Effects of nonionic collectors with oxygen-containing functional groups on flotation performance of low-rank coal

Abstract

This study aims to investigate the influence of nonionic collectors (diesel, methyl linoleate, oleic acid, and castor oil acid) on the flotation response of low-rank coal particles using X-ray photoelectron spectroscopy analysis, particle-bubble adhesion tests, and froth floatation measurements, in addition to density functional theory, molecular dynamics, and grand canonical Monte Carlo simulations. The results of the XPS analysis and the particle-bubble adhesion index showed that methyl linoleate, oleic acid, and castor oil acid could effectively adsorb onto the surfaces of low-rank coal particles and upgrade their surface hydrophobicity. The greatest content of hydrophobic functional group CC/CH and the flotation yield obtained by adding methyl linoleate during the flotation process were 78.88% and 86.95%, respectively. The electron-absorption induction effect of oxygen-containing groups and large π bonds of methyl linoleate considerably improved the wetting process on the surface of low-rank coal particles compared with that of dodecane, which contains a saturated bonding structure. The highest average adsorption capacity was obtained when methyl linoleate was applied to the surface of low-rank coal particles. The results suggest that ester surfactants such as methyl linoleate can substantially enhance the flotation response of low-rank coal.