Present situation and development of disaster prev

The coal industry is an important basic industry related to the national economic lifeline, and coal is the main energy in China. In 2004, the proportion of coal in China's primary energy production and consumption structure accounted for 75.6% and 67.7% respectively. During the Tenth Five Year Plan period, China's coal output has increased from 1.38 billion tons in 2001 to 2.19 billion tons in 2005, with an average annual growth of 202 million tons, ensuring the needs of economic and social development and supporting the rapid development of the national economy. At the same time, the rapid growth of the national economy has also driven the rapid development of the coal industry. The state attaches great importance to coal mine safety production. The 81st executive meeting of the State Council specially studied coal mine safety production. The meeting pointed out: "the coal industry is also a high-risk industry, with high gas and gas outburst mines accounting for about half, and coal mine safety is the top priority of the whole industrial safety production work." In 2005, the number of disasters and accidents in coal mines nationwide has dropped to 3306, with 5938 deaths and a mortality rate of 2.81 million tons, falling below 3 for the first time. From 2001 to 2004, coal mine accidents and deaths accounted for 30% and 40% of the total number of industrial and mining enterprises in China. China's coal output accounts for 31% of the world's total output, but the number of accident deaths accounts for 79%. There is a big gap in the level of safety production. The severe situation of coal mine safety production is also manifested in serious occupational hazards. As of 2002, more than 580000 cases of pneumoconiosis have been detected nationwide, accounting for about 49% of the coal industry

I. overview of coal mine disasters

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China's coal mines have poor natural conditions and complex geological conditions. The mainland of China is formed by the convergence of many small plots in multiple episodes, and the main coal fields have undergone multiple stages, multiple directions and strong transformation. The geological conditions of the coal field are complex, and there are many associated real disasters. Coal mines in China are all mines with gas emission, and the annual gas emission of coal mines in China is more than 10billion cubic meters. Among the key state-owned coal mines, high gassy and outburst mines account for 49.8%, and the coal output accounts for 42%; Coal mines with coal dust explosion risk accounted for 87.4%; 51.3% of the coal mines have the risk of spontaneous combustion; Coal mines with complex or extremely complex geological conditions account for 36%, and those with simple geological conditions account for 23%; 27% of coal mines have complex or extremely complex hydrogeological conditions, and 34% are simple ones. Under such complex geological conditions, coal mines in China, especially gas mines, are prone to disasters. A systematic analysis of a large number of disasters and accidents in China's coal mines shows that roof and gas accidents are the main types of disasters and accidents in China's coal mines. Tile accident has become the "first killer" of coal mines, and the frequency of roof accidents is the highest

taking the data of 2005 as an example, the number of roof accidents accounted for 52.9% of the total number of disaster accidents, and the death toll accounted for 33.3% of the total death toll of accidents. Gas accidents are the most harmful and dangerous. In 2005, the number of gas accidents accounted for 12.13%, but the death toll reached 36.5%; Gas accidents account for 59% of the major accidents with more than 3 deaths; In a major accident that killed more than 10 people, 69% of the accidents were caused by repeated accidents; Since the founding of the people's Republic of China, among the 22 particularly serious accidents with more than 100 deaths, 20 were gas and coal dust accidents, accounting for 91% and 94% of the accidents and deaths respectively. Therefore, the prevention and control of gas disasters and accidents is the top priority of coal mine safety work

the average mining depth of coal mines in China increases by 10 ~ 20 meters every year. With the increase of mining depth, the in-situ stress, gas pressure and ground temperature are also higher and higher, the threat of coal natural disasters is gradually increasing, and the difficulty of governance is also increasing. The gas pressure of coal seams increases by 0.1 ~ 0.3 MPa on average every year, and the absolute gas emission increases by about 1.5 billion cubic meters every year. For example, the proportion of high gas and outburst mines in 45 key monitoring enterprises increased by 10% in 2005 compared with 2004. The absolute gas emission of Huainan mining area increased from 473m3/min in 1997 to about 1000m3/min in 2005. In recent three years, three mines have been upgraded to outburst mines. In addition, the number of Mines threatened by rockburst and heat damage has also increased. 102 mines have experienced rockburst to varying degrees, and more than 70 mines have been threatened by heat damage

with the transformation of the economic growth mode of the coal industry, great changes have taken place in the production mode and structure of coal mines. The degree of mechanization of production has been greatly improved, and the degree of centralization of high-yield and high-efficiency mine production has been continuously enhanced. This new production mode also has some new safety problems. The gas emission of the mine increases, and the dust intensity of the mining face increases sharply, which puts forward higher requirements for the reliability of the mine ventilation system. In other words, the change of natural conditions of coal mining and the progress and change of production technology will constantly put forward new and higher requirements for coal mine safety assurance technology. According to the actual needs of coal mine safety production, with the support and guidance of the state, during the "Ninth Five Year Plan" and "Tenth Five Year Plan", scientific and technological breakthroughs focusing on gas prevention technology have been carried out, and a series of scientific and technological achievements have been achieved. It has laid a good foundation for the prevention and control of coal mine disasters

Second, the progress of coal mine safety technology

the development of China's coal mine production is inseparable from the progress of coal mine safety technology. The progress of coal mine safety technology continues to support the progress of coal mine production technology and the improvement of production level, and plays an important role in providing reliable energy security for the development of national economy. With the support of the national development and Reform Commission and the Ministry of science and technology, the former Ministry of coal industry, the State Administration of coal industry and the State Administration of work safety have successively organized scientific and technological breakthroughs in coal mine safety technology during the ninth five year plan and the tenth five year plan. Giving full play to the overall advantages of the General Academy of Coal Sciences, China University of mines and other colleges and universities, scientific research institutes and coal mining enterprises in the demonstration mining area, we have carried out scientific and technological research in the mines affiliated to Pingdingshan Coal Industry Group Co., Ltd., Yangquan Coal Industry Group Co., Ltd., Furong Mining Bureau and Huainan Mining Group Co., Ltd. by combining production, study and research. In line with the purpose of combining the construction of gas disaster control demonstration mines with the key technology research of coal mine safety, and focusing on the actual needs of gas disaster prevention and control in the two mining areas, the "comprehensive supporting and key technology research for improving coal mine safety" was carried out in Pingdingshan Mining Area during the "Ninth Five Year Plan". During the Tenth Five Year Plan period, "Research on prevention and monitoring technology of major gas and coal dust explosion accidents in mines" was carried out in Huainan mining area. Through scientific and technological research, the first is to establish two gas comprehensive treatment technology demonstration projects, "Pingdingshan mining area" and "Huainan mining area"; The second is to focus on some key technologies that restrict the safety production of coal mines, and study and solve the key technologies of gas prevention, fire prevention, mine ventilation, dust control and emergency rescue with common significance

a series of achievements have been made in scientific and technological research during the ninth five year plan. In the aspect of gas prevention and control technology, the prediction method of gas emission in fully mechanized mining face is established, so that the prediction accuracy reaches 85%; Breakthroughs have been made in goaf gas drainage and gas control technology in the upper corner. Magnesite soil drainage pipe specially used for goaf buried pipe drainage and a monitor for real-time monitoring of CH4 and CO concentration in the drainage pipe have been successfully developed, and the control indicators of CH4 and CO concentration when safely draining goaf gas have been proposed. The successful research can not only effectively drain goaf gas, but also control natural ignition process technology and supporting equipment. The gas extraction rate in the goaf will reach 7%, and the number of gas overruns will be reduced by 89%; After treating the gas in the upper corner, the developed series of fans and extraction devices can reduce the gas in the return air by 27% and increase the output of a single shift by 50%; For the first time, the prediction technology of coal and gas outburst area has been studied and achieved preliminary results. According to the characteristics of gas geology, in-situ stress and outburst coal, combined with geophysical exploration technology, the prediction and prediction of outburst risk areas in new levels, new mining areas and new areas have been realized. In the two mining areas actually applied, the predicted area of non hazardous area reaches 63% and 52% respectively, the prediction accuracy of non hazardous area reaches 100%, the quantity of measures is reduced by 89%, and the mining speed is increased by 13.5%; In terms of outburst prevention technology, great progress has been made in the outburst prevention measures and equipment of mining faces. A portable outburst prevention drill has been successfully developed, a breakthrough has been made in the complete set of presplitting blasting technology of mining faces, and geophysical exploration technologies such as geological radar and electromagnetic radiation have been successfully used to monitor the outburst structure in front of tunneling work, providing a means for the implementation of outburst prevention technology and outburst prediction technology; Major breakthroughs have been made in gas drainage technology and equipment. The construction technology of directional long drilling and powerful drilling rig have been successfully developed, and 603.5m rock horizontal long drilling and 865m coal seam horizontal long drilling have been successfully constructed, providing technology and equipment for gas drainage in adjacent layers. The test and Research on the gas drainage technology of high gas drainage roadway are successful, and the powerful drilling machine and gas drainage technology along the coal seam suitable for the high gas soft outburst coal seam are successfully studied. In the outburst coal seam, the borehole with a depth of more than 100m and a maximum depth of 239.6m is successfully drilled along the coal seam. Therefore, the gas pre drainage rate of this coal seam is greatly improved, reaching 28.8 ~ 32%, which provides a powerful technical means to solve the problem of prevention of coal mining face and reduce the amount of gas emission

through the scientific and technological breakthrough of the tenth five year plan, the comprehensive gas control technology has further developed. In terms of coal and gas outburst area prediction technology, measuring the wear resistance of coherent cemented carbide adopts the gas geological method, and establishes a new gas geological method for gas outburst area prediction of multi-scale (mine outburst area and working face Outburst Zone) integrated with multi technology (digital seismic exploration, radio wave perspective and structural soft coal logging curve identification) combining gas geological theory and geophysical exploration technology. The core technology of gas enrichment detection is established, which is composed of 3D3C seismic technology, AVO technology, seismic inversion technology, seismic attribute analysis technology, chimney dust emission concentration display value of 8mg/nm3~10mg/nm3 seismic waveform classification technology, etc. Using the method of geo dynamic zoning, the influence of active structures and rock mass stress on outburst is determined, and the stress rise area, stress decrease area and stress gradient are divided. It lays a foundation for highlighting the division of danger zone, threat zone and safety zone. Using electromagnetic wave perspective technology, the technology and equipment for detecting coal seam gas disaster prone areas have been successfully developed, and the database of electromagnetic wave reflection and absorption characteristics and the identification system of geological abnormal bodies have been established

in the aspect of dynamic prediction technology of coal and gas outburst, the continuous monitoring technology and equipment of outburst risk in working face based on dynamic gas emission law, AE acoustic emission principle and electromagnetic radiation principle are studied respectively. The continuous prediction indexes such as the dynamic emission of gas per ton of coal, the variation coefficient of gas emission and the maximum rate of gas emission after blasting are established 30 minutes after blasting in coal roadway excavation, which realizes the dynamic prediction of gas in blasting face and provides a new method and technology for outburst prediction technology. A set of technical equipment for AE acoustic emission monitoring of outburst has been developed. Through the ways of noise prevention, noise isolation, noise simulation, noise filtering and effective AE signal extraction, the noise filtering technology has made a breakthrough. AE acoustic emission technology including sensors has been studied, which provides a means for the prediction of gas dynamic disasters. By continuously monitoring the signal intensity and pulse number of electromagnetic radiation produced in the rheological failure process of gas bearing coal and rock and their changes, the relationship between electromagnetic radiation and the influencing factors of coal and gas outburst and rockburst is revealed, and the combination of critical value method and dynamic trend method is proposed