Bioleaching of a Smelter Copper Dust in a Continuous Series of Airlift Reactors

Bioleaching of the copper flue dust emitted from the smelters at Sarcheshmeh Copper Complex has been studied. At the present, the dust is recycled to the smelters which reduces their efficiencies and increases the required energy for smelting. In this study, as an alternative process, bioleaching of the copper dust was investigated in a continuous series of two-stage airlift bioreactors each with a working volume of 6.2 liter. The effects of pulp densities, retention times and temperatures on bioleach performance of the copper dust were evaluated. Lower pulp densities resulted in a stable redox potential in both reactors. However, increasing the pulp density to 7%, created an unstable redox potential in the first bioreactor especially at lower temperatures. Overall copper extractions calculated for pulp densities of 2%, 4%, and 7%, were 90.1%, 89%, and 86.1% with retention times of 2.7, 4 and 5 days, respectively. The results showed that the process is net acid consuming. The high copper extractions showed that the process of treating copper dust using mesophile bacteria has the potential for further development and assessment for commercial applications.

Keywords:

Airlift , bacteria , bioleaching , bioreactor , copper flue dust