Investigation of the effect and mechanism on the flotation performance of alkylglycine-based collectors by acyl group

The structure difference of the flotation reagent has a significant influence on its flotation performance. In this work, sodium N-lauroyl glycinate (SNG) was synthesized by introducing an acyl group into sodium N-dodecylglycinate (SN), and was using the collector in the oxide ores flotation. Properties of these two collectors were compared, and the effects behavior and mechanism of introducing the acyl group on the flotation performance of alkylglycine-based collectors to the zinc oxide minerals were systematically investigated. Flotation results proved that the introduction of C = O group into SN barely affected the floatability of smithsonite, hemimorphite and calcite, while the floatability of quartz was greatly reduced. Contact angle tests, surface tension tests, and froth collapse measurements indicated that the introduction of the acyl group into SN could selectively weaken its ability to improve the hydrophobicity of mineral surfaces, reduce its surface tension, adsorption capacity and intensity on the mineral surface, and the froth stability, thereby enhancing its selectivity, consistent with the flotation results. Fourier transform infrared spectroscopy (FTIR) analyses and density functional theory (DFT) calculations revealed that the introduction of the acyl group could increase the cross-sectional area and reduce the charge of the SNG polar groups to selectively weaken the adsorption interaction, particularly by significantly reducing the electrostatic adsorption between SNS and quartz surfaces. These also confirm that SNG is a promising highly selective collector for the flotation separation of zinc oxide minerals.