Study On The Flotation Of Scheelite And Wolframite By Hydroxamates

In the flotation of scheelite and wolframite, there are the problems of poor selectivity and collecting ability decline at low temperature by using sodium oleate as collector. As a matter of fact, the combination of hydroxamates and sodium oleate is usually applied to improve the flotation efficiency. In this paper, the author studied the performance of cyclohexyl hydroxamate, tert-butyl benzoyl hydroxamate, benzoyl hydroxamate, octyl hydroxamate and salicylic hydroxamate in the flotation of scheelite and wolframite, on the base of which, the effect of the addition of hydroxamates on the flotation of scheelite and wolframite by using sodium oleate was investigated. The effect of hydroxamates in the flotation of scheelite and wolframite by using sodium oleate was studied through adsorption capacity measurements, Zeta potential experiments and infrared spectrum analysis. The author would like to provide theoretical guidance to the research of new combination collectors in flotation of tungsten.The study showed that the optimum pH was9.0in both scheelite and wolframite flotation by using hydroxamates, and the collecting ability to scheelite was stronger than wolframite. The collecting ability of five kind hydroxamates to scheelite and wolframite was in the following order: cyclohexyl hydroxamate> tert-butyl benzoyl hydroxamate> octyl hydroxamate> salicylic hydroxamate> benzoyl hydroxamate. The flotation recovery of scheelite and wolframite was more than90%when the dose of hydroxamates was above300mg/L. At the optimum flotation pH, which was close to the pKa of the hydroxamic acids, the adsorption of hydroxamates on scheelite and wolframite surface reached the highest amounts. The results may be due to the molecule-ion association of hydroxamic acids.Temperature had more influence on the adsorption of hydroxamic acids on wolframite surface than that on scheelite surface. At15℃, the adsorption amounts of hydroxamic acid on wolframite than that at25℃, which may be one of the reason that the floatability of wolframite was poorer than scheelite.Compared with pure sodium oleate, the combination of hydroxamates and sodium oleate had greater collecting ability in the flotation of scheelite and wolframite due to the positive synergistic effect between hydroxamates and sodium oleate. The existence of hydroxamates raised the adsorption amounts of sodium oleate on scheelite and wolframite surface and the effect was more obvious in lower temperature (15℃). Coadsorption of hydroxamates and sodium oleate occurred on the surface of wolframite and scheelite, which was also proved chemical adsorption. There are67graphs,2tables and83references in this dissertation.