Surface chemistry and flotation of cassiterite with alkyl hydroxamates

Abstract

Abstract Surface chemistry and flotation of cassiterite in the presence of alkyl hydroxamic acid/salt surfactant has been investigated. Results of the adsorption isotherms, electrokinetic and infrared spectroscopy indicate that octyl hydroxamate adsorbs on cassiterite by both physical and specific forces. Adsorption of the surfactant was high in the acidic pH range indicating the involvement of octyl hydroxamic acid molecule (pKa≅9) and uncharged or/and moderately negatively charged cassiterite in the sorption process. Based on the experimental observations the possible modes of sorption were discussed. Flotation of cassiterite was studied with alkyl hydroxamates of carbon chain length 8, 10 and 14 on different sizes of particles. Flotation with potassium octyl hydroxamate gave distinct maxima at about pH 6.2, which extends upto pH 9 at higher concentrations. The pH region of good floatability broadens with decrease in the particle size and increase in the chain length of the collector. Flotation studies in the presence of metallic ions like Fe+3, Fe+2 and Al+3 indicated both activation and depression depending on the concentration of the metallic ions and pH of the medium.