Application study on complex wetting agent for dust-proof after gas drainage by outburst seams in coal mines

After gas drainage, the outburst seam is dry and, consequently, during subsequent mechanized mining, unwanted dust production is extensive. Because the hard dustfall typically has a small particle size it contains a high percentage of respirable dust. Considering these factors, this paper improved the efficiency of dustfall by reducing the surface tension of the liquid used as a wetting agent, then configuring five kinds of wetting agents by adopting various doses and types of surfactants, neutral inorganic salts and chemical additives, etc. After purchasing DA-85 and SRJ-1 wetting agent, the surface tension and critical micelle concentration of seven kinds of wetting agents were measured using the capillary rise method. Wetting agent A was confirmed to have the best comprehensive effect. The experiments were optimized by measuring and comparatively analyzing contact angles of pure water, SRJ-1 wetting agent and wetting agent A on the surface of different coal samples using a contact angle measurement instrument (HARKE-SPCA). By comparative analysis, dust-proof effects of seam, dynamic pressure water infusion and high-pressure spray in the tunneling face at the Daning coal mine using pure water, wetting agent SRJ-1and A, it was determined that after using wetting agent A, the average dust concentration in the place of the mining machine driver, 10 m and 110 m away from the tunneling front is approximately 300 mg/m3, 240 mg/m3 and 100 mg/m3, respectively. This practice increased the dust-proof efficiency dramatically and achieved a good comprehensive dust-proof effect.