Surface Characterization Of Chalcopyrite Interacting With Leptospirillum Ferriphilum

The alteration of surface properties of chalcopyrite after biological conditioning with Leptospirillum ferriphilum was studied by adsorption, zeta-potential, contact angle and bioleaching tests. The strains of L. ferriphilum cultured using different energy sources (either soluble ferrous ion or chalcopyrite) were used. The adhesion of bacteria to the chalcopyrite surface was a fast process. Additionally, the adsorption of substrate-grown bacteria was greater and faster than that of liquid-grown ones. The isoelectric point (IEP) of chalcopyrite moved toward that of pure L. ferriphilum after conditioning with bacteria. The chalcopyrite contact angle curves motioned diversely in the 9K culture with and without chalcopyrite powders. The results of X-ray diffraction patterns (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis indicated that in the bioleaching process by L. ferriphilum, the surface of chalcopyrite was covered with sulfur and jarosite. Furthermore, iron phase dissolved preferentially from chalcopyrite surface during bioleaching from EDS detection. The copper extraction was low resulting from the formation of a passivation layer. The major component of the passivation layer that blocked continuous copper extraction was sulfur, not jarosite.