Numerical Simulation Study On Spontaneous Combustion Characteristics Of Residual Coal And CO₂ Fire Prevention And Extinguishing Technology At High Gassy Mine In Yangmei Wu Coal Mine

Aiming at the problem that gas extraction in high gas mines will lead to the increased risk of natural ignition of coal relics in the mining void area.The paper takes the 8419 working face of Yangcoal Five Mine as the background,and studies the law of gas production and parameters of spontaneous combustion characteristics of coal samples from 15#coal seam from both theoretical and experimental aspects,and divides the"three zones"of spontaneous combustion in the mining area based on the oxygen content and temperature in the mining area of 8419 working face,so as to confirm the validity of simulated spontaneous combustion.Based on the validity of the"three zones",and using the numerical simulation method,we study the influence of gas extraction and CO₂ injection on the spontaneous combustion"three zones"in the mining area,and research the best gas control conditions and reasonable CO₂ injection anti-fire prevention technology.Through the low temperature oxidation test of coal,the indicator gases of 15#coal were determined as CO,C₂H₄ and C₂H₂,and the corresponding characteristic temperatures were obtained and analyzed,and the expressions of the relationship between oxygen consumption of coal,heat generation and its temperature were obtained.Through the analysis of field measurements,it is concluded that the area 40-84m from the working face is the oxidation zone range on the inlet side of the mining area,with a width of 44m,and the area 32-60m from the working face is the oxidation zone range on the return side,with a width of 28m;using the field data to verify the feasibility of the numerical simulation of spontaneous combustion"three zones",the oxidation zone range in the mining area is"V"-shaped distribution,and the oxygen concentration on the inlet and return wind side matches with the field data;the minimum advance speed is 1.58m/d.Numerical simulation method is used to obtain the influence law of air volume conditions and gas extraction parameters on the spontaneous combustion"three belts"in the mining area.The air volume decreases,the width of the oxidation zone decreases,and the air supply to the working face can be reduced appropriately under the premise of meeting the requirements of gas control;the extraction flow of the low extraction lane has less influence on the distribution of the oxidation zone in the mining area;the increase of the flow of the high extraction lane increases the width of the oxidation zone on the return wind side,and the extraction flow of the high extraction lane is235-280m³/min as appropriate.The influence law of CO₂ injection on the spontaneous combustion"three zones"in the mining area was analyzed by numerical simulation.The range of oxidation zone in the extraction area is effectively reduced after CO₂ injection,and the optimal location of injection effect is 40m in the depth direction of the extraction area on the inlet side,and the optimal flow rate of injection effect is 1080m³/h.The low temperature CO₂ has a better effect on reducing the range of oxidation zone.The research results can provide guidance for similar working faces in Yangcoal Five Mine,optimize gas extraction parameters,provide the best parameters for CO₂ injection,create a safe and good working environment,promote production and realize carbon sequestration,which is in line with the current low carbon economy and circular economy development model advocated globally.The Article has 45 images,17 forms,and 92 bibliographies.