Electrochemical Oxidation Mechanism of Gold in Copper(Ⅱ)-ethylenediamine-thiosulfate Gold Leaching System
Thiosulfate is considered to be the most promising gold extraction reagent 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).Characterization of surface oxidation products of gold electrodes using 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,and under the electrochemical conditions in this paper,the reaction rate is controlled by the step of charge transfer when the gold electrode is in the 5 mmol/L Cu2+-10 mmol/L en-100 mmol/L S2O32-system.The thiosulfate concentration in the system controls the dissolution of gold by affecting its surface properties and surface reaction rate.The electrochemical oxidation mechanism of gold electrodes in the Cu2+-en-S2O32-leaching gold system was this paper elucidated,and a theoretical basis was provided for the regulation of the composition of gold leaching reagents.
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