Method for taking out and picking high gassy seam group dislodging gob-side entry retaining Y type ventilated decompression firedamp

Abstract

The invention relates to a highly gassy coal seam group mining gob-side entry retaining Y-shaped ventilation and decompression gas extraction method. The invention is characterized in that: free desorption gas which comes from an adjacent decompression layer and is gathered into a roof plate decompression crack ring and a bottom plate decompression crack ring through crack channels which are formed by mining affection on roof plate coal seam and strata and bottom plate coal seam and strata is extracted in a gob-side entry through an upward extraction gas drill hole which is arranged inside the roof plate decompression crack ring and a downward extraction gas drill hole which is arranged inside the bottom plate decompression crack ring in a roof plate decompression area and a bottom plate decompression area of a gob-side entry retaining gob of a coal face of a primarily extracted coal seam of a highly gassy coal seam group. The highly gassy coal seam group mining gob-side entry retaining Y-shaped ventilation and decompression gas extraction method solves the problem of low extraction rate of the highly gassy low permeability coal seam group, simultaneously solves the ultralimit problem of airflow gas of spatial angles and return airways on the coal face of the primarily extracted coal seam of the highly gassy coal seam group, and realizes extraction utilization of high concentration gas and highly efficient and safe extraction of the highly gassy coal seam group without coal pillars.

Description

Technical field: [0001] The invention relates to a method for safe production of coal mines, and more specifically to a method for pressure-relief gas extraction in the goaf area and roof and floor overlying coal seams of the protective layer of the high gas coal seam group. Background technique: [0002] Anhui Huainan mining area is located in the hinterland of East China and is an important coal energy base in my country. The proven coal seams are soft, low-permeability and high-gas coal seams, with gas reserves reaching 592.8 billion m 3 . The mining area is rich in coal resources, with a large number of mineable coal seams. The coal seams are rich in gas and have poor gas permeability. As mining goes deeper, it becomes more and more difficult to control gas. According to statistics, the amount of gas emitted from the goaf of the first mining face in coal seam mining accounts for more than 60% of the amount of gas emitted from the face. Most of the gas emission in the goaf com...

AI Technical Summary

Problems solved by technology

The problems of this arrangement are as follows: First, rock roadways need to be arranged near the bottom of the coal seam. The length of the rock roadways on the floor is basically the same as the length of the working face. there is no time to lay out the floor rock alley

Therefore, it is impossible to construct boreholes to extract gas from the lower adjacent coal seams.

Second, in the case of the rock roadway adjacent to the coal seam floor at the lower part of the construction, the gas drainage drilling through the bed is usually pre-constructed in the floor roadway. Due to the small effective range of gas drainage in the original coal seam drilling with low permeability, the pre-drainage rate Low; at the same time, low-permeability coal seams are relatively soft, the boreholes are easy to collapse, the porosity rate of the drainage boreholes is low, and the gas drainage effect is poor

Therefore, for the lower working face of the protective layer of the gas-rich coal seam, the gas problem during the mining of the protective layer working face has not been fundamentally resolved.

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