Selective flotation separation of fluorite and calcite by utilising a novel anionic/nonionic collector

Abstract

The efficient separation of complex associated fluorite and calcium-containing gangue minerals is difficult to achieve using a traditional fatty acid collector due to the poor selectivity and adaptability of such collector. This study utilised a novel anionic/nonionic collector, namely, a mixture of sodium oleate (NaOL) and oleamide, to investigate selective adsorption onto fluorite and calcite surfaces. Flotation tests were conducted to study the flotation performance of fluorite and calcite, and X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analyses were performed to identify the reaction mechanism of an anionic/nonionic collector on mineral surfaces. The anionic/nonionic collector exhibited excellent selective capability for fluorite. Calcite recovery decreased to 45% when the molar ratio of NaOL and oleamide was 8:2, whilst fluorite recovery was maintained at 85%. The changes in binding energy and atomic content indicated that the adsorption of NaOL/oleamide onto the fluorite surface was stronger compared with that onto the calcite surface. Adsorption morphology showed that the mixed micelles of NaOL and oleamide were uniformly adsorbed onto the fluorite surface as bulks, demonstrating tight multilayer adsorption. Meanwhile, the adsorption of mixed micelles onto the calcite surface was sparse, which resulted in the poor hydrophobicity of calcite surface and providing a basis for the selective separation of fluorite and calcite.