Molecular-level insights into the adsorption of a hydroxy-containing tertiary amine collector on the surface of magnesite ore

Abstract A molecular dynamics simulation was used to investigate the adsorption performance and mechanism of a tertiary amine surfactant and the surface of magnesite ore in aqueous solution at the molecular level. The molecular dynamics simulation results revealed distinct differences among the adsorption performances to quartz, magnesite, and dolomite with bis(2-hydroxyethyl)dodecylamine (BHDA) (quartz > dolomite > magnesite). The results of adsorption tests, flotation, and zeta potential measurements confirmed the same tendencies in the adsorption behaviors. The differences in flotation behavior could be ascribed to electrostatic attraction and hydrogen bonding. Property analyses showed that hydrogen bonding played a considerable role in the adsorption process of BHDA. The introduction of multiple hydroxyl groups improved the water solubility of BHDA and enhanced its adsorption on mineral surfaces containing exposed O atoms. The higher flotation selectivity of BHDA compared to dodecylamine (DDA) was attributed to the relatively weaker electronegativity and the stronger steric hindrance of BHDA.