运用循环伏安、稳态极化扫描和交流阻抗等电化学测试方法,研究黄铁矿在氧化亚铁硫杆菌浸矿体系和无菌酸性体系下的电化学氧化机理.结果表明,在无菌和A.ferrooxidans菌存在的条件下,黄铁矿的氧化反应分为两步:第一步是黄铁矿氧化生成元素S；第二步是元素S被氧化生成SO2-4.加入A.ferrooxidans后黄铁矿的氧化机理没有发生改变,但是氧化速度加快.随着黄铁矿与A.ferrooxidans作用时间的延长,极化电流密度增加,黄铁矿表面钝化膜溶解的点蚀电位降低.在细菌存在的条件下,电极的阻抗值下降,表明微生物的存在加速了黄铁矿电极的腐蚀作用,有利于黄铁矿的氧化溶解.
The electrochemical oxidation behavior of pyrite in bioleaching system ofAcidthiobacillusferrooxidans was investigated by cyclic voltammetry (CV),polarization curve and electrochemical impedance spectroscopy (EIS).The results show that in the presence or absence ofA.ferrooxidans,the oxidation reaction of pyrite is divided into two steps:the first reaction step involves the oxidation of pyrite to S,and the second reaction step is the oxidation of S to SO42-.The oxidation mechanism of pyrite is not changed in the presence of A.ferrooxidans,but the oxidation rate of pyrite is accelerated.With the extension of reaction time of A.ferrooxidan with pyrite,the polarization current density of pyrite increases and the breakdown potential at which the passive film dissolves decreases.The impedance in the presence of A.ferrooxidans is obviously lower than that in the absence ofA.ferrooxidans,further indicating that microorganism accelerates the corrosion process of pyrite.
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