Method for cleaning coal powder at sealing section of gas extraction drill hole

Abstract

The invention discloses a method for cleaning coal powder at a sealing section of a gas extraction drill hole. A coal mine underground compressed air system is utilized and connected with a gas injection pipe, so that the gas injection pipe can better blow the coal powder in a sealing area; a gas inlet of a gas suction pipe is matched with a nozzle of the gas injection pipe, the blown coal powdercan be sucked to the maximum extent, the coal powder enters a coal powder storage tank through the gas suction pipe, and water mist can be in contact with the coal powder quickly and wrap the surfaceof the coal powder; meanwhile, under the action of liquid nitrogen mist, the water mist on the surface of the coal powder is condensed quickly, the descending speed of the coal powder is increased, and the coal powder is enabled to settle to the bottom of the coal powder storage tank quickly; and a device for cleaning residual coal powder in the sealing section of the gas extraction drill hole canmove in the gas extraction drill hole, so that the coal powder at all positions in the drill hole is cleaned. Therefore, the method has the advantages of being good in coal powder cleaning effect andhigh in efficiency; and meanwhile, in the cleaning process, the dust cannot affect the roadway operation environment, air leakage after drill hole sealing can be reduced, the gas extraction effect isimproved, and wide practicability is achieved.

Description

technical field [0001] The invention relates to a method for cleaning residual coal powder in a borehole, in particular to a method for cleaning coal powder in the sealing section of a gas drainage borehole. Background technique [0002] The sealing quality of boreholes for underground gas drainage in coal mines is one of the important factors that determine the effect of drilling gas extraction. Field investigations found that if a large amount of coal powder remains in the sealing section of gas drainage drilling, the possible consequences are as follows Aspects: ①The pulverized coal in the borehole hinders the normal insertion of the sealing device, and when there is too much pulverized coal, it may even cause the sealing device to fail to insert into the designated position; The space inside and outside the borehole forms an air guide channel, which greatly reduces the sealing quality of the borehole. The existing methods for cleaning the drilled coal powder mainly incl...

AI Technical Summary

Problems solved by technology

High-pressure water injection can solve the coal dust cleaning of non-near-horizontal drilling holes in hard coal seams, but for soft coal seams, under the action of high-pressure water, there will be negative effects, that is, the soft coal bodies around the drilling holes will collapse when they encounter water, resulting in drilling failure

The method of high-pressure air injection has the following problems when cleaning the drilled coal powder: ①The coal powder at the position of the high-pressure air outlet is blown up and settles nearby, eventually forming a wavy line of coal powder accumulation, the farther away from the drill hole, The worse the cleaning effect of coal dust is; ②When the high-pressure air is injected, the fine coal dust will flow out of the drill hole, forming dust in the roadway, polluting the working environment in the roadway, and seriously endangering the health of coal miners

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