Leaching of Gold with Copper–Tartrate–Thiosulfate Solutions

As the most promising alternative reagent to cyanide, thiosulfate has received renewed interest. However, the traditional copper–ammonia–thiosulfate system may face critical challenges in terms of process sustainability because ammonia is toxic and unstable. The use of tartrate as an alternative reagent to ammonia offers a green and eco-friendly choice for gold extraction. In this work, the effect of temperature, pH, copper, tartrate, and thiosulfate concentrations on the leaching kinetics of pure gold disc was examined. The results show that thiosulfate is the only effective complexing agent with aurous ions, while tartrate works as a copper ligand. The process of gold dissolution in copper–tartrate–thiosulfate solutions can be divided into two stages under the experimental conditions. Both stages are controlled by chemical reactions. The reaction orders of gold dissolution with respect to copper, tartrate, and thiosulfate concentrations were 0.523, − 0.572, 0.659 and 0.218, − 0.942, 1.072 in the first and second stages, respectively.