Investigation of some heavy metals toxicity for indigenous Acidithiobacillus ferrooxidans isolated from Sarcheshmeh copper mine

Introduction and objective: Today mining operations in the metallurgy generate secondary products which cannot be used directly in the basic technology. The mineral industry is increasingly faced with the need to process low grade ores and waste from current mining operations. Heap bioleaching of low grade sulfide is a developing technology that has been applied to the extraction of metal from secondary sulfide minerals. The microorganisms used in the bioleaching of the low grade sulfide ores are mostly different strains of Thiobacillus. The resistance of indigenous Acidithiobacillus ferrooxidans to metals such Cd⁺², Co⁺² and Zn⁺² was investigated in the process of bioleaching tailing and low grade ore.

Materials and methods: Iron-sulfur oxidizing bacterium, At. ferrooxidans, has been isolated from pregnant leaching solution (PLS) of the Sarcheshmeh copper mine. At. Ferrooxidans was isolated, then it’s resistance to some heavy metals was investigated with shaking flasks at 150rpm and 30°C.

Results: The results indicated indigenous At. ferrooxidans tolerated high levels of Zn²⁺ about 30 (g/L) concentration, but it had less tolerance to Cd²⁺ and Co²⁺ (10g/L Cd²⁺ and 110ppm Co²⁺).

Conclusion: This experiment demonstrated that Zn⁺² toxicity is less than Cd⁺² and Co⁺² for isolated At. ferrooxidans. For this reason, isolated At. ferrooxidans can be used for bioleaching of tailing with high amount of zinc and waste with relative amount of cadmium.

Significance and impact of the study: Using of isolated At. ferrooxidans in bioleaching of low grade sulfide ore which can tolerate presence of other heavy metals in mineral concentrate.