Experimental Study on Ion-Enhanced Wetting of Coal in Water for Mine Dust Removal

According to the common types of ions in mine water, the influence of ions on water solution and the change of the wetting ability of coal dust were studied. The surface tension of different ionic solutions and the change of contact angle after acting on coal were tested, which reflects the change of the wettability of the solutions. Based on zeta potential and FTIR tests, the microwetting process of coal dust surface under ionic solution was studied. The results show that the surface tension of the solution was influenced by the charge interactions, ion concentration, and ion species. The wettability enhancement effect of ions can be ordered as CO₃ ^2- > Cl^- > SO₄ ^2- and Mg²⁺ > Na⁺ > Ca²⁺ when the ionic solution initially contacts with the coal dust surface, affected by the surface tension and the electricity of the coal dust. Through FTIR analysis, it is found that after the ionic solution acts on the surface of coal dust for a long time, CO₃ ^2-, Mg²⁺, and Ca²⁺ treatment can increase the relative content of CC in coal, while Na⁺ can reduce the relative content of CC in coal, and the higher the relative content of CC in coal, the less easily is coal dust wettable. The results of the zeta potential experiment also show that there is a strong correlation between coal wettability and zeta potential with the increase of ion concentration. This study proves that the presence of ions in the water is beneficial to the improvement of the wettability of the solution, and the research results provide a theoretical basis for the optimization of mine water quality.