Mechanism of synergistic effect of aluminum ions and water glass on talc flotation depression

Abstract

Talc, a prevalent gangue mineral in sulfide ores, poses a significant challenge in the flotation process due to its good floatability. The application of water glass as a standalone reagent has been found to be less effective in suppressing talc. In this study, we delve into the synergistic inhibitory mechanism of Al³⁺ in conjunction with water glass on talc through a series of micro-flotation tests, wettability tests, ICP-MS tests and FTIR spectroscopy tests. Our findings demonstrated that the presence of Al³⁺ significantly enhanced the adsorption capacity of water glass on talc surface. Talc recovery was 23.34 % with the addition of both inhibitors, which was lower than the recovery of 55.82 % with the addition of water glass only. DFT calculation revealed that the adsorption of H₄SiO₄ and [H₃SiO₄]⁻ on the talc surface is relatively weak, with adsorption energies of −7.71 kJ/mol and −23.15 kJ/mol. Following the adsorption of Al³⁺ onto the talc surface, the adsorption energies of H₄SiO₄ and [H₃SiO₄]⁻ were further decreased to −78.41 kJ/mol and −119.63 kJ/mol. The presence of Al³⁺ significantly enhanced the interaction between water glass and the talc surface. This enhancement was attributed to the formation of hydrogen bonds between water glass and the Al³⁺ water complex–Al(OH)₃·H₂O, which augmented the interaction with the talc surface.