Surface chemical and adsorption studies using Thiobacillus ferrooxidans with reference to bacterial adhesion to sulfide minerals.

Adhesion of Thiobacillus ferrooxidans to pyrite and chalcopyrite in relatio n to its importance in bioleaching and bioflotation has been studied. Elect rokinetic studies as well as FT-IR spectra suggest that the surface chemist ry of Thiobacillus ferrooxidans depends on bacterial growth conditions. Sul fur-,Pyrite- and chalcopyrite-grown Thiobacillus ferrooxidans were found to be relatively more hydrophobic. The altered surface chemistry of Thiobacil lus ferrooxidans was due to secretion of newer and specific proteinaceous c ompounds. The adsorption density corresponds to a monolayer coverage in a h orizontal orientation of the cells. The xanthate flotation of pyrite in pre sence of Thiobacillus ferrooxidans is strongly depressed where as the cells have insignificant effect on chalcopyrite flotation. This study demonstrat e that : (a)Thiobacillus ferrooxidans cells can be used for selective flotation of c halcopyrite from pyrite and importantly at natural pH values. (b)Sulfur-grown cells exhibits higher leaching kinetics than ferrous ion-gr own cells.