Biofilm forming and leaching mechanism during
bioleaching chalcopyrite byThiobacillus ferrooxidans①
bioleaching chalcopyrite byThiobacillus ferrooxidans①
(1. School of Minerals Processing and Bio-engineering,
Central South University, Changsha 410083, China;
2. College of Chemistry and Chemical Engineering, Hunan Normal University,
Changsha 410081, China)
Central South University, Changsha 410083, China;
2. College of Chemistry and Chemical Engineering, Hunan Normal University,
Changsha 410081, China)
Abstract: The mechanism of attachment and leaching ofthiobacillus ferrooxidans(T.f.) on chalcopyrite were studied. The shaking flasks with bacteria were observed by SEM. The process ofT.fattached to the surface of the mineral sample and the biofilm forming were described. The promoting role of the biofilm for bioleaching was discussed. The existence of Fe2+in the exopolysaccharide layer ofT.fwas demonstrated by EM(electronic microscope)cell-chemistry analysis. These results show that under the proper growth condition of bacteria, bioleaching of chalcopyrite results in the formation of complete biofilm after 2-3 weeks. There are iron ions in the outer layer polymer ofT.f., which provides the micro-environment for themselves, and can guaruntee the energy needed for the bacteria growth in the biofilm. At the same time, Fe3+ions produced oxidize sulfide which brings about the increase of both growth rate of the bacterial and
leaching rate of sulfide minerals.
leaching rate of sulfide minerals.
Key words: bioleaching; bacterial attachment; biofilm forming; EM cell-chemistry