Study On Numerical Simulation Of Goaf Spontaneous Combustion "Three Zones" And Nitrogen Injection Prevention Of Dahuangshan Mine

Mine fire has been an important problem in coal mine production safety work for a long time, especially in the process of mining thick coal seam, mine fire is extremely important. The main mining process of thick coal seam is mechanized mining and top coal caving, compared with other coal mining technology, this process is characterized by a large quantity of working face and a large piled high left coal and float coal of goaf. This provides a good material condition for the thermal storage of goaf coal, coupled with the impact of factors such as goaf air leakage, tendency of oxidation and spontaneous combustion of goaf coal is greatly increased. So, the research of goaf spontaneous combustion "three-zones" has a very important significance to the prevention of coal mine fire.This paper based on the.actual conditions of+735working face of Dahuangshan mine from Xinyu coal mine in Xinjiang, researches the range of+735working face’s goaf spontaneous combustion "three zones" and+735 working face’s fire prevention technology. The main contents of this paper are as follows:First of all, this paper introduces the environment characteristics of goaf, studies on the characteristics of the overlying roof of goaf and characteristics of goaf coal broken and permeability etc. Then the theory of spontaneous combustion of goaf coal and the division conditions of goaf spontaneous combustion "three zones" are introduced.Secondly, based on heterogeneity seepage continuous equation, component gas immiscible diffusion equation and the theory of porous media, describes the nonlinear flow equations and differential equations inside the goaf. Then according to the actual conditions of+735working face esTablelishes the physical and mathematical models of goaf.Thirdly, use FLUENT numerical simulation software to divide the range of+735working face’s goaf spontaneous combustion "three zones" based on goaf oxygen concentration index and air velocity index. And research and analysis the feature of goaf spontaneous combustion "three zones". In order to verify the numerical simulation results, analyzes the comparison of face field data from the beam tube monitoring system and the results of numerical simulation. It shows that:the result of numerical simulation is consistent with the results from the real side.Finally, designs the nitrogen injection process of+735working face, analyzes the variation of the goaf gas concentration after nitrogen injection. Then, the nitrogen injection of goaf spontaneous combustion "three zones" range is simulated by using FLUENT software. By comparing the variation of goaf spontaneous combustion "three zones" before and after nitrogen injection, it proves that the working face using nitrogen injection method can reduce the concentration of oxygen in the goaf and reduce the oxidation temperature width of the band, thus effectively preventing spontaneous combustion of coal in goaf.Through the study of the variation of goaf coal spontaneous combustion "three zones" of+735working face in Dahuangshan mine can provide a theoretical support for the prevention of working face goaf fire. Thus can ensuring the safe and efficient conduct of coal mining work.