Mine fire hazards and preventive measures
Coal mine fire hazard to mine production and safety of workers mainly in the following aspects.
(1) The underground space is small, the mine ventilation and roadway communication are complicated, and the air supply is limited. When a fire occurs, the personnel evacuation will be limited by the underground environmental conditions. (2) There are a large number of inflammable materials everywhere in the coal mine. The fire is easy to spread and spread. The high-temperature fire smoke will form a new fire source at the air-mixing site when it is mixed with fresh air current. (3) Produce a large amount of high temperature flames and harmful gases, causing casualties. Fire can produce a large number of toxic and harmful gases, such as CO, CO2, etc. These gases flow into the underground working sites along with high-temperature fire smoke, causing poisoning and suffocation. (4) Cause gas and coal dust explosion. Mine fires not only provide heat sources for gas and coal dust explosions, but also cause downhole combustibles (coal, wood, etc.) to release explosive gases such as H2 and other hydrocarbons due to the retorting of fire. Therefore, the fire will cause gas and coal dust explosions, further expanding the disaster and casualties. (5) Fire burning equipment and coal resources. In the event of a fire in the underground, due to improper fire-fighting measures or delays, the fire-fighting opportunity is often missed, and the fire is enlarged, which will burn a large amount of equipment, equipment and coal resources. Sometimes closing the fire zone will also cause some equipment to be lost in the fire zone for a long time, resulting in a large amount of coal resources sluggish and affecting the normal production of the mine. (6) The fire reversed the downhole wind and caused the disaster to expand. After the mine fire occurs, the air flowing through the high-temperature thick smoke changes and the temperature rises. Fire and wind pressure is generated in the well. On the one hand, the wind pressure changes the total air volume of the mine, and on the other hand, the direction of the wind flow in the mine ventilation network changes, so that the flow of the flue gas is out of control, causing the ventilation system to be disordered, further expanding the scope of the disaster area, and allowing more underground personnel to be affected. The poisoning of fire smoke, at the same time, brings great difficulties and dangers to the safe evacuation of underground mines, increasing the difficulty of accidents and the difficulty of fire fighting and disaster relief.
2 Mine fire prevention measures
2.1 Prevention of fires outside the mine
The characteristics of external fires are: sudden occurrences and rapid development. If they cannot be discovered and controlled in time, they often lead to major accidents. Among the total number of mine fires, the proportion of external fires is small (4% to 10%), but it cannot be ignored. According to statistics, more than 90% of major malignant fire accidents recorded in China are caused by external fires. It is very necessary to do a good job of preventing fires outside the mine. The specific measures are as follows:
(1) All personnel are prohibited from carrying tobacco and ignition tools to the well. It is forbidden to use electric stoves and light bulbs for heating. Electric welding, gas welding and torch welding are not allowed in the underground and wellhead rooms. In special cases, safety measures must be formulated and reported to the relevant departments for approval. Within 20m of the wellhead room and the ventilator, there shall be no fireworks or heating with a stove. (2) Gasoline, kerosene and transformer oil are not allowed to be stored underground. Lubricants for downhole use, cotton, cloth, and paper must be placed reclosable iron tub. Used to be sent to the ground for regular processing. (3) Explosion-proof or intrinsically safe electrical equipment must be used in the underground to strengthen maintenance, ensure good performance of power system and electrical equipment, ensure the normal operation of mechanical equipment, and prevent accidents caused by electric spark, arc and friction heat. (4) Strengthen the management of firearms and use safe explosives. It is not allowed to dump the flame-retardant powder in the medicine roll. It is not allowed to put out the guns and cannons. It is not allowed to use open flames and power lines. The blasthole seals should be filled and used. Water cannon mud; strictly according to the regulations, charging, connecting and shooting. Avoid firing flames. (5) Use non-flame retardant cables, flame retardant conveyor belts and flame retardant air ducts in accordance with regulations. (6) Non-combustible materials shall be used for wellhead houses, derricks and wellhead buildings, inlet shafts, return shafts, flat rafts, joints of main roadways, main dikes and underground substations. Excavated in the rock lane. (7) Fire doors should be installed at the inlet and outlet air inlets to prevent fires at the wellhead and nearby ground fires from reaching the well. Fire doors shall be provided at the joints between the intake shaft and the downhole yards at all production levels, and the quality and flexibility of the fire doors shall be checked regularly. (8) The mine must have a fire material warehouse within 100m of the wellhead. Fire protection materials warehouse should be set up in the main transportation lanes of each production level, and fire-fighting equipment should be reserved. Fire-fighting trains are also available. Fire-fighting materials and tools must meet the needs of the mine when it is extinguished, and it is not allowed to be used for other purposes. The underground gunpowder warehouse, charging chamber, winch room, pump house and mining substation must be equipped with sufficient fire-fighting equipment. (9) Each mine shall construct a ground fire pool. In the lower level of the mine, in addition to the ground fire pool, the upper level of the water tank can also be used as a fire pool. Fire water pipes shall be laid in all major roadways in the underground, and fire faucets shall be provided at regular intervals.
2.2 Prevention of fires in mines
Internal fire refers to coal under certain conditions, such as broken coal pillars, coal walls, concentrated floating coal, and a certain amount of air supply, physical and chemical changes, oxygen, oxidation, heat, heat accumulation caused by fire The fire formed.
The occurrence of internal fires is often accompanied by a process of gestation that can be detected early on according to the signs. However, due to the hidden source of fire, it often occurs in goafs or coal pillars that people can hardly enter. It is difficult to find the source of fire accurately. Therefore, it is difficult to extinguish, so that the fire can last for several months, years, or even as long as 10 years. Sometimes the scope of combustion gradually spreads, burning a lot of coal and freezing a lot of resources. According to statistics from 1985, the amount of coal frozen due to fire has accumulated to nearly 60 million tons.
According to statistics, in China's integrated and key coal mines, mines with natural fire hazard account for 46% to 49% of the total number of mines, and natural fire coals account for 60% of the total recoverable coal seams. According to the statistics of 1953-1984, the number of internal fires accounted for 94% of the total number of mine fires. Therefore, the internal fire is of course taken seriously by people and has become the focus of research.
Measures to prevent fires in mines involve all aspects of coal mine production: (1) Reduce the risk of fire and prevent spontaneous combustion of coal. In terms of mining technology, it is necessary to correctly select the mine development method, coal mining method and mining procedure, rationally arrange the mining area, and do not arbitrarily extract the specified inter-section and interval coal pillars to improve the innate fire prevention capability of mines with natural fire hazard coal seams. . In terms of ventilation technology, it is necessary to select a reasonable ventilation method, correctly set up facilities to control airflow, adopt equal pressure fire prevention measures, and strengthen ventilation and fire management to reduce air leakage, which plays an important role in preventing coal from spontaneously generating fire. Preventive grouting, injection inhibitor, inert gas, etc. (2) Master the signs of natural fire, timely forecast the fire, and eliminate the natural fire in the “emergence†stage. (3) All kinds of fire hazards left over from the mining production process should be dealt with in a timely manner, such as strengthening the disposal of used roads, filling coal roads in time, and timely processing high temperature fire points.
2.3 Apply new technology and new equipment to improve fire prevention capability (1) Apply automatic fire alarm device. The application alarm system can accurately detect the abnormal state and provide information to the maintenance personnel through processing, so that the hidden danger of the fire can be eliminated in the bud. (2) Actively carry out research on the mechanism and law of occurrence and development of mine fires, continuously research and develop mine fire alarm equipment, fire extinguishing equipment and escape equipment; make mine electrical fires prevent, monitor and save three aspects, and realize three-dimensional prevention and control measures .
3 Fire prevention and control techniques in different locations
(1) Fire at the wellhead building. When a fire occurs in a building at the entrance of the wind inlet, measures to prevent the intrusion of fire gas and flame into the well should be taken: immediately reverse the air flow or close the fire door at the wellhead, and if necessary, stop the main fan; guide the personnel according to the provisions of the mine disaster prevention and treatment plan Out of the well; quickly extinguish the source of fire. (2) Fire in the wellbore. In the event of a fire in the intake wellbore, in order to prevent fire gas from intruding into the downhole roadway, measures must be taken to reverse the wind or stop the operation of the main ventilator. (3) Fire at the bottom of the yard. When a fire occurs in the bottom of the intake shaft and the adjacent chamber, the wind must be reversed or short-circuited to ensure that the fire gas does not invade the work area. When a fire occurs at the bottom of the return air well, the normal wind direction should be maintained. Under the premise that the combustible gas does not accumulate to the explosion limit, the air volume entering the fire area can be reduced. Mine rescue personnel should use the maximum manpower and material resources to directly extinguish fires and prevent the spread of fire. In order to prevent the concrete raft and the raft above the roadway from burning, you can set a water curtain by drilling or breaking on the raft. If the expansion of the fire jeopardizes key locations (such as wellbore, gunpowder, substation, pump house, etc.), the main manpower and material resources are used to protect these locations. (4) Fires in the underground diverticulum. If there is a fire in the diverticulum and there is no fire door in the diverticulum, the wind barrier should be used to control the wind, water, fire extinguisher, high-fold foam or sand to extinguish the fire. (5) Fire in the inclined roadway. When a fire occurs in a sloping air intake roadway, measures must be taken to prevent fire gas from intruding into the place where people work, especially the coal mining face. For this reason, measures such as wind current short circuit and partial wind back, regional wind reversal can be taken. (6) Fires in stone gates and other horizontal roadways. When there is a fire in the roadway, stone gate and other horizontal roadways in the mine or one wing main wind tunnel, the most effective ventilation method (reverse wind, wind current short circuit, multi-zone double-zone anti-wind, normal ventilation, etc.) should be selected so that Save people and put out fires. When preventing short-circuit ventilation by expanding the fire, make sure that the harmful gases in the fire do not reverse. (7) Fire in coal mining face. In the event of a fire in the coal mining face, it is generally necessary to extinguish the fire under normal ventilation. It must be done: fire extinguishing from the inlet side, and fire extinguishers and dust pipes should be used effectively. When the coal face of the steeply inclined coal seam is on fire, it is not allowed to extinguish the fire above the fire source to prevent the water vapor from injuring people; it is also not allowed to extinguish the fire under the fire source to prevent the collapse of the fire area from injuring people. From the side (ie, the working face or the goaf), use the protective platen and the protective cover to extinguish the fire from the fire source. When it is difficult to achieve the effect on the wind side, it is possible to take a partial wind back and extinguish the fire from the return air side, but a water curtain should be set on the air inlet side and the personnel should be evacuated. When the coal mining face returns to the wind tunnel, an effective method must be taken to prevent gas emission and accumulation in the goaf. When the above method is invalid, it should be insulated by an isolation method and an integrated method. (8) A fire in a single lane. In the event of a fire in a single lane, it is necessary to actively extinguish the fire while maintaining the normal ventilation of the local ventilator. To maintain the original ventilation of the single roadway, that is, do not open the fan when it stops running. Do not blindly stop the fan, and take measures after reconnaissance.
Flyknit Machine,Shoe Knitting Machine,Vamp Knitting Machine,3D Flat Knitting Machine
Zhejiang Fengfan NC Machinery Co., Ltd. , https://www.ffknittingmachine.com