Thiosulfate leaching of gold: An review on novel catalytic systems

Eco-friendly thiosulfate is a promising alternative to the high-toxic cyanide for gold extraction with copper− ammonia catalytic system being the most popular. However, the copper−ammonia catalysis causes the issues of high thiosulfate consumption, complex gold recovery process and ammonia pollution. An effective strategy to tackle these issues is to improve or replace the copper−ammonia system with a novel catalytic system (NCS). Various NCSs are classified and their current status and future prospectives are reviewed. The critical constituent factors of NCSs are summarized. The noteworthy developing trends of potential NCSs are also discussed. Furthermore, besides resin adsorption, other recovery methods such as solvent extraction deserve more attention to achieve selective gold recovery. Crucial insights into developing suitable NCSs to solve the existing challenges in the current thiosulfate leaching technology once and for all are offered, thus promoting its large-scale industrial application.