Surface properties of fractured and polished pyrite in relation to flotation

Abstract

This research was designed to answer the question: can conventionally polished mineral surfaces be used in electrochemical studies in relation to flotation where minerals are fractured? Pyrite surfaces were prepared by fracturing and polishing, separately, and then subjected to electrochemical studies including open circuit potential (OCP), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements as well as X-ray photoelectron spectroscopy (XPS) analyses. Differences on polished and fractured pyrite surfaces were observed in the initial stage of electrochemical measurements, but became minor after conditioning in solution for a short time as the surfaces tended to reach an equilibrium quickly. In the presence of xanthate, dixanthogen formed on both the fractured and polished pyrite surfaces through xanthate oxidation. Immediately after fracturing, pyrite surfaces displayed the stoichiometry nearly in accordance with FeS2, while polished pyrite surfaces showed an iron loss and the formation of polysulfide. However, the surface composition of the fractured pyrite and polished pyrite became similar after conditioning in buffer solution. It was also similar to that on samples directly taken from flotation. It is concluded that polished pyrite surfaces can be used in electrochemical studies representing fractured pyrite surfaces in relation to flotation.