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

The effect of Fe2+ and Mn2+ 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 Fe2+ and Mn2+ species on the wolframite surface are the active sites to interact with OHA collector. However, microflotation and contact angle tests show that the excess Fe2+ and Mn2+ 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 Fe2+ and Mn2+. 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 Mn2+ and Fe2+ ions in the aqoeous solution also will consume OHA collector. These two processes decrease the adsorption of OHA and the flotation recovery of wolframite.