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Last Updated :2024/11/22

研究者情報

マスター

アカウント（マスター）

  • 氏名

    伊藤　真由美(イトウ　マユミ), イトウ　マユミ

所属（マスター）

  • 工学研究院　環境循環システム部門　資源循環工学分野

所属（マスター）

  • 工学研究院　環境循環システム部門　資源循環工学分野

独自項目

syllabus

  • 2021, 大学院共通授業科目（一般科目）：自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, physical separation, mineral processing, solid waste, recycling
  • 2021, 選鉱・リサイクル工学, Mineral Processing and Resources Recycling, 修士課程, 工学院, 物理選別　選鉱　廃棄物　リサイクル　
  • 2021, 選鉱・リサイクル工学, Mineral Processing and Resources Recycling, 修士課程, 工学院, physical separation, mineral processing, solid waste, recycling
  • 2021, 選鉱・リサイクル工学特論, Mineral Processing and Resources Recycling, 修士課程, 工学院, 物理選別　選鉱　廃棄物　リサイクル　
  • 2021, 選鉱・リサイクル工学特論, Mineral Processing and Resources Recycling, 修士課程, 工学院, physical separation, mineral processing, solid waste, recycling
  • 2021, 大学院共通授業科目（教育プログラム）：JICA開発大学院連携プログラム, Inter-Graduate School Classes(Educational Program):JICA Development Study Program, 修士課程, 大学院共通科目, Japan's experience for resources development and environmental conservation, Japan's ODA, Technical cooperation project, Grant aid project, Yen loan project
  • 2021, 選鉱・リサイクル工学特論, Mineral Processing and Resources Recycling, 博士後期課程, 工学院, 物理選別　選鉱　廃棄物　リサイクル　
  • 2021, 選鉱・リサイクル工学特論, Mineral Processing and Resources Recycling, 博士後期課程, 工学院, physical separation, mineral processing, solid waste, recycling
  • 2021, 物理化学, Physical Chemistry, 学士課程, 工学部, 熱力学　化学平衡　反応速度　界面化学
  • 2021, 物理化学演習, Exercise in Physical Chemistry, 学士課程, 工学部, 熱力学　化学平衡　反応速度　界面化学
  • 2021, 資源循環デザイン, Engineering Design on Sustainable Resources, 学士課程, 工学部, エンジニアリングデザイン，資源循環システム，影響評価，コミュニケーション，チームワーク
  • 2021, 資源循環システム実験Ⅰ, Experiments for Sustainable Resources Engineering Ⅰ, 学士課程, 工学部, 基本操作、物理計測、化学分析
  • 2021, 火薬及び爆破工学, Explosives and Blasting Engineering, 学士課程, 工学部, 火薬，爆薬，火工品，発破
  • 2021, 資源循環システム実験Ⅲ, Experiments for Sustainable Resources Engineering Ⅲ, 学士課程, 工学部, 構造解析，物性評価，鉱物の利用，流体の分析，選別技術
  • 2021, 資源循環システム実験Ⅱ, Experiments for Sustainable Resources Engineering Ⅱ, 学士課程, 工学部, 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
  • 2021, 資源工学概論, Introduction to Mineral Resources Engineering, 学士課程, 工学部, 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

PositionHistory

  • 大学院工学研究院副研究院長, 2023年4月1日, 2025年3月31日

researchmap

プロフィール情報

学位

  • 博士（工学）（2000年03月 北海道大学）

プロフィール情報

  • 姓

    伊藤, イトウ

  • 名

    真由美, マユミ

  • ID各種

    200901089911481692

対象リソース

業績リスト

研究キーワード

  • 選鉱   資源開発工学   地球・資源システム工学   リサイクル工学   リサイクル   土壌汚染   土壌洗浄法   廃棄物   海洋資源   物理選別   比重選別   浮選   磁力選別   ジグ   プラスチック選別   湿式製錬   銅   薄膜形成技術   鉱山酸性汚濁水   

研究分野

  • エネルギー / 地球資源工学、エネルギー学
  • 環境・農学 / 環境材料、リサイクル技術

経歴

  • 2022年08月 - 現在 北海道大学 大学院工学研究院 教授
  • 2010年12月 - 現在 北海道大学 大学院工学研究院 准教授
  • 2004年05月 - 2010年11月 北海道大学 工学研究院 助教
  • 2001年04月 - 2004年03月 早稲田大学 理工学部 助手
  • 2000年04月 - 2001年03月 早稲田大学 理工学部 客員研究員
  • 1996年04月 - 1999年03月 日本学術振興会 特別研究員（DC1）

学歴

  • 1996年04月 - 2000年03月   北海道大学   大学院工学研究科   資源開発工学専攻博士後期課程
  • 1994年04月 - 1996年03月   北海道大学   大学院工学研究科   資源開発工学専攻修士課程
  • 1990年04月 - 1994年03月   北海道大学   工学部   資源開発工学科

委員歴

  • 2017年04月 - 現在   経済産業省   北海道地方鉱山保安協議会
  • 2012年04月 - 現在   北海道   北海道認定リサイクル製品審査委員会
  • 2024年06月 - 現在   JICA   「エジプト日本科学技術大学（E-JUST）プロジェクトフェーズ３」国内支援委 員会委員
  • 2017年10月 - 2023年03月   JOGMEC   銅原料中の不純物低減技術開発委員
  • - 2020年03月   原子力安全研究協会   中間貯蔵除去土壌等の減容・再生利用技術開発戦略検討会 土壌分級システム実証事業ワーキンググループ
  • 2010年04月 - 2018年03月   JOGMEC   海底熱水鉱床開発委員会選鉱・製錬技術ワーキンググループ

受賞

  • 2023年03月 資源・素材学会 論文賞
     Kinetic analysis for agglomeration-flotation of finely ground chalcopyrite: Comparison of first order kinetic model and experimental results. 
    受賞者: V. Hornn;M. Ito;R. Yamazawa;H. Shimada;C.B. Tabelin;S. Jeon;I. Park;N. Hiroyoshi
  • 2021年06月 廃棄物資源循環学会 令和元年論文賞
     The effects of particle geometry on separation efficiency 
    受賞者: heerayut Phengsaart;Mayumi Ito;Arisa Azuma;Carlito Baltazar Tabelin;Naoki Hiroyoshi
  • 2020年03月 国際科学技術財団 平成記念研究助成
     アフリカにおける有害金属の汚染対策と環境修復技術 -動物と人が健康に暮らせる世界の創成を目指して 
    受賞者: 中山 翔太;中田 北斗内田;伊藤 真由美;樋渡 雅人
  • 2020年03月 資源・素材学会 第45回論文賞
     alvanic Microencapsulation (GME) Using Zero-Valent Aluminum and Zero-Valent Iron to Suppress Pyrite Oxidation 
    受賞者: S. Seng, C.B. Tabelin, M. Kojima, N. Hiroyoshi, M. Ito
  • 2005年03月 資源・素材学会 資源・素材学会第6回若手ポスター賞
     単体分離促進のための電気パルスによる選択粉砕機構の解明～石炭含有鉱物の粉砕性は何で決まるのか～ 
    受賞者: 伊藤 真由美
  • 2005年03月 資源・素材学会 資源・素材学会第30回奨励賞
     Advanced Coal Cleaningに関する一連の研究’ 
    受賞者: 伊藤 真由美
  • 2003年06月 環境資源工学会 環境資源工学会第110回例会，ポスター賞
     
    受賞者: 伊藤 真由美

論文

  • 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 2024年10月02日
  • Ilhwan Park, Dai Uchida, Sanghee Jeon, Kosei Aikawa, Naoki Hiroyoshi, Mayumi Ito
    Minerals Engineering 213 108756 - 108756 2024年08月
  • Joshua Zoleta, Kosei Aikawa, Nako Okada, Ilhwan Park, Mayumi Ito, Yogarajah Elakneswaran, Naoki Hiroyoshi
    Metals 14 5 550 - 550 2024年05月07日 
    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.
  • 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年03月26日 
    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.
  • Nyein Chan Soe, Yared Beyene Yohannes, Takamitsu Ohigashi, Hokuto Nakata, Chikae Tatsumi, Yoshitaka Uchida, Walubita Mufalo, Mayumi Ito, Tsutomu Sato, Toshifumi Igarashi, Yoshinori Ikenaka, Mayumi Ishizuka, Shouta M. M. Nakayama
    Journal of Soils and Sediments 2024年03月13日
  • Walubita Mufalo, Takahiko Arima, Toshifumi Igarashi, Mayumi Ito, Tsutomu Sato, Shingo Tomiyama, Imasiku Nyambe, Carlito Baltazar Tabelin, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    Environmental Geochemistry and Health 46 2 2024年02月06日
  • Joshua Pascual Pocaan, Casey Oliver A. Turingan, Carlito Baltazar Tabelin, Joshua B. Zoleta, Takahiko Arima, Ilhwan Park, Mayumi Ito, Aileen H. Orbecido
    2024年01月05日 
    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.
  • Takahiko ARIMA, Kenta NOTO, Walubita MUFALO, Toshifumi IGARASHI, Mayumi ITO, Tsutomu SATO, Hokuto NAKATA, Shouta NAKAYAMA, Mayumi ISHIZUKA
    Resources Processing 70 3 141 - 150 2024年
  • 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年10月14日 
    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.
  • Ilhwan Park, Mayumi Ito, Sanghee Jeon, Carlito Baltazar Tabelin, Theerayut Phengsaart, Marthias Silwamba, Naoki Hiroyoshi
    Minerals Engineering 201 108202 - 108202 2023年10月
  • 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年09月18日 
    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.
  • Takunda Joseph Mhandu, Ilhwan Park, Sanghee Jeon, Sohta Hamatsu, Yogarajah Elakneswaran, Mayumi Ito, Naoki Hiroyoshi
    Metals 13 8 1357 - 1357 2023年07月28日 
    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%.
  • 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年07月19日 
    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.
  • Joshua Zoleta, Sanghee Jeon, Akuru Kuze, Nako Okada, Ilhwan Park, Mayumi Ito, Yogarajah Elakneswaran, Naoki Hiroyoshi
    Metals 13 7 1289 - 1289 2023年07月18日 
    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.
  • Muhammad Bilal, Ilhwan Park, Mayumi Ito, Fawad Ul Hassan, Kosei Aikawa, Sanghee Jeon, Naoki Hiroyoshi
    Minerals 13 7 916 - 916 2023年07月07日 
    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.
  • Walubita Mufalo, Pawit Tangviroon, Takahiko Arima, Toshifumi Igarashi, Mayumi Ito, Tsutomu Sato, Kenta Noto, Takeshi Kawashima, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    Journal of Geochemical Exploration 249 107209 - 107209 2023年06月
  • Daichi Yamada, Masato Hiwatari, Daiju Narita, Peter Hangoma, Bona Chitah, Hokuto Nakata, Shouta M.M. Nakayama, John Yabe, Mayumi Ito, Toshifumi Igarashi, Mayumi Ishizuka, Golden Zyambo
    Science of The Total Environment 865 161281 - 161281 2023年03月
  • 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.
  • Shinsaku Nakamura, Toshifumi Igarashi, Yoshitaka Uchida, Mayumi Ito, Kazuyo Hirose, Tsutomu Sato, Walubita Mufalo, Meki Chirwa, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    Minerals 12 5 2022年05月 
    Effects of the water content of ground surface on windborne lead (Pb) dispersion from the zinc (Zn) leach residue site at the Kabwe mine, Zambia, were simulated. The Pb-bearing Zn plant leach residue site was selected as the source of the dispersion, and water conditions of the surface of the source were evaluated by the modified normalized difference water index (MNDWI) under the actual weather conditions in the year 2019. The MNDWI was calculated based on Sentinel-2 datasets, which were acquired in the year 2019. The index was used for monitoring the surface condition of the source necessary for simulating Pb dispersion, because the higher surface water content reduces the intensity of windborne source. The results showed that the wind speeds and directions had huge impacts on Pb dispersion when the MNDWI had negative values, and that the dispersion was inhibited when the MNDWI had positive values. These indicate that the water content of the surface is sensitive to dispersion, and that MNDWI is an effective parameter that expresses the source strength.
  • 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.
  • S. Jeon, S. Bright, I. Park, C.B. Tabelin, M. Ito, N. Hiroyoshi
    Hydrometallurgy 208 2022年02月 [査読有り]
  • S. Jeon, S. Bright, I. Park, A. Kuze, M. Ito, N. Hiroyoshi
    Minerals 12 1 2022年01月 [査読有り]
  • Mayumi Ito, Ayumu Saito, Megumi Takeuchi, Nana Murase, Theerayut Phengsaart, Carlito Baltazar Tabelin, Naoki Hiroyoshi
    Minerals Engineering 174 2021年12月01日 
    We have developed various types of jigs for resources recycling focusing primarily on plastic-plastic separation. The RETAC jig could be used to separate plastics heavier than water (specific gravity (SG) > 1.0) with different SGs while the hybrid jig—a process combining jig and flotation—was developed to separate plastics with similar SGs but different surface wettabilities. Meanwhile the reverse jig—a RETAC jig with a top screen—is used to separate plastics lighter than water with different SGs. In this study, a novel method that combines the principle of reverse and hybrid jigs, called “reverse hybrid jig separation” was developed to separate plastics lighter than water having similar SGs but different surface wettabilities. The tests were carried out with wastes from an eco-cable wire recycling facility in Japan, which is composed of polyethylene (PE) and cross-linked polyethylene (XLPE). The reverse hybrid jig separation results showed that bubble attachment to and detachment from plastic particles strongly influenced the separation efficiency. In addition, the effects of particle size on separation efficiency were also evaluated.
  • I. Park, Y. Kanazawa, N. Sato, P. Galtchandmani, M. K. Jha, C.B. Tabelin, S. Jeon, M. Ito, N. Hiroyoshi
    Minerals 11 12 2021年12月 [査読有り]
  • S. Choi, S Jeon, I. Park, M. Ito, N. Hiroyoshi
    Journal of Environmental Chemical Engineering 9 6 2021年12月 [査読有り]
  • Walubita Mufalo, Pawit Tangviroon, Toshifumi Igarashi, Mayumi Ito, Tsutomu Sato, Meki Chirwa, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    Toxics 9 10 2021年10月04日 
    Zambia's Kabwe mine wastes (KMWs) are responsible for contaminating the surrounding soil and dust in the Kabwe district. Unfortunately, these wastes arise from the historical mining activities of lead (Pb) and Zinc (Zn), which lacked adequate waste management strategies. As a result, potentially toxic elements (PTEs) (Pb and Zn) spread across the Kabwe district. To assess the soil pollution derived from previous mining activities, we studied topsoil samples (n = 8) from the school playground soils (SPs). In this study, the degree of contamination, geochemical partitioning, and leachability, coupled with the release and retention of Pb and Zn, were studied. The SPs were classified as extremely enriched (EF > 40) and contaminated with Pb (Igeo > 5). On average, Pb (up to 89%) and Zn (up to 69%) were bound with exchangeable, weak acid-soluble, reducible and oxidizable phases, which are considered as 'geochemically mobile' phases in the environment. The leachates from the soils (n = 5) exceeded the Zambian standard (ZS: 190:2010) for Pb in potable drinking water (Pb < 0.01 mg/L). Furthermore, the spatial distribution of Pb and Zn showed a significant reduction in contents of Pb and Zn with the distance from the mine area.
  • Marthias Silwamba, Mayumi Ito, Carlito Baltazar Tabelin, Ilhwan Park, Sanghee Jeon, MasaoTakada, Yasushi Kubo, Naohiro Hokari, Masami Tsunekawa, Naoki Hiroyoshi
    Environmental Advances 5 2021年10月 [査読有り]
  • 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年10月 [査読有り]
  • I. Park, T. Ryota, T Yuto, C.B. Tabelin, T. Phengsaart, S. Jeon, M. Ito, N. Hiroyoshi
    Journal of Environmental Management 295 2021年10月 [査読有り]
  • V. Horn, I. Park, M. Ito, H Shimada, T. Suto, C.B. Tabelin, S. Jeon, N. Hiroyoshi
    Minerals Engineering 171 2021年09月 [査読有り]
  • S. Jeon, S. Bright, I. Park, C.B. Tabelin, M. Ito, N. Hiroyoshi
    Metals 11 9 2021年08月 [査読有り]
  • 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年08月 [査読有り]
  • Shinsaku Nakamura, Toshifumi Igarashi, Yoshitaka Uchida, Mayumi Ito, Kazuyo Hirose, Tsutomu Sato, Walubita Mufalo, Meki Chirwa, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    MINERALS 11 8 2021年08月 
    Dispersion of lead (Pb) in mine wastes was simulated for reproducing Pb contamination of soil in Kabwe District, Zambia. Local weather data of year 2019 were monitored in situ and used for the simulations. The plume model, weak puff model, and no puff model were adopted for calculation of Pb dispersion under different wind conditions. The results showed that Pb dispersion from the Kabwe mine was directly affected by wind directions and speeds in the dry season, although it was not appreciably affected in the rainy season. This may be because the source strength is lower in the rainy season due to higher water content of the surface. This indicates that Pb dispersion patterns depend on the season. In addition, the distribution of the amount of deposited Pb-bearing soils around the mine corresponded to the distribution of Pb contents in soils. These results suggest that Pb contamination in soils primarily results from dispersion of fine mine wastes.
  • 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年07月 [査読有り]
  • 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年07月 [査読有り]
  • Sanghyeon Choi, Sanghee Jeon, Ilhwan Park, Carlito Baltazar Tabelin, Mayumi Ito, Naoki Hiroyoshi
    Hydrometallurgy 201 2021年05月01日 
    Cadmium (Cd), cobalt (Co), nickel (Ni), and zinc (Zn) are important components of batteries and renewable energy technologies but their recovery from pregnant leach solutions or removal from polluted soil systems and water bodies remain challenging. In this study, we report the removal/recovery of heavy metal ions (Cd2+, Co2+ and Ni2+, and Zn2+) from sulfate solutions by a novel cementation technique using aluminum (Al) and activated carbon (AC) called “AC/Al-cementation”. The results showed ~0% removal/recovery efficiencies with Al only for the four heavy metals but with “AC/Al-cementation”, these values increased to 96%, 61%, 57%, and 45% for Zn2+, Ni2+, Co2+, and Cd2+, respectively. Detailed residue characterizations using SEM-EDX, XPS, and AES showed substantial deposition of heavy metal ions in their elemental forms, indicating that the primary mechanism of removal/recovery was cementation. Moreover, the results identified the critical role of AC as an electron pathway from Al (electron donor) to metal ions (electron acceptors) even though Al was covered with Al2O3. Finally, hydrogen overpotential and the subsequent passivation of cemented heavy metals by Al(OH)3 were important limiting factors and processes affecting the efficiency of “AC/Al-cementation” technique.
  • I. Park, K. Higuchi, C.B. Tabelin, S. Jeon, M. Ito, N. Hiroyoshi
    Chemosphere 269 2021年04月 [査読有り]
  • Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi
    Metals 11 3 1 - 11 2021年03月01日 
    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.
  • M. Bilal, M. Ito, K. Koike, V. Hornn, F.U. Hassan, S. Jeon, I. Park, N. Hiroyoshi
    Minerals Engineering 163 2021年03月 [査読有り]
  • 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.
  • S. Choi, S Jeon, I. Park, M. Ito, N. Hiroyoshi
    Metals 11 2 2021年02月 [査読有り]
  • Ilhwan Park, Seunggwan Hong, Sanghee Jeon, Mayumi Ito, Naoki Hiroyoshi
    Metals 10 12 2020年12月 [査読有り]
  • 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
  • Wilson Mwandira, Kazunori Nakashima, Satoru Kawasaki, Allison Arabelo, Kawawa Banda, Imasiku Nyambe, Meki Chirwa, Mayumi Ito, Tsutomu Sato, Toshifumi Igarashi, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    Scientific Reports 10 1 2020年12月 
    AbstractThe present study investigated biosorption of Pb (II) and Zn (II) using a heavy metal tolerant bacterium Oceanobacillus profundus KBZ 3-2 isolated from a contaminated site. The effects of process parameters such as effect on bacterial growth, pH and initial lead ion concentration were studied. The results showed that the maximum removal percentage for Pb (II) was 97% at an initial concentration of 50 mg/L whereas maximum removal percentage for Zn (II) was at 54% at an initial concentration of 2 mg/L obtained at pH 6 and 30 °C. The isolated bacteria were found to sequester both Pb (II) and Zn (II) in the extracellular polymeric substance (EPS). The EPS facilitates ion exchange and metal chelation-complexation by virtue of the existence of ionizable functional groups such as carboxyl, sulfate, and phosphate present in the protein and polysaccharides. Therefore, the use of indigenous bacteria in the remediation of contaminated water is an eco-friendly way of solving anthropogenic contamination.
  • Mayumi Ito, Ayumu Saito, Nana Murase, Theerayut Phengsaart, Shoko Kimura, Naho Kitajima, Megumi Takeuchi, Carlito Baltazar Tabelin, Naoki Hiroyoshi
    Journal of Material Cycles and Waste Management 22 6 2071 - 2080 2020年11月01日 
    The hybrid jig, which combines the principles of jig separation and flotation, was recently developed to separate mixed-plastics with similar specific gravities (SG) effectively. In this type of jig, air bubbles are introduced during water pulsation to modify the apparent SG (SGapparent) of plastics by the attachment of air bubbles to the particles so that the hybrid jig can separate materials having identical SGs if their surface wettabilities are different. Because the change in SGapparent—determined by the volume of attached bubbles on the particle surface—is critical for efficient separation in hybrid jigs, a method to estimate this parameter should be developed. In this study, a laser-assisted measurement apparatus was developed to quantify the attached-bubble volume on plastics during water pulsation. Hybrid jig separation was also conducted using three mixtures containing plastics of almost identical SGs: (i) polyvinyl chloride (PVC)/polyethylene terephthalate (PET), (ii) polypropylene with glass fiber (PPGF)/high-impact polystyrene (HIPS), and (iii) cross-linked polyethylene (XLPE)/polyethylene (PE). Finally, to estimate the separation efficiency of hybrid jig, a new index called the apparent concentration criterion (CCapparent) is proposed. The results showed that SGapparent and CCapparent calculated using the proposed methods could be used to estimate the hybrid jig separation efficiency.
  • 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.
  • Vothy Hornn, Mayumi Ito, Ryosuke Yamazawa, Hiromasa Shimada, Carlito Baltazar Tabelin, Sanghee Jeon, Ilhwan Park, Naoki Hiroyoshi
    61 10 2020年09月 [査読有り]
  • Pawit Tangviroon, Kenta Noto, Toshifumi Igarashi, Takeshi Kawashima, Mayumi Ito, Tsutomu Sato, Walubita Mufalo, Meki Chirwa, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama, Mayumi Ishizuka
    MINERALS 10 9 2020年09月 
    Massive amount of highly contaminated mining residual materials (MRM) has been left unattended and has leached heavy metals, particularly lead (Pb) and zinc (Zn) to the surrounding environments. Thus, the performance of three immobilizers, raw dolomite (RD), calcined dolomite (CD), and magnesium oxide (MO), was evaluated using batch experiments to determine their ability to immobilize Pb and Zn, leached from MRM. The addition of immobilizers increased the leachate pH and decreased the amounts of dissolved Pb and Zn to different extents. The performance of immobilizers to immobilize Pb and Zn followed the following trend: MO > CD > RD. pH played an important role in immobilizing Pb and Zn. Dolomite in RD could slightly raise the pH of the MRM leachate. Therefore, the addition of RD immobilized Pb and Zn via adsorption and co-precipitation, and up to 10% of RD addition did not reduce the concentrations of Pb and Zn to be lower than the effluent standards in Zambia. In contrast, the presence of magnesia in CD and MO significantly contributed to the rise of leachate pH to the value where it was sufficient to precipitate hydroxides of Pb and Zn and decrease their leaching concentrations below the regulated values. Even though MO outperformed CD, by considering the local availability of RD to produce CD, CD could be a potential immobilizer to be implemented in Zambia.
  • 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]
  • Theerayut Phengsaart, Mayumi Ito, Arisa Azuma, Carlito Baltazar Tabelin, Naoki Hiroyoshi
    Journal of Material Cycles and Waste Management 22 3 787 - 800 2020年05月01日 
    Secondary resources (i.e., wastes) contain a wide variety of materials (e.g., plastics, metals, and wood) of various sizes and shapes that complicate separation especially when using gravity-based separation techniques. In this study, the effects of particle geometry (i.e., size and shape) on jig separation of crushed plastics were investigated. Plastic boards with 2-mm and 3-mm thicknesses of acrylonitrile butadiene styrene (ABS, specific gravity (SG) = 1.03) and polystyrene (PS, SG = 1.06) were crushed to obtain a size fraction of + 2.0–8.0 mm. The shape distribution in each size fraction (+ 2.0–2.8, + 2.8–4.0, + 4.0–5.6, and + 5.6–8.0 mm) showed the strong effects of crushing on particle shape that is, particles are more disk-like at coarser size fraction but becomes more sphere-like at finer size fraction. Settling velocity of sphere-like PS increased with increasing particle size while those of disk-like ABS had similar values regardless of the size, which were consistent with the results of jig separation of single-type plastics. The results of jig separation of mixed-type plastics showed that separation efficiency was higher for the mixture of light, disk-like particles (ABS) and heavy, sphere-like particles (PS).
  • 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.
  • Joshua B. Zoleta, Gevelyn B. Itao, Vannie Joy T. Resabal, Arnold A. Lubguban, Ryan D. Corpuz, Mayumi Ito, Naoki Hiroyoshi, Carlito Baltazar Tabelin
    Heliyon 6 1 2020年01月01日 
    This study describes the effects of ceria (CeO2) and dolomite [CaMg(CO3)2] additives on the pyrolysis behavior and fire resistive property of conventional intumescent flame retardant (IFR) coating system for I-beam steel substrate called ammonium polyphosphate-melamine-expandable graphite (APP-MEL-EG) system. The fire resistance of various formulations was evaluated using the standard vertical Bunsen burner fire test. Thermogravimetric analysis (TGA) was used to understand the degradation of coating formulations. Observations by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) demonstrated that significant amounts of additives favored the formation of homogeneous compacted char structures, which were predominantly composed of carbon (C), phosphorus (P) and oxygen (O). These three main components of the char were also found to be in various binding combinations with other lighter elements like nitrogen (N) and hydrogen (H) as illustrated by the attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy results. X-ray photoelectron spectroscopy (XPS) further suggest that polyethylene([(CH2–C2H2–CH2)n−]) free radicals were abundant on the char surface for the two best formulations and the binding energy of this radical promoted the formation of aromatic carbon chains that enhanced the char's thermal stability. This means that the selection of appropriate additives and combinations of flame-retardant ingredients could significantly change the morphology of the char layer and improve its thermal stability during fire exposure. Chemical engineering Materials chemistry Materials science Intumescent coating Char formation Ceria I-beam Thermal stability Ammonium polyphosphate Pyrolysis Fire retardant Dolomite XPS
  • Sanghee Jeon, Carlito Baltazar Tabelin, Hirotaka Takahashi, Ilhwan Park, Mayumi Ito, Naoki Hiroyoshi
    Hydrometallurgy 191 2020年01月01日 
    In gold (Au) hydrometallurgy, ammonium thiosulfate is the most attractive and promising alternative to conventional lixiviants like cyanide or the halides because it is non-toxic, less corrosive and has high selectivity for Au. However, its industrial-scale application for Au extraction is still severely limited because the recovery of dissolved Au from pregnant solutions remains challenging. The present study proposes a novel, simple and effective technique to address this difficulty using zero-valent aluminum (ZVAl) and activated carbon. Gold recovery was investigated by mixing 0.15 g of ZVAl and/or activated carbon and 10 ml of a solution containing 1 M Na2S2O3, 0.5 M NH3, 0.25 M (NH4)2SO4 and 10 mM CuSO4 with 100 mg/l of dissolved Au in a constant temperature water bath shaker at 25 °C for 24 h. Gold recovery from the ammonium thiosulfate solution was negligible when only ZVAl or activated carbon was added. When ZVAl and activated carbon were both present in the ammonium thiosulfate solution, however, over 99% of Au ions were successfully recovered. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) observations of the solid residues indicate that Au was predominantly deposited on activated carbon attached to ZVAl. Based on the rest potentials of these two materials, their synergistic effect on Au recovery could be attributed to the formation of numerous galvanic cells in solution where ZVAl acted as anodes (i.e., primary electron donor) while activated carbon acted as the cathode onto which Au ions are reduced via cementation to elemental Au.
  • 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]
  • C. B. Tabelin, I. Park, X. Li, S. Seng, M. Villacorte-Tabelin, T. Igarashi, M. Ito, N. Hiroyoshi
    IOP Conference Series: Earth and Environmental Science 351 1 2019年10月28日 
    Acid mine drainage (AMD) is one of the most serious environmental problems encountered in mining areas worldwide. When released into the environment without treatment, AMD pollutes the surrounding water bodies and soils with hazardous and toxic elements like arsenic (As), selenium (Se) and heavy metals such as lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) that rapidly destroy affected ecosystems. The most commonly used method to treat AMD is chemical neutralization, a technique whereby basic materials like limestone or lime are mixed with AMD to raise its pH and remove most of the contaminants via precipitation. Although effective, this approach requires the continuous supply of chemicals, energy, and manpower, which makes it unsustainable because AMD generation has been documented to continue for a very long time (up to several centuries to millennia). One promising alternative to chemical neutralization is (micro) encapsulation, a technique that directly treats pyrite, the main mineral responsible for AMD formation, and renders it unreactive by encapsulating the mineral with protective coatings. In this study, we introduced two advanced pyrite passivation techniques to limit AMD formation called "carrier-microencapsulation" (CME) and "galvanic microencapsulation" (GME). CME uses a redox-reactive organic carrier to deliver the coating material on the surface of pyrite. Because the carrier only decomposes oxidatively, the primary strength of this technique is its high selectivity for pyrite even in complex systems like mine tailings and pyrite-rich waste rocks. Meanwhile, GME is based on galvanic interactions between pyrite and metals with lower rest potentials so this technique could be applied directly in a ball mill during ore processing or coal cleaning.
  • 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]
  • Wilson Mwandira, Kazunori Nakashima, Satoru Kawasaki, Mayumi Ito, Tsutomu Sato, Toshifumi Igarashi, Meki Chirwa, Kawawa Banda, Imasiku Nyambe, Shouta Nakayama, Hokuto Nakata, Mayumi Ishizuka
    Chemosphere 228 17 - 25 2019年08月 [査読有り][通常論文]
     
    Environmental impacts resulting from historic lead and zinc mining in Kabwe, Zambia affect human health due to the dust generated from the mine waste that contains lead, a known hazardous pollutant. We employed microbially induced calcium carbonate precipitation (MICP), an alternative capping method, to prevent dust generation and reduce the mobility of contaminants. Pb-resistant Oceanobacillus profundus KBZ 1-3 and O. profundus KBZ 2-5 isolated from Kabwe were used to biocement the sand that would act as a cover to prevent dust and water infiltration. Sand biocemented by KBZ 1-3 and KBZ 2-5 had maximum unconfined compressive strength values of 3.2 MPa and 5.5 MPa, respectively. Additionally, biocemented sand exhibited reduced water permeability values of 9.6 × 10-8 m/s and 8.9 × 10-8 m/s for O. profundus KBZ 1-3 and KBZ 2-5, respectively, which could potentially limit the entrance of water and oxygen into the dump, hence reducing the leaching of heavy metals. We propose that these isolates represent an option for bioremediating contaminated waste by preventing both metallic dust from becoming airborne and rainwater from infiltrating into the waste. O. profundus KBZ 1-3 and O. profundus KBZ 2-5 isolated form Kabwe represent a novel species that has, for the first time, been applied in a bioremediation study.
  • Wilson Mwandira, Kazunori Nakashima, Satoru Kawasaki, Mayumi Ito, Tsutomu Sato, Toshifumi Igarashi, Kawawa Banda, Meki Chirwa, Imasiku Nyambe, Shouta Nakayama, Mayumi Ishizuka
    Environmental science and pollution research international 26 15 15653 - 15664 2019年05月 [査読有り][通常論文]
     
    Biocementation of hazardous waste is used in reducing the mobility of contaminants, but studies on evaluating its efficacy have not been well documented. Therefore, to evaluate the efficacy of this method, physicochemical factors affecting stabilized hazardous products of in situ microbially induced calcium carbonate precipitation (MICP) were determined. The strength and leach resistance were investigated using the bacterium Pararhodobacter sp. Pb-contaminated kiln slag (KS) and leach plant residue (LPR) collected from Kabwe, Zambia, were investigated. Biocemented KS and KS/LPR had leachate Pb concentrations below the detection limit of < 0.001 mg/L, resisted slaking, and had maximum unconfined compressive strengths of 8 MPa for KS and 4 MPa for KS/LPR. Furthermore, biocemented KS and KS/LPR exhibited lower water absorption coefficient values, which could potentially reduce the water transportation of Pb2+. The results of this study show that MICP can reduce Pb2+ mobility in mine wastes. The improved physicochemical properties of the biocemented materials, therefore, indicates that this technique is an effective tool in stabilizing hazardous mine wastes and, consequently, preventing water and soil contamination.
  • Development of suitable product recovery systems of continuous hybrid jig for plastic-plastic separation
    M. Ito, A. Saito, N. Murase, T. Phengsaart, S. Kimura, C.B. Tabelin, N. Hiroyoshi
    Minerals Engineering 2019年 [査読有り][通常論文]
  • Galvanic Microencapsulation (GME) Using Zero-Valent Aluminum and Zero-Valent Iron to Suppress Pyrite Oxidation.
    S. Seng, C.B. Tabelin, M. Kojima, N. Hiroyoshi, M. Ito
    Materials Transactions 60 277 - 286 2019年 [査読有り][通常論文]
  • A review of recent strategies for acid mine drainage prevention and mine tailings recycling.
    I. Park, C.B. Tabelin, S. Jeon, X. Li, K. Seno, M. Ito, N. Hiroyoshi
    Chemosphere 219 588 - 606 2019年 [査読有り][通常論文]
  • Suppression of pyrite oxidation by ferric-catecholate complexes: An electrochemical study
    X. Li, M. Gao, N. Hiroyoshi, C.B. Tabelin, T. Taketsugu, M. Ito
    Minerals Engineering 138 226 - 237 2019年 [査読有り][通常論文]
  • Suppressive effects of ferric-catecholate complexes on pyrite oxidation
    X. Li, N. Hiroyoshi, C.B. Tabelin, K. Naruwa, C. Harada, M. Ito
    Chemosphere 214 70 - 78 2019年 [査読有り][通常論文]
  • A physical separation scheme to improve ammonium thiosulfate leaching of gold by separation of base metals in crushed mobile phones
    S. Jeon, M. Ito, C.B. Tabelin, R. Pongsumrankul, S. Tanaka, N. Kitajima, A. Saito, I. Park, N. Hiroyoshi
    Minerals Engineering 138 168 - 177 2019年 [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]
  • 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.
  • Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes
    I. Park, C.B. Tabelin, K. Seno, S. Jeon, M. Ito, N. Hiroyoshi
    Chemosphere 205 414 - 425 2018年 [査読有り][通常論文]
  • Suppression of the release of arsenic from arsenopyrite by carrier-microencapsulation using Ti-catechol complex
    I. Park, C.B. Tabelin, K. Magaribuchi, K. Seno, M. Ito, N. Hiroyoshi
    Journal of Hazardous Materials 344 322 - 332 2018年 [査読有り][通常論文]
  • 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
    C.B. Tabelin, T. Igarashi, M. Villacorte-Tabelin, I. Park, E.M. Opiso, M. Ito, N. Hiroyoshi
    Science of The Total Environment 645 1522 - 1553 2018年 [査読有り][通常論文]
  • Interference of coexisting copper and aluminum on the ammonium thiosulfate leaching of gold from printed circuit boards of waste mobile phones
    S. Jeon, C.B. Tabelin, H. Takahashi, I. Park, M. Ito, N. Hiroyoshi
    Waste Management 81 148 - 156 2018年 [査読有り][通常論文]
  • Improvement of jig efficiency by shape separation, and a novel method to estimate the separation efficiency of metal wires in crushed electronic wastes using bending behavior and “entanglement factor”
    T. Phengsaart, M. Ito, N. Hamaya, C.B. Tabelin, N. Hiroyoshi
    Minerals Engineering 129 54 - 62 2018年 [査読有り][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.
  • Formation of schwertmannite-like and scorodite-like coatings on pyrite and its implications in acid mine drainage control. In: E. Peek, M. Buarzaiga and J. Dutrizac, Eds., Iron Control – Practice and Research, (e-book). Quebec
    C.B. Tabelin, R.D. Corpuz, S. Veerawattananun, M. Ito, N. Hiroyoshi, T. Igarashi
    Canadian Institute of Mining, Metallurgy and Petroleum 133 - 144 2016年 [査読有り][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.
  • K. P. Watanabe, Y. K. Kawai, S. M.M. Nakayama, Y. Ikenaka, H. Mizukawa, N. Takaesu, M. Ito, S. I. Ikushiro, T. Sakaki, M. Ishizuka
    Journal of Veterinary Pharmacology and Therapeutics 38 2 190 - 195 2015年04月01日 [査読有り][通常論文]
     
    Large interspecies differences in avian xenobiotic metabolism have been revealed by microsome-based studies, but specific enzyme isoforms in different bird species have not yet been compared. We have previously shown that CYP2C23 genes are the most induced CYP isoforms in chicken liver. In this study, we collected partial CYP2C23a gene sequences from eight avian species (ostrich, blue-eared pheasant, snowy owl, great-horned owl, Chilean flamingo, peregrin falcon, Humboldt penguin, and black-crowned night heron) selected to cover the whole avian lineage: Paleognathae, Galloanserae, and Neoaves. Genetic analysis showed that CYP2C23 genes of Galloanserae species (chicken and blue-eared pheasant) had unique characteristics. We found some duplicated genes (CYP2C23a and CYP2C23b) and two missing amino acid residues in Galloanserae compared to the other two lineages. The genes have lower homology than in other avian lineages, which suggests Galloanserae-specific rapid evolutionary changes. These genetic features suggested that the Galloanserae are not the most representative avian species, considering that the Neoaves comprise more than 95% of birds. Moreover, we succeeded in synthesizing an antipeptide polyclonal antibody against the region of CYP2C23 protein conserved in avians. However, comparative quantitation of CYP2C23 proteins in livers from six species showed that expression levels of these proteins differed no more than fourfold. Further study is needed to clarify the function of avian CYP2C23 proteins.
  • 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]
  • 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.
  • Sang Ho Cho, Mitsuhiro Yokota, Mayumi Ito, Satoru Kawasaki, Soo Bok Jeong, Byoung Kon Kim, Katsuhiko Kaneko
    MINERALS ENGINEERING 57 79 - 85 2014年03月 [査読有り][通常論文]
     
    Electrical disintegration is an effective liberation technique in mineral processing where the liberation ratio depends on the mineralogical properties of the mineral grains. However elucidation of the liberation behavior is difficult since the fragments after the electrical disintegration are fine and complex. This study applies electrical disintegration to cement paste samples with various dispersed mineral particles (calcite, quartz, albite, and pyrite) and the disintegrated products are observed with a micro-focus X-ray CT scanner. Current channels and crack extension behavior from the channels are identified by cross sectional CT and three dimensional reconstructed images. A classification of the crack patterns was carried out and compared with the results of liberation ratio measurements of the products. (C) 2014 Elsevier Ltd. All rights reserved.
  • 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]
  • 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.
  • 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.
  • 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, Noki Hiroyoshi, Masami Tsunekawa
    JOURNAL OF MATERIAL CYCLES AND WASTE MANAGEMENT 13 3 240 - 246 2011年10月 [査読有り][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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • M. Ito, S. Owada, T. Nishimura, T. Ota
    INTERNATIONAL JOURNAL OF MINERAL PROCESSING 92 1-2 7 - 14 2009年07月 [査読有り][通常論文]
     
    Preferential breakage, where the boundary of mineral particles and coal substances are selectively broken up, is an effective comminution method for poor liberation coals such as middling coal subjected to jig treatment. A comparison of electrical disintegration (ED) product and roll crusher product of Nantun (China) clean coal was carried out in this study. Coal particles of 4 to 8 mm diameter with specific gravities of 1.35 to 1.45 were used as the feed and the crushed product was classified into 12 fractions by size and specific gravity and analyzed for ash and mineral content using a norm calculation method. The generation ratios of light clean coal and heavy waste fractions in the ED product were higher than in the roll crusher product and this indicates that ED improved the mineral liberation. The microscopic observations supported this. The norm calculation results showed that calcite, dolomite, and pyrite were concentrated in the heavy and fine fractions, a behavior that is different from that of kaolinite. (C) 2009 Elsevier B.V. All rights reserved.
  • 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.
  • 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]
  • 伊藤 真由美
    Journal of MMIJ : journal of the Mining and Materials Processing Institute of Japan 124 12 865 - 870 社団法人 資源・素材学会 2008年12月25日 [査読無し][通常論文]
     
    The rise in demand for coal due to growth in Asia is inducing coal price increases and it will be necessary to develop cleaning method for difficult-to-treat coal. High-efficiency power generation techniques are required to reduce greenhouse gas emissions and it is necessary to reduce ash content of coal significantly before combustion. Advanced coal cleaning techniques can generate low ash coals and this paper reviews recent applications of low ash coal, recent developments in commercial scale and lab scale flotation, and research results of enhanced gravity separators and comminution.
  • 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]
  • 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.
  • 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.
  • 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.
  • 伊藤 真由美, 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 122 4/5 142 - 149 社団法人 資源・素材学会 2006年05月25日 [査読無し][通常論文]
     
    As the earth has a finite amount of resources, resource-saving is important to maintain an affluent life. In Japan various types of Recycling Laws were implemented to promote a recycling-oriented society, and packaging materials, home appliance, automobile and personal computer are collected and treated for recycling. Waste plastics are utilized for substitute for blast furnace coke or fuel and also they are recycled as plastic materials. Developing advanced separation techniques which can treat the waste plastics at low cost and get high grade plastics are required to recycle the plastics ...
  • 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...
  • 大和田 秀二, 伊藤 真由美, 楢木 健, 武田 邦義, 黒川 和成, 大宮 隆之
    資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 121 1 28 - 33 社団法人 資源・素材学会 2005年01月25日 [査読無し][通常論文]
     
    This paper describes a new liberation model considering preferential breakage at phase boundaries to make a predicted degree of liberation to be feasible. This model is a modification of the Wiegel model, which is one of the most popular and widely acceptable models, introducing an index of "Preferential Breakage Probability, e" at phase boundaries. Concept, structure, simulation results, and validation of the model were shown in this paper, including the results of applicability for various kinds of natural and synthetic composite materials. This index of "Preferential Breakage Probabili...
  • 恒川昌美, YOO Kyoungkeun, 広吉直樹, 伊藤真由美
    環境資源工学 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.
  • 伊藤 真由美, 大和田 秀二
    粉体と工業 35 5 40 - 52 粉体と工業社 2003年05月 [査読無し][通常論文]
  • 伊藤真由美, 大和田秀二
    粉体と工業 35 5 40 - 52 粉体と工業社 2003年05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, 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...
  • 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 社団法人 資源・素材学会 1999年10月25日 [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 a...
  • 恒川 昌美, 今 行忠, 伊藤 真由美, 平島 剛, 広吉 直樹
    資源と素材 : 資源・素材学会誌 : journal of the Mining and Materials Processing Institute of Japan 114 6 421 - 425 社団法人 資源・素材学会 1998年06月25日 [査読無し][通常論文]
     
    The authors have developed a new method to evaluate coal flotation behavior. The liberation degree of mineral matter in feed and the ultimate ash content of froth product can be estimated using this method. Modified release analysis and oil agglomeration tests were carried out using different feed size of coal. The results were plotted on combustible recovery vs. ash content of clean coal curves and on combustible (or mineral matter) recovery vs. yield curves. Graphic analysis of these curves is proposed to give the ultimate ash content of coal concentrate obtained under ideal conditions an...
  • 広吉 直樹, 伊藤 真由美, 恒川 昌美, 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 112 3 171 - 175 資源・素材学会 1996年03月25日 [査読無し][通常論文]
  • 広吉 直樹, NAKAMURA Takeshi, TSUNEKAWA Masami, HIRAJIMA Tsuyoshi, ITO Mayumi
    シゲン ト ソザイ 111 13 943 - 948 資源・素材学会 1995年 [査読有り][通常論文]

MISC

書籍等出版物

  • プラスチックのケミカルリサイクル技術
    監修 吉岡敏明 (担当:分担執筆範囲:第III編 湿式法 ＜選別＞ 比重選別および浮遊選別)
    シーエムシー出版 2021年09月
  • バリューチェーンと単位操作から見たリサイクル
    化学工学会, 環境部会リサイクル分科会著 (担当:分担執筆範囲:第2章技術編 2.1.2物理選別)
    三恵社 2020年12月
  • 海底鉱物資源の産業利用
    伊藤 真由美 (担当:分担執筆範囲:96-112)
    シーエムシー出版，東京 2013年

所属学協会

  • 日本エネルギー学会   廃棄物資源循環学会   環境資源工学会   資源・素材学会   

共同研究・競争的資金等の研究課題

  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2023年04月 -2026年03月 
    代表者 : 中山 翔太, 伊藤 真由美, 山崎 淳平, 江口 哲史, 内田 義崇
  • 銅精鉱の安定供給に向けた難処理銅鉱石のカスタマイズ処理条件を提示するプロトコ ールの策定
    (独）石油天然ガス・金属鉱物資源機構：金属資源の生産技術に関する基礎研究
    研究期間 : 2022年06月 -2023年03月 
    代表者 : 伊藤真由美, パク イルファン
  • 銅亜鉛分離浮選における亜鉛鉱物抑制機構の解明のための基礎研究」/閃亜鉛鉱の浮遊性に及ぼす各種因子の影響把握と，閃亜鉛鉱と銅鉱物の浮選速度差の増大のための手法の開発
    (独）石油天然ガス・金属鉱物資源機構：金属資源の生産技術に関する基礎研究
    研究期間 : 2021年06月 -2022年03月 
    代表者 : 伊藤真由美, パク イルファン
  • ザンビア鉱山地区における鉛汚染環境および鉛中毒対策としてのリスクベースアプローチの実践と効果検証
    JST：Axis
    研究期間 : 2020年04月 -2022年03月 
    代表者 : 研究代表者, 石塚真由美
  • ザンビアにおける鉛汚染のメカニズムの解明と健康・経済リスク評価手法および予防・修復技術の開発
    JICA-JST：SATREPS
    研究期間 : 2015年06月 -2022年03月 
    代表者 : 研究代表者, 石塚真由美
  • 銅亜鉛分離浮選における亜鉛鉱物抑制機構の解明のための基礎研究」/閃亜鉛鉱の浮遊性に及ぼす各種因子の影響把握と，閃亜鉛鉱と銅鉱物の浮選速度差の増大のための手法の開発
    (独）石油天然ガス・金属鉱物資源機構：金属資源の生産技術に関する基礎研究
    研究期間 : 2020年06月 -2021年03月 
    代表者 : 伊藤真由美
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2017年04月 -2020年03月 
    代表者 : 廣吉 直樹, 伊藤 真由美, タベリン カーリット
     
    酸性鉱山廃水の発生原因となる黄鉄鉱の酸化溶解を防止する新しい技術として、金属イオン錯体を用いて鉱物表面に保護被膜を生成するキャリアマイクロエンカプセレーションについて研究した。鉱山の操業現場で入手・利用しやすいAlやFeイオンのカテコール錯体を用いた新規の手法を電気化学実験や表面分析などにより検討し、保護被膜の生成と黄鉄鉱酸化抑制の効果を確かめた。2種類の金属イオン（TiとFeイオン）のカテコール錯体を共存させると、どちらか一方の錯体を用いた場合よりも耐酸性に優れた被膜が生成した。この被膜は鉱物表面を被覆して溶存酸素の還元反応の速度を低下させ、黄鉄鉱の酸化溶解を抑制した。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2011年04月 -2014年03月 
    代表者 : 廣吉 直樹, 伊藤 真由美, 福嶋 正巳
     
    マグネタイトを用いて金・白金などの貴金属を一般金属イオンが共存する浸出液から選択的に抽出・回収する方法を開発した。酸化還元電位が高い貴金属はマグネタイトから電子を受け取って還元・析出するが、酸化還元電位の低い銅などの一般金属はマグネタイト上に析出しない。表面に貴金属が析出したマグネタイトは，鉱石やスクラップなどの浸出残滓の懸濁液から磁力選別で分離・回収できる。銅製錬スラグの粉砕物から磁力選別で回収した磁着物（スラグマグネタイト）も貴金属の回収に利用できることを確かめた。
  • 文部科学省：科学研究費補助金(基盤研究(A))
    研究期間 : 2010年 -2012年 
    代表者 : 金子 勝比古, 川崎 了, 坂口 清敏, 広吉 直樹, 伊藤 真由美, 原田 周作
     
    岩石の亀裂自己修復機能に関する基礎的検討を実施し,以下の成果を得た。(1)岩石のサブクリティカル亀裂進展特性,特に超低速領域における亀裂進展速度と応力拡大係数との関係を計測するための実験装置を設計・試作するとともにその較正試験を実施した。開発した装置は,ダブルトーション型高剛性載荷装置,荷重・変位制御装置,供試体恒温槽とこれらを格納する環境制御チェンバー及び防振台から構成され,1ヶ月程度の実験期間で超低速領域の亀裂進展挙動計測が実現できる。(2)亀裂を有する岩質材料試料を水中浸漬させて鉱物析出による亀裂充填挙動を計測するとともにその定量評価のための3次元画像処理法を開発した。特に,窒素雰囲気で人工海水及び模擬降水系地下水中に一定時間浸漬した供試体について,マイクロフォーカスX線CT装置による3次元微視構造の観察を行い,亀裂開口部のみに炭酸カルシウムが析出することを確認するとともにその充填速度と分布を明らかにした。(3)自然界における岩石の自己修復機能を調査するために,原位置において,携行型蛍光X線成分分析計によりビーチロック表面の元素分析を行い,表面析出鉱物の組成分析を実施した。(4)3次元亀裂進展解析法の開発のために,デローニー分割により巨視的不連続面を含む3次元有限要素モデルを作成するプログラムコードを開発した。
  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 2011年 -2011年 
    代表者 : 伊藤 真由美
     
    我が国は少ないエネルギーで資源を最大限に活用する循環型社会へと移行しており，廃製品から効率よく有価物を取り出す技術の開発は重要である。我々はこれまでに石炭処理で広く使われている比重選別機（TACUBジグ）をプラスチックのような比較的低比重の粒子選別用に改良し，さらに似た様な比重の粒子も分けられる装置としてハイブリッドジグを開発した。この装置では送気により粒子に気泡を付着させてみかけ比重差を作り出し，選別を行う。そのためには高度な気泡付着の制御が必要であり，粒子側の濡れ性の制御および，気泡径の高度な制御について研究した。また，浮遊している粒子の回収システムの開発も行った。
  • 文部科学省：科学研究費補助金(若手研究(B))
    研究期間 : 2008年 -2010年 
    代表者 : 伊藤 真由美
     
    深海底鉱石であるコバルトリッチクラスト・ノジュールは未開発の資源であり,今後の開発が期待されている。本研究では,海底基盤岩からのクラスト部分の物理選別について検討した。破砕産物についての粒度別の単体分離度測定を行い,さらに選別の難しい細粒部分の物理選別試験を行った。試験はRETACジグおよびアドバンスドジグを用いて行われ,コバルトリッチクラスト・ノジュールについての選鉱処理フローの提案を行った。
  • 文部科学省：科学研究費補助金(基盤研究(B))
    研究期間 : 2008年 -2010年 
    代表者 : 廣吉 直樹, 恒川 昌美, 伊藤 真由美, 五十嵐 敏文, 福嶋 正巳
     
    多量の黄鉄鉱を含む低品位石炭を燃焼させると黄鉄鉱から酸性雨の原因となる亜硫酸ガスが発生するので、燃焼前に石炭から黄鉄鉱を効率よく分離除去する技術を開発することが課題になっている。しかし,石炭から分離して堆積場に捨てられた黄鉄鉱が風化すると重金属を含んだ酸性汚濁水が生じるので,その発生を抑制する技術を開発することも必要である。本研究では,これら2つの課題を同時に解決することを目的として,石炭中の黄鉄鉱の表面を選択的に親水/抗酸化性の薄膜で被覆した後に,石炭から浮選分離する新しい方法を提案し,モデル実験によりメカニズムと効果,最適施工条件などを明らかにした。
  • 文部科学省：科学研究費補助金(挑戦的萌芽研究)
    研究期間 : 2009年 -2009年 
    代表者 : 恒川 昌美, 廣吉 直樹, 伊藤 真由美
     
    研究代表者および分担者らの研究室で開発した網下気室型湿式比重選別機(TACUB JIG)をベースにして,より選別効率の高い比重選別機の開発に取り組み,以下に述べる3タイプの新しい比重選別機を開発した。1)TACUB JIGのフィード部および産物回収部に改良を加え,さらに制御法を工夫して,廃棄物の資源化・リサイクルに適した比重選別機(RETAC JIG)を開発し,種々のプラスチックを素材別に選別することを可能にした。2)このRETAC JIGをベースにして,比重差が無くても濡れ性に差があれば比重選別できるHybrid JIGを開発した。この選別機では,気泡を導入して,より疎水性の粒子表面に微細気泡を選択的に付着させることで,その見かけ比重を小さくして,物質間に見かけ比重差を生じさせて,比重分離する。このJIGにより,比重の同じプラスチックの相互選別が可能になった。3)水より軽い物質相互を分離するため,RETAC JIGの選別槽上部に天網を設置し,この天網の下にフィードして上下に脈動を与えることで,天網下部に比重別に産物を成層させて選別できるREVERSE JIGを開発した。4)上述の新たに開発した3タイプの比重選別機をあわせてAdvanced JIGと総称し,本Advanced JIGを組み合わせることで廃家電リサイクルプラントから排出されるプラスチックを素材別に選別して,マテ...
  • 文部科学省：科学研究費補助金(基盤研究(A))
    研究期間 : 2007年 -2009年 
    代表者 : 金子 勝比古, 高橋 弘, 五十嵐 敏文, 佐藤 努, 村田 澄彦, 川崎 了, 伊藤 真由美
     
    マイクロ・リストラクチャリングの要素技術とその工学的応用に関する一連の研究を実施した。特に,微視構造の人為的改変による物性改良法として,環境制御により微視亀裂進展を抑制させて強度を改善する方法,微生物代謝を利用して炭酸カルシウムやシリカを析出させて間隙を充填する方法,還元環境操作により地下水中から炭酸カルシウム等の鉱物を析出させて亀裂を閉塞させる方法など,工学的目的に応じた複数の手法を開発した。
  • 文部科学省：科学研究費補助金(若手研究(B))
    研究期間 : 2005年 -2007年 
    代表者 : 伊藤 真由美
     
    現在,日本で行われている重金属汚染土の物理洗浄法(物理選別)は,欧米方式をそのまま採用しているが,この方法では重金属微粒子と土微粒子の物理選別ができないため,微粒群は全量,最終処分対象となり,微粒土の割合が欧米に比べて高い日本では,最終処分する微粒土が多量に発生するという問題が生じている。そこで本研究では,限られた形態の重金属しか除去できなかった既存の処理法に化学的前処理を融合させ,重金属の存在形態の転換を図ることで各種形態の重金属の物理選別を可能にする土壌処理プロセスを考案し,検討している。具体的には1)環境中で容易に分解する錯体を用いて重金属を可溶化し,2)可溶化した重金属を媒体表面にセメンテーションの原理を利用して選択濃縮し,3)この重金属が濃縮した媒体を物理選別で精度よく分離・除去する方法の開発を目的としている。本年度は最終年度である。初年度は「模擬試料を用いた各工程の個別試験」を行い,2年度は「実汚染土壌を用いた処理試験」を行なった。最終年度(本年度)は,実汚染土壌の処理に際しての処理条件の最適化および処理を阻害する因子の検討を行い,考案した処理手法の有用性を確かめることができた。以上のように,おおよそ研究実施計画通りに研究を順調に進めることができた。
  • 文部科学省：科学研究費補助金(基盤研究(B))
    研究期間 : 2005年 -2007年 
    代表者 : 廣吉 直樹, 恒川 昌美, 米田 哲朗, 伊藤 真由美
     
    近年、斑岩銅鉱床の低品位鉱から銅を生産するためにヒープリーチング(露天掘り採掘した鉱石を野積みし、この上部から硫酸溶液を散布して銅分をイオンの形で溶出させ、溶媒抽出-電解採取などにより高純度の金属銅を生産する方法)が広く用いられるようになってきている。しかし、ヒープリーチングの対象は鉱床浅部に存在する酸化銅鉱や2次硫化銅鉱に限られ、鉱床深部の主要銅鉱物である黄銅鉱(CuFeS_2)は浸出速度が遅いので対象とできなかった。鉱床浅部の酸化銅鉱や2次硫化銅鉱はいずれ枯渇するので、黄銅鉱に適したヒープリーチング技術を開発することは重要である。黄銅鉱は酸化反応で浸出されるので,従来は高い浸出速度を得るためには酸化的雰囲気(高い酸化還元電位)を保つべきだと考えられてきた。しかし,我々は過度に高い電位では黄銅鉱表面が不働態化して浸出速度が低下することをこれまでの基礎研究で明らかにしてきた。この知見に基づき,本研究では,酸化還元電位を制御することで黄銅鉱の浸出を高速化することを目指した。平成17年度は,フラスコ浸出実験と電気化学実験により黄銅鉱浸出速度の電位依存性を調べ,浸出の最適電位がCu^<2+>、Fe^<2+>濃度の関数となることを明らかにした.平成18年度は,カラム浸出実験を実施し,鉱石堆積層の上部から散布する溶液のpHと電位の制御で黄銅鉱の浸出を促進できることを確かめた.平成19年...
  • 文部科学省：科学研究費補助金(萌芽研究)
    研究期間 : 2005年 -2007年 
    代表者 : 恒川 昌美, 柳 庚槿, 廣吉 直樹, 伊藤 真由美, 米田 哲朗, 吉田 豊
     
    循環型社会を構築していくうえで鍵を握るのは,都市域における廃棄物の資源化・リサイクル技術および環境保全技術の開発である。我々は,廃自動車や廃家電・OA機器類の資源化技術を開発してきている。この開発過程で,現状の処理プロセスでは解砕・破砕が主として減容化を目的に行われているため,その後の有価物選別・回収の段階で低い選別精度,回収率にとどまること,解砕・破砕時に発生するシュレッダーダストの軽比重物(例えばウレタンなど)に絡み込んでいる有価物が十分に回収できないことを見出した。そこで種々の有機・無機複合廃棄物を効率的に資源化・リサイクルする立場から,解砕・破砕,選別を合理的に行うための要素技術の開発研究に取り組んだ。最終年度にあたる19年度は,下記のような検討を行い,有用な知見を得た。1)二つの使用済み自動車のシュレーダーダストを対象に,破砕後に種々の風力分級をして,産物について化学分析,灰分測定,組成解析などを行った。その結果,サーマルリサイクルに適した,ウレタンなどの可燃分からなる産物を回収できるプロセスの条件を明らかにした。2)ウレタン類に鉄・銅・アルミニウムなどの金属類,繊維などが絡まっている場合は,ある種の界面活性剤溶液に浸漬することで,有価金属類を分離回収できることを見出した。3)17〜19年度の成果を踏まえ,各種有機・無機複合廃棄物に対する適切な破砕・解砕法と有価物回...
  • 文部科学省：科学研究費補助金(基盤研究(A))
    研究期間 : 2004年 -2007年 
    代表者 : 恒川 昌美, 廣吉 直樹, 伊藤 真由美, 米田 哲朗, 名和 豊春, 平島 剛
     
    都市域の廃棄物資源化拠点としてのアーバンマインについて検討し,その構築に不可欠な要素技術を開発するとともに,これらの成果を活用した自律分散型のアーバンマインとそれらを緩やかにリンクさせたシステム(ホロニック・パス)について考察し提言した。主な成果は,以下のようである。1) 廃棄物中の有価物を資源化・リサイクルするのに適した湿式比重選別機として網下気室型比重選別機 (RETAC Jig) を開発し,本機を用いて次のような実証試験を行い,その有用性を確認した。a) 廃コンクリートからの骨材,モルタル分の回収・リサイクル b) 廃蛍光管からの各種ガラスの回収・リサイクル c) 鉛汚染土壌中の鉛粒子の回収 d) 使用済自動車や廃家電のリサイクル工場で発生するシュレッダーダスト中の有価物回収2) また本機をベースに,固体粒子の比重と表面濡れ性の差を利用して,比重差が無くても選別できるHybrid Jigを世界で初めて開発した。さらに,水より軽い物質の選別が可能なReverse Jigも開発した。3) Ni-水素電池から正極物質,負極物質を効率よく分離・回収するプロセスを開発した。4) 重金属汚染土壌からの重金属回収,汚染防止のための技術として,microencapsulation法およびleaching,cementation, magnetic separationからなるハイブリッ...
  • 文部科学省：科学研究費補助金(基盤研究(B))
    研究期間 : 2005年 -2006年 
    代表者 : 田中 信壽, 松藤 敏彦, 東條 安匡, 恒川 昌美, 広吉 直樹, 伊藤 真由美, 角田 芳忠
     
    比較的低温の熱処理技術である炭化処理に注目し,16種類の様々な都市廃棄物と産廃廃棄物の炭化物を製造し、廃棄物およびその処理により得られた炭化物の物理・化学的な組成、発熱量などを分析し,質向上の方法について検討した。まず炭化物の燃料利用の際に装置腐食などの問題を起こす塩素に注目し、水溶性の程度によって形態を分類・定量した。炭化物中塩素の大部分は水溶性であり、水洗による塩素除去効果は高い。一方、セメントキルン用燃料としては揮発性塩素0.1%が目標となっており、水洗により0.16%,炭酸化処理により0.11%程度となり、ほぼ満足出来ることが分かった。炭化物中の灰分除去方法として重液選別、および石炭の灰分除去技術である浮選、液中造粒を適用し、合わせて灰分の存在形態について考察した。炭化物の発熱量(質)と可燃分回収率にはトレードオフ関係が見られ,都市ごみ炭化物の場合浮選あるいは液中造粒によって発熱量20000kJ/kg及び灰分30%以下の目標値を満足はできるが,可燃分の回収率は20%まで低下した。カーシュレッダー炭化物については、基準値を満足させることが不可能であった。炭化物中の灰分は可燃分と結合しており,粉砕等を行っても分離は困難である。最後に,炭化処理を廃棄物の埋立前処理として検討するため、嫌気性埋立、好気性埋立を各々模擬したカラム実験を行った。炭化物からの有機物溶出は原廃棄物と比...
  • 文部科学省：科学研究費補助金(萌芽研究)
    研究期間 : 2005年 -2006年 
    代表者 : 廣吉 直樹, 恒川 昌美, 伊藤 真由美
     
    本研究では,鉱山酸性汚濁水の発生を防止する新しい方法としてキャリアマイクロエンカプセレーション(Carrier Micro Encapsulation, CME)を提案する.本法では,地殻中に存在するTiO_2などの鉱物中のTiを有機キャリアで水に可溶化して,汚染源となる黄鉄鉱FeS_2などの表面に吸着させた後,キャリアを分解して化学的に安定なTiO_2薄膜で汚染源を被覆し,水や空気から遮蔽する.昨年度の結果に基づき,Tiとの錯体形成能力や酸化分解性に優れたカテコール(1,2-dihydroxybenzene, C_6H_4(OH)_2)をキャリアとして選択し,黄鉄鉱粉末(粒子径53〜75μm)の溶解に対するCMEの効果を振盪フラスコ法によるモデル実験で調べた.実験は天然Ti鉱物の代替物として試薬アナターゼ(TiO_2)5kg/Lを用いて,黄鉄鉱-溶液比0.6kg/L,温度25℃,大気下で行った。CMEを施した実験(カテコールとTiO_2を添加した実験)では,黄鉄鉱表面にTiO_2あるいはTi(OH)_2の被膜が形成され、対照実験(カテコールとTiO_2の双方あるいは一方を添加しなかった実験)に比べて黄鉄鉱の溶解量(硫酸とFeの溶出量)が少なくなり,pHの低下が緩和された.黄鉄鉱溶解に対するCMEの抑制作用は,カテコール添加濃度0.01kmol m^<-3>以上,pH4〜7の...

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