生物发电浸出中黄铁矿阳极的交流阻抗

Anodic Oxidation of Pyrite in Bio-electro-generative Simultaneous Leaching by Alternating Current Impedance Technique

文章采用双电池体系研究了生物发电浸出过程中黄铁矿阳极电极电位随时间的变化,并用电化学三电极体系研究了黄铁矿碳糊电极体系在氧化亚铁硫杆菌(A.f菌)中的界面过程,建立了黄铁矿生物发电浸出过程的模拟等效电路,通过交流阻抗分析软件对黄铁矿电极在不同电极电位下交流阻抗Nyquist图进行了拟合和分析。研究结果表明:反应初期黄铁矿阳极电极电势迅速增加,反应6小时后,阳极电极电势在0.6V附近趋于平稳;电极电势从0.4V增加到0.7V,A.f菌在黄铁矿表面都能氧化单质硫;电极电势为0.4V和0.5V时,微生物作用还不显著,黄铁矿浸出过程由电化学极化和浓差极化混合控制;电极电势为0.6V和0.7V时,黄铁矿浸出主要由生物电化学极化反应控制。

A dual cell system was used to study the relationships between the anodic pyrite potential and time for Bio-electro-generative simultaneous leaching （BEGL）. A three-electrode system was adopted to study the interface dynamic behaviors of pyrite carbon paste electrodes in the presence of Acidithiobacillus ferrooxidans （A. ferrooxidans ）. An equivalent circuit of the BEGL process was postulated based on the reactions of pyrite bio-electro-generative leaching. The alternating current impedance analysis software Z - View2 was used to fit and analysis Nyquist diagrams of pyrite anode under different initial electric potential. The results show that the anodic potential increases rapidly early in BEGL process, and reaches stable value about 0.6V （ vs. SCE） after 6hs. According to fit - result by Z - View2, the accumulated sulfur on the surface of ores could be oxidized by oxygen in promotion of A. ferrooxidans as the electric potential increased from 0.4V to 0.7V （ vs. SCE）. The oxidization of sulfur is insignificant under electric potential 0.4 and 0.5V （vs. SCE） when the BEGL process of pyrite is controlled by electrochemistry and diffusion simultaneously. As the electrode potential increases to 0.6 and 0.7V （ vs. SCE）, the BEGL process is controlled by electrochemistry.