The distance between the mining air duct and the excavation head meets the requirements of the operating regulations: the air supply of the air duct must meet the requirement that the air supply volume per person must not be less than 4 cubic meters per minute; The allowable airflow velocity in the tunnel is 0.25-4m/s; In the air intake of the working face, the oxygen concentration shall not be less than 20% and the carbon dioxide concentration shall not exceed 0.5%. The hanging of the telescopic air duct should be flat, straight, tight, and stable, and it must be hung on every ring; The air duct interface is tight (feel airtight at a distance of 0.1m from the joint), without any cracks or reverse joints, and the air duct joint and reverse edge meet the requirements. The air duct joint should be connected using an air duct connector. Check whether the distance from the air outlet of the air duct to the front meets the requirements of the operating procedures, and whether the air volume of the working face is sufficient; Check whether the suspension of the air duct is flat, straight, tight, and stable, and whether it must be hung on every ring; Whether the interface of the air duct is tight (feel no air leakage at a distance of 0.1m from the joint), whether there are cracks, and whether there are reverse joints.
Measures to prevent spontaneous combustion of coal seams in positive and negative pressure air duct mining working face:
1. There is a dedicated person in the working face to inspect the composition and temperature changes of gas and goaf gas, as well as whether the positive and negative pressure air ducts are tight. If the oxygen content decreases, the carbon dioxide in the tunnel air duct increases and carbon monoxide appears, the production of carbon monoxide gradually increases. The manufacturer of the negative pressure air duct can analyze that there may be spontaneous combustion changes.
2. The mining sequence is from the boundary of the mine field to the direction of the wellbore, starting from mining up the mountain and then mining down the mountain.
3. After returning to the pillar, the top plate should collapse in a timely manner. If the collapse is not sufficient, it must be filled tightly with yellow mud in a timely manner.
4. According to the actual mining situation in our mine, the coal mining method is backward mining, with a mining height of 2 meters, without any loss of top or bottom coal, and it is not allowed to leave coal pillars.
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