Mechanistic analysis and validation of an efficient novel inhibitor for scheelite and calcite flotation separation: A DFT and MD simulation study

[Display omitted] •The addition of 3 mg/L of POCA significantly reduced the flotation recovery of calcite.•POCA decreased the hydrophobicity of calcite surface by chemical adsorption.•POCA could spontaneously form bonds with the Ca sites of calcite (104) through two functional groups: –SO3H and –PO3H2.•The adsorption of POCA increased the concentration of water molecules on the calcite surface. Due to the similar surface characteristics of scheelite and calcium-bearing minerals, the efficient utilization of scheelite has become a current research focus. This study investigated a novel inhibitor, phosphonic carboxylic acid copolymer (POCA), and explored its influence on the flotation separation of scheelite and calcite in a sodium oleate collector system. The flotation experiments demonstrated that 3 mg/L POCA can effectively inhibit the flotation of calcite. The results of zeta potential and Fourier transform infrared spectroscopy (FTIR) indicate the emergence of a novel carboxyl (C = O) characteristic peak in the infrared spectrum of calcite following the introduction of POCA. This suggests that the interaction between POCA and the calcite surface occurs via chemical adsorption. Additionally, a markedly negative shift in the surface potential of calcite is observed, suggesting that this interaction is more robust compared to the interaction with scheelite. Density functional theory (DFT) and molecular dynamics (MD) simulations suggest that POCA can chemically adsorb onto the Ca site on the calcite surface through the –SO3H and –PO3H2 functional groups, simultaneously enhancing the hydrophilicity of the calcite surface to a certain degree.