ABSTRACT

This study investigated the electrochemical oxidation behaviors of arsenopyrite in sulfuric acid (pH 1) containing various concentrations of ferric ions by cyclic voltammetry, Tafel polarization curves and electrochemical impedance spectra (EIS) measurements. Results indicated that the addition of ferric ions did not affect the electrochemical dissolution mechanism of arsenopyrite. With the increase of the ferric concentration, the corrosion potential of arsenopyrite shifted positively, and the corrosion current density increased. EIS tests showed that arsenopyrite oxidation consisted of two charge transfer processes, i.e., the release of iron and arsenic from arsenopyrite lattice and the oxidation of elemental sulfur formed on the arsenopyrite surface. The overall oxidation of arsenopyrite was controlled by the oxidation of elemental sulfur. The presence of ferric ions decreased the electron transfer resistances of both processes, contributing to the accelerated dissolution of arsenopyrite. Cyclic voltammetry and Tafel plots implied that the enhanced cathodic reaction was the dominant reason for the improved dissolution of arsenopyrite in the presence of ferric ions.

摘要

本研究通过循环伏安法、塔菲尔极化曲线和电化学阻抗谱 (EIS) 测量研究了毒砂在含有不同浓度铁离子的硫酸 (pH 1) 中的电化学氧化行为。结果表明，铁离子的添加​​不影响毒砂的电化学溶解机理。随着铁浓度的增加，毒砂的腐蚀电位正移，腐蚀电流密度增大。EIS 测试表明，毒砂氧化包括两个电荷转移过程，即从毒砂晶格中释放出铁和砷以及氧化毒砂表面形成的元素硫。毒砂的整体氧化由元素硫的氧化控制。铁离子的存在降低了这两个过程的电子转移阻力，有助于加速毒砂的溶解。循环伏安法和塔菲尔图表明，增强的阴极反应是提高毒砂在铁离子存在下溶解的主要原因。