Utilisation of sodium oleate/alkylamide collectors for the selective separation of fluorite and calcite

The similar surface characteristics of fluorite and calcite pose a considerable challenge to their selective separation. This study employed a combination of sodium oleate (NaOL) and alkylamides as collectors to address this issue. Flotation results showed that the addition of alkylamides substantially enhanced the selective flotation of fluorite compared with NaOL alone, particularly with the addition of erucamide. When the molar ratio of NaOL/erucamide was 10:4, pH was 8 and dosage was 4 x 10(-5) mol/L, the discrepancy in flotation recovery between fluorite and calcite exceeded 50 %. In accordance with surface tension and fluorescence spectra, the mixed collectors exhibited higher surface activity, indicating a synergistic effect between NaOL and alkylamide. The analysis results of X-ray photoelectron spectroscopy and atomic force microscopy revealed that the mixed collectors had higher adsorption selectivity than NaOL. The adsorption strength and density of the mixed collectors on the fluorite surface significantly surpassed those on calcite. This result may be attributed to the introduction of amine groups through the addition of alkylamides in the mixed collectors. These amine groups have the capability to establish stronger hydrogen bonds with the fluorine atoms present on the fluorite surface, effectively enhancing flotation selectivity. Hence, the findings of this research are expected to provide valuable references for the separation process of fluorite and calcite.