Experimental study on the influence of water immersion on the wettability of coal dust

In order to enhance the understanding of the wetting mechanism of coal dust and explore additional approaches to improve the wettability of hydrophobic coal dust. Two coal dust samples with different particle sizes were selected and subjected to water immersion treatments. The wetting behavior of coal dust was investigated through a sinking experiment, focusing on the effects of the water immersion process, immersion time, and particle size. Fourier-transform infrared spectroscopy was employed to analyze the changes in functional groups of coal dust during the water immersion process. The results indicated a significant improvement in the wettability of coal dust after a short-term water immersion treatment, and this enhancement effect can be synergistic with the action of surfactants. The increase in hydroxyl content was identified as a crucial factor in enhancing the wettability of coal dust after water immersion. Moreover, the limitations of using the fractal dimension of particle size distribution to characterize the wettability of coal were explored. The results indicated that coal dust with similar fractal dimensions could exhibit significant differences in wettability, suggesting the need for further investigation into the effects of particle size polydispersity and other particle size parameters on coal dust wettability.