Interaction between smithsonite and carboxyl collectors with different molecular structure in the presence of water: A theoretical and experimental study

The effects of six kinds of carboxyl collectors with different structures on the flotation behaviors of smithsonite have been studied by theoretical and experimental methods. Micro-flotation experiment suggested that with the increase of carbon chains length and double bonds, the flotation recovery increased. Linoleic acid and oleic acid showed great collectivity and naphthenic acid hardly floated smithsonite. DFT calculation results suggested benzenoid and saturated carboxyl collectors exhibited small electrophilicity and unsaturated carboxyl collectors possessed large electrophilicity. Water molecules had a great impact on the adsorption of carboxyl collectors on smithsonite surface. In the absence of water molecules, the simulation result of carboxyl collector adsorption was inconsistent with the flotation experiment. In the presence of water molecules, only oleic acid and linoleic acid showed great collecting power to smithsonite, which coincides well with the experiment results. It was found that adsorption of water weakend the hybridization of 3s and 3p orbitals and electrophilicity of surface Zn atom, and thus unfavorable for the adsorption of carboxyl collector with small electrophilicity. The results could provide a theoretical guidance for the design of an effective collector of zinc oxide flotation.