The effect of various surfactants on fatty acid for apatite flotation and their adsorption mechanism

Abstract

The synergistic effect of surfactants, i.e., Tween-80 (polyethylene glycol sorbitan monooleate), Span-80 (sorbitanoleate), and MES (fatty acid methyl ester sulfonates), on fatty acid collectors were investigated using single mineral flotation experiments, surface tension measurement, Fourier transform infrared spectrum, and contact angle measurements. The single mineral flotation experiments showed that it was possible to efficiently separate apatite from magnetite, quartz, and biotite by mixing fatty acids with surfactants. The surface tension measurement showed that the surfactants could significantly reduce the surface tension and Critical Micelle Concentration (CMC) of fatty acids. Fourier transform infrared spectroscopy analysis indicated that all of the surfactants did not react with the fatty acids, but only physically adsorbed on the surface of apatite, thus promoting the chemical adsorption of fatty acids on apatite. However, the surfactant chemisorbed on magnetite and competing with a fatty acid, which led to a decrease in the flotation recovery. The results for contact angle measurement showed that the contact angle difference between apatite and magnetite increased with the addition of surfactant, and resulted in an efficient separation.