Bioleaching of Covellite Concentrate and Process Enhancement

The influential factors of bioleaching of covellite concentrate collected from Zijinshan copper ore in Fujian Province with bacteria were investigated. As a result, the optimal influential parameters of bioleaching process were determined, which are concentration of inoculum 100%, pulp density less than 5%, and initial Fe2+ concentration 4.0 g/L. Within 20 d, the copper recovery rate reached 60%. In order to enhance the redox potential (Eh) level in the bioleaching process, several efforts such as the additions of Fe3+, pyrite and hydrogen peroxide were attempted in the experiments. The results show that the optimal choice to increase Eh level is the addition of pure pyrite. This condition can effectively raise the Eh of bioleaching process while the impact of environmental change is negligible. It can quicken the leaching process and enhance the final copper recovery through the addition of pyrite by 1:1 or 1:2 mass ratio of covellite concentrate to pyrite.