Action Of Hydroxamic Acids On Minerals In The Flotation Of Fine Cassiterite

In this paper, study on the flotation of single minerals and the separation of cassiterite from gangue minerals in the tailings of gravity concentration was carried out through selecting appropriate combined collectors.Firstly, researches on the flotation of cassiterite, calcite and quartz single minerals were carried out, using hydroxamic acids as collectors. Results showed that the alkyl hydroxamic acids were effective collectors in the flotation of fine cassiterite, and a wider range of appropriate pH could be obtained with a longer chain length of the collector. Octyl hydroxamic acid showed good selectivity with cassiterite in the neutral and acidic conditions, a similar results but a relatively lower recovery rate was obtained when using salicylhydroxamic acid as collector. Through applying the combined collectors composed of equal dosages of octyl hydroxamic acid and salicylhydroxamic acid, a good result of recovery differential between cassiterite and gangue minerals could be obtained. Thus with the optimum combined collectors mentioned above, the effect of metal cations on the flotation of cassiterite were investigated. Results showed that the metal cations influenced the flotation mostly depending on the pH of the medium and the concentration of metal cations.The combined collectors could lead an effective separation of cassiterite from the quartz mineral.The carboxymethylcellulose and sodium hexametaphosphate could depress the flotation of calcite in the alkalic conditions. Under the conditions of optimum combined collectors without depressant, cassiterite could be preferably separated from calcite in the faintly acidic and neutral conditions.Solution chemistry result revealed that a coadsorption between molecules and ions of octyl hydroxamic acid onto cassiterite surface was considered in the optimum pH range of cassiterite flotation. The adsorption of octyl hydroxamic acid on the cassiterite shifted the curve of zeta potential to the left and made the zeta potential of cassiterite more negative. In terms of zeta potential and infrared spectra studies, the main interactions involved both electrostatic interaction, hydrogen bonding interaction and complexation, with the resultant product proposed as an O, O-five membered rings chelat compound. The adsorption measurement results showed that when the concentration of octyl hydroxamic acid exceeded30mg/L, multilayer adsorption might be formed on the surface of cassiterite.The flotation technology of pre-desulfuration before cassiterite floation was applied to the fine-grained cassiterite from the shaking table tailings, the cassiterite concentrate with grade and recovery of3.58%and81.93%respectively was obtained in the closed circuit experiment.