually, they could only partially remove sulfate (SO₄²⁻) and some heavy metals. To address this limitation, a mixed media approach using these four materials is proposed to neutralize the pH of AMD and maximize heavy metals (Cu, Fe, Mn, Ni, and Al) and SO₄²⁻ removal. A total of twenty (20) mixtures of the four materials were identified based on the response surface methodology (RSM) experimental design. Laboratory-scale experiments using simulated AMD were performed to assess the performance of each mixture by monitoring the pH, oxidation-reduction potential (Eh), electrical conductivity (EC), metal concentrations, and SO₄²⁻ concentration. Based on the results, three optimized mixed media compositions were identified in wt%: (i) 43% LGO, 40% limestone, 17% CW; (ii) 44% LGO, 51% limestone, 6% CW; and (iii) 89% limestone, 11% LGO. Overall, simulated AMD passively treated by the optimized mixed media compositions met the Philippine effluent standards except for SO₄²⁻. Simulated AMD treated by the optimized mixed media achieved pH values of < 9 and removal efficiencies for Cu, Fe, Mn, Ni, and Al of about 99%, 99%, 98%, 70%, and 96%, respectively.
• Modified Diglycolamide Resin: Characterization and Potential Application for Rare Earth Element Recovery

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

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

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

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

  Minerals Engineering 201 108202 - 108202 0892-6875 2023/10
• Recent Studies and Technologies in the Separation of Polyvinyl Chloride for Resources Recycling: A Systematic Review

  Theerayut Phengsaart, Pongsiri Julapong, Chaiwat Manositchaikul, Palot Srichonphaisarn, Monthicha Rawangphai, Onchanok Juntarasakul, Kosei Aikawa, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Mayumi Ito

  Sustainability 15 (18) 13842 - 13842 2023/09/18 

  Material recycling and thermal treatment are the two most common recycling methods employed for plastic waste management. Thermal treatment for energy recovery is more widely applied compared with material recycling because the latter requires a high efficiency of separation and a high purity of products. Unfortunately, certain plastics like polyvinyl chloride (PVC) are unsuitable for thermal treatment because they contain additives like chloride (Cl−) that have adverse effects on refractory materials used in boilers. As a result of this, mixed plastic wastes containing PVC generally end up in landfills. PVC-bearing mixed plastics, however, remain valuable resources as championed by the United Nation Sustainable Development Goals (UN-SDGs): Goal 12 “Responsible production and consumption”, and their recycling after the removal of PVC is important. In this paper, recent studies (2012–2021) related to the separation of PVC from other types of plastics were systematically reviewed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 66 articles were selected, reviewed, and summarized. The results showed that various separation technologies conventionally applied to mineral processing—selective comminution, gravity separation, magnetic separation, electrical separation, and flotation—have been studied for PVC separation, and the majority of these works (>60%) focused on flotation. In addition, more advanced technologies including sorting and density-surface-based separation were introduced between 2019 and 2021.
• A Pretreatment of Refractory Gold Ores Containing Sulfide Minerals to Improve Gold Leaching by Ammonium Thiosulfate: A Model Experiment Using Gold Powder and Arsenic-Bearing Sulfide Minerals

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

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

  The use of thiosulfate to extract gold from refractory ores is promising because of its non-toxicity and high selectivity. Sulfide minerals (i.e., pyrite, arsenopyrite, chalcopyrite), major gold carriers in refractory gold ores, however, hinder gold extraction due to the high consumption of a lixiviant. In this study, a new method to improve gold extraction from sulfide bearing gold ores is proposed based on the model experiments using a mixture of gold powder and arsenopyrite-bearing sulfide (HAsBS) ore. The effects of HAsBS ore on gold leaching in ammonium thiosulfate solutions were investigated, and it was found that gold extraction in the presence of HAsBS ore was suppressed because of the unwanted decomposition of thiosulfate on the surface of sulfide minerals. To improve gold extraction in the presence of the sulfide minerals, this study investigated the effects of the pretreatment of HAsBS ore using ammonium solutions containing cupric ions and confirmed that HAsBS ore was oxidized in the pretreatment and its surface was covered by the oxidation products. As a result, thiosulfate consumption was minimized in the subsequent gold leaching step using ammonium thiosulfate, resulting in an improvement in gold extraction from 10% to 79%.
• Rare Earth Elements Recovery from Primary and Secondary Resources Using Flotation: A Systematic Review

  Pongsiri Julapong, Apisit Numprasanthai, Ladda Tangwattananukul, Onchanok Juntarasakul, Palot Srichonphaisarn, Kosei Aikawa, Ilhwan Park, Mayumi Ito, Carlito Baltazar Tabelin, Theerayut Phengsaart

  Applied Sciences 13 (14) 8364 - 8364 2023/07/19 

  Rare earth minerals (REMs) contain rare earth elements (REEs) that are important in modern technologies due to their unique magnetic, phosphorescent, and catalytic properties. However, REMs are not only non-renewable resources but also non-uniformly distributed on the Earth’s crust, so the processing of REE-bearing secondary resources via recycling is one potential route to ensure the long-term sustainability of REE supply. Flotation—a method that separates materials based on differences in their surface wettability—is a process applied for both mineral processing and recycling of REEs, especially when the particles are fine and/or a high-purity product is required. In this review, studies about rare earth flotation from 2012 to 2021 were systematically reviewed using the PRISMA guideline. It was found that most REM flotation research works focused on finding better collectors and depressants while, for recycling, studies on advanced flotation techniques like froth flotation, ion flotation, solvent sublation, electroflotation, and adsorbing colloid flotation with an emphasis on the recovery of dissolved REEs from aqueous solutions dominated.
• Selective Cementation of Gold Using an Iron Oxide and Zero-Valent Aluminum Galvanic System from Gold–Copper Ammoniacal Thiosulfate Solutions

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

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

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

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

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

  Carrier flotation is a technique that can recover fine particles by using coarse carrier particles during the flotation process. In heterogeneous carrier flotation, coarse mineral particles of different minerals are used as carriers to recover fine mineral particles. By using Cu2+-treated pyrite particles as carriers, fine chalcopyrite particles recovery could be improved. However, a disadvantage of this heterogeneous carrier flotation is that it requires a post-flotation separation process to improve the grade of the final Cu concentrate. This study tested mechanical and chemical treatments to detach finely ground chalcopyrite (D50~3.5 µm) particles from Cu2+-treated coarse pyrite particles (−125 + 106 µm) after flotation. The results showed that the ultrasonic treatment was not effective to detach chalcopyrite fines from Cu2+-treated pyrite particles. However, acid treatment was effective to detach chalcopyrite fines from coarse pyrite particles. At pH 2, approximately 96% of chalcopyrite fines were detached from coarse Cu2+-treated pyrite particles. The acid treatment of flotation froth (mixture of chalcopyrite fines and Cu2+-treated pyrite particles) decomposed the collector KAX (potassium amyl xanthate) and dissolved the Cu precipitates adsorbed on the pyrite surface. This weakened the hydrophobic attraction force between the chalcopyrite fines and coarse pyrite particles, thus promoting the detachment of chalcopyrite fines from Cu2+-treated coarse pyrite particles.
• Development of a three-step approach to repurpose nickel-laterite mining waste into magnetite adsorbents for As(III) and As(V) removal: Synthesis, characterization and adsorption studies

  Einstine M. Opiso, Carlito Baltazar Tabelin, Leonard Marc Ramos, Leonar Jun R. Gabiana, Marybeth Hope T. Banda, Jet Ryan Y. Delfinado, Aileen H. Orbecido, Joshua B. Zoleta, Ilhwan Park, Takahiko Arima, Mylah Villacorte-Tabelin

  Journal of Environmental Chemical Engineering 11 (1) 108992 - 108992 2213-3437 2023/02
• Geochemical audit of a historical tailings storage facility in Japan: Acid mine drainage formation, zinc migration and mitigation strategies

  Carlito Baltazar Tabelin, Asuka Uyama, Shingo Tomiyama, Mylah Villacorte-Tabelin, Theerayut Phengsaart, Marthias Silwamba, Sanghee Jeon, Ilhwan Park, Takahiko Arima, Toshifumi Igarashi

  Journal of Hazardous Materials 438 129453 - 129453 0304-3894 2022/09
• Flotation of Copper Ores with High Cu/Zn Ratio: Effects of Pyrite on Cu/Zn Separation and an Efficient Method to Enhance Sphalerite Depression

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

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

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

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

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

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

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

  Minerals 12 (4) 2022/04 

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

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

  Minerals Engineering 180 0892-6875 2022/04 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  Chemosphere 269 2021/04 [Refereed]
  
• Flotation separation of chalcopyrite and molybdenite assisted by microencapsulation using ferrous and phosphate ions: Part II. flotation

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

  Metals 11 (3) 1 - 11 2075-4701 2021/03/01 

  Porphyry-type deposits are the major sources of copper and molybdenum, and flotation has been adopted to recover them separately. The conventional reagents used for depressing copper minerals, such as NaHS, Na2S, and Nokes reagent, have the potential to emit toxic H2S gas when pulp pH was not properly controlled. Thus, in this study the applicability of microencapsulation (ME) using ferrous and phosphate ions as an alternative process to depress the floatability of chalcopyrite was investigated. During ME treatment, the use of high concentrations of ferrous and phosphate ions together with air introduction increased the amount of FePO4 coating formed on the chalcopyrite surface, which was proportional to the degree of depression of its floatability. Although ME treatment also reduced the floatability of molybdenite, ~92% Mo could be recovered by utilizing emulsified kerosene. Flotation of chalcopyrite/molybdenite mixture confirmed that the separation efficiency was greatly improved from 10.9% to 66.8% by employing ME treatment as a conditioning process for Cu-Mo flotation separation.
• Effects of coarse chalcopyrite on flotation behavior of fine chalcopyrite

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

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

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

  Metals 11 (2) 253 - 253 2021/02/02 

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

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

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

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

  Metals 10 (12) 2020/12 [Refereed]
  
• Kinetic Analysis for Agglomeration-Flotation of Finely Ground Chalcopyrite: Comparison of First Order Kinetic Model and Experimental Results

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

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

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

  Journal of Environmental Chemical Engineering 8 (4) 104197 - 104197 2213-3437 2020/08 [Refereed][Not invited]
   

  Zinc plant leach residues (ZPLRs) are hazardous solid wastes generated from zinc metal production owing to their substantial contents of lead (Pb), a toxic heavy metal. This study investigated the detoxification of historic ZPLRs from Kabwe, Zambia by removing Pb using a coupled extraction-cementation method in chloride media. For the coupled extraction-cementation method, micro-scale zero-valent iron (mZVI) was added during ZPLRs leaching in acidified chloride solution. Cemented Pb on the surface of mZVI was recovered easily from the leaching pulp by magnetic separation. Pb removal was evaluated in different solution compositions (NaCl:1-5.13 M, HCl: 0-0.1 M) with and without the addition of mZVI. The addition of mZVI during ZPLRs leaching (i.e., coupled extraction-cementation) increased Pb removal from 3% to 24%, 1.3% to 27.5%, 5.2% to 34.9%, and 6.5% to 55.8% when NaCl concentration was fixed at 0.86 M and HCl concentrations were 0 M, 0.01 M, 0.05 M and 0.1 M, respectively. When NaCl concentration was increased above 3.42 M and HCl maintained at 0.1 M HCl, Pb removal increased to 80%. Analysis of the Pb-loaded mZVI (magnetic fraction) by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) revealed that Pb was recovered during leaching via cementation as Pb degrees. The toxicity characteristic leaching procedure (TCLP) and in vitro solubility and bioavailability research consortium gastric phase (SBRC-G) tests for Pb of ZPLRs before and after treatment decreased drastically from 11.3 to 3.5 mg/L (below 5 mg/L threshold) and 12 300 to 2 840 mg/Kg, respectively.
• Agglomeration–Flotation of Finely Ground Chalcopyrite Using Emulsified Oil Stabilized by Emulsifiers: Implications for Porphyry Copper Ore Flotation

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

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

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

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

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

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

  Hydrometallurgy 194 105299 - 105299 0304-386X 2020/06 [Refereed][Not invited]
  
• Improvement of Copper Metal Leaching in Sulfuric Acid Solution by Simultaneous Use of Oxygen and Cupric Ions

  Kyoungkeun Yoo, Yujin Park, Sanghyeon Choi, Ilhwan Park

  Metals 10 (6) 721 - 721 2020/05/28 [Refereed][Not invited]
   

  A new concept for copper (Cu) metal leaching by the simultaneous use of cupric ions (Cu2+) and oxygen (O2) was proposed to improve Cu metal leaching in sulfuric acid. According to this concept, Cu2+ oxidizes Cu metal into cuprous ion (Cu+), and O2 oxidizes Cu+ into Cu2+. The improvement in Cu leaching efficiency from Cu metal was investigated experimentally in the sulfuric acid solution using Cu2+ and O2 simultaneously. Furthermore, the result was compared with that for the sulfuric acid solution containing neither Cu2+ nor O2 and with the sulfuric acid solution without Cu2+ and O2. When both Cu2+ and O2 were used in the leaching solution, the leaching rate of Cu from Cu metal powder was higher than at other leaching conditions, and the leaching efficiency of Cu increased to more than 99.9% in 1 mol/L sulfuric acid solution at 400 rpm and 50 °C with ≤75 µm Cu metal powder, 1% pulp density, 10,000 mg/L initial Cu2+ concentration, and 100 cc/min O2 introduction. These results indicated that the leaching of Cu from Cu metal could be accelerated by adding Cu2+ and O2 in the sulfuric acid solution.
• Agglomeration-Flotation of Finely Ground Chalcopyrite and Quartz: Effects of Agitation Strength during Agglomeration Using Emulsified Oil on Chalcopyrite

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

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

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

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

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

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

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

  Hydrometallurgy 191 105165  2020 [Refereed][Not invited]
  
• Agglomeration flotation of finely ground chalcopyrite: Comparison of model calculation vs. Experimental results

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

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

  In the flotation of fine particles, collisions between rising bubbles and the particles become poor because of the small mass and low momentum of particles. Because of this, fine particles do not collide and attach to bubbles, leading to substantial losses of desired minerals. In this study, oil agglomeration-flotation technique was studied to improve the floatability of finely ground chalcopyrite using mathematical modelling, a very useful approach to scale-up and improve the design, and operation of oil agglomeration-flotation in actual plants. Flotation of finely ground chalcopyrite samples and agglomerated particles were carried out, and the experimental results were fitted with conventional first order kinetic model for flotation. In this flotation experiments, potassium xanthate was used as a collector for three ground samples having different size distributions without agglomeration. The results of model calculations agreed well with the experimental results (recovery-time curve) when size distribution measured in the flotation pulp was used. Oil agglomeration-flotation using emulsified oil and collector was applied on finely ground chalcopyrite. When the agglomerated chalcopyrite was used for the calculation, the model calculation did not fit well with the experimental results (recovery-time curve). In this paper, factors that may cause this misfitting are discussed.
• Agglomeration-flotation of finely ground chalcopyrite: Effects of agitation strength in agglomeration on flotation separation efficiency

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

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

  In flotation, recovery of mineral in froth depends on the size of mineral particles. When the size becomes fine, collision efficiency of the particles and air bubbles becomes low, causing low recovery. To improve the collision efficiency and flotation rate, agglomeration of finely ground chalcopyrite was carried out before flotation and the effects of the agglomeration on flotation were investigated. Agglomeration of finely ground chalcopyrite (D50= 3.5 µm) suspended in distilled water (pulp density of 5%) was carried out in a mixer with potassium amyl xanthate (KAX) as surface modifier and kerosene as bridging liquid. Flotation of the agglomerated products was done in a mechanical agitation cell with 25 µL/L of MIBC as the frother. In this study, the effects of KAX dosage and agglomeration agitation strength on the flotation rate and separation efficiency were discussed. Agglomerated product with 1000g/t of KAX exhibited a faster flotation rate than the agglomerated product with 200g/t of KAX. Agglomeration with stronger agitation strength increased flotation rate. Additionally, separation efficiency of quartz and chalcopyrite in flotation was improved, when more KAX and stronger agitation strength were used during agglomeration.
• Effects of flatness ratio on the particle motion during jig separation of plastic and improvement of jig separation efficiency using modified water pulsation

  Theerayut Phengsaart, Daiki Kitayama, Arisa Azuma, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Mayumi Ito

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

  RETAC jig is a modified TACUB jig developed to separate crushed plastics for resources recycling. Because secondary resources like mixed-plastic wastes are composed of particles with various shapes, jig separation is not only affected by the difference of particle density but also particle geometry (i.e., size and shape). In this study, the effects of particle shape on particle motion during water pulsation were measured and discussed. In the jig separation experiments, acrylonitrile butadiene styrene (ABS specific gravity (SG) of 1.03) and polystyrene (PS SG of 1.06) boards were cut into cuboids with the same equivalent volume diameters but different flatness ratios. The motion of these particles during water pulsation was recorded using a video camera and analyzed by image analysis. Water pulsation during jig separation is comprised of 4 steps: (1) rising, (2) initial holding, (3) downwelling, and (4) final holding. During the water rising step (step 1), disk-like particles rose faster than sphere-like particles. In contrast, the motions of disk-like and sphere-like particles were very similar in steps 2-4, indicating that jig separation efficiency is strongly influenced by particle motion during step 1. Based on these results, modifications of water pulsation to reduce the effects of particle shape on jig separation efficiency are proposed.
• Development of discharge systems using restraining walls for continuous jig separation of plastics to improve purity of bottom layer products

  Theerayut Phengsaart, Shoko Kimura, Arisa Azuma, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Mayumi Ito

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

  In this study, a new discharge system for continuous jig separation of mixed-plastic samples that improves the purity of bottom layer products is proposed. Batch and continuous jig results were compared using plastic mixtures with different light and heavy particles ratio. The purity of bottom layer products of continuous jig was lower than those of batch jig because of the entrainment of light particles induced by the screw-type extractor. Moreover, the purity of bottom layer products during continuous jig separation was influenced by the difference of light and heavy particles ratio that is, purity was lower when the ratio of heavy plastic was low. To improve the purity of bottom layer products of continuous jig, a new discharge system using a vertical restraining wall was developed. The restraining wall was installed to divide the separation chamber into two and particles can transfer from one to another only through a narrow channel below the wall. The results showed that when the ratio of heavy plastic was low, the purity of bottom layer products of continuous jig was improved by the restraining wall.
• Lead removal in zinc leach residues from Kabwe, Zambia by carrier-in-pulp method using zero-valent iron

  M. Silwamba, M. Ito, T. Fukushima, I. Park, S. Jeon, C. B. Tabelin, N. Hiroyoshi

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

  Zinc leach residues (ZLRs) are hazardous materials because they contain toxic heavy metals such as lead (Pb) and pose serious risks to the ecosystem and people living nearby. This study investigated Pb removal from ZLRs collected from Kabwe (Zambia), one of the most Pb-polluted towns in the world, using carrier-in-pulp method. ZLRs and zero-valent iron (ZVI), which was used as the carrier, were simultaneously mixed in NaCl solution. Pb was extracted from ZRLs and formed Pb-chloride complexes, which was reductively precipitated as Pb0 on ZVI. The Pb-loaded ZVI was then separated from the leach pulp by magnetic separation. Pb removal was evaluated under various conditions such as leaching time, ZVI dosage and solution composition. The maximum Pb removal from ZLRs (about 78 wt% Pb) was collated with Pb bound to acid leachable solid phases determined by sequential extraction. Comparing Pb removal when ZLRs were leached with and without the addition of ZVI, it was found that the addition of ZVI significantly improved the removal of Pb at low concentrations of NaCl.
• Estimation of settling velocity and jig separation efficiency of non-spherical plastics using flatness ratio

  Theerayut Phengsaart, Arisa Azuma, Daiki Kitayama, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Mayumi Ito

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

  In this study, the effects of flatness ratio of plastic particles on jig separation were investigated. Acrylonitrile butadiene styrene (ABS specific gravity (SG) of 1.03) boards 2-mm, 3-mm, 4-mm, and 5-mm thick and polystyrene (PS SG of 1.06) boards 2-mm and 3-mm thick were cut into cuboids having the same equivalent volume diameters but with different flatness ratios. Because separation during jigging mainly occurs at the downward motion of particles, the settling motion of a particle in water inside the jig separation chamber was recorded using a video camera and analyzed by image analysis. The results showed that particles with low flatness ratios (i.e., disk-like) settled down at a much slower rate than those with high flatness ratios (i.e., sphere-like). These results were consistent with the jig separation results showing that separation efficiency was higher for a mixture of disk-like light plastic and sphere-like heavy plastic than that composed of sphere-like light plastic and disk-like heavy plastic. This could be attributed to the differences in settling velocities of disk-like and sphere-like particles. In addition, new equations to estimate the settling velocity of plastic particles and jig separation efficiency of mixed-plastic samples based on the flatness ratio are proposed.
• Effects of particle geometry on the bubble attachment during hybrid jig separation

  Theerayut Phengsaart, Arisa Azuma, Daiki Kitayama, Shoko Kimura, Sumetas Rittiboon, Apiset Wongthanuwat, Dawan Wiwattanadate, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Naoki Hiroyoshi, Mayumi Ito

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

  Separation of plastics with similar specific gravities (SG) has been one of the biggest challenges in the recycling of mixed-plastic wastes. To tackle this problem, the authors developed the hybrid jig, a technique that combines the concepts of surface wettability from flotation and gravity separation using jigs to separate plastics with similar SGs. Mixed-plastic wastes are composed of particles having a wide variety of shapes and sizes (i.e., particle geometry), and both of which will likely have strong effects on the separation efficiency of hybrid jig separation similar to our previous observations on conventional jig separation. In this study, the volume of bubbles attached to plastic particles with different SGs (polyethylene terephthalate (PET SG of 1.31) and polyvinyl chloride (PVC SG of 1.38)), sizes (2-8 mm), and shapes (disk-like to sphere-like) were measured during water pulsation.
• Effects of galvanic interactions between lead-activated sphalerite and pyrite on flotation

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

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

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

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

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

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

  Hydrometallurgy 191 105214 - 105214 0304-386X 2020/01 [Refereed][Not invited]
  
• Improvement of flotation and suppression of pyrite oxidation using phosphate-enhanced galvanic microencapsulation (GME) in a ball mill with steel ball media

  Sophea Seng, Carlito Baltazar Tabelin, Yuta Makino, Monyneath Clea, Theerayut Phengsaart, Ilhwan Park, Naoki Hiroyoshi, Mayumi Ito

  Minerals Engineering 143 105931  2019 [Refereed][Not invited]
  
• Development of advanced pyrite passivation strategies towards sustainable management of acid mine drainage

  Carlito Baltazar Tabelin, Ilhwan Park, Xinlong Li, Sophea Seng, Mylah Villacorte-Tabelin, Toshifumi Igarashi, Mayumi Ito, Naoki Hiroyoshi

  IOP Conference Series: Earth and Environmental Science 351 012010  2019 [Refereed][Not invited]
  
• A physical separation scheme to improve ammonium thiosulfate leaching of gold by separation of base metals in crushed mobile phones

  Sanghee Jeon, Mayumi Ito, Carlito Baltazar Tabelin, Rongrit Pongsumrankul, Shinya Tanaka, Naho Kitajima, Ayumu Saito, Ilhwan Park, Naoki Hiroyoshi

  Minerals Engineering 138 168 - 177 2019 [Refereed][Not invited]
  
• Carrier-microencapsulation using Al-catecholate complex to suppress arsenopyrite oxidation: Evaluation of the coating stability under simulated weathering conditions

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

  MATEC Web of Conferences 268 06002  2019 [Refereed][Not invited]
  
• Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

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

  MATEC Web of Conferences 268 06015  2019 [Refereed][Not invited]
  
• A review of recent strategies for acid mine drainage prevention and mine tailings recycling

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

  Chemosphere 219 588 - 606 2019 [Refereed][Not invited]
  
• Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes (vol 205C, pg 414, 2018)

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

  CHEMOSPHERE 209 1021  0045-6535 2018/10 [Refereed][Not invited]
  
• Gold recovery from shredder light fraction of E-waste recycling plant by flotation-ammonium thiosulfate leaching

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

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

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

  Jayhyun Park, Ilhwan Park, Jumi Oh, Kyoungkeun Yoo

  The Korean Society of Mineral and Energy Resources Engineers 55 (5) 414 - 420 2018 [Refereed][Not invited]
  
• Arsenic, selenium, boron, lead, cadmium, copper, and zinc in naturally contaminated rocks: A review of their sources, modes of enrichment, mechanisms of release, and mitigation strategies

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

  Science of the Total Environment 645 1522 - 1553 2018 [Refereed][Not invited]
  
• Interference of coexisting copper and aluminum on the ammonium thiosulfate leaching of gold from printed circuit boards of waste mobile phones

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

  Waste Management 81 148 - 156 2018 [Refereed][Not invited]
  
• Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes

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

  Chemosphere 205 414 - 425 2018 [Refereed][Not invited]
  
• Suppression of the release of arsenic from arsenopyrite by carrier-microencapsulation using Ti-catechol complex

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

  Journal of hazardous materials 344 322 - 332 2018 [Refereed][Not invited]
  
• Simultaneous leaching of arsenite, arsenate, selenite and selenate, and their migration in tunnel-excavated sedimentary rocks: II. Kinetic and reactive transport modeling

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

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

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

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

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

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

  Ilhwan Park, Kyoungkeun Yoo, Richard Diaz Alorro, Min-Seuk Kim, Soo-Kyung Kim

  MATERIALS TRANSACTIONS 58 (10) 1500 - 1504 1345-9678 2017 [Refereed][Not invited]
   

  The leaching behavior of copper from Cu2O in H2SO4 solution was investigated to establish the leaching process for cathode powders produced by the recycling of waste printed circuit boards. When air was not introduced in sulfuric acid solution, the dissolution of copper from Cu2O was inhibited by the formation of elemental copper (Cu-0). The dissociated cuprous ions (Cu+) transformed into elemental copper (Cu-0) or cupric ions (Cu2+) owing to the instability of Cu+ in H2SO4. Cu+ can be reduced to elemental copper (Cu-0) by accepting an electron generated from the oxidation of another Cu+ to Cu2+, which is known as a disproportionation reaction. The introduction of air enhanced the leaching efficiency of copper due to the role of oxygen in the air as oxidant by accepting the electron generated from the oxidation of Cu+ to Cu2+. In the leaching test using Cu2O reagent, the leaching efficiencies of copper increased with increasing air flow rate, temperature and agitation speed, but decreased with increasing pulp density. Copper leaching efficiency increased to up to 99% within 60 min in the aerated sulfuric acid solution at 30 degrees C, 400 rpm, and pulp density of 2%.
• The Effect of Grinding and Roasting Conditions on the Selective Leaching of Nd and Dy from NdFeB Magnet Scraps

  Ho-Sung Yoon, Chul-Joo Kim, Kyung Woo Chung, Sanghee Jeon, Ilhwan Park, Kyoungkeun Yoo, Manis Kumar Jha

  METALS 5 (3) 1306 - 1314 2075-4701 2015/09 [Refereed][Not invited]
   

  The pretreatment processes consisting of grinding followed by roasting were investigated to improve the selective leaching of Nd and Dy from neodymium- iron- boron ( NdFeB) magnet scraps. The peaks of Nd( OH) 3 and Fe were observed in XRD results after grinding with NaOH as the amount of water addition increased to 5 cm(3). These results indicate that the components of Nd and Fe in NdFeB magnet could be changed successfully into Nd( OH) 3 and Fe, respectively. In the roasting tests using the ground product, with increasing roasting temperature to 500 degrees C, the peaks of Nd( OH) 3 and Fe disappeared while those of Nd2O(3) and Fe2O(3) were shown. The peaks of NdFeO3 in the sample roasted at 600 degrees C were observed in the XRD pattern. Consequently, 94.2%, 93.1%, 1.0% of Nd, Dy, Fe were leached at 400 rpm and 90 degrees C in 1 kmol . m- 3 acetic acid solution with 1% pulp density using a sample prepared under the following conditions: 15 in stoichiometric molar ratio of NaOH: Nd, 550 rpm in rotational grinding speed, 5 cm3 in water addition, 30 min in grinding time, 400 degrees C and 2 h in roasting temperature and time. The results indicate that the selective leaching of Nd and Dy from NdFeB magnet could be achieved successfully by grinding and then roasting treatments.
• Fine Particle Classification and Dewatering of Construction Waste Slurry Using Hydrocyclone

  Hee-young Shin, Sang-woo Ji, Sanghyeon Choi, Ilhwan Park, Kyoungkeun Yoo, Jay Hyun Park, Richard Diaz Alorro

  The Korean Society of Mineral and Energy Resources Engineers 52 (6) 627 - 631 2015 [Refereed][Not invited]
  
• The effects of temperature and agitation speed on the leaching behaviors of tin and bismuth from spent lead free solder in nitric acid leach solution

  Sanghee Jeon, Ilhwan Park, Kyoungkeun Yoo, Hojin Ryu

  Geosystem Engineering 18 (4) 213 - 218 2015 [Refereed][Not invited]
  

MISC

• Carrier magnetic separation to recover finely ground rare earth minerals: The effect of gravity separation as a pre-concentration step

  Ilhwan Park, Taito Horii, Mayumi Ito, Naoki Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2022  2022/12
• Flotation of finely ground chalcopyrite in the presence of nanobubbles

  Yukun Liu, Naoki Hiroyoshi, Mayumi Ito, Ilhwan Park  Proceedings of International Symposium on Earth Science and Technology 2022  2022/12
• Iron Oxide as Electron Mediator in Gold Cementation with Zero-Valent Aluminum in Gold-Copper Ammoniacal Thiosulfate Medium

  Joshua B. Zoleta, Sanghee Jeon, Akuru Kuze, Ilhwan Park, Mayumi Ito, Naoki Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2022  2022/12
• Application of microencapsulation technique for improving flotation separation of chalcopyrite and molybdenite

  Ilhwan Park, Dai Uchida, Kosei Aikawa, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi  Proceedings of Copper 2022  2022/11
• Refractory gold ores: A focus on advances in pretreatment techniques in thiosulfate leaching systems of As/Sb bearing gold ores

  Takunda Joseph Mhandu, Shota Hamatsu, Sanhee Jeon, Ilhwan Park, Mayumi Ito, Naoki Hiroyoshi  Proceedings of the 16th International Symposium on East Asian Resources Recycling Technology  2022/10
• Effects of anglesite on the flotation of sphalerite in complex sulphide ores and a method to suppress sphalerite floatability

  K. Aikawa, M. Ito, A. Kusano, S. Jeon, I. Park, N. Hiroyoshi  Proceedings of International Mineral Processing Congress Asia-Pacific 2022  2022/08
• Investigation of Flotation Behaviors of Fine Particles in a Complex Ore Consisting of Various Copper Minerals

  Y. Ebisu, J. V. Satur, K. Mitsuhashi, K. Aikawa, T. Suto, I. Park, M. Ito, N. Hiroyoshi  Proceedings of International Mineral Processing Congress Asia-Pacific 2022  2022/08
• Challenges and approaches to flotation of seafloor massive sulphide ores

  K. Aikawa, I. Park, N. Hiroyoshi, M. Ito  Proceedings of International Future Mining Conference 2021 (web)  2021/12
• A study on the water injection method of Falcon-Knelson concentrator

  R. Matsuoka, M. Ito, S. Jeon, I. Park, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2021  2021/11
• Effects of coexisting pyrite on suppression of sphalerite in the flotation of copper-zinc sulfides

  N. Orii, M. Ito, K. Aikawa, S. Jeon, I. Park, R. Magwaneng, T. Ono, T. Sakakibara, K. Sunada, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2021  2021/11
• Study of autogenous carrier flotation technique for finely ground chalcopyrite particles – a review

  M. Bilal, M. Ito, K. Koike, V. Hornn, F.U. Hassan, S. Jeon, I. Park, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2021  2021/11
• A new method to detect product boundary in jig separator using pressure sensor

  N. Sawada, M. Ito, S. Kimura, I. Park, S. Jeon, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2021  2021/11
• A REVIEW OF GOLD EXTRACTION FROM ARSENIC/ANTIMONY BEARING ORES

  T.J. Mhandu, N. Hiroyoshi, M. Ito, I. Park, S. Jeon  Proceedings of International Symposium on Earth Science and Technology 2021  2021/11
• Enhanced magnetic separation of finely-ground rare earth minerals by oil agglomeration

  Y. Kanazawa, M. Ito, N. Sato, S. Jeon, I. Park, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology 2021  2021/11
• Agglomeration-flotation to minimize the loss of finely-ground copper sulfides to tailings causing environmental pollution at mine sites

  T. Suto, M. Ito, H. Shimada, S. Jeon, I. Park, N. Hiroyoshi  Proceedings of Geo-environmental Engineering and Recycling (GER) 2021 (web)  2021/11
• Selective formation of hydrophilic iron phosphate coating on chalcopyrite to separate from sphalerite in flotation

  I. Park, S. Hong, U. Dai, S. Jeon, M. Ito, N. Hiroyoshi  Proceedings of Geo-environmental Engineering and Recycling (GER) 2021 (web)  2021/11
• Concurrent treatment combining extraction and cementation of anglesite for depression of sphalerite floatability

  相川公政, 伊藤真由美, 草野敦大, JEON Sanghee, PARK Ilhwan, 広吉直樹  資源・素材(Web)  2021-  2021
• A study of autogenous carrier flotation technique for selective separation of fine chalcopyrite

  M. Bilal, M. Ito, K. Koike, I. Park, S. Jeon, N. Hiroyoshi  Proceedings of International Conference on Innovations for Sustainable and Responsible Mining (ISRM) 2020  2020/10
• Microencapsulation of Chalcopyrite and Molybdenite using Fe2+ and PO43– for Selective Flotation

  S. Hong, I. Park, S. Jeon, M. Ito, N. Hiroyoshi  Proceedings of International Conference on Innovations for Sustainable and Responsible Mining (ISRM) 2020  2020/10
• Simultaneous extraction and sequestration of lead and zinc from zinc leach residues using acidified brine solution and zero-valent aluminum

  M. Silwamba, M. Ito, I. Park, C.B. Tabelin, S. Jeon, N. Hiroyoshi  Proceedings of International Mineral Processing Congress (IMPC) 2020  2020/10
• A review of recent advances in depression techniques for flotation separation of cu–mo sulfides in porphyry copper deposits

  Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi  Metals  10-  (9)  1  -26  2020/09/01  

  Porphyry copper deposits (PCDs) are some of the most important sources of copper (Cu) and molybdenum (Mo). Typically, the separation and recovery of chalcopyrite (CuFeS2 ) and molybdenite (MoS2 ), the major Cu and Mo minerals, respectively, in PCDs are achieved by two-step flotation involving (1) bulk flotation to separate Cu–Mo concentrates and tailings (e.g., pyrite, silicate, and aluminosilicate minerals) and (2) Cu–Mo flotation to separate chalcopyrite and molybdenite. In Cu–Mo flotation, chalcopyrite is depressed using Cu depressants, such as NaHS, Na2 S, Nokes reagent (P2 S5 + NaOH), and NaCN, meaning that it is recovered as tailings, while molybdenite is floated and recovered as froth product. Although conventionally used depressants are effective in the separation of Cu and Mo, they have the potential to emit toxic and deadly gases such as H2 S and HCN when operating conditions are not properly controlled. To address these problems caused by the use of conventional depressants, many studies aimed to develop alternative methods of depressing either chalcopyrite or molybdenite. In this review, recent advances in chalcopyrite and molybdenite depressions for Cu–Mo flotation separation are reviewed, including alternative organic and inorganic depressants for Cu or Mo, as well as oxidation-treatment technologies, such as ozone (O3 ), plasma, hydrogen peroxide (H2 O2 ), and electrolysis, which create hydrophilic coatings on the mineral surface.
• Effects of pyrite on the floatability of lead-activated sphalerite in flotation

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

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

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

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

  伊藤真由美, 草野敦大, 相川公政, JEON Sanghee, PARK Ilhwan, 広吉直樹  資源・素材(Web)  2020-  2020
• 鉛で活性化された閃亜鉛鉱の浮遊性に及ぼすガルバニック相互作用の影響

  伊藤真由美, 相川公政, 瀬川達也, JEON Sanghee, PARK Ilhwan, TABELIN Carlito, 広吉直樹  資源・素材学会北海道支部春季講演会講演要旨集  2019-  2019
• Suppression of the release of arsenic from arsenopyrite by titanium- and aluminum-based carrier-microencapsulation

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

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

  C.B. Tabelin, R. Sasaki, T. Igarashi, I. Park, S. Tamoto, T. Arima, M. Ito, N. Hiroyoshi  Proc. of the 17th Global Joint Seminar on Geo-environmental Engineering  312  -319  2018  [Not refereed][Not invited]
  
• Carrier-microencapsulation using Al-catechol complex for suppressing arsenic release from arsenopyrite

  I. Park, K. Seno, K. Magaribuchi, C.B. Tabelin, M. Ito, N. Hiroyoshi  the 14th International Symposium on East Asian Resources Recycling Technology and the Mining and Materials Processing Institute of Japan Fall Meeting  10  -15  2017  [Not refereed][Not invited]
  
• Suppressive effects of aluminum-catechol complexes on the release of arsenic from arsenopyrite

  I. Park, K. Seno, K. Magaribuchi, C.B. Tabelin, M. Ito, N. Hiroyoshi  Proceedings of 1st International Kabwe Mine Pollution Amelioration Initiative (KAMPAI) Symposium  31  2017  [Not refereed][Not invited]
  
• Effects of aluminum-catechol complexes on pyrite oxidation

  I. Park, C.B. Tabelin, K. Seno, K. Magaribuchi, M. Ito, N. Hiroyoshi  Proceedings of International Symposium on Earth Science and Technology  611  -614  2017  [Not refereed][Not invited]
  
• Suppression of arsenopyrite oxidation by carrier microencapsulation using Ti-catechol complex.

  I. Park, K. Magaribuchi, S. Veerawattananum, C.B. Tabelin, M. Ito, N. Hiroyoshi, T. Igarashi  the 9th International Conference on Earth Resources Technology,  918  -928  2016  [Not refereed][Not invited]
  

Research Projects

• Development of an advanced magnetic separation technology assisted by agglomeration for improving the recovery of rare earth minerals from finely ground low-grade ores

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists

  Date (from‐to) : 2020/04 -2023/03 

  Author : Ilhwan Park

   

  This research aims at developing advanced magnetic separation techniques for the recovery of rare earth element (REE)-bearing minerals from Mongolian ore deposits. The most important achievements of this study are summarized as follows: 1. Dry high-intensity magnetic separation (DHIMS) of ground REE ore (-0.5 + .01 mm) could achieve the enrichment ratio of 2.8 with a TREO recovery of 70%. 2. Wet high-intensity magnetic separation (WHIMS) of ground REE ore (-106 + 75 μm) enriched TREO content by 5.5 times with a TREO recovery of ~80%. 3. Agglomeration of finely-ground bastnaesite (D50 = ~3 μm) using BHA increased the particle size to > 8 μm, which improved its recovery by WHIMS from 50% to 95%.
• Development of a novel and high efficient recovery process for gold from gold ore in ammonium thiosulfate solvent

  Japan Oil, Gas and Metals National Corporation (JOGMEC)：金属資源の生産技術に関する基礎研究

  Date (from‐to) : 2020/04 -2022/03 

  Author : Sanghee Jeon, Naoki Hiroyoshi, Mayumi Ito, Ilhwan Park, Sharrydon Brigh
• Application of Microencapsulation Technique for the Selective Flotation of Sulfide Minerals

  Japan Oil, Gas and Metals National Corporation (JOGMEC)：金属資源の生産技術に関する基礎研究

  Date (from‐to) : 2019/04 -2021/03 

  Author : Ilhwan Park, Naoki Hiroyoshi, Mayumi Ito, Higuchi Kazuki, Seunggwan Hong
• Development of flotation technology for fine particles

  Sumitomo Metal Mining Co., Ltd.：

  Date (from‐to) : 2019/04 

  Author : Naoki Hiroyoshi, Mayumi Ito, Ilhwan Park, Vothy Hornn, Hiromasa Shimada
• A basic study for elucidating the mechanism of Zn-mineral depression in Cu-Zn flotation separation

  Japan Oil, Gas and Metals National Corporation (JOGMEC)：難処理鉱選鉱製錬技術開発事業

  Date (from‐to) : 2019/04 

  Author : Mayumi Ito, Ilhwan Park, Kosei Aikawa, Nodoka Orii