The rate of release of the coal from the falling coal depends on the gas content, structure and particle size of the coal. The smaller the particle size, the faster the gas is released; the larger the particle size, the slower the gas emission rate. It can be seen from Fig. 1 that the gas generated during the blasting process often has a peak on the curve, and the gas escaping during the armoring process maintains a high concentration. At this time, it is a critical moment for controlling the gas emission abnormality of the heading face, slightly Be cautious, it will cause gas to accumulate. Therefore, in order to fundamentally prevent the occurrence of gas accidents, we have carried out the whole process of the shooting and armoring process on the basis of strengthening local ventilation, monitoring and monitoring and personnel management. 1 Strengthen local ventilation The high-quality and reliable supply of wind to eliminate the potential danger of gas concentration in the time and space is the fundamental way to control the abnormal gas emission in the heading face. (1) The double-fan dual power supply must be installed in the driving face. The local ventilator and the excavation working face electrical equipment must be equipped with wind power lockout and manual re-powering. The mining power supply must be separated. (2) The local ventilator should be assigned a special person (part-time), and be listed and managed to ensure normal operation. Each class is assigned a special person to inspect and test once, and it can be automatically switched and used normally. It is strictly forbidden to stop the fan and disconnect the air duct. (3) The air cylinder must adopt anti-static and flame-retardant air cylinders, and hang straight without cracks and joints. (4) The wind tunnel of φ600mm or more is used for the excavation working face above 10m2 and the key management area of ​​the gas, and the φ500mm air duct is used for other excavation working faces. 2 Strengthen supervision and inspection and blasting management The effective supervision and inspection of the in-depth blasting process is an important guarantee for the gas emission abnormality in the excavation working face and the safety of the tunneling face. (1) The blaster implements a time control card system. From the release of the guns and explosives to the assembly of the medicine, the fixed shots, the shooting, the inventory and other physical conditions, fill in the time control card, go to the work area after the well, the work area will be three shifts after the control card is collected The department will record and prepare for inspection. If the parameters are not in accordance with the actual conditions, the blaster shall be punished according to the “three violationsâ€. (2) Strengthen the supervision and inspection of shooting. The safety inspectors are required to be responsible for the whole process of the firework, strictly implement the signing system for the acceptance of the safety supervision personnel; the safety supervision and supervision personnel are supervised to supervise the entire process of shooting, and the gunners are not allowed to put drugs and fire without the approval of the safety supervision personnel. (3) All coal and semi-coal rock roads are promoted to use wind coal drills to avoid eye accidents caused by the use of electric coal drills, and the power gas discharged from wind coal drills increases the ability to dilute gas at head. (4) Dedicated storage for blasting items. A standard gunpowder storage chamber with a door lock is built outside the cannoning distance of the excavation face, and the explosives box, detonator box, special gun box, gun mud box, water gun mud box, gun gun, and gun busbar are stored inside. The blasthole layout and shooting system are suspended. (5) It is strictly forbidden to work in parallel with other processes in the tunneling face. Before the cannon is fired, the high-pressure air duct must be used to clean the coal dust and high-concentration gas in the blasthole. Blasting must be carried out before and after shooting, dusting, dust removal, "one shot three inspections", "three insurance" system, and there are records to check. (6) It is strictly forbidden to blast the blasthole, bare and short busbar without sealing mud or insufficient mud. The blasting must use water cannon mud. The remaining blastholes outside the water cannon are filled with clay mud. When the depth of the blasthole exceeds 1.3m, the mud mud mud sealing volume should not be lower than 40cm. The water cannon mud is filled with yellow mud mud, but the minimum seal length is not less than 20cm. 3 Do a good job of gas emission abnormality during the whole process of armoring As shown in Fig. 2, in the normal ventilation condition of the head, compared with the main wind flow, the thickness of the bottom wall of the near wall in the wind vortex area is sufficiently large, and a large amount of accumulated gas is formed in these parts, so the armoring process governs the gas. The key to the abnormality is to eliminate or reduce the vortex area of ​​the head and the air outlet of the air duct. In order to effectively discharge the gas and coal dust generated during the armoring process, the distance from the air duct to the head is not less than 5m, so as to increase the gas diffusion coefficient or strength of the bottom wall area and disperse the accumulated gas. A high-pressure remote spray is installed at a distance of 3m from the air outlet of the air duct and 0.5m from the side of the air duct to enhance the turbulence of the wind flow, increase the ability of the wind to clear the gas, and also play a good dust-reducing effect. After taking these measures, the effect of accumulating gas in the vortex area is shown in Table 1. 4 Strengthen gas inspector and gunner management "Equipment and management are equally important. At present, it is necessary to strengthen management." This is the principle of safe production in coal mines. Ezhuang Mine is equipped with KJ66 coal mine safety monitoring system. Gas, wind speed and local fan opening and closing sensors (with gas over-limit power-off function) are installed in all excavation faces. At the same time, gunners, mobile electric fitters and engineering techniques are required. Personnel and other wells must carry a portable gas alarm. The gas inspector measures the gas concentration in the heading face every 2 to 3 hours, increases the gas monitoring range in time and space, and effectively prevents the road surface from being accidentally caused by the abnormal danger in the gas. Focus on key management of gas inspectors and gunners. Implementing “adding people, increasing quantity, increasing responsibility, and raising wages†to gas inspectors, increasing personnel, and marking the key areas of gas in the area; increasing the workload and realizing inspections of flood prevention facilities along the route; increasing responsibilities and realizing the placement of guns and other staff through supervision and inspection and anti-working illegal punishment; to increase salaries and improve treatment adapted to their responsibilities. Implementing "double test, double test, double supervision, double responsibility" for the gunners, double test, attendance at the work area, and dispatching attendance at the work station (hanging the plaque); double pipe, work area management, shooting work, piece rate, and defense Professional management of the gunman's regular operation and the gunner's allowance; double supervisors, safety supervisors, gas inspectors to supervise and inspect the gunners; double responsibility, the gunners bear the management of the guns, "one shot three inspections" work. Aiming at the changing law of gas emission from the working face of the blasting machine, the above countermeasures were taken to comprehensively control, and good results were obtained, which eliminated the hidden dangers of the accident and provided strong support for the safe excavation of the excavation face. 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Gas comprehensive treatment technology for gun excavation face
The mine field was affected by the East-West fault, which caused the minefield to sink deep and was affected by geological movements. The inclination of the formation to the oblique axis is gentle, and the strong permeability of the surrounding rock reduces the permeability of the surrounding rock, which is conducive to sealing more gas. With the deepening of the mining depth of the Ezhuang Mine, most of the excavation mining roadways are close to or in the oblique axis, and the gas concentration in the blasthole is 40% to 60%. After the blasting of coal , a large amount of adsorption gas in the coal body is rapidly converted into free gas release, and the gas concentration reaches a maximum at 4 to 5 minutes, which seriously threatens the full production of the mine.