Study On Co-management Of Gas And Fire In Goaf Under Combined Layout System Of "Partial W+ High Drainage Roadway" In Lu'an Yiyuan Coal Face

When mining the spontaneous combustion coal seams of high gas mines,not only existence of spontaneous combustion of coal left over in goaf of working face,but also existing problem of gas exceeding limit in working face.There is a coupling problem between gas accumulation and residual coal spontaneous combustion in the goaf.Therefore,in order to solve the coupling problem of gas accumulation and residual coal spontaneous combustion in goaf of high gas and spontaneous combustion mine,we should start from the source of ventilation system design to achieve the goal of gas and fire co-governance in goaf.Based on the engineering background of the 150103 working face of Luan Yiyuan Coal Industry,starting from the law of gas migration in goaf and the hypothesis of spontaneous combustion of residual coal,and combining with the existing mature technical measures to control gas accumulation and spontaneous combustion of residual coal in goaf,the scheme of co-treatment of gas and fire in goaf is put forward and optimized.Through on-site detection and investigation,the law and source of gas emission in working face are analyzed;according to the lithological characteristics of the overlying strata in No.15 coal seam of one edge coal industry,the height of caving zone and fissure zone in working face is obtained through theoretical calculation and analysis;summarize the previous studies on the three zones of goaf caving zone,and get the relevant parameters of the three zones of goaf caving zone in numerical simulation.The Fluent software used to study the scheme of gas and fire co-treatment in goaf mainly includes the following contents:The optimization of ventilation system in working face:the W-type ventilation system are compared and analyzed in three dimensions,including the number of inlet and return air roadways,the air distribution ratio of two inlet air roadways and the relative position of return air roadways.It is concluded that the optimum layout of W-type ventilation system is two intakes and one return partial W-type ventilation system in the middle of the return air roadways.The coal pillar width of the return air roadways and the intake roadways I is 30m,and the air distribution ratio of the two intake roadways is 1:1.25.Layer optimization of high extraction roadway under partial W ventilation system:with the increase of the distance between the high drainage roadway and the working face,the gas control effect in the goaf is better,and the oxidation zone in the middle of the goaf be pointed by high drainage roadway is slightly lower.With the increase of the horizontal distance between the high drainage roadway and the return air roadways,the gas control effect in the goaf present“parabolic”trend,and the treatment effect is good before bad,however,there is no impact on spontaneous combustion of coal in the goaf under the difference horizontal distance between the high drainage roadway and the return air roadways.Considering the effect of drainage and the economic cost in the process of extraction,it is concluded that the high drainage roadway is arranged in the fracture zone of 35m from the vertical plane of the working face and 35m from the horizontal spacing of the return air roadway.The comprehensive management effect of gas accumulation in goaf and spontaneous combustion of residual coal in goaf is the best.Parameter optimization of"Partial W+high extraction roadway"joint layout system:(1)The mixing volume of high extraction roadway decreases with the decrease of negative pressure,but the concentration of extraction increases accordingly.Reducing the suction negative pressure began to have little effect on the drainage effect,and then the effect was significantly worse.At the same time,the width of the oxidized zone in the middle of the goaf is also reduced,which begins to decrease significantly and then tends to be gentle.After comparative analysis,the gas accumulation in the goaf and the spontaneous combustion of the coal in the goaf are the best when the negative pressure is 11kPa.(2)With the decrease of the air volume at the working face,the extraction volume and the extraction concentration of the high drainage roadway are basically unchanged.The intake air volume reduction and the return air volume reduction of the working face are about 1:1,and the return wind gas concentration in the return air roadway,the gas concentration in the upper corner and the gas concentration in the near coal wall are increase.At the same time,the width of the oxidation zone in the goaf is reduced,the initial effect is significant,and then tends to be gentle.After comparative analysis,the comprehensive control effect of gas accumulation and spontaneous combustion of residual coal in goaf is the best when the air volume is 3300 m~3/min.