Prospects for thiourea as a leaching agent in Colombian gold small-scale mining: a comprehensive review

Thiourea, as an alternative medium, is one of the most promising leaching agents for gold recovery by its commercial benefits and research challenges associated with performance and environmental impacts. This review article describes the operational conditions for the use of Thiourea vs cyanide, its chemistry, limitations, toxicity factors, environment, and recovery processes. Although thiourea gold extraction processes have not been applied on a large scale due to the instability of the reagent, its potential to overcome the limitations of cyanide is attractive to the process; with pH, potential, oxidant dosage, and temperature control, solubilized gold thiourea species are achieved. These can be recovered from the pregnant leach solution through methods such as activated carbon absorption and adsorption, polyurethane foams, ion exchange, and electrodeposition.