The bioleaching of nickel-copper sulfides

Demand for nickel, largely driven by the Chinese stainless steel market, currently exceeds production, causing an unprecedented rise in the price of nickel and renewed interest in bioleaching technology for the processing of low grade nickel sulfide ores and concentrates. Although nickel inhibits bacterial physiological functions such as iron- and sulfur-oxidation, some bacteria adapt readily to high concentrations. In pilot‐scale continuous reactors, mixed microbial populations grew actively over many months in the presence of up to 400 mM nickel (23 g/L). The results of bench-scale test work have been sufficiently encouraging to prompt pilot- and demonstration-scale trials in heaps and agitated tanks in Australia, China, Finland and South Africa in recent years. The first commercial implementation of nickel sulfide heap leaching is likely to be the operation at Talvivaara, Finland.