Dispersion of sodium phytate on muscovite and the implications for arsenopyrite flotation

Abstract

The effective flotation separation of sulfides and sliming silicate minerals is always a difficult problem. In this paper, the selective flotation of arsenopyrite from muscovite was studied by using sodium phytate (SP) as dispersant, and the mechanism was investigated through SEM/EDS, zeta potential, FTIR and XPS measurements. Single mineral flotation results showed that with the increasing isoamyl xanthate (IAX) dosage the recovery of arsenopyrite increased, until 8×10-5 mol/L IAX (79.40% recovery, pH=7), after that it decreased slightly. While muscovite floated poorly at any IAX concentration. For the mixed minerals, arsenopyrite recovery was only 54.63% while that of muscovite was 42.70%, which was attributed to the coverage of muscovite on arsenopyrite surface. When 6×10 -5 mol/L SP was added into the mixed minerals system, the recovery of arsenopyrite recovered to 68.26% while that of muscovite was 8.48% (approximate the value of the single mineral). SEM/EDS results showed that SP could disperse muscovite and prevented its coverage on arsenopyrite surface. Zeta potential results showed that the electrokinetic potential of muscovite and arsenopyrite decrease from -26.60mV to -39.01 mV and from -26.90 mV to -27.84 mV at pH=7, respectively. It was obvious that the negatively charged phytate ions selectively adsorbed on the surface of muscovite. FTIR and XPS resulted co-proved the chemisorption of SP with active sites on muscovite while arsenopyrite spectrum did not change significantly, which was consistent with flotation and zeta potential results. The selective adsorption of SP on muscovite compared to arsenopyrite was responsible for the effective separation of them.