[Procedures] Article 353 In the solid coal of the mining face of high gas and prominent mines, deep hole pre-cracking controlled blasting of more than 10 m for increasing coal body cracks and loosening coal bodies may be used. The secondary coal mine permits the use of explosives and develops safety measures.
[Executive Note] In order to prevent the occurrence of deflagration, it is necessary to use a water-type coal mine permit explosive, strictly limiting the single-hole charge. Before the mine allows the use of the millisecond detonator, it must be inspected beforehand. The layout of the blasthole, the depth of the blasthole, the amount of charge, and the order of initiation must be strictly enforced. Since there is coal slag in the blasthole and is affected by the ground stress, when the blasthole drill pipe is pulled out, the hole is drilled by the boring tube, and the depth of the blasthole is recorded, and the quantity and length of the charge are determined. . In order to ensure the reliability of the interval charge of the elongated drug roll or the continuous charge detonation, it is necessary to lay a permitted detonating cord for the coal mine along the entire length of the hole in the blasthole. The length of the blasthole seal is subject to the provisions of Article 359 of the Regulations. Blasting strictly enforces the "one gun and three inspection system" and the "three-person chain blasting system." Before blasting, the blaster must do a full resistance check on the electric blast network. In order to prevent the delay from protruding, wait at least 20 minutes after blasting before entering the work surface. There must be safety protection measures such as evacuation, power outage, warning, long-distance blasting, and reverse damper. After the pre-splitting blasting of the mine mining face, the operation is stopped for 4-8 hours. The evacuation and blasting distance are determined according to the degree of outstanding danger, generally not less than 200m, and the evacuated personnel should be in fresh airflow.
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