Electrokinetics, adsorption and floatation studies of sphalerite using di (2-ethyl hexyl) phosphoric acid

Abstract

Electrokinetics, adsorption and flotation studies have been carried out to investigate the possible interaction of the solvent extractant, di (2-ethyl hexyl) phosphoric acid (D(2)EHPA), with sphalerite. The zeta potential measurements reveal that the iso-electric point of sphalerite is located around pH 4.1. The zeta potential becomes more negative and the isoelectric point shifted to < 2.8 following the adsorption of the reagent D(2)EHPA on the mineral surface. The adsorption density of D(2)EHPA on sphalerite has shown higher values at acidic pH compared to alkaline pH values. The adsorption isotherm exhibits Freundlich behaviour. The dissolution experiments have indicated the release of zinc ions from the sphalerite surface with respect to pH and time. The dissolution of zinc ions is suppressed with the addition of D(2)EHPA. Flotation studies carried out on sphalerite and the synthetic mixture of sphalerite and quartz have shown complementing results with the adsorption studies. A zinc recovery of 97% at pH 3.74 with the reagent concentration of 200 g/tonne was obtained. It was also possible to recover 90% of Zn at pH 4.2 from Pb-Zn ore of Zawar Mines, India containing 3.38% Zn.