Biomining in reverse gear: Using bacteria to extract metals from oxidised ores

• Extraction of metals from oxidised ores.
• Bio-reductive mineral dissolution.
• Recovery of nickel and copper from lateritic ores.

Biomining, as traditionally practised, uses aerobic, acidophilic microorganisms to accelerate the oxidative dissolution of sulfide minerals present in ores and concentrates, thereby either causing target metals to be solubilised (e.g. copper) or made accessible to chemical extraction (e.g. gold). Many acidophiles are also able to catalyse the dissimilatory reduction of ferric iron in anoxic or oxygen-depleted environments, and can accelerate the reductive dissolution of ferric iron minerals, such as goethite, under such conditions. Recent work has demonstrated how this approach can be used to extract metals (nickel, copper, cobalt and manganese) from oxidised ores, such as laterites deposits, at low (∼30 °C) temperatures. Reductive mineral dissolution has been trialled successfully with a variety of ores, pointing to a generic application of this approach.