Leaching of Gold and Silver from a Complex Sulfide Concentrate in Copper-Tartrate-Thiosulfate Solutions

Abstract

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.

Effect of Thiosulfate Concentration and Leaching Temperature in Ammoniacal Thiosulfate Leaching of Refractory Sulfide Gold Ore

“…Temperature has a significant effect on the leaching process, namely on chemically controlled reactions. Similar findings were reported by other researchers regarding the effect of temperature [21]- [24] (Altinkaya et al, 2020;Chen et al, 2022;. This conforms to the activation energy equation commonly known as the Arrhenius equation [17].…”

Sustainable Recovery of Platinum Group Metals from Spent Automotive Three-Way Catalysts through a Biogenic Thiosulfate-Copper-Ammonia System

“…In the study conducted by Chen et al [16], the impact of copper concentration on gold and silver extraction within thiosulfate solutions is explored. Notably, gold extraction exhibits a remarkable upsurge from 24 to 66% for gold and from 2 to 26% for silver with a modest increment in copper concentration (0.01 to 0.1 M).…”

“…These complexes promote PGM dissolution, leading to improved extraction rates. However, high copper concentrations can lead to the formation of excessive copper-thiosulfate complexes, which can compete with metal-thiosulfate complexes for available thiosulfate ions, reducing the efficiency of metal leaching [16,44,50,51].…”

“…Hence, ongoing efforts focus on the development of more eco-friendly and efficient methods for PGM recovery from TWCs, such as the use of green solvents [7,16]. Thiosulfate is a chemical compound that has been used in the recovery of precious metals and PGMs from various sources [16][17][18].…”

“…Hence, ongoing efforts focus on the development of more eco-friendly and efficient methods for PGM recovery from TWCs, such as the use of green solvents [7,16]. Thiosulfate is a chemical compound that has been used in the recovery of precious metals and PGMs from various sources [16][17][18]. This anionic complexing agent forms stable complexes with metals, allowing them to be solubilized from ore or other sources, primarily through the coordination of sulfur atoms to the metal ions [19].…”