Effectiveness of bioleaching of low grade Indian chalcopyrite ore using pure and mixed culture of mesophiles

In this research, efforts were made to examine bioleaching behaviour of copper from a low grade Indian copper ore (0.3% Cu) containing chalcopyrite as the major mineral phase using enriched culture of Acidithiobacillus ferrooxidans and a mixed culture (4:1 ratio) containing Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The experiments were carried out in shake flasks with the inocula of bacteria obtained from source mine water of Malanjkhand Copper Project (MCP) after adaptation on the ore. Results showed that metal extraction employing a mixed culture of Acidithiobacillus ferrooxidans (At.f) and Acidithiobacillus thiooxidans (At.t) was higher of 88% copper than that of 75% copper dissolution with a bacterial culture viz. At.f at 2.0 pH, 35oC temperature using <50µm size particles. The selection of the pH and effective particle size during the bioleaching process were found to influence metal dissolution. The paper also highlights the mechanism of bioleaching, the role of iron and its precipitation as jarosite, and the correlation of redox potential with copper recovery.