Study On Spontaneous Combustion Mechanism And Prevention In Fully Mechanized Caving Mining Gob With Steeply Inclined And High Gas

With the constant increase of the aging and mining depth of some mining areas in our country, the conditions for the exploitation of coal mining become more and more complex. Therefore, it is necessary to adopt the steeply inclined coal seam, high gas and deep mining. According to statistics, in our coal resources, the reserve volume of steeply inclined coal seam accounts for4%of the total coal reserves, and80%of the mining areas in the southern regions exist steeply inclined coal seams. When it comes to the mining method, to increase the mining intensity and production, some steeply inclined mines explore to adopt the fully mechanized caving mining. However, it results in the increase of spontaneous combustion risks in the gob because of the intense mining, obvious caving height, many residual coals and serious problem of leaking air. The paper study on the problem of spontaneous combustion in the fully mechanized caving mining gob of steeply inclined high gas. And it combines the actual site to find out effective measures to prevent and control this problem.In the first place, if you want to prevent coals from the spontaneous combustion, you should conduct a study on its tendency of coals. The paper not only analyzes the limitations of our current appraisal methods, but also puts forward the way of combining the thermoanalysis technology and theory of activation energy. In addition, it also adopts the combination of the thermogravimetry, infrared and mass spectrometry, uses the model function of dynamic mechanics, gives an overall analysis of the low temperature oxidation reaction ability and oxidative pyrolysis process of coals, confirms the indication gas, characteristic temperature, solves the activation energy and at last analyzes the tendency of the spontaneous combustion of coals.With regard to the fully mechanized caving face of the steeply inclined high gas which has the tendency of spontaneous combustion, you should make a deep analysis of the gas movement law in the flow field of the gob. This thesis aims at the characteristics of this flow field of the gob, uses the theory of porous media and establishes the mathematical model of three-dimensional anisotropic flow field in the gob. The gas flow in the gob complies with the Darcy’s law, continuity equation and momentum equation. Moreover, you should combine the CFD technology to confirm and optimize the transmission coefficient in the gob, analyze the hydrodynamic dispersion phenomenon of the gas composition and its mechanism, establish the hydrodynamic dispersion equation of the gas composition in the gob and then do the simulation towards the flow field of the gob.When it comes to the spontaneous combustion monitoring of coals, the paper proposes to combine the thermometry and analytic method of the mark gas, achieving complete, rapid and accurate monitoring and control by the optimization of monitoring process, measuring-point arrangement and monitoring indexes, etc.And for the division of three zones in the gob, it integrates the distribution characteristics of coals in the gob of the fully mechanized caving face of the steeply inclined high gas with the factors of the division. Then it puts forward the classification index of "three zones" of the spontaneous combustion and confirms their distribution trends and characteristics there.At last, it determines the measuring and controlling parameters of spontaneous combustion in the gob by means of simulations, experiments and field tests and brings forward effective synthesis technique of the fire prevention and extinguishing. Especially in the condition of regulation of the dynamic air, it makes the calculations of air volume coupling against the gas and fire. Then you can take technical measures such as the gas extraction and nitrogen injection against fire to control irreconcilable conflicts. In addition, this paper also makes the analysis and simulation of the related technical parameters of gas extraction and nitrogen injection against fire and the effects on "three zones" in the gob, ensuring the safety of the gas and fire in the steeply inclined high gas mine. And it acquires preferable application effects after the practice.