Bacteria biooxidation is an oxidation process caused by microbes where the valuable metal remains (but becomes enriched) in the solid phase.
The BIOX® process involves bacterial oxidation in agitated tanks for pre-treatment of refractory ores and concentrates ahead of conventional cyanide leach for gold recovery.
Under controlled continuous plant conditions, the number of bacterial cells and their activity is optimised to attain the highest rate of sulfide oxidation.
The bacteria require a very acidic environment (pH 1.0 to 4.0), a temperature of between 30 and 45 °C, and a steady supply of oxygen and carbon dioxide for optimum growth and activity.
The unusual operating conditions for the bacteria are not favourable for the growth of most other microbes, thus eliminating the need for sterility during the bacterial oxidation process.