Floatability and adsorption of ethyl xanthate on copper-activated sphalerite in weakly acidic medium

Abstract

The effect of copper(II) ion concentration and the time of activation on the ethyl xanthate adsorption and floatability of sphalerite (13% Fe) in weakly acidic medium were examined. Infrared internal reflection spectroscopy was used to determine the copper xanthate species adsorbed on sphalerite under different conditions. Both, Cu(I) xanthate and the monolayer form of Cu(II) xanthate, were identified on the sphalerite surface, depending on the CuSO 4, concentration and the activation time. The results acquired corroborated the assumption that the activation is a two-step process. The rise in CuSO 4, concentration caused, within the short time of activation (2 min), an increased production of Cu(I) xanthate on the sphalerite surface. For the same CuSO 4 and potassium ethyl xanthate (KEX) concentrations, the increase in the time of activation (up to 45 min) led to a lower production of surface Cu(I) xanthate. The diffusion of copper ions through the layer of the copper sulphide produced was a slow process with a long activation time. When the time of activation was longer, the remaining amount of copper ions in the solutions was small and, consequently, the formation of Cu(I) xanthate was also reduced.