Influence of ferrous ions on surface properties of malachite and its response to sulfidization xanthate flotation

Sulfidization flotation is the principal method used for recovering malachite. There are some unavoidable metal ions appear in the solution during enrichment, and the existence of ferrous ions has a certain impact on the surface sulfidization and xanthate adsorption on surface of malachite. In this work, the influence of the ferrous species on the sulfidization flotation of malachite were investigated, and it showed that the ferrous species could be adsorbed on the mineral surface before and after sulfidization. Meanwhile, the hydroxyl species increased due to the addition of ferrous ions adsorbed as Fe-hydroxyl species, and depressed the formation of S2- and Sn-species. However, the SOn-species with excessive oxidation increased significantly. The content of the Cu(I) species decreased, implying that the addition of ferrous ions was not conducive to the sulfidization process of malachite and the reactivity of sulfidization products with subsequent reagents decreased. In addition, the S and Fe species adsorption layer on malachite surface were visually characterised using time-of-flight secondary ion mass spectrometry analysis, and verifies the above experimental results. After ferrous ions was introduced into flotation system, the adsorption of collector decreased and the consumption of collector in solution increased. Therefore, the flotation recovery of malachite was reduced by the addition of ferrous ions before and after sulfidization.