A Review of Ammoniacal Thiosulfate Leaching of Gold: An Update Useful for Further Research in Non-cyanide Gold Lixiviants

ABSTRACT

This literature review provides an update of ammoniacal thiosulfate as a potential lixiviant of gold, the history of thiosulfate leaching and recent progress on thiosulfate leaching of gold, as well as the production, oxidation, and stabilization of thiosulfate. The leaching results of different types of gold ores including oxide, sulfide, carbonaceous, and refractory ores/concentrates and the fundamentals relevant to the oxidation of pure gold are summarized. The factors affecting gold leaching such as pH, temperature, and oxidants in leaching solutions, reagent concentrations, and foreign ions are presented to update the current understanding on gold dissolution in a Cu(II)-NH₃-S₂O₃^2-system.

KEYWORDS:

• Ammonia
• copper(II)
• gold
• leaching
• thiosulfate