Flotation separation of dolomite and apatite using polyaspartic acid as inhibitor

Abstract

In this paper, polyaspartic acid (PASP) was exploited as a novel dolomite depressant for flotation separation of apatite and dolomite. A series of tests with Zeta potential, FTIR and XPS were used to reveal the inhibitory mechanism of PASP on dolomite. The microflotation test illustrated that PASP has a strong inhibitory impact on dolomite, and little effect on the floatability of apatite in the pH range of 9-11. When using 2.7 Mg/L PASP as the depressant under sodium oleate (NaOl) system, the flotation recovery of dolomite dropped dramatically to 9.95%, and the recovery of apatite remained at about 88.27% at pH 10. Both dolomite and apatite have calcium ion on the surface. The calcium ion on the surface of apatite were strongly inhibited and repelled by the localized anions, while the important role on the surface of dolomite was positively charged magnesium ion and localized calcium species. PASP could ionize carboxylate ion under alkaline conditions, which could chemically chelate with the exposed metal ion and be adsorbed on the surface of dolomite. And then prevent the further adsorption of NaOl onto dolomite, which greatly weaken the floatability of dolomite and enhanced the flotation separation of the two minerals.