A review of environmentally friendly gold lixiviants: Fundamentals, applications, and commonalities

Gold is mainly extracted by cyanidation; however, cyanide is not only highly toxic to organisms but is also not a very effective lixiviant for refractory gold ores. Environmentally friendly leaching agents for gold include thiosulfate, thiourea, polysulfide, lime sulfur, halogens and their compounds, and alkaline amino acids. This review elaborates on the structure, fundamentals, applications, and existing problems of environmentally friendly gold lixiviants. Moreover, it summarises the common characteristics of chemical reagents with gold leaching performance and discusses the conditions that should be satisfied for the molecular design of gold lixiviants. The review concludes with an outlook on the emerging trends and challenges in this exciting field.