Degradation mechanism of surface hydrophobicity by ferrous ions in the sulfidization flotation system of smithsonite

Metal ions commonly exist in the flotation pulp, which will affect the mineral surface properties and lead to a change in the mineral floatability. In this work, the effect of Fe2+ on the flotation behavior of smithsonite was investigated, and the interaction mechanism of Fe2+ with the smithsonite surface in the sulfidization flotation system was clarified. The results of microflotation tests showed that the presence of Fe2+ can greatly reduce the flotation recovery of smithsonite. The results of zeta-potential measurement, time-of-flight secondary-ion mass spectrometry, and X-ray photoelectron spectroscopy indicated that addition of Fe2+ before sulfidization generated FeOOH species and hindered formation of active sulfide species on smithsonite. The results of infrared spectroscopy and contact-angle measurement showed that addition of Fe2+ was harmful for adsorption of the collector on smithsonite, and it was difficult to obtain hydrophobic smithsonite surfaces in the Fe2+-sulfidization-xanthate flotation system. Considering the above results, the presence of Fe2+ depressed adsorption of sulfide ions and the collector on smithsonite, making smithsonite show poor floatability, and it was difficult to obtain the ideal flotation recovery of smithsonite.