Adsorption of Fe(III) on smithsonite surfaces and implications for flotation

Recently, there has been interest in the effects of ionic species on the flotation performance of minerals in liquid phase. Metal ions that are commonly present in flotation pulp can cause non-selective activation of target minerals and gangue particles during flotation. We have investigated the influence of Fe(III) adsorption on smithsonite surfaces using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), zeta potential measurements, scanning electron microscopy, and micro-flotation tests. The results indicate that Fe(III) can adsorb onto the smithsonite surface, resulting in a series of changes to the surface properties. XPS results show that Fe(III) adsorption can change the atomic composition of the smithsonite surface, along with its chemical state. The zeta potential of the smithsonite became more positive and its pH shifted from 7.6 to 9.2 in the presence of 1 × 10−4 mol/L Fe(III). Micro-flotation tests revealed that iron ions have a strong inhibitory effect on smithsonite. The recovery of smithsonite decreased sharply as the Fe(III) concentration increased. When the concentration reached 5 × 10−4 mol/L, the recovery was only 21.35%. The Fe(III)-driven smithsonite inhibition mechanism may be attributed to strong oxidation and hydrolysis.