Effect of sodium silicate modified with Fe2+ and Al3+ as dispersant on flotation of molybdenite and chalcopyrite in presence of kaolinite and seawater

Abstract

Mineral processing is increasingly challenging due to the low grades of ores being processed and the high content of ultra-fine particles, such as clays. Negative effects of the presence of clays on the flotation process include modification of the rheology of slurries, changes in the hydrodynamics of the particle-bubble attachment and slime coating, which reduce the recovery of valuable material. The negative effects have been addressed by using dispersants such as silicates. In this paper, the effect that the presence of silicates modified with Fe2+ and Al3+ has on flotation of molybdenite and chalcopyrite is studied. Microflotation of ores with high content of chalcopyrite and molybdenite were carried out, using kaolinite as ultra-fine particulate system, and conventional and sea water as aqueous medium. Results showed that the effect of modified and unmodified sodium silicates is higher in the flotation of the molybdenite than in the flotation of chalcopyrite. This was corroborated in the measurements of zeta potential in solutions of different ionic charges. The measurements of the zeta potential showed that the addition of sodium silicate modified with Fe2+ maintained the potential in the most negative zone in the different aqueous solutions tested for the case of the chalcopyrite, which would indicate that there is a major repulsion of the precipitates of calcium and magnesium of the surface mineral compared with the measurements in which Al3+ was utilized.