High-Efficiency Flotation of Fine-Grained Collophanite Through the Use of Sulfonated Fatty Acid Ester: Experiment and Dft Calculation

Abstract

A self-synthesized sulphonated fatty acid ester (SFAE) was used for the first time as a collector in the reverse flotation of collophanite. Flotation tests demonstrated that at an SFAE dosage of 800 g/t, the P2O5 grade of the concentrate was 25.43%, with a recovery rate of 89.42%, while the MgO grade was 0.51%, with a recovery rate of 15.41%. In a closed-circuit flotation process,  a phosphorus concentrate with a P2O5 grade of 34.53% and a recovery rate of 91.28% was yielded, while the MgO grade was only 0.41%, with a recovery rate of 4.1%. Infrared spectroscopy revealed the formation of a new complex when collophanite reacted with SFAE. In the presence of Mg2+, this absorption peak was significantly weakened, confirming stronger SFAE adsorption by Mg2+ than by collophanite. Density functional theory (DFT) calculations showed that SFAE formed a Mg–O bond with dolomite and a Ca–O bond with collophanite. The Mg–O bond length (1.42156 Å) and population value (0.42) indicated strong interaction, whereas the Ca–O bond length (2.61587 Å) and population value (0.02) suggested weaker interaction. The adsorption energy of SFAE on dolomite (–156.34 kJ·mol-1) was substantially higher than that on collophanite (–31.58 kJ·mol-1), confirming a stronger interaction with dolomite.

Keywords: Keywrds: Collophanite, Reverse flotation, collector, Sulphonated fatty acid ester (SFAE), surface chemistry