康金星, 冯雅丽, 李浩然, 杜竹玮, 邓祥意, 王洪君. Acidithiobacillus ferrooxidans对软锰矿浸出的影响[J]. 工程科学学报, 2019, 41(5): 591-599. DOI: 10.13374/j.issn2095-9389.2019.05.005
引用本文: 康金星, 冯雅丽, 李浩然, 杜竹玮, 邓祥意, 王洪君. Acidithiobacillus ferrooxidans对软锰矿浸出的影响[J]. 工程科学学报, 2019, 41(5): 591-599. DOI: 10.13374/j.issn2095-9389.2019.05.005
KANG Jin-xing, FENG Ya-li, LI Hao-ran, DU Zhu-wei, DENG Xiang-yi, WANG Hong-jun. Effect of Acidithiobacillus ferrooxidans on pyrolusite bioleaching[J]. Chinese Journal of Engineering, 2019, 41(5): 591-599. DOI: 10.13374/j.issn2095-9389.2019.05.005
Citation: KANG Jin-xing, FENG Ya-li, LI Hao-ran, DU Zhu-wei, DENG Xiang-yi, WANG Hong-jun. Effect of Acidithiobacillus ferrooxidans on pyrolusite bioleaching[J]. Chinese Journal of Engineering, 2019, 41(5): 591-599. DOI: 10.13374/j.issn2095-9389.2019.05.005

Acidithiobacillus ferrooxidans对软锰矿浸出的影响

Effect of Acidithiobacillus ferrooxidans on pyrolusite bioleaching

  • 摘要: 利用循环伏安、交流阻抗谱和极化曲线研究了Acidithiobacillus ferrooxidans对软锰矿在模拟浸出溶液(9K基础培养基, A.ferrooxidans, Fe (Ⅲ), A.ferrooxidans+Fe (Ⅲ))中电化学腐蚀行为的影响; 利用模拟有菌/无菌浸出溶液中钝化膜的Mott-Schottky理论比较了有无细菌存在情况下形成的钝化膜的优劣性.结果表明, A.ferrooxidans促进MnO2/Mn2+氧化还原转化, 催化MnO2/Mn (OH)2电极反应; 加速软锰矿/溶液界面电子交换, 无铁存在时A.ferrooxidans使电荷转移内阻降低34%, 比含Fe (Ⅲ)无菌体系低11%;引起软锰矿电极极化, 增强其氧化活性; 加速MnO2向MnO·OH转化及其产物扩散.A.ferrooxidans与软锰矿作用更倾向于间接作用机理.在选取的各模拟电解液(pH值为2.0)中, 0.2~0.4 V区间内软锰矿形成耗尽层, 在模拟浸出溶液中形成的钝化膜都表现出p-n-p-n型半导体性能.在选取的0.2 V极化电位下, 无铁时引入A.ferrooxidans使膜中的施主/受主密度减少, 细菌含有多种基团参与半导体/溶液界面电子转移反应, 接受界面间自由电子或填充空穴, 促使软锰矿与溶液界面物质交换变频繁; 含铁溶液中加入A.ferrooxidans使得钝化膜受主/施主密度增大, A.ferrooxidans降低了膜的耐腐蚀性, 因而促进软锰矿浸出.

     

    Abstract: Biohydrometallurgy is an increasingly popular ore extraction technology and is especially applicable for low-grade ores. In particular, Acidithiobacillus ferrooxidans (A. ferrooxidans) is by far the most widely used bioleaching microorganism for leaching ores, including for sulfide ores and manganese dioxide ores. At present, many works are focused on the vital facilitating role of A. ferrooxidans in the cycles of sulfur and iron for sulfide ores bioleaching. However, research on the effect of A. ferrooxidans on manganese dioxide ores leaching is limited. The effects of A. ferrooxidans on the electrochemistry behavior of pyrolusite in simulated solutions (9K basic medium, A. ferrooxidans, Fe(Ⅲ), A. ferrooxidans+Fe(Ⅲ)) were investigated using cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. Mott-Schottky curves were utilized to determine the passive film formed on the surface of pyrolusite ore in the presence or absence of bacteria bath solutions. The results show that A. ferrooxidans promotes the redox of MnO2/Mn2+ and triggers the reaction of MnO2/Mn(OH)2. A. ferrooxidans accelerates electron exchange between pyrolusite and solution; in the A. ferrooxidans-simulated solution, the charge-transfer reaction resistance of manganese dioxide is 34% lower than that of the control (9K) and 11% lower than that of the Fe(Ⅲ) solution. Germs cause polarization of pyrolusite, leading to an increase in oxidative activity of manganese dioxide. Bacteria facilitate the transformation of MnO2 to MnO·OH and is beneficial to its diffusion. The indirect action mechanism is adopted to explain the interaction between A. ferrooxidans and pyrolusite. The passive films formed in simulated solutions exhibit p-n-p-n type semiconductor properties at the polarization potential of 0.2 V when pH is 2.0, and the depletion layer of pyrolusite appears between 0.2 and 0.4 V. Introducing A.ferrooxidans to the Fe(Ⅲ)-free solution decreases the donor density and the acceptor density because bacteria contain a variety of groups involved in electron transfer, which accept free electrons or fill holes, prompting the exchange of species between manganese oxide and solution. Admixing A. ferrooxidans to Fe(Ⅲ)-containing solution increases carrier density, reducing the corrosion resistance of membrane. The corrosion rate of pyrolusite increases with the addition of A. ferrooxidans.

     

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