A new gas extraction technique for high-gas multi-seam mining: a case study in Yangquan Coalfield, China

As mining depth increases, the gas content and pressure of the coal seams increase, and gas emissions from the coal face are significantly higher than those at shallower locations. This is more likely to occur in high-gas multi-seam mines and can result in fatal gas disasters. Therefore, extracting multiple seams with high methane content frequently requires implementing highly efficient methane extraction technique. Yangquan Coalfield, China, was selected as a case study, theoretical analysis on the evolution law of mining-induced overlying strata fracture was conducted, similarity model test was used to determine the gas enrichment areas, the results indicate that the distressed gas in the multi-seam is enriched in high-level and low-level area, based on the gas zoning enrichment law, a technique for coordinated extraction of the distressed gas in the high-gas multi-seam mining is proposed, and the high-level drilling holes are arranged to extract the gas in the high-level enrichment area, while low-level drilling holes are arranged to extract the gas in the low-level area; after the coordinated proposal was implemented, the workface was advanced faster, and coordinated extraction technique can also be used under other conditions for high-gas multi-seam mining.