Studies on interaction mechanism of fine wolframite with octyl hydroxamic acid

Abstract

Interaction mechanism of fine wolframite with octyl hydroxamic acid (OHA) during flotation process was investigated. Flotation and adsorption tests indicated that wolframite showed better floatability as a consequence of OHA adsorption at pH 7.0–10.0. Zeta-potential measurements revealed that OHA adsorbed specifically on wolframite surface. The results of solubility behavior of wolframite indicated that the anion-exchange reaction occurred between OHA− in solution and WO42- in the crystal lattice. OHA− might interact with Mn2+/Fe2+ cations of wolframite surface to form ferrous/manganous hydroxamate precipitations, with a release of WO42- ions. The XPS analysis confirmed that the mechanism of OHA adsorption onto wolframite surface associating coadsorption/surface reaction process was presented in flotation conditions. OHA could bond with ferrous/manganous species on wolframite surface, accompanying molecule OHA physical adsorption onto the chemisorbed layer of ferrous/manganous hydroxamate precipitations. This interaction process appeared to be strong enough to ensure adequate adsorption ability of OHA on wolframite surface and led to good hydrophobicity of wolframite.