Biological Leaching

Biological leaching, or bio-oxidation, was pioneered in copper mining and has been adapted for gold.

It is a low temperature, aqueous method of treating refractory sulphide ore through pre-treatment with bacterial cultures. The bacteria catalyse the oxidation of the ore. The activity is stimulated within process tanks known as bio-reactors, in which temperature, oxygen and nutrients create the right conditions for the micro-organisms to flourish. Only naturally occurring strains of bacteria are currently used but in the future, genetically engineered bacteria may be developed. One of the most recent projects is Newmont Mining's bio-leach facility at its Carlin operations in Nevada, USA.

     Looking at the top of a bioleach plant.                                  Looking into Bioleach facility.

             An example of bioleaching on copper.