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The leaching behavior of gold from an oxide gold ore using copper–tartrate–thiosulfate solutions has been investigated. Experimental parameters, including temperature, initial pH, and concentrations of copper tartrate and thiosulfate, were systematically studied. The capability of gold leaching using copper–tartrate–thiosulfate solutions is comparable to that of cyanidation, as well as the traditional copper–ammonia–thiosulfate leaching system at elevated temperatures. The kinetics are much faster than that of gold cyanidation, and thiosulfate consumption was greatly reduced in the presence of the tartrate. A considerable gold extraction of 90.42% was obtained under the optimized conditions of 0.1 mol/L CuSO4, 0.2 mol/L Na2L, 0.3 mol/L Na2S2O3, pH 11.0, and 75°C after 16 h of leaching. The process of gold dissolution in copper–tartrate–thiosulfate solutions may be controlled by product layer diffusion under the experimental conditions with an apparent activation energy of 35.474 kJ/mol. Increasing the temperature and the concentration of copper and thiosulfate while decreasing the content of tartrate can accelerate the rate of gold leaching. The system is quite unstable when the solution pH is less than 7.0, causing a noticeably lower content of the thiosulfate and copper–tartrate complex. At an initial pH of 9.0 or higher, however, faster kinetics can be achieved. [ABSTRACT FROM AUTHOR]

The leaching behaviors of gold and silver from a complex sulfide concentrate in copper-tartrate-thiosulfate solutions were investigated in this paper. Experimental parameters, including temperature, initial pulp pH, and concentration of copper, tartrate, and thiosulfate, were systematically studied. The copper-tartrate-thiosulfate leaching system exhibits promising performance in dealing with the complex sulfide concentrate. Thiosulfate consumption could be greatly reduced due to the in-situ generation of thiosulfate derived from sulfur or disulfide ions. Increasing the temperature and concentrations of copper, tartrate, and thiosulfate can promote gold leaching. A low tartrate content and a moderate increase in temperature and copper and thiosulfate concentrations can accelerate silver leaching, but a higher temperature or copper content may depress silver extraction. A suitable pulp pH is critical for gold and silver leaching in copper-tartrate-thiosulfate solutions. An extraction of 74.50% Au and 36.33% Ag was obtained with the direct leaching of the concentrate, while the percentages can be significantly increased up to 82.60% and 70.38%, respectively, when leaching the calcine following the oxidative roasting pretreatment. The recycling of leaching solutions demonstrates that a suitable free tartrate content is of great significance in maintaining the stability of the novel system. As an alternative to the traditional cyanide or copper-ammonia-thiosulfate leaching processes, the copper-tartrate-thiosulfate leaching system provides an environmentally friendly, nontoxic, and relatively low-cost method for gold and silver leaching from ores or concentrates. [ABSTRACT FROM AUTHOR]