Development and application of a new compound wetting agent for coal seam water infusion

Abstract

To improve the dust-suppression effect of water infusion in coal seams, a compound wetting agent was developed as a water infusion additive by using the synergistic effect between various surfactants and surfactant compounding with inorganic salts. Firstly, single factor experiments were conducted to select three surfactants with good wettability from nine surfactants by taking surface tension and contact angle as research objects. Then, the critical micelle concentration (CMC) of surfactants was selected as the concentration of the compound solution and the three selected surfactants and two inorganic salts were then mixed. The optimum ratio of the new compound wetting agent is 0.1% wt% rapid infiltration T +0.1 wt% OA-12% +0.1 wt% NaCl by comparing the surface tension and contact angle of various compounds in solution. Finally, the wettability of the compound wetting agent was obtained by coal dust settling and low-field nuclear magnetic resonance (L-FNMR) experiments. The results imply that the compound wetting agent can significantly improve the coal dust settling velocity to 18.38 mg/s, and increase the wetting rate of coal pore water. The test indicates that the new compound wetting agent can improve the dust removal efficacy of water infusion. The average water content increment in a water-infused coal seam with the new compound wetting agent is about 2.33%, and the dust reduction rates of total dust and respirable dust are increased from 63.6% and 67.5% to 89.2% and 91.6%, respectively. The new compound wetting agent exerts significant dust reduction effect on the N1105 fully mechanized coal mining face in the Yuwu Coal Mine.