The nontoxicity, low cost, and environmental friendliness of the Cu2+–NH3–S2O32− gold leaching system make it a viable alternative to cyanide-based systems. However, the strong influence of certain sulphide minerals (e.g., pyrite) on the performance of the former system complicates its compositional regulation. Herein, the mechanism of electrochemical pyrite oxidation in the Cu2+–NH3–S2O32− system is probed by electrochemical techniques combined with surface analysis techniques. The results indicate that the anodic oxidation of pyrite can be assigned to active, passive, or transpassive regions, depending on the applied potential, with high potentials accelerating the reactions on the pyrite surface. Thiosulphate concentration is shown to influence the surface properties and the rate of surface reactions of pyrite. AFM images indicated that the morphological changes on the pyrite electrode surface became much rougher with increasing potential. Moreover, Raman spectroscopy and XPS provided strong evidence for the analysis of the surface species of pyrite surface oxidation. Our work will further explain and provide a mechanism for the oxidation of pyrite in the Cu2+–NH3–S2O32− system. More importantly, this study is expected to be able to provide a theoretical basis for guiding the regulation and control of gold leaching reagent in the Cu2+–NH3–S2O32− system.

中文翻译：

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对铜 （II）-氨-硫代硫酸盐金浸出系统中黄铁矿氧化机制的新见解：电化学、AFM、拉曼光谱和 XPS 研究


Cu2+–NH3–S2O32− 金浸出体系的无毒、低成本和环境友好性使其成为氰化物体系的可行替代品。然而，某些硫化物矿物（例如黄铁矿）对前一种系统性能的强烈影响使其成分调节复杂化。在此，通过电化学技术结合表面分析技术探测了 Cu2+-NH3-S2O32− 系统中电化学黄铁矿氧化的机理。结果表明，黄铁矿的阳极氧化可以分为主动、被动或跨被动区域，具体取决于施加的电位，高电位会加速黄铁矿表面的反应。硫代硫酸盐浓度会影响黄铁矿的表面性质和表面反应速率。AFM 图像表明，随着电位的增加，黄铁矿电极表面的形态变化变得更加粗糙。此外，拉曼光谱和 XPS 为黄铁矿表面氧化表面种类的分析提供了有力的证据。我们的工作将进一步解释并提供 Cu2+–NH3–S2O32− 系统中黄铁矿氧化的机制。更重要的是，本研究有望为指导 Cu2+–NH3–S2O32− 系统中金浸出试剂的调控提供理论依据。