Research On Inert Gas Diffusion Law In Goaf Of Large Inclined Workingface

The coal seams with large dip angle in China are mainly distributed in Sichuan,Gansu,Xinjiang and other western regions.With the increasing depletion of coal resources in the eastern mining areas of China,the focus of coal mining in China is shifting to the western region,and the proportion of mining coal seams with large dip angle is also increasing.Because of the large dip angle and thickness of coal seam,and the large amount and uneven distribution of coal in the goaf,the fire prevention and extinguishing work in the goaf is more complicated,so it is particularly important to adopt the reasonable prevention and control technology of coal spontaneous combustion in the goaf under the condition of Stratified Mining in the thick seam with large dip angle.In this paper,from the point of view of space inerting prevention and fire fighting in goaf,the distribution of inert gas in goaf with large dip angle is studied when N₂ and CO₂ are injected,so as to determine the best process parameters for inerting effect,which has certain guiding significance for the prevention and control of coal spontaneous combustion.In this paper,Dongxia coal mine of Huating Coal Industry Group Co.,Ltd.in Gansu Province is taken as the research object.Based on the research of predecessors,the spatial distribution pattern of goaf with large dip angle is analyzed briefly.Based on this physical model,a similar simulation experiment platform for inert gas injection in goaf with large dip angle is built.The way of combining physical simulation and numerical simulation is adopted to study the large dip The variation rule of O₂ concentration and distribution rule of inert gas in goaf when inert gas is injected into goaf of angle working face.The results show that the distribution of N₂concentration along the strike of the working face is approximately L-shaped in the range of the floor when N₂ is injected.The farther away from the working face,the wider the width of N₂ influence is;in the vertical height,along the strike direction,the distribution of N₂ concentration presents a"inverted trapezoid"distribution with high width,low width and narrow.When pouring CO₂,within the range of the floor,the concentration of CO₂ is approximately distributed in a"trumpet"shape,and the trumpet is the pouring port;in the vertical height,from the air inlet to the return air lane,the influence height of CO₂ is gradually increasing,but the maximum influence is 12m from the floor.According to the basic characteristics of 37121-1 working face in Dongxia coal mine,this paper analyzes the factors of coal spontaneous combustion in the goaf of34121-1 working face,combined with the migration and distribution law of inert gas in the goaf with a large angle of inclination,puts forward a combined inert gas fire prevention and control scheme of injecting CO₂ in the air inlet side and N₂ in the air return side,which can prevent and control the coal spontaneous combustion,and obtains nitrogen injection in the air return side by means of numerical simulation When the flow rate is 200 m³/h and the depth of buried pipe is 60m,when the flow rate of CO₂ injected into the air inlet side is 600 m³/h and the depth of buried pipe is40m,the effect of goaf inerting is the best.This thesis contains 36 figures,12 tables and 85 references.