FORMATION PROCESS OF BIOLOGICAL OXIDE FILM ON CHALCOPYRITE CRYSTAL SURFACE

Abstract

Chalcopyrite (CuFeS2) is the most common copper bearing sulfide in the natural world, and it is also the most widespread copper ore in the world. Pyrometallurgy is used to extract copper from chalcopyrite as main industrial method. However, environmentally friendly metallurgy is advocated because of increasingly serious environmental pollution. The bacterial metallurgy is considered a new clean smelting technology to deal with low-grade and complicated composition metal resources because of short flow, simple operation, low investment and friendly environment. In the process of bioleaching, the formation of oxide film on the chalcopyrite crystal surface hindered the rapid dissolution of chalcopyrite and restricted the large-scale application of copper bioleaching. It is concluded that the oxide film inhibits material exchange between chalcopyrite and leaching liquid on the surface of the chalcopyrite and depresses its leaching rate significantly. In the paper, the advanced surface analysis technologies, such as SEM, XRD and X-ray photoelectron spectroscopy (XPS) are used to observe and analysis the surface layer in the bacterial leaching process. It is studied for the formation of bio-oxide film on the natural chalcopyrite crystal surface, in order to reveal the passivation mechanism of chalcopyrite bioleaching. Through the observation of the microcosmic morphology characteristic changes of chalcopyrite during bioleaching, different chemical composition analysis of surface oxide layer in the different bacterial oxide phase were studied. The results show that the insoluble oxide film inhibits material exchange between chalcopyrite and leaching liquid on the surface of the chalcopyrite and depresses its leaching rate significantly. The results show that the rudiments of oxide film are formed on the surface of chalcopyrite after leaching for 72 h. The oxide