Investigation on the flotation separation of fluorite from celestite using a novel depressant: Sodium polynaphthalene formaldehyde sulfonate

Abstract Sulfate minerals have gradually become the main gangue minerals of fluorite deposits, and the flotation separation of fluorite and sulfate minerals is difficult with commonly used depressants. In this paper, the high selectivity of a novel depressant sodium polynaphthalene formaldehyde sulfonate (SPS) for the flotation separation of fluorite and celestite both in single mineral and artificial mixed ore experiments was studied, and the underlying separation mechanism was investigated by zeta potential measurement, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) analysis, and Atomic force microscopy (AFM) imaging analysis. Flotation results showed that, in the presence of sodium oleate (NaOL) and SPS, the flotation recovery difference between fluorite and celestite reached 76.26% and the grade of fluorite concentrates increased by 32.11% at pH 6.0. The analysis results showed that the adsorption of SPS on the fluorite surface was limited at pH 6.0, and the adsorption was most likely be through electrostatic interaction. For celestite, the adsorption of SPS on the surface significantly changed the chemical surrounding of celestite surface inhibiting the chemical adsorption of NaOL, and the chemical adsorption of SPS was more significant at pH 6.0.