Effect of SO42- and PO43- on flotation and surface adsorption of dolomite: Experimental and molecular dynamics simulation studies

H2SO4 and H3PO4 are commonly used as depressants for flotation of dolomite from apatite. Unsatisfactorily, the dissociated anions such as SO42- and PO43- may cause trouble to the flotation. In this study, the effect of SO42-, PO43- on the floatability and surface adsorption of dolomite were revealed by experimental and molecular dynamics simulation studies. The results show that SO42- and PO43-, especially PO43-, have a negative effect on flotation of dolomite. The mechanism is that the presence of SO42- and PO43- could inhibit the adsorption of sodium oleate collector on the dolomite surface, and decrease its adsorption capacity. In addition, SO42- and PO43- could react with Ca2+ to form the hydrophilic CaSO4·2H2O and Ca(H2PO4)2, respectively, the synergistic effect resulted in a decrease in the surface hydrophobicity. As a result, the flotation of dolomite was inhibited. This study clarifies the adverse effects of dissociated anions on dolomite flotation, which also lays a foundation for the targeted removal of these ions in the next step.