A Gas Drainage Method for Layered Mining of Extra-thick Coal Seam

Abstract

The invention relates to a gas extraction method for layered mining of an extra-thick coal seam, and belongs to the technical field of coal mine gas extraction and treatment. The method comprises thesteps that a mining roadway, adjacent to a last mining layered working face of a last mining section, of a section to be mined is used for gob-side entry retaining, and a high negative pressure extraction pipe and a low negative pressure extraction pipe are laid; bedding drilling holes are constructed, hole sealing is carried out, the bedding drilling holes are connected with the high negative pressure extraction pipe in a lap joint mode, and the bedding drilling holes are used for pre-gas extraction before coal mining and pressure relief gas extraction during extraction; multi-layered sharinglarge-diameter drilling holes are constructed, protected by casing pipes and connected with the low negative pressure extraction pipe in a lap joint mode, gas extraction is carried out in a goaf, andthe multi-layered sharing large-diameter drilling holes are used as nitrogen injection drilling holes to inject nitrogen into the goaf so as to prevent and extinguish fire in the goaf. The gas extraction method realizes multiple purposes of one lane, replacing of the lane with a hole and multiple purposes of one hole, the engineering quantity of the gas treatment construction is reduced, the gasextraction effect of layered mining of the extra-thick coal seam is improved, the effective governance of the gas emission of layered mining of the extra-thick coal seam is achieved, and economical benefits are remarkable.

Description

technical field [0001] The invention belongs to the technical field of coal mine gas drainage and control, and relates to a gas drainage method for layered mining of extra-thick coal seams. Background technique [0002] Coal is one of the main energy sources that meet people's needs for production and life. The high-quality development of the coal industry is necessary for the sustainable and healthy development of my country's national economy. my country's extra-thick coal seams (thickness greater than 8m) are rich in reserves, which is the high-quality development of the coal industry. Quality development provides resource guarantee. In the mining of extra-thick coal seams, due to the large thickness of the extra-thick coal seams, the gas content in the coal seams is relatively high. Already over 20m 3 / t, gas control becomes more difficult. [0003] Gas drainage is the main means to effectively solve the gas gushing in extra-thick coal seam mining. For the gas drainag...

AI Technical Summary

Problems solved by technology

For the gas drainage involved in the layered mining of extra-thick coal seams, due to the large thickness of the coal seam, high original gas content, and low gas permeability of the coal seam, it is difficult to pre-extract gas from the coal seam before mining, and it takes a long time for the drainage to meet the standard; Influenced by layered pressure relief and gas gushing, the amount of gas gushing out from the working face and the gob area is large, and the difficulty of gas control is further increased

During the gas pre-extraction of the working face, due to the particularly large thickness of the coal seam, the gas drainage method of drilling along the bedding is often ineffective, and the gas drainage method of drilling through the floor through the bed requires a large amount of drilling work and high construction costs; During gas drainage, due to the large amount of gas emission in the working face and goaf, the effect of buried pipe drainage is poor, and the management and control is difficult, and the cost of pipeline laying is high (repeated laying of each layer). Hole extraction method can only be applied to coal seam first layer mining

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