金在铜(Ⅱ)-乙二胺-硫代硫酸盐浸金体系的电化学氧化机理研究

硫代硫酸盐因无毒、高效等优点被认为是浸金工艺中最具应用前景的提金技术。本文采用电化学测试方法(开路电位、循环伏安、Tafel曲线及电化学阻抗)探究了金电极在Cu2+-en-S2O32-浸金体系中电化学行为，并利用拉曼光谱和XPS对金电极的表面氧化产物进行鉴定，阐明金在Cu2+-en-S2O32-体系中的氧化机理。实验结果表明：S2O32-能够促进金表面氧化，当金电极在5 mM Cu2+-10 mM en-100 mM S2O32-体系时，反应速率由电荷转移这一步骤控制。体系中硫代硫酸盐浓度通过影响其表面性质和表面反应速率来控制金的溶解情况。因此，阐明金电极在Cu2+-en-S2O32-浸金体系中电化学氧化机理，并为金浸出试剂成分的调控提供了理论依据。

Study on Electrochemical Oxidation Mechanism of Gold in Copper(Ⅱ)-ethylenediamine-thiosulfate Gold Leaching System

The thiosulfate is considered to be the most promising gold extraction technology in gold leaching process due to its advantages of non-toxicity and high efficiency. The electrochemical behavior of gold electrode in Cu2+- en - S2O32 - gold leaching system was investigated by electrochemical testing methods (open circuit potential, cyclic voltammetry, Tafel curve and electrochemical impedance). The surface oxidation products of gold electrode were identified by Raman spectroscopy and XPS, and the oxidation mechanism of gold was clarified. The experimental results show that: S2O32- can promote the oxidation of the gold surface, when the gold electrode is in 5 mM Cu2+-10 mM en-100 mM S2O32-, the effect is the best, and the reaction rate is controlled by the charge transfer step. The thiosulfate concentration in the system controls the dissolution of gold by affecting its surface properties and surface reaction rate. Therefore, the electrochemical oxidation mechanism of gold electrodes in the Cu2+-en-S2O32- leaching gold system was elucidated, and a theoretical basis was provided for the regulation of the composition of gold leaching reagents.