The role of microorganisms in gold processing and recovery—A review

• Gold grades in mineral resources have been projected to decline.
• Applications for extracting gold from low grade ores are of increasing interest.
• Microorganisms contribute to biogeochemical cycling of gold.
• Biooxidation, biolixiviants and permeability enhancement may improve gold recovery.
• Microorganisms may also decrease gold solubility through various mechanisms.

With a projected steady decline of gold ore grade in mineral resources, mining applications enabling efficient metal extraction from low-grade ores are of increasing interest to the minerals industry. Microbial processes may provide one such solution since they can participate in the biogeochemical cycling of gold in many direct and indirect ways. This review examines current literature on the role of microorganisms in gold processing and recovery. The review covers aspects such as the biotechnical pre-treatment of gold ores and concentrates, microbially catalysed permeability enhancement of ore bodies, gold solubilisation through biooxidation and complexation with biogenic lixiviants, and microbially mediated gold recovery and loss from leach liquors.