有菌和無菌體系下輝銅礦氧化電化學

廖勃; 溫建康; 武彪; 尚鶴; 陳勃偉

doi:10.13374/j.issn2095-9389.2018.12.007

有菌和無菌體系下輝銅礦氧化電化學

doi: 10.13374/j.issn2095-9389.2018.12.007

北京有色金屬研究總院生物冶金國家工程實驗室, 北京 100088

基金項目:

國家自然科學基金資助項目（51574036）

詳細信息

中圖分類號: TF803.21
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出版歷程
- 收稿日期: 2017-12-27

Electrochemistry of oxidation of chalcocite in the presence and absence of microorganisms

National Engineering Laboratory of Biohydrometallurgy, General Research Institute for Nonferrous Metals, Beijing 100088, China

摘要

摘要: 運用循環伏安曲線、穩態極化曲線和Tafel曲線等電化學手段以及X射線光電能譜（XPS）法研究了輝銅礦在有菌和無菌體系下氧化過程的電化學行為.研究結果驗證了輝銅礦在有菌體系和無菌體系下的兩步氧化溶解機理，第一步氧化反應為輝銅礦不斷氧化生成缺銅的中間產物Cu_xS（1≤x<2），直至生成CuS，在較低電位下即可進行；第二步反應為中間產物CuS的氧化，需要在較高電位下才可進行，反應速率較慢，是整個氧化反應的限制性步驟.循環伏安實驗顯示有菌體系電流密度明顯大于無菌體系，表明細菌加快了輝銅礦的氧化速率.穩態極化實驗顯示輝銅礦點蝕電位較低，無菌體系第一段反應活化區電位范圍小于有菌體系，表明輝銅礦氧化過程生成的中間產物硫膜具有鈍化效應，細菌可以通過自身氧化作用破壞硫膜，減弱輝銅礦表面的鈍化效果，加快輝銅礦的氧化溶解速率.X射線光電子能譜分析顯示電極表面鈍化層物質組成復雜，包含了CuS、多硫化物（S_n^2-）、（S⁰）和含（SO₄^2-）的氧化中間產物等多種物質，其中主要的鈍化物為CuS，表明輝銅礦的氧化遵循多硫化物途徑.
- 輝銅礦 /
- 電化學 /
- 生物浸出 /
- 鈍化 /
- 多硫代物
Abstract: The electrochemical behavior of the chalcocite oxidation process in the presence and absence of microorganisms was investigated using electrochemical techniques, including cyclic voltammetry, anodic polarization curves, Tafel curves, and X-ray photoelectron spectroscopy (XPS) analysis. The research results prove the stepwise dissolution mechanism of chalcocite in the presence and absence of microorganisms. The initial stage of oxidation is initiated at low redox potentials. During the initial stage, the intermediate products of Cu_xS (1 ≤ x < 2) are successively oxidized until CuS is formed. The later stage is the oxidation of the intermediate product CuS and this period requires initiation at high redox potentials owing to the formation of a passivation layer on the electrode surface, and the reaction rate of the later stage is extremely slow; in this case, it is the rate-limiting step of the whole reaction. The cyclic voltammograms show that the electric current density in the presence of microorganisms is higher than that in the absence of microorganisms, indicating that the microorganisms accelerates the dissolution rate of chalcocite. The anodic polarization curves show that the pitting potential of chalcocite is low; the potential range of the first active corrosion zone in the presence of microorganisms is much wider than that in the absence of microorganisms, indicating that the intermediate products of the sulfur film are passivating, and their effects could be reduced by the oxidation of microorganisms; in this manner, the dissolution rate of chalcocite is promoted. To identify the components of the passivation layer during the process of chalcocite dissolution in the presence and absence of microorganisms, the electrodes were detected via XPS. The XPS analysis results show that the components of the passivation layer on the electrode surface are complex, including CuS, polysulfide (S_n^2-), elemental sulfur (S⁰) and intermediate oxidation products that contain sulfate (SO₄^2-) and that CuS is the main passivating component; therefore, the oxidation of chalcocite follows the multisulfur method.
- chalcocite /
- electrochemistry /
- bioleaching /
- passivation /
- polysulfide

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