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記述言語：英語   出版者・発行元：公益社団法人 日本金属学会  

This study investigated the effects of potassium amyl xanthate (KAX) and oxidation treatment using hydrogen peroxide (H2O2) on the selective flotation of copper concentrates containing arsenic-bearing copper minerals. The mineralogical analysis revealed that enargite and chalcopyrite were the main arsenic-bearing copper and copper sulfide minerals, respectively, in the copper concentrate. KAX treatment at pH 9 improved the recoveries of copper sulfide and arsenic-bearing copper minerals. However, arsenic-bearing copper minerals floated more rapidly than copper sulfide minerals, indicating better separation selectivity. The separation selectivity of the KAX treatment was significantly improved at pH 10. H2O2 treatment was found to selectively improve the recovery of arsenic-bearing copper minerals. A combination treatment using 0.1M H2O2 and 60 g/t of KAX at pH 9 enhanced the separation selectivity in the selective flotation of copper sulfide and arsenic-bearing copper minerals by producing a copper concentrate with the lowest arsenic grade and highest copper grade in tailings compared to those obtained from separated KAX and H2O2 treatments.

DOI： 10.2320/matertrans.m-m2023811

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記述言語：その他   掲載種別：研究論文（学術雑誌）   出版者・発行元：Powder Technology  

Molybdenite is associated with primary and secondary copper sulfide minerals. Few studies have focused on the selective flotation of molybdenite to separate it from secondary copper sulfide minerals, such as chalcocite. This study evaluated the use of oxidation treatment to separate molybdenite from chalcocite. The effects of oxidation treatment with hydrogen peroxide (H2O2) on the flotation behaviors of molybdenite and chalcocite in the presence of collectors (i.e., potassium amyl xanthate and diesel oil) were evaluated, and the impacts of H2O2 concentration, oxidation treatment duration, and pH level were assessed. Chalcocite flotation tests showed that the H2O2 treatment significantly reduced the recovery of chalcocite due to the formation of copper hydroxide and sulfate species on the chalcocite surface, which altered its surface hydrophobicity. On the other hand, the low surface oxidation of molybdenite led to high flotation recovery after the oxidation treatment. Oxidation treatment with a 10 mM H2O2 solution at a pH of 9 for 20 min resulted in a separation efficiency of 87%, with 98% molybdenite recovery and 11% chalcocite recovery. The results show that H2O2 oxidation treatment enables the selective flotation of molybdenite to separate it from chalcocite.

DOI： 10.1016/j.powtec.2023.119078

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記述言語：その他   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Powder Technology  

The main challenge for the selective flotation of copper and molybdenum (Cu-Mo) sulfide minerals in seawater is the formation of colloidal precipitates in strongly alkaline conditions. These precipitates hinder the selective separation of copper from molybdenum minerals in seawater by lowering the floatability of Cu-Mo sulfide minerals. The present study aimed to examine the direct utilization of seawater in the selective flotation of Cu-Mo sulfides. Additionally, the effectiveness of sodium metabisulfite (Na2S2O5) as a copper depressant for selective flotation of Cu-Mo sulfides in seawater was studied under weakly acidic, neutral, and moderately alkaline conditions. A complex Cu-Mo concentrate that largely consisted of chalcopyrite and molybdenite, as well as a tiny amount of pyrite and quartz, was used in the flotation tests. The flotation results revealed that treatment with 3.6 kg/t Na2S2O5 in seawater at pH 5.5 significantly lowered the copper recovery from 97% to 11% and caused a modest reduction in the molybdenum recovery from 98% to 94% with a Cu-Mo separation efficiency of 83%. These flotation results demonstrate that Na2S2O5 treatment in seawater selectively depresses the floatability of copper minerals. Consequently, molybdenum can be separated from copper minerals under a weakly acidic condition in seawater. In addition, this study discusses the effects of various pH conditions and dosages of Na2S2O5. The surface properties of Cu-Mo minerals were studied using X-ray photoelectron and infrared spectroscopies, and a mechanism to explain the selective flotation of Cu-Mo using Na2S2O5 treatment in seawater is proposed.

DOI： 10.1016/j.apt.2023.104258

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記述言語：その他   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Environmental Chemical Engineering  

Chalcopyrite flotation is selectively depressed by oxidation treatment. The presence of ferric oxyhydroxide on the surface of chalcopyrite after oxidation treatment is a key factor in depressing chalcopyrite flotation. However, there is no concrete evidence that ferric oxyhydroxide has a depressing effect. In addition, the effectiveness of this depressing effect could be enhanced by directly applying ferric oxyhydroxide nanoparticles. This study investigated the effect of goethite (α-FeOOH) nanoparticles on the surface properties and flotation behavior of chalcopyrite. α-FeOOH nanoparticles were produced through chemical precipitation followed by hydrothermal treatment. The crystalline structure of irregular rice grain-shaped α-FeOOH nanoparticles was confirmed by the X-ray diffraction pattern and scanning electron microscope image. Micro-flotation experiments showed that chalcopyrite recovery decreased significantly from 93 % to 13 % when 30 mg/L α-FeOOH nanoparticles was used. This flotation result demonstrated the potential of α-FeOOH nanoparticles as a nanodepressant for the flotation of chalcopyrite. These nanoparticles physically adsorbed on the chalcopyrite surface and rendered its surface hydrophilic, thereby reducing the chalcopyrite flotation recovery. The attractive electrostatic force between the positively charged α-FeOOH nanoparticles and the negatively charged chalcopyrite surface is likely responsible for the adsorption of α-FeOOH nanoparticles on chalcopyrite.

DOI： 10.1016/j.jece.2023.110006

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記述言語：その他   掲載種別：研究論文（学術雑誌）   出版者・発行元：International Journal of Mining Science and Technology  

Enargite is typically associated with chalcocite. Owing to the similarity in the flotation behaviors of these minerals, both minerals are reported to concentrate in the conventional flotation circuit. However, inorganic arsenic in enargite can decrease the copper concentrate quality and increase the operating cost of processing this concentrate. Separating these minerals is important for cleaner copper production to avoid these effects. In this context, this study investigated the effect of hydrogen peroxide (H2O2) treatment on the flotation behavior of chalcocite and enargite. Flotation tests of pure and mixed minerals indicated that H2O2 treatment reduced the floatability of chalcocite and enargite by forming sulfate and copper hydroxide on their surfaces. Despite the detrimental effect of the H2O2 treatment, there was a narrow window of H2O2 concentration for separating both minerals, in which enargite floated and chalcocite was depressed. This selective flotation behavior was caused by the rapid adsorption of potassium amyl xanthate (KAX) and lower surface oxidation of enargite compared with that of chalcocite.

DOI： 10.1016/j.ijmst.2023.01.002

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種別：大会・シンポジウム等 

種別：審査・学術的助言 

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種別：大会・シンポジウム等 

種別：大会・シンポジウム等 

種別：大会・シンポジウム等