Flotation behavior and adsorption mechanism of fine wolframite with octyl hydroxamic acid

Flotation behavior and adsorption mechanism of octyl hydroxamic acid (OHA) on wolframite were investigated through flotation experiments, adsorption tests, zeta-potential measurements, infrared spectroscopy and solution chemistry calculations. Results of flotation and adsorption experiments show that the maximum values of flotation recovery and adsorption capacity occur around pH 9. In term of the solution chemistry calculations, the concentration of metal hydroxamate is greater than that of metal tungstate and metal hydroxyl, and metal hydroxamate compounds are identified to be the main species on wolframite surface at pH region of 8-10, contributing to the increase of OHA adsorption and flotation performance. Results of zeta-potential and IR spectra demonstrate that OHA adsorbs onto wolframite surface by chemisorptions. Hydroxamate ions can bond with Mn2+/Fe2+ cations of wolframite surface, forming metal hydroxamate compounds, which is a key factor in inducing the hydrophobicity of wolframite under the conditions of maximum flotation.