Chapter 4 - Interaction of water and oxygen with sulfide mineral surface

Abstract

Reactions in the process of flotation occur on the interface between minerals. Hence, the structure and properties of the solid–liquid interface play an important role in the flotation that determines the adsorption of flotation reagent on the mineral surface. The adsorption of water molecule on the MoS2 (001), Sb2S3 (010), Cu2S (100), ZnS (110), PbS (100), and FeS2 (100) surfaces has been simulated. The effect of water molecule on the surface relaxation, density of states, and Mulliken population is presented. The comparison of a single, mono-, and multilayer water adsorption on hydrophobic galena (PbS) and hydrophilic pyrite (FeS2) (100) surfaces is performed. Various H2O–O2 coadsorption models on the pyrite surface by considering the adsorption sequence of H2O and O2 are constructed. It is found that the H2O molecule undergoes stepwise dissociation in the presence of the O2 molecule. Hydroxyl radical center dot OH is the reactive oxygen species during H2O dissociation. Coadsorption of water and oxygen on galena surface suggests that the dissociation of both H2O and O2 molecules occur, and water molecule dissociates into Ow and H radicals, which then react with surface S atom and adsorbed O2 molecule to form S=Ow radical and hydrogen peroxide, respectively. Further adsorption of hydrogen peroxide on surface Pb atoms produces lead hydroxyl radicals.