Bacterial solubilisation of copper from a low grade sulphide mineral

Abstract

The bio-dissolution of copper from a low grade ore containing chalcopyrite ore (0.3%Cu)from Malanjkhand Copper Mines, India was investigated using adapted pure species of Acidithiobacillus ferrooxidans (A.ferrooxidans) and also in association with Acidithiobacillus thiooxidans (A.thiooxidans) as consortia. Bench scale experiments for bioleaching of copper were carried out to investigate the effect of different parameters such as pulp density (PD), pH, particle size and temperature in presence of 10% (v/v) inoculum of A.ferrooxidans and a consortium (4:1 ratio) of A.ferrooxidans and A.thiooxidans. A maximum copper recovery of 75.3% was obtained in 35 days with the adapted A.ferrooxidans at 2.0 pH, 35oC temperature using <50μm size particles as compared to the copper recovery of 88% when a mixed culture of A.ferrooxidans and A.thiooxidans was employed. The paper highlights the mechanism of bioleaching with the single species (A.ferrooxidans) and the consortia, while correlating redox potential and iron level in solution with copper recovery.