Countermeasures and basic principles for preventin

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Countermeasures and basic principles for the prevention and control of spontaneous combustion in coal mines

1. Extend the natural ignition period

according to the characteristics of layered mining, implement centralized production, speed up the promotion speed, and take preventive measures based on flame retardancy to extend the natural ignition period

(1) inject water into the first coal seam

(2) control grouting by pre drilling shallow holes and dense drilling within 20m of two layers and two lines of 2, 3 and 4

(3) the grouting pipeline is embedded in the mining line, and the centralized grouting is carried out after the working face is properly pushed and mined, such as impact, adjusting the distance (generally 40m) such as zero, lifting, falling, pressurization, decompression, pump start, pump stop, etc. on the flat plate of composite materials

(4) within the range of 30m within the mining line and 30m outside the stoping line, the inhibitor shall be spread all over the working face. After the stoping of the working face is completed and sealed, the engineers and developers can make correct decisions on the utilization of their products and the raw materials and processes adopted in production

2. Take measures on plugging

(1) optimize the ventilation system to reduce ventilation resistance

(2) the first layer of layered mining is paved with metal to ensure the quality of grouting, which is conducive to roof regeneration and reduce air leakage

(3) after the mining of the working face is completed, it shall be sealed in time. Within 5m around the two sides and the roof, it shall be sealed by injecting gel

(4) inject slurry with high concentration into the goaf to improve the sealing quality

(5) inject gel near the fault and broken coal seam to block the air leakage channel

3. Improve the layout of roadways

(1) promote pillar free mining, and protect the pillar by injecting the stable isolation zone generated by gel into the goaf

(2) layered roadways are overlapped to eliminate hidden dangers

(3) when excavating the layered roadway, try to dig through at one time to shorten the time of air leakage in the goaf caused by local fan pressurization

(4) the centralized connection roadway of the working face is changed from the outer layout of the working face to the inner layout, which gradually shrinks with the pushing and mining of the working face, and finally eliminates the roadway pillar passing through the coal seam section

(5) parallel ventilation is implemented in mining areas and layered working faces

(6) replace wooden shed support with section steel support

(7) the air inlet and return tunnels in the mining area shall be arranged in the rock as far as possible; If it is arranged in the coal seam, the roadway must be anchored and sprayed or arched, and the middle must be filled with incombustible materials or filled with gel

4. Increase the intensity of pressure equalizing fire prevention and extinguishing

through the optimization of the ventilation system, reduce the pressure difference between the inlet and return air sides of the goaf, which usually takes vehicle weight reduction as the marketing selling point, so as to prevent the development and spread of spontaneous combustion

5. Actively promote new technology

using gel plugging method, the gel has good heat resistance, easy to control the setting speed, and the formed isolation layer is elastic, not easy to break, and has strong heat insulation. It has received good results in field application

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