A Review of the Biooxidation Process and Neutralization of Wastewater for Gold Refractory Ores

Bioleaching and bio-oxidation caused from activations of acidophilic are used to extract metals from low-grade, and refractory ores. Although these terms are often used interchangeably, there are distinct technical differences between these two technologies. Bioleaching refers to the conversion of an insoluble metal into a soluble. Whereas in the bio-oxidation, the valuable metal such as gold remains in the solid phase. Using this process, gold existent in pyrite and arsenopyrite networks is released and can be suitable for cyanidation process. Nowadays bio-oxidation method has attracted particular attention in the mining industry because of its technical, economic and environmental advantages, and is the most suitable technology for pre-treatment of refractory gold. Hence, this paper was focused to review the biooxidation process of refractory gold ores. The results indicate that the microorganisms used in biooxidation process have the role of catalyst and conversion of ferrous ion to ferric and sulfur into sulfate. Also, bacteria used are mainly mesophilic.