Study On Spontaneous Combustion And Prevention And Control Technology Of Coal Seams Group Mining In Shendong Mining Area

For Shendong mining area of shallow buried easy spontaneous combustion of coal seam group mining,coal seam group of multiple mining power easy cracks,caused the surface and coal seam of goaf formed complex air leakage passage,and traces of goaf coal spontaneous combustion risk problem,and the laboratory experiment,numerical simulatio n,field test,the method of combining in shallow buried easy spontaneous combustion of coal seam spontaneous combustion prevention and control technology research group of mining,It is of great significance to the prevention and control of spontaneous combustion in shallow coal seam group.The main research results are as follows:Move through the traces of working face coal transport,distribution and fracture similarity simulation experiment,it is concluded that:22 after coal mining,rock formations b reak with12 coal seam,mobile and tilt phenomenon,12 coal caving original heritage coal caving again,almost all traces of 22 of roof coal caving in 22 coal mined-out area floor,central goaf coal accumulation is more.The coal pillar in goaf gradually formed shear cracks,and the layered cracks far away from the working face were gradually compacted,and shear cracks became the main channel of air leakage.With the advance of the working face,the height of cracks gradually increased,and when the working face advanced to 190m,the vertical cracks penetrated through the surface.According to the three-dimensional air leakage law test of mined-out area of shallow coal seam group prone to spontaneous combustion,the main air leakage sources in mined-out area are surface air leakage,interlayer air leakage,air leakage in this layer,and air leakage in the surrounding small kiln.The surface air leakage and interlayer air leakage have become the main air leakage sources for natural combustion of mined-out residual coal.At the same time,gas extraction,the change of surface atmospheric pressure and the increase of air supply in working face aggravate the risk of spontaneous combustion of coal.Through the temperature programmed experiment of low temperature oxidation of coal,it can be concluded that the gas production of different main coal seams in Shendong mining area in low temperature oxidation stage changes exponentially with the change of temperature,and the indicator gases of natural ignition of coal seam are CO,C₂H₄ and C₂H₂,and the characteristic temperature of corresponding gas generation is obtained.The auxiliary analysis index parameter of natural ignition in No.12 coal seam of Shangwan coal mine is C ₂H₆,the auxiliary analysis index parameter of natural ignition in No.22 coal seam of Bulianta coal mine and No.31 coal seam of Shigetai coal mine are C₃H₈,C₂H₆,CO/CO₂.Experimental results show that the critical oxygen concentration of shendong coal spontaneous combustion is 8.0%.Shangwan mine,mine fill lianta mine,Shigetai mine coal sample the shortest natural firing period is 33,35,39 days respectively.A four-level warning system for spontaneous combustion of coal in Shendong mining area is established and the prevention and control measur es of spontaneous combustion at each level are put forward.Through numerical simulation and field test,it is concluded that with the increase of the air supply volume of the working face,the heat dissipation zone,oxidation heating zone and suffocation zone of the gob move to the deep part of the gob as a whole,and the scope of the spontaneous combustion danger zone in the gob increases.Through the research on the evolution process of mining cracks,the three-dimensional air leakage law,and the natural ignition characteristics of the shallow-buried coal seam group that is easy to spontaneously combust,a technical system of spontaneous ignition prevention and control strategy of"Prediction,plugging and oxygen isolation,rapid tunneling,inerting and cooling"is established under the mining conditions of short-distance thick coal seams.This system effectively prevents spontaneous combustion of coal in Shendong mining area.In Bulianta coal mine of Shendong,the comprehensive fire prevention measures,such as three dimensional grouting plugging air,nitrogen injection and wind control,have been implemented to effectively prevent the spontaneous combustion of coal in Shendong mining area with good results.The study of spontaneous combustion prevention and control technology in shallow coal seam group mining is of great significance to spontaneous combustion prevention,fire control under complex mining conditions,and safe and efficient mining.