A method of caving top coal in weakened hard coal seams based on carbon dioxide blasting

Abstract

The invention belongs to the technical field of coal mining, in particular to a method for caving top coal in weakened hard coal seams based on carbon dioxide blasting. The method of the present invention is that at the top plate of the coal wall between the top beams of the two hydraulic supports, every 5 to 8 hydraulic supports are provided with drill holes for penetrating the caving coal body to reach the coal seam roof, and the carbon dioxide cracker is placed in the drill hole. In the hole, carbon dioxide is sequentially discharged according to the drilling sequence, and finally cracks are generated in the hard top coal, and the strength is weakened. After the hard top coal is weakened by carbon dioxide blasting in the present invention, the top coal discharge rate is increased by 20% to 30% compared with that before the roof cracking, the cracking effect is obvious, and remarkable economic benefits are obtained.

Description

technical field [0001] The invention belongs to the technical field of coal mining, in particular to a method for caving top coal in weakened hard coal seams based on carbon dioxide blasting. Background technique [0002] In the top-coal caving mining of hard coal seams, the outstanding technical problems encountered are that the top-coal cannot be fully broken by itself, the top-coal caving has a large degree of lumpiness, and it cannot be released from the support coal opening, resulting in a low recovery rate of coal resources. Most of the leftover coal leaves hidden dangers of spontaneous combustion and fire, which threatens mine safety. The existing methods to solve this problem are coal seam high-pressure water injection or blasting. [0003] Among them, the high-pressure water injection in the coal seam always produces cracks under the action of the support pressure, and the high-pressure water is easy to leak out along the original cracks in the coal seam (including ...

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Problems solved by technology

[0004] The blasting in the tunnel is to transport the tunnel and the return air tunnel to the top coal drilling and blasting on the working face. Since this method is a deep hole blasting, it is easy to cause the blast hole to be blocked too hard, and there will be blasting blind areas at both ends of the working face. It will affect the extraction of the top coal. The amount of work required by this method is large, and the blasting process conflicts with the belt conveyor system for transportation along the trough; the blasting weakening of the process lane fully utilizes the crushing process in which the bearing pressure can be refractured after the blasting is weakened. It achieves the purpose of reducing the lumpiness and increasing the recovery rate of the top coal, but it increases the excavation amount of the roadway, which makes the investment in the working face larger

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