Bioleaching of chalcopyrite by a moderately thermophilic culture at different conditions and community dynamics of planktonic and attached populations

A moderately thermophilic culture was used to bioleach chalcopyrite. It showed a good performance in copper extraction. In order to further improve efficiency of chalcopyrite bioleaching, effects of pH control and redox potential (ORP) control on chalcopyrite dissolution were investigated. The community dynamics of planktonic and attached populations were also monitored during bioleaching of chalcopyrite at different conditions. The copper extraction was improved by controlling pH or ORP, especially in the final stage of the bioleaching. The maximal growth rate of microorganisms was up to 0.94 generations/day when the pH was controlled in the range of 1.40-1.85. The ORP controlled at 420 +/- 20 mV caused a reduced jarosite formation. Community dynamics analyses show that the pH control and the ORP control had significant effects on community dynamics of planktonic and attached moderate thermophiles. The species contained in the culture showed different succession trends compared with each other, not only in the leachate but also on the mineral surfaces. The pH control was not favorable for the attachment of microorganisms. It can also be found that succession of attached cells is significantly different from the community dynamics for their planktonic counterparts. (C) 2014 Elsevier B.V. All rights reserved.