Three dimensional gas drainage technology and its application in slicing face of coal mine
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Abstract
In order to solve the problem of gas overrun in the upper corner of working face or return airway in the process of sublevel mining under slicing mining, based on the analysis of gas control requirements of coal mining face, the three dimensional gas drainage technology is developed, which includes pre-drainage of surface wells, bedding drilling in working face, surface well drainage in mining area, high-level drilling drainage and gas drainage in mining area in goaf.According to the prepared reserves, workable reserves and different periods of coal mining, the implementation method and technical system of continuous comprehensive three-dimensional gas drainage are put forward.The technology has been applied to Yuecheng Coal Mine in Jincheng of Shanxi Province.The test results show that: after adopting the optimized layout of comprehensive three-dimensional gas drainage, the average gas drainage amount of surface wells in mining area is 11 500 m3/d, and the average gas concentration is 44.5%, when the working face is pushed near the surface wells, the pure amount of gas drainage increases significantly, and the total amount of gas drainage of surface wells in the mining stage is about 2 455 000 m3; at the same time, the average extraction concentration of single hole in the underground high-level borehole is 80.61%, the average extraction pure quantity is 1.33 m3/min, the average operation time is about 60 days, the average total amount of gas extracted by single hole is 116 500 m3; the average pure flow rate of gas extracted from buried pipes in the mining stability area is 0.29 m3/min, and the total amount of gas extracted is about 2.008 million m3.Under the three-dimensional linkage gas drainage measures, the gas concentration in the return airway is less than 0.50%, the average decrease of gas concentration in the return airway is 58.8%, and the average decrease of gas concentration in the upper corner is 56.0%, which ensures the safety of coal mine production.
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