DFT study of ethyl xanthate interaction with sphalerite (1Â 1Â 0) surface in the absence and presence of copper

The interaction among sphalerite (1 1 0) surface, copper and ethyl xanthate (EX) was simulated using the density functional theory (DFT). The results of DFT indicate that four types of stable interaction models exist among sphalerite surface, copper and EX, i.e., EX interacts with the Cu substituted for Zn, Cu adsorbed on the top site of S, Cu adsorbed on the bridge site of S and Cu(OH)2 adsorbed on the sphalerite surface. The four interaction models can result in the activation flotation of sphalerite. Density of states (DOS) analysis shows that the energy level discrepancy of the Zn 3d orbital in ZnS and the bonding S 3p orbital in EX results in the weak adsorption of EX on un-activated sphalerite surface. However, after copper activation, the Cu 3d orbital peak and bonding S 3p orbital peak are just maximally overlapped nearby the Fermi level. This study provides an insight into the nature that sphalerite responds not well to EX and also a comprehensive understanding on the possible interaction cases existing among sphalerite surface, copper and EX.