Influence of flotation reagents on separation mechanism of macerals: A multi-scale study

Abstract

The precise separation of macerals is the premise and foundation for the efficient utilization of coal resources, and flotation is the separation method with the greatest industrial potential. The differences in the surface hydrophobicity of macerals provide the basis for flotation, but the complexity of their surface properties makes separation challenging. In this study, sub-bituminous coal was used to obtain vitrinite and inertinite, and a detailed analysis was carried out on the samples. The surface morphologies of vitrinite and inertinite were observed in the QITM (quantitative imaging) mode of AFM (atomic force microscope) to explore the adsorption of the reagents. The effect of the reagents on the interaction forces between the coal particles and bubbles was measured to reveal the change in hydrophobicity. The attachment performance of macerals under different reagent treatments was investigated using a laboratory-built apparatus. Overall, the results demonstrated that the difference in zeta potential between vitrinite and inertinite was a viable approach for separating the macerals. CTAB adsorption on coal samples changed the surface morphology and the interaction force between particles and bubbles. Interestingly, CTAB adsorption on the gas–liquid interface decreased the interaction force. Vitrinite and inertinite attachment performances were enhanced when Al3+ and SDS were used simultaneously.