Division And Prevention Technology Of Spontaneous Combustion Dangerous Area In Fully Mechanized Mining Face Of Qinan Coal Mine

As China’s main energy,coal provides a huge driving force for China’s economic construction,and the dominant position of coal resources as the energy structure will not change for a long time in the future.Mine fire is one of the main disasters of coal mining in China.With the increase of mining depth,the ground temperature also increases,and the probability of spontaneous combustion of residual coal in goaf is also increasing.This paper takes 6₁44 working face of 6₁ coal seam in Qinan Coal Mine as the engineering research object.Through the identification of 6₁44 working face coal samples,it is concluded that the spontaneous combustion tendency of 6₁ coal seam is class II spontaneous combustion coal seam,and the shortest ignition period is 60 days.Through the oxidation temperature rise experiment of two coal samples at different positions of the working face through the programmed temperature rise system,it is determined that the natural ignition index gas of 6₁44 working face is mainly CO,supplemented by C₂H₄,C₂H₆ and C₃H₈.According to the site characteristics of 6₁44 fully mechanized mining face in Qinan mine,the on-site air extraction and temperature measurement system is arranged.Embedded bundle pipes and temperature measuring optical fibers are used at the side of air inlet and return roadway,and air extraction bundle pipes and thermocouples are alternately arranged at 120,100,80 and 60 frames of working face to monitor the gas composition and temperature at different depths of goaf.According to the oxygen concentration value and temperature change law in the test results,the distribution range of"three zones"in the goaf of 6₁44 working face is divided into:heat dissipation zone:0～13m,oxidation zone:13～118m,suffocation zone:more than 118m.According to the divided"three zones"of spontaneous combustion,it is calculated that the minimum advancing speed of the working face to prevent spontaneous combustion in goaf is2.95m/d.Combined with the distribution law of"three zones"in the goaf and the production conditions of the working face,the risk of spontaneous combustion in the goaf of 6₁44working face is evaluated based on the set pair analysis theory.The evaluation results show that the risk of spontaneous combustion in the goaf is not high,but it does not rule out the goaf fire caused by negligence of management or loopholes in monitoring.Therefore,it is proposed to establish a working face prediction system Nitrogen injection fire prevention and extinguishing technology and isolation wall plugging technology at the inlet and return air corners are used as the fire prevention and extinguishing system of this working face.The results show that nitrogen injection and isolation wall in goaf can effectively reduce air leakage,reduce the width of oxidation zone and prevent coal spontaneous combustion.The research and application of fire prevention and extinguishing technology in 6₁44fully mechanized mining face ensure the safety of mining,and provide reference for the fire prevention and extinguishing design of other working faces in coal seam 6₁.Figure[38]Table[13]Reference[74]...