Investigation And Application Of New Techniques And Air-leak Sealants For Coal Spontaneous Combustion Prevention And Extinguishment

The spontaneous combustion of coal, one of the serious disasters in coal mine, threatens people's personal safety and property seriously, affects the social stability and has been hindering the sustainable development of coal industry.The key technology of the prevention and extinguishment of spontaneous combustion in coal seam is made up of 3 parts: early predictation, precise detection of fire's position and information check of fire area. It mainly resolves following three issues: when the spontaneous combustion happens (short for "WHEN"), how badly the spontaneous combustion is (short for "HOW"), and where the position of spontaneous combustion is (short for "WHERE"). Aiming at the above three issues is paper investigated the new equipments and materials for prevention and extinguishment of spontaneous combustion of coal, which have been successfully applied to coal mines.Based on the actual scene conditions, using self-developed coal spontaneous combustion and radon measurements stand, the paper simulated the heat accumulation, air leakage conditions, granularity and thickness of floating coal, tracked and measured the variation of temperature and gas of the whole process of exothermic oxidation heating. The paper investigated and analyzed the spontaneous combustion of coal sample from Kangjiatan coal mine, Shendong mining area, and firstly proposed the term of "coal spontaneous combustion equivalent intensity". The temperature field of coal spontaneous combustion was dynamically simulated, and the value of coal spontaneous combustion equivalent intensity was determined by using MSC.NASTRAN high general finite element structure analysis software.Computational Fluid Dynamics (CFD) was firstly used at home and abroad to investigate the dangerous spontaneous combustion area in mining-out section. A mobile mine shaft fire gas beam pipe sampling system was developed independently. Based on the long-term continuous observation on the gas in mining-out section on 31401 fully-mechanized working face, the gas flow field and the air leak condition were measured by using tracing gas SF₆, thereby the moving rule of gas flow field in mining-out section and the spontaneous combustion "three areas" in mining-out section were obtained.This paper developed fire-prevention equipments and materials, which have been used in many serious spontaneous combustion mines, such as "mobile underground fire gas beam pipes sampling equipment" to overcome the difficulties in maintenance of the entire of mine beam pipe monitoring system, "ground drilling thermometer and gas sampling equipment" to overcome the difficulties in hole temperature measurement in fire area and gas information collection, "underground drilling thermometer" to measure the coal wall temperature and internal temperature in the mining-out section with no power supply, and "underground mobile fire-fighting gel pump" to provide technical support for the local fire fighting.Polyurethane elastomer (PUE) was firstly applied to mining coal roadway as air leak resistance and sealing material. On the basis of the investigation of mechanical properties of PUE, the composition of PUE and antistatic agent were determined. The reinforced and toughened PUE nanocomposite was obtained by adding surface modified TiO₂ and SiO₂ nanoparticles. The modified PUE was characterized in terms of morphology, particle size, crystal structure and thermal stability by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and thermogravimetric analysis (TGA). Its mechanical properties and flame-retardant performance were also tested. The results show that the modified PUE nanocomposites were antistatic and flame-retardant with super mechanical properties. The modified PUE was successfully applied to the mines and showed super air-leak sealing effect.