Surface characteristics and dispersion behaviours of fluorapatite and dolomite in the presence of H2PO4− in grinding environment

• H 2 PO 4 − in grinding environment improved the flotation selectivity of FAp and Dol. • H 2 PO 4 − enhanced the hydrophilicity of FAp by react with Ca sites on FAp surface. • H 2 PO 4 − promoted the dispersion stability and reduced “slime coating” effect of Dol. Grinding is a complex physical and chemical process that directly affects the subsequent flotation behaviour. In the reverse flotation of calcareous phosphate ore, owing to dissolution of apatite (Ap) and reuse of water, plenty of H 2 PO 4 − are present in the grinding and flotation pulp. H 2 PO 4 − affects the surface properties and dispersion behaviours of fluorapatite(FAp) and dolomite(Dol), leading to changes in the flotation behaviour of the mineral. In this research, the effects of H 2 PO 4 − in grinding environment on surface properties, dispersion behaviours and floatability of FAp and Dol were systematically investigated using contact angle measurements, bubble-particle attachment test, zeta potential tests, sedimentation tests, TOF-SIMS, XPS and DLVO theory. H 2 PO 4 − in the grinding environment significantly inhibits the flotation of FAp and has a noticeable promoting effect on the flotation of Dol. H 2 PO 4 − reduces the surface hydrophobicity of FAp, improves the dispersion stability of minerals and reduces “slime coating” effect of Dol. Thus, the wettability and floatability difference between FAp and Dol increase, resulting in better flotation selectivity. Therefore, regulate the concentration and dissolution equilibrium of H 2 PO 4 − in the grinding and flotation process, keep H 2 PO 4 − as the dominant component, is of great significance for promoting the flotation separation of FAp and Dol.