Investigations on the effect of Fe2+ and Mn2+ in the flotation of fine wolframite with octyl hydroxamic acid

• Fe and Mn species are active sites for OHA adsorption on wolframite surfaces. • Excess Fe 2+ and Mn 2+ inhibit the flotation performance of wolframite. • Fe(OH) 2(s) and Mn(OH) 2(s) precipitates hinder the OHA adsorption. • Mn 2+ and Fe 2+ ions in the aqoeous solution consume OHA collector. The effect of Fe 2+ and Mn 2+ in the flotation of fine wolframite with octyl hydroxamic acid (OHA) as a collector was studied through a series of experiments. The XPS analysis indicates that Fe 2+ and Mn 2+ species on the wolframite surface are the active sites to interact with OHA collector. However, microflotation and contact angle tests show that the excess Fe 2+ and Mn 2+ ions in pulps decrease the flotation recovery and surface hydrophobicity of wolframite, playing inhibition roles on the flotation performance. The zeta potentials of wolframite shift toward positive values in the presence of Fe 2+ and Mn 2+ . Fe(OH) 2(s) and Mn(OH) 2(s) precipitates being dominated species preferentially coat onto wolframite surfaces and then hinder the OHA adsorption. The adsorption results further give evidences that the excess Mn 2+ and Fe 2+ ions in the aqoeous solution also will consume OHA collector. These two processes decrease the adsorption of OHA and the flotation recovery of wolframite.