The coal mine is located in Chengzihe Coal Mine, Tongshan County, Jiangsu Province, on the south bank of Weishan Lake and in Liu Quan Township, 22 kilometers north of Xuzhou City. It belongs to Tongshan County Coal Company, and it was sold several times when the benefit was particularly poor in the 1990s. Later, it was taken over by Xuzhou local coal company, later renamed Tianneng Coal Group, and later sold to China Resources Group as a whole. Now it is also called China Resources Tianneng Xuzhou Coal and Electricity Company. The benefit is not good, the output is not high, and it is just a living.
As for why Chengzihe Coal Mine was later renamed as Liu Quan Coal Mine, one reason is that it is located in Liu Quan Township, and the other reason is that on June 20th, 2002, a gas explosion occurred in Chengzihe Coal Mine in Jixi, killing 124 people and shaking the whole country. For good luck, it was quickly renamed Liu Quan Coal Mine.
Lessons and Thinking of the "6.20" Extraordinary Gas Accident in Chengzihe Coal Mine of Jixi Mining Group Company
At 9: 45 on June 20, 2002, a major gas explosion occurred in the west second mining area of Chengzihe Coal Mine of Jixi Mining Group Company, causing 124 deaths, 24 injuries and a direct loss of 9848094 yuan.
First, the main cause of the accident
Chengzihe Coal Mine is a gas-rich mine, with an absolute emission of CH4 of 41.75m3/min, a relative emission of CH4 of 22.6m3/t and a coal dust explosion index of 33.5%-33.9%. KJ4 gas monitoring system has been put into use in this mine, and 22 gas sensors and 17 gas power-off instrument have been installed in three working faces. Underground gas drainage system without gas. The accident occurred in the West No.2 Mining Area, which mainly mined coal in the 3B layer and the 24th and 25th layers. 3B layer has 145 fully mechanized working face, 80 1 all-coal driving and the original 802 all-coal return air stopping down the mountain (240m).
The gas explosion occurred at the sliding door 146 meters away from the all-coal downhill air duct (the original 802 production stop lane) of 3B floor. The roadway is driven down the mountain along the 3B-layer full coal, which is constructed by drilling and blasting method and supported by bolt. The roadway section is 6.3 square meters. During tunneling at the beginning of the year, double local fans and double air ducts were used for air supply at the same time, with the air supply volume of 360m3//min, the CH4 concentration of roadway return air was 0.9%, and the absolute gas emission reached 3.24m3//min. 1 2, due to local fans stopping wind power, workers mistakenly sent electricity and cables exploded, resulting in gas burning. 1 The roadway was closed at the end of the month. After gas drainage on May 24th, the roadway was unsealed and the equipment was ready to be withdrawn. 16 in June, the mine decided to change the roadway into a temporary water warehouse of the newly put into production 145 fully mechanized mining face. By the time of the accident on June 20, the water in the roadway was 80 meters long, and the all-coal roadway above the water level was 160 meters long. Before the accident, 160m3//min was supplied with 28KW local ventilator, and 1 1KW local ventilator was used as backup. A monitoring probe is set at15m below the sliding door point of the coal roadway, and the monitoring signal can be reflected to the monitoring room in the ventilation area. After the accident, the technical investigation team of the State Council conducted on-site investigation in the disaster area, investigated and obtained evidence from 35 insiders, and dissected and obtained evidence from the underground power supply system and four power supplies. It is confirmed that the automatic transfer line of the main and standby local fans on site is disconnected, the wind power lockout is short-circuited, and the gas-electricity lockout is not connected. After full investigation and technical appraisal, it is determined that the main cause of the accident is:
1, local ventilator stops working due to gas accumulation in coal roadway. The workers in the outsourcing team sent electricity by mistake, which caused the submersible pump switch (the latch switch did not explode) to generate arc sparks, which led to gas explosion. In the process of explosion flame propagation, some coal dust in transportation roadway and 145 working face and the destroyed closed blind roadway participated in the explosion. Increase the destructive power of explosion.
2. The outsourcing team's safety management is chaotic and the outsourcing management is serious. 32 people were killed in the on-site outsourcing team in the disaster area. When the outsourcing team enters the well, there is no formal employment contract, no formal safety training, no effective safety management system, and no unified safety supervision and management for underground operations.
3, underground accident area bus electricity management confusion. The outsourcing team has no report or approval of power outage and power transmission. There are no full-time electricians in the outsourcing team, and temporary workers who don't know the knowledge of power supply often pick up electricity at will, stop sending electricity at will, and short-circuit or throw electricity at will when wind power and gas power are blocked.
4. After the key gas tunneling faces (all-coal roadways) are sealed and unsealed and reused, reliable ventilation safety measures have not been re-formulated and implemented. The coal roadway was designated as a key gas working face before the accident. The concentration of CH4 in the return air is 0.7%, and the absolute amount of gas reaches 1. 12m3/min. It is necessary to continue to manage the key gas working faces and implement special ventilation safety measures such as "three pairs and two locks".
5, flame-proof and safety protection equipment investment is not complete. On-the-spot investigation in the disaster area found that there were four temporary ventilation facilities in the production system of the 3B floor, and the quality was unqualified. There is no flame-proof facility installed at the crosscut between the 3B layer and the No.24 and No.25 coal seams. Two coal miners, three drivers and outsourcers in the disaster area did not wear self-rescuers and the team leader did not bring portable gas alarms, which expanded the scope of the disaster and increased casualties.
6. The quality of electric tongs monitoring workers is low, and they have no certificates. The three electromechanical maintenance workers of the contracting team did not know how to connect the wind power atresia and the gas power atresia, and did not receive pre-job training. There is no full-time operator in the gas monitoring room, and I don't know the report of exceeding the standard. The monitoring system showed that the gas exceeded the standard for 40 minutes, and no one observed or reported it. The maintenance man and microcomputer observed the gas monitoring records within one hour and asked him why he didn't report the gas overrun, saying that the post responsibility system was not stipulated.
Second, the lessons and reflections of the accident
Chengzihe Coal Mine "6? The "20" catastrophic gas explosion accident fully exposed the serious loopholes in the safety management of underground production mining areas, especially in employment management, power supply, gas monitoring management and so on. The multifaceted seriousness of accidents and "three violations" hidden dangers is really shocking! Through in-depth investigation, it also reveals the deep root of the hidden danger of accidents: there is a dead end in safety and measures are not implemented. Reflecting on this accident, the main lessons that should be learned are as follows:
1,160m Why did the all-coal shutdown lane stop for 42 minutes? The accident happened at the stop lane of 240m (water accumulated in the lower part of 80m) where all coal in the 3B layer of the West Second District went up the mountain, and the construction started at 200 1 and 10. It was closed in February 2002 and opened on May 24, 2002. The equipment is ventilated and emptied. Before the accident, the actual air supply was 160m3//min, the return air gas concentration was 0.7%, and the absolute gas emission was 1. 12m3/min. This is also a key area that can not be ignored, with high gas source? According to the data stored by the host computer of the mine gas monitoring system, there is a monitoring probe at a distance of 15 meters from the mine gate. The probe monitoring data shows that the local ventilator in the mine stopped running at 9: 03, and the Nevas concentration in the mine rose rapidly, from 9: 03 to 9: 01; 9: 24; At 9: 42, the gas concentration reached 65438 0.4%, 2.02% and 3.065438 0% respectively. At 9: 45, the gas concentration at the probe position reached 3.565438 0%, and the gas concentration at the explosion source position in the shutdown lane reached about 7.2%. According to experts' calculation, when the wind stops for 42 minutes, the gas in the roadway can accumulate 47.04m3, the original gas accumulation amount is 7.06m3, 160m long coal roadway, and the gas accumulation can reach 54. 1m3 when there is no wind. If we can find it early, call the police in time and take effective remedial measures, the accident may still be avoidable? But after the accident site investigation, the underground gas monitoring system didn't work? The power failure alarm didn't work? Security inspection and tile inspection "posts, nets and sentries" didn't work! Monitoring operators and underground tile inspectors failed to report to mine dispatching and mine leaders, and missed the opportunity of remedy.
2. Why does the misfire switch generate arc sparks? There is no smoking fire source such as blasting fire source, mechanical collision and falling rock friction spark in the roadway where the accident occurred. The pin switch of submersible pump in the explosion source center of drainage roadway is in the state of virtual connection and explosion damage, the local fan for air supply is interlocked with the power switch of submersible pump, and the gas electric lock is not connected. In this case, workers start the interlock switch and send electricity through the water pump switch, which is bound to generate sparks to detonate the arc? If so, the water pump power supply has achieved gas-electricity locking. Although the accumulation of Nevas in coal roadway exceeds the standard, the locking switch of water pump cannot send electricity. In fact, this accident can be avoided? If it is known that wind power and gas power cannot be blocked, but the gas is checked before power transmission, as long as the gas concentration does not exceed 1% before power transmission, the tragedy will not happen? If the workers who mistakenly send electricity are professionals who know electricity and wind, check the gas before sending electricity. If the gas concentration is above 3%, please ask the rescue team to discharge it, and if it is below 3%, the leader of the well area will command the gas discharge. The tile inspector below 2% will supply air and exhaust gas first, and then send electricity when the gas concentration drops below 1%. Will this unprecedented mine disaster disappear? As we all know, there are hidden dangers of gas and natural gas accumulation when the wind stops in mining roadway; After inspection, there are problems in the operation and technical supervision of the gas emission measures of "grading and limiting discharge". If the post responsibilities were fulfilled in advance, or the hidden dangers were completely eliminated in time, this extraordinarily serious gas explosion accident could have been avoided?
3. Why is coal dust flying involved in gas explosion? The coal seam 3B at the accident site belongs to coal dust explosion coal seam, and the coal dust explosion index is 34.82%. After the accident, the rescue team and the expert group found that there were many typical corner-shaped high-temperature overheated coal dust coking at the entrance of the upper roadway, the leading single coal pillar, the fully mechanized support at the upper part of the working face and the entrance of the lower roadway. The laboratory analysis of coal dust coke shows that the ash content of dust samples increased from 24.87% before the accident to 47.92%, the volatile content decreased from 25.9% before the accident to 65,438 07.65%, and the CO concentration in the upper corner and lower corner of the coal mining face was 3500ppm and 3000ppm respectively, which proves that coal dust not only participated in the explosion, but also increased the destructive power of the explosion. There was coal dust flying in the explosion, indicating that there must be dead corners and hidden dangers of dust accumulation in the early comprehensive dust prevention. It reflects that the daily dust prevention work in underground mine is weak, coal dust is deposited in fully mechanized coal mining pillars and belt transportation roadway, dust prevention supervision is lax, there is no detection system for excessive coal dust concentration, and there is no evaluation method for dust prevention measures.
4. Why is the security management of outsourcing team so chaotic? The contract of outsourcing team entering the well is only a verbal agreement of mine leaders! The outsourcing team entered the mining area where the accident occurred and mixed with the mining team of this mine, so there was no unified and effective safety management. When the outsourcing team enters the well to contract the working face, there is no unified and formal safety supervision on ventilation, power supply, maintenance and attendance. Underground power transmission, wind and three pairs of two brakes stop at will, resulting in gas accumulation, which can not be completely treated as soon as possible. The lessons of negligence here must be carefully learned?
5. Why are the ventilation safety protection facilities incomplete? There is 180m between the 3B layer where the accident occurred and the 24 layers of coal affected by the accident, and there is no flame-proof facility installed in the crosscut between coal seams; 145 There are four temporary ventilation facilities near the fully mechanized mining, especially all the personnel entering the well did not wear self-rescuers, and the team leader and electrical fitter did not wear portable gas alarm devices, which led to the weakening of disaster resistance and the expansion of disaster casualties. The safety debt exposed by the accident is the result of the recent economic difficulties in the coal mine. But as long as the mine leaders pay attention to the small debts of these monitoring instruments, they can be solved as soon as possible.
6.604 workers in distress how to escape safely? After the gas explosion, because the whole ventilation system and ventilation facilities in the West Second Mining Area have been destroyed, five workers of the 604 driving team and 1 tile inspector heard a muffled sound, and then a lot of fly ash and black smoke rolled in. Facing the sudden disaster, the panicked workers want to take risks to escape! However, tile inspector Zhang stopped them and instructed them to retreat to the inside of the working face, turn off the miner's lamp, take measures to save themselves and wait for rescue. After waiting for 30 minutes, the full wind pressure system gradually recovered, and the black smoke produced by the explosion gradually became scarce in the 604 driving roadway. The tile inspector led the workers to cover their mouths with wet towels and quickly evacuate the disaster area. Created an example of successful escape. If there was no tile inspector to guide the outsourcing workers to evacuate the working face and save themselves, and to avoid the peak of carbon monoxide temporarily, but to run around with black smoke, then everyone would be poisoned in the face of the disaster area environment with CO concentration as high as 3500-4000 ppm.
Three. Preventive measures for similar accidents
Coal miners, cadres and technicians must learn lessons and sound alarm bells; We should draw inferences from others, avoid delaying the opportunity, consciously and carefully investigate hidden dangers and plug loopholes. Pay equal attention to ventilation safety management, equipment and training; Adhere to the principle of "machine governance, machine governance and people governance" in gas prevention and control; Adhere to the idea of simultaneous investigation of hidden dangers of ideological paralysis and on-site accidents, make up your mind, concentrate your efforts, and fight a tough battle of "pre-prevention, comprehensive management and source control" to eradicate gas.
1, highlight the key points of prevention and control, and implement the "twelve-character" policy. Gas prevention and control in high gas coal seam and key gas working face should be listed as the top priority of safety work. It is necessary to grasp the three fundamental links of "pumping before mining, monitoring and controlling, and determining production by wind", and implement them item by item to realize comprehensive gas control measures. 3B coal seam in Chengzihe Coal Mine must be "pumped before mining".
2, relying on scientific and technological progress, improve the prevention and control equipment. Gas monitoring system must be installed in high outburst mine, and the coverage rate of monitoring probes for gas and local ventilator and throttle switch in mining face should reach100%; The cut-off rate of low biogas mine working face should reach100%; The integrity rate of underground monitoring power-off instruments and probes should reach100%; The input rate of underground wind measurement, dust measurement, tile inspection, safety supervision instruments and self-help protective devices should also reach 100%, and each coal seam in each mining area should explore the law of gas emission and formulate and implement perfect targeted measures.
3. Ensure that the main and local ventilators run frequently to achieve sufficient mining air volume. The local ventilator used underground should be powered by special power supply and equipped with variable frequency power supply, and the underground coal mining must be ventilated by full wind pressure; The local fan must be locked by wind power and gas power, and the automatic delay locking device of wind power and the remote monitoring technology of local fan stopping wind should be popularized. Any gas accumulation caused by the random stop of the main fan shall be traced and handled according to the accident.
4, strict management of blind alley, eliminate gas overrun accumulation. Mining construction is not allowed to leave an unsealed blind lane. The closing, sealing and unsealing of driving roadway must be strictly implemented. The unsealing and reuse of blind roadway at one end must first detect the gas, then discharge the gas and restore the ventilation system. As a key gas working face, it must still be strictly supervised according to the key working face.
5, strict ventilation safety training, improve the technical quality of workers. Workers should be trained in the professional safety knowledge of Mining Machinery Express in a formal and systematic way, focusing on the demonstration education of safety laws and regulations, safety practical technology, self-help, mutual rescue and safe escape in major and various accidents and disasters; Organize the demonstration education of simulated explosion of gas and coal dust, enhance the technical quality of underground workers to deal with major accidents and realize self-help, and fundamentally improve the mine disaster resistance.
6, without safety training outside the mine contractors are not allowed to enter the well construction work.