Copper Recovery from Chalcopyrite Concentrate by an Indigenous Acidithiobacillus ferrooxidans in an Air-Lift Bioreactor

In this study, effects of solid concentration, temperature, and initial Fe2+ concentration on bioleaching of sulfide mineral (chalcopyrite) obtained from Sarcheshmeh Copper Mine in the region of Kerman located in the south of Iran were investigated. A mesophilic iron oxidizing bacterium, Acidithiobacillus ferrooxidans has been isolated from a typical chalcopyrite copper concentrate of the mentioned mine. Bioleaching experiments were carried out in two batch air-lift bioreactors with recycling stream. One reactor contained 2 liters of medium and 10% (v/v) inoculum while in the other reactor, control bioleaching tests were carried out with sterilized concentrate without inoculum by the addition of 40 ml of 0.5% (v/v) formaline in ethanol. The results indicate that the efficiency of copper extraction is dependent on all of the aforementioned variables. In addition, results show that the effects of solid concentration and temperature had more effect compared to the initial Fe2+ concentration. Maximum copper recovery was achieved 70% at pH=1.5, initial Fe2+ concentration=7g/L and pulp density = 10% (w/v) in bioreactor, after 10 days.