The impact of metal ions on flotation of coal gasification fine slag: an experimental study

This study investigates the flotation performance of coal gasification fine slag in the presence of metal ions with different valences. The impact of metal ions on the surface topography, wettability, zeta potential, functional group, and particle size distribution of coal gasification fine slag were analyzed. The results demonstrated that K+, Ca2+, Mg2+, and Al3+ all have a positive effect on flotation, with Al3+ being particularly effective. At a concentration of 0.2 mol/L, Al3+ increased the recovery of combustible matter in coal gasification fine slag from 66.70% to 91.05% compared to deionized water. Metal ions reduce the absolute value of the gasification fine slag potential, compress its double layer while increasing its surface hydrophobicity. Higher ion concentration leads to a closer-to-zero potential and increased hydrophobicity. Additionally, Al3+ promote diesel adsorption onto coal gasification fine slag. This work explains the effects of metal ions on coal gasification fine slag flotation.