Ilmenite Flotation: surface dissolution impacts on collector adsorption and flotation Kinetics

The effects of surface dissolution by oxalic acid were investigated on the flotation kinetics and kinetics of collector adsorption in ilmenite flotation in the presence of olivine-pyroxene, tremolite-clinochlore and quartz. Fitting of first order kinetic model on the results of flotation before and after surface dissolution showed that flotation kinetic constant (K) and ultimate recovery (R∞) of ilmenite is increased after surface dissolution and they are decreased for gangue minerals. The results showed that kinetic selectivity index of ilmenite in the presence of olivine-pyroxene, tremolite-clinochlore and quartz are increased from 1.28 to 1.98, 1.42 to 3.02 and 3.58, respectively, after surface dissolution indicating the positive effect of surface dissolution process. Investigating the kinetics of collector adsorption showed that the collector adsorption is conforming to second order kinetic model. After surface dissolution, the kinetics of collector adsorption and initial rate of collector adsorption on ilmenite surface is increased from 3.85 to 8.44 g.mol-1 min-1 and it is decreased for olivine-pyroxene, tremolite-clinochlore and quartz from 6.33 to 5.03, 7.3 to 6.22 and 7.77 to 7.37 g.mol-1 min-1, respectively. These results are in good agreements with the results of collector adsorption via UV analysis which the collector adsorption on ilmenite surface is increased and it is decreased for gangue minerals after surface dissolution. The results of SEM showed that the surface of ilmenite becomes smoother and uniform and about the gangue minerals, some cavities are produced due to dissolution of surface cations.