An AFM Study of the Adsorption of Amyl Xanthate on Copper Sulfides

"In froth flotation, the adsorption of collector on mineral surface is critical for a successful flotation process. In present work, an atomic force microscopy (AFM) has been applied to study the adsorption of potassium amyl xanthate (PAX) on copper sulfides, i.e., chalcopyrite, chalcocite and bornite. The in-situ collected AFM images show that PAX adsorbs on chalcopyrite mainly in the form of oily dixanthogen; while it strongly adsorbs on chalcocite and bornite in the form of insoluble metal xanthate, which binds strongly with the mineral surface. The information obtained from the AFM study shed lights on the collectivity and therefore the selection of specific collector for different copper sulfide minerals in industrial practice.INTRODUCTIONFroth flotation, which treats the highest throughput in mining industry and produces the maximum economic outcome of any surface chemistry process, has been widely applied for the concentration of copper sulfide minerals, i.e., chalcopyrite, chalcocite and bornite. In flotation, collectors are added into the pulp (mixture of water and fine-grained minerals) to selectively adsorb onto the target mineral and render its surface with high hydrophobicity, which is generally beneficial for a strong mineral-bubble attachment and thus a high flotation recovery. Therefore, the adsorption of collector on mineral surface is vital for a successful flotation process and it has been studied by applying various surface analysis techniques, such as IR (Infrared Spectroscopy), CV (Cyclic Voltammetry) and XPS (X-ray Photoelectron Spectroscopy). (Poling, 1963; Allison et al., 1972; Mielczarski et al., 1984; Leppinen et al., 1989; Kartio et al., 1996) These studies have revealed a lot of information, such as the reaction, product and mechanism, of the adsorption of chemicals on mineral surface. It is also of great interest to directly get the image of adsorbed collectors on mineral surface changing with pulp chemistry, such as pH, redox potential, ionic strength and chemical’s dosage."