The effect of surface potential on the flotation of chromite

The flotation of chromite from “slime fraction” of the gravity circuit of Kemi concentrator, Finland was studied. The main gangue minerals are chlorite, tremolite and talc. Amines or fatty acid collectors are normally used for this sort of mineral composition. Theoretically, a sufficient selectivity should be expected in the region where the surface charge of chromite is opposite to that of the gangue minerals. ectrokinetic potential of the main components was determined as a function of pH. The results showed that the region of selectivity lies at a pH below three, where chromite is positively charged and the other components negatively. This suggest the use of an anionic collector. No selective region was found for chromite with negative surface charge, excluding the use of amine collectors. mmercial fatty acid collectors, F2874 from Hoechst and A C825 from Cytec, were used in the actual flotation tests. Both are designed for low pH values. In an open circuit F2874 gave a concentrate around 95% of chromite with a recovery of 70%. The flotation was also found to favour the recovery of chromite particles with high chrome to iron ratio. periments showed a distinct abundance between the chromite surface charge and the selectivity as well as reversible adsorption-desorption behaviour. This confirms the hypothesis of physical adsorption of fatty acids on chromite at low pH.