Adsorption of tannic acid as depressant in the flotation separation of fluorite and bastnaesite

Fluorite, a strategic industrial mineral, was investigated for flotation separation from bastnaesite with tannic acid (TA) as depressant. In this study, the adsorption analysis indicates that the adsorption density of TA on bastnaesite was greater than that of fluorite. The zeta potential, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) provide the evidence that chemisorption and electrostatic attraction occurred simultaneously between TA and fluorite or bastnaesite at optimal pH, the latter also involving hydrogen bonding interactions. Furthermore, the micro-flotation and batch flotation results suggest that TA could effectively depress bastnaesite with a negligible effect on fluorite at low concentrations, and that TA attached to the surface of bastnaesite precluded the adsorption of phthalic acid (PA) as collector, whereas it could be adsorbed on the fluorite surface. These findings offer a robust theoretical foundation and valid guidance for the flotation separation of fluorite from bastnaesite in industrial processes.