Method for extracting top coal gas during fully-mechanized top coal caving period of extra-thick coal seam

Abstract

The invention relates to the technical field of coal mine gas extraction, and discloses a method for extracting top coal gas during a fully-mechanized top coal caving period of an extra-thick coal seam. The method comprises the following steps of (1) designing bedding directional long drilling parameters: designing the bedding directional long drilling parameters according to coal seam occurrence conditions and firmness coefficients; (2) conducting directional drilling construction, specifically, conducting bedding directional long drilling on the coal seam before working face stoping, connecting a pipeline to a hole opening, and the pipeline is connected with negative pressure extraction equipment; (3) crushing the top coal: repeatedly supporting and extruding the top coal by a bracket of a stope face to generate cracks in the coal seam, and continuously desorbing the gas in the coal seam; and (4) conducting top coal caving: during the top coal caving period, a large amount of gas rushes to the top of the working face and is continuously pumped out through a drill hole. The method solves the problem that a large amount of desorbable gas generated in the coal caving period cannot be effectively extracted in time through a coal seam roof high-position drilling hole or a high drainage roadway, the desorbable gas instantly flows into the working face, so that the gas of an upper corner or a return airway exceeds the limit.

Description

technical field [0001] The invention relates to the technical field of coal mine gas drainage, in particular to a method for extracting top coal gas during fully mechanized top coal caving in extra thick coal seams. Background technique [0002] During the production of fully mechanized top-coal caving in high gassy thick coal seams, especially in the early stage of mining, it is difficult to control gas. During the recovery period of the mining face, a large amount of gas generated by top-coal caving pours into the working face, resulting in problems such as gas exceeding the limit in the upper corner , seriously affecting the safe recovery of the working face. [0003] In order to solve the above technical problems, the method adopted in the prior art is: [0004] (1) Pre-extraction of coal seam gas before mining: Drain the coal body within the effective range of the extraction radius through the drainage borehole, promote the transformation and release of the adsorbed ga...

AI Technical Summary

Problems solved by technology

[0009] The present invention intends to provide a method for extracting top-coal gas during fully-mechanized top-coal caving in extra-thick coal seams, so as to solve the instantaneous influx of a large amount of desorbable gas generated during the coal-caving period when high-level drilling on the roof or high-level drainage roadway cannot be timely extracted The problem of gas exceeding the limit in the upper corner or return airway caused by the working face