【公開日：2025.06.10】【最終更新日：2025.04.22】
課題データ / Project Data
課題番号 / Project Issue Number
24KU1009
利用課題名 / Title
Selective depression of copper-activated pyrite by oxalic acid: Implications for enhanced chalcopyrite–pyrite separation
利用した実施機関 / Support Institute
九州大学 / Kyushu Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）物質・材料合成プロセス/Molecule & Material Synthesis（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials（副 / Sub）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials
キーワード / Keywords
PyriteCopper activationChalcopyriteOxalic acidSelective flotation
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
SUYANTARA Gde Pandhe Wisnu
所属名 / Affiliation
九州大学大学院地球資源システム工学部門資源処理・環境修復工学研究室
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
KIM CHAERIN
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）,技術補助/Technical Assistance
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
The selective separation of pyrite (FeS2) and chalcopyrite (CuFeS2) in flotation processes poses significant challenges due to the activation of the pyrite surfaces by copper ions dissolved from associated copper sulfide minerals. This study proposes oxalic acid as an environment-friendly reagent to inhibit the copper-induced activation of pyrite. Chalcopyrite was used as a model mineral to evaluate the selectivity of oxalic acid treatment. The flotation experiments demonstrated that oxalic acid reduced the flotation recovery of copper-activated pyrite from 58 % to 16 % at pH 9 while exerting no discernible effect on chalcopyrite flotation. Further tests using artificial mixtures of chalcopyrite and pyrite confirmed the ability of oxalic acid to selectively separate chalcopyrite from copper-activated pyrite under mildly alkaline conditions, improving the separation efficiency from 30 % to 78 % with the addition of 15 kg/t (0.55 mM) oxalic acid at pH 9. The mechanism underlying this selectivity was investigated using infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The results revealed that oxalic acid reacts with copper ions to form copper oxalate, which effectively prevents copper deposition on the pyrite surface. This reaction inhibits pyrite activation and suppresses the adsorption of xanthate collectors. These findings highlight the potential of oxalic acid as a sustainable reagent for enhancing the selectivity and efficiency of chalcopyrite–pyrite separation in flotation processes.
実験 / Experimental
Flotation tests were conducted to assess the capacity of pure and mixed chalcopyrite and pyrite to float under different treatment conditions. A pure mineral suspension was prepared by combining 0.6 g of mineral with 180 mL of ultrapure water. A mixed mineral suspension was prepared by combining 0.3 g of chalcopyrite and 0.3 g of pyrite in 180 mL of ultrapure water. The mineral suspensions were then treated with 1 kg/t (0.021 mM) copper sulfate to replicate Cu-activated pyrite flotation. To evaluate the effect of oxalic acid on inhibiting Cu-activated pyrite flotation, varying amounts of oxalic acid (0–15 kg/t or 0–0.55 mM) were added prior to the addition of copper sulfate.
Surface analysis was conducted using IR and XPS to examine the impact of oxalic acid on the adsorption of potassium amyl xanthate and the chemical composition of the mineral surface.
結果と考察 / Results and Discussion
This study investigated the potential of oxalic acid as an environment-friendly reagent to suppress the flotation of Cu-activated pyrite while enabling the selective separation of chalcopyrite from Cu-activated pyrite. Flotation tests conducted with both pure samples and binary mixtures of chalcopyrite and pyrite revealed that oxalic acid effectively inhibited the flotation of Cu-activated pyrite without compromising the flotation of chalcopyrite. Specifically, the flotation recovery of Cu-activated pyrite decreased significantly from 62.6 % to 16.5 % following treatment with 0.55 mM oxalic acid at pH 9. Consequently, the separation efficiency between chalcopyrite and pyrite reached an impressive 77.8 %.Surface analysis further elucidated that this selective separation arises from the interaction between oxalic acid and Cu2+, forming copper oxalate. This interaction prevents the formation of Cu species on the pyrite surface, removing Cu species from the surface and thereby inhibiting its activation. As a result, amyl xanthate ions are unable to adsorb onto the pyrite surface, substantially reducing its flotation capability. Furthermore, copper oxalate reacts with amyl xanthate, decreasing the amount of amyl xanthate available for adsorption onto the pyrite surface. Conversely, amyl xanthate ions readily form chemical bonds with Cu atoms within the chalcopyrite crystal structure, enabling their adsorption on the chalcopyrite surface. These findings underscore the effectiveness of oxalic acid treatment as a sustainable method for selectively separating chalcopyrite from Cu-activated pyrite under slightly alkaline conditions.
図・表・数式 / Figures, Tables and Equations
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
This work received funding from the Japan Society for the Promotion of Science (JSPS) via Grants-in-Aid for Science Research (JSPS KAKENHI) (grant numbers: JP22K14636 and JP22H00310). The X-ray photoelectron spectroscopy study was funded by the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the “Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)” initiative (proposal number: JPMXP1224KU1009).
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
-
Gde Pandhe Wisnu Suyantara, Selective depression of copper-activated pyrite by oxalic acid: Implications for enhanced chalcopyrite–pyrite separation, Powder Technology, 454, 120681(2025).
DOI: https://doi.org/10.1016/j.powtec.2025.120681
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件