Process Oriented Characterization in Bioleaching Co-Cu Minerals

This chapter presents the results from mesophilic bioleaching of high purity carrollite interpreted in view of the various interaction patterns between the microorganisms and the mineral substrate. The results outline the role which bacteria play in bringing cobalt and copper in solution. During the early bioleach stages, up to day 10, a pronounced attachment of the microorganisms on the mineral surface takes place which facilitates leaching reactions. SEM observations show evidence of contact bacteria-substrate which provokes release of ferrous ions in solution and formation of biofilm, the ferrous ions being subsequently oxidized by the “planktonic” bacteria. Two types of “fixed” bacteria are investigated: transiently-bound (reversibly detachable) and strongly-bound. The results suggest that when the mineral is in intimate contact with bacteria (“fixed” case) an enhanced oxidation takes place, in contrast to when bacteria are met in solution only (“planktonic” case).