Study On The Influence Of High Drainage Roadway Drainage And Nitrogen Injection On "three Zones" Of Spontaneous Combustion In Goaf

When the mine gas and the coal seam spontaneous fire disaster occur under the same condition,there is the risk of gas explosion,which seriously threatens the safety of personnel.For the underground mining of high gas and easy spontaneous combustion coal seam,the gas concentration is usually controlled by the method of gas extraction from high roadway along the strike,but the gas extraction from high roadway will cause the increase of air leakage in Goaf,in order to provide sufficient oxygen for spontaneous combustion of coal in Goaf,nitrogen injection into Goaf is widely used in mine as one of the measures to prevent spontaneous combustion of coal seam.In order to further study the effect of nitrogen injection on the prevention and control of spontaneous combustion in Goaf under the conditions of high extraction roadway and extraction,on the basis of 40203 working face of Xiaozhuang Coal Mine,by means of field data collection and theoretical analysis,the mathematical model of Goaf is established and the relevant parameters of porous medium in Goaf are determined,and the"three zones"of coal spontaneous combustion in 40203 working face are divided and simulated.By using numerical simulation method,the influence of negative pressure and location of extraction on spontaneous combustion"three zones"in Goaf is studied,the influence of the location of nitrogen injection,the depth of buried pipe and the flow rate of nitrogen injection on the three zones of spontaneous combustion in Goaf is studied,with the increase of the distance between the high extraction roadway and the return roadway,the oxidation zone in the air inlet side of the Goaf becomes narrower,the oxidation zone in the air inlet side moves towards the working face,the oxidation zone in the air inlet side becomes narrower,and the oxidation zone in the air inlet side moves towards the Goaf.?2?with the increase of the negative pressure,the distance between the oxidation zone and the working face increases,and the change rate decreases gradually.The influence of the negative pressure on the position of the"three zones"of spontaneous combustion is slightly greater than that on the width.?3?with the increase of the distance between the nitrogen release port and the working face,the distance between the oxidation zone and the working face increases first and then decreases,and the width of the oxidation zone increases gradually,the distance between the oxidation zone and the working face increases gradually,the width of oxidation band is increasing.?4?with the increase of the buried pipe depth,the distance between the oxidation zone and the working face in the air inlet side of the Goaf increases at first and then decreases,and the width of the oxidation zone increases gradually,the width of oxidation band is also increasing.?5?with the increase of the flow rate of N₂,the oxidation zone in the air inlet side of the goaf becomes wider gradually,and the distance between the oxidation zone and the working face does not change obviously.The paper provides a strong support for the technical parameters of high-pumping roadway and nitrogen injection in the prevention and control of spontaneous combustion in Goaf of Xiaozhuang coal mine.