Research and application of high gas coal seam air leakage control technology based on polymer material cross-linking mechanism

In order to alleviate the problem of corner gas accumulation caused by air leakage in goaf of high gas coal seam. The rapid film-forming sealing material for the corner wall and the grouting sealing material for the corner roof were developed and optimized, and the' plugging-injection' combined air leakage sealing scheme was proposed. Orthogonal test was used as the research method, and the 12 h and 24 h decay rate, gel viscosity, and setting time of the blocking film were used as the research indexes to screen out the optimal ratio of the materials. The engineering test shows that: (1) 1.5% sodium alginate solution and 7.5% calcium chloride solution can be sprayed in turn to quickly form a plugging film and stick to the corner wall; (2) 2.5% polyvinyl alcohol, 0.6% borax and 0.5% thickener were mixed into water and stirred to obtain polymer plugging slurry. (3) According to the monitoring results, the gas concentration of each monitoring point decreased by more than 62% after using the plugging material, and the gas concentration in the upper corner decreased by 67%. The air leakage decreased by more than 50%, and the upper corner decreased by 57%. The air leakage blocking program composed of these two new materials can effectively reduce the accumulation of gas in the corner, reduce the probability of gas protrusion accidents in the coal face, and ensure the safe mining of the coal face.