Research On Gas Disaster Control In Goaf Of Spontaneous Combustion Coal Seam In Deep Mine With Roof Cutting And Self-retention

With the increase of coal intensification,many mines have gradually entered the stage of deep mining.However,compared with shallow mining,deep mining will face many new thorny problems,such as the"three highs"impact of high ground stress,high gas,and high ground temperature.The amount of gas gushing out increases,at the same time,the high temperature of the deep well,the increase of the air volume of the working face,and the gas drainage,etc,they increase the air leakage,and the risk of coal spontaneous combustion in the goaf is higher.Therefore,deep mining will face the dual challenges of preventing and controlling gas and spontaneous combustion of residual coal.For this reason,it is necessary to pay more attention to the impact of compound disasters,however,the prevention and control measures of compound disasters are mutually restrictive,and it is easy to fall into the difficult problem of taking care of one and losing the other.In order to effectively and reasonably prevent and control the problem of gas control in deep working faces under spontaneous combustion coal seams considering the prevention and control of coal residues in gobs,this paper takes the 110 method of Zhujixi Coal Mine as an example,theoretical analyses and summarizes the mutual influence relationship and prevention mechanism of gas and coal spontaneous combustion disasters,as well as the multi-field coupling influence relationship of various specific prevention and control measures in goafs.So the paper takes the prevention of spontaneous coal seam gas disasters as the main focus,on this basis,the joint prevention and control of gas and coal spontaneous combustion disasters was studied,a mathematical and physical model of the goaf was constructed,and the porosity,permeability coefficient and gas emission source item were compiled using software.Using the above model,COMSOL software is used to analyze different air volume ratios in the working face,different drainage volumes and layers in high-level drilling,different drainage distances and drainage volumes in the tail buried pipe,inert gas injection volume,when the control measures such as the drainage volume of the return air corner buried pipe and the inert gas injection amount under the condition of the return air corner buried pipe extraction after the tailgate is used as the auxiliary air inlet ventilation mode,the changing rule of the gas and oxygen concentration field in the gob were analyzed and summarized.The following results can be obtained,The air volume of the working face increases,the high-concentration gas and spontaneous combustion zone in the goaf move to the deep,and the movement is most obvious at the corner of the air inlet,the transportation roadway of 1500m~3/min and the track roadway of 600m~3/min are selected as the guiding air volume of the on-site working face;High-level drilling drainage is effective in controlling gas in the goaf,but large-flow drainage will increase the spontaneous combustion zone in the goaf,and the return air side of the retaining roadway and the central goaf have relatively obvious changes,therefore,it is necessary to control the flow of drainage and strengthen the sealing of the gangue retaining wall;The tail pumping should be more than 100m away from the working face,at this time,it has little effect on the air leakage of the working face and the spontaneous combustion zone in the goaf,and only has a greater impact near the drainage outlet of the retaining roadway,this negative impact can be reduced by controlling the flow rate of drainage and strengthening the blocking of the gangue wall;When the inert gas is injected 40m away from the working face in the goaf on the air inlet side,the fire prevention and extinguishing effect is the most obvious on the air inlet side and the central goaf,but some gas will be squeezed to the working face,and it is necessary to use appropriate amount of high-level hole drainage to prevent the gas from gushing out;After changing the ventilation mode,the oxidation zone area in the goaf is significantly reduced,which is beneficial to the prevention and control of coal residue in the goaf,however,since the return air corner becomes the lowest energy level and air leakage sink in the new mined-out area,the high-concentration gas is more likely to overflow to the air flow in the entryway and flow to the working face,so gas control and gangue wall sealing are more important;The intubation drainage at the return air corner has a good effect on the control of gas disasters in the return air corner,the spontaneous combustion zone of the central and the return air side goaf have a relatively large increase,and attention should be paid to avoid large-flow drainage,which will cause the increase of air leakage near the return air corner and the spontaneous combustion zone in the gob;When the extraction rate of the return air corner is35 m~3/min,as the nitrogen injection rate increases,the high-concentration gas will gradually move to the deep.Considering the oxygen concentration safety of the working face and the fire prevention and extinguishing effect of the goaf,the effect is better when the injection amount is 10m~3/min,meanwhile,the gas parameter monitoring work should be done well.Based on the research results of numerical simulation,combined with the practice of gas and residual coal prevention and control in the 13403 working face of Zhujixi Coal Mine,the various gas control and fire prevention measures and their comprehensive control effects were analyzed,they show a good agreement with the simulation results.It is mainly reflected in the air volume of the working face from the initial stage of recovery to the recovery of373m,and the air volume of 1500m~3/min is selected as the air intake volume,and then the air volume is adjusted to 1200m~3/min in combination with the gas in the working face not exceeding the limit and the fire prevention and extinguishing of the goaf;Under the controllable conditions of gas,the high-level drilling,buried pipe at the tail,and intubation in the roadway control the drainage flow rate,which reduces the impact of increased air leakage caused by drainage;The roadway intubation is selected to be opened after 100m away from the working face to guide the gas to transfer to the deep;The air inlet side is blocked by stacking bags to reduce air leakage on the air inlet side and a dynamic sealing strategy is implemented for the gangue wall;After changing the ventilation mode,the effect of gas extraction is increased and the difficulty of fire prevention is reduced.Through the mutual confirmation of simulation and practice,it is expected to improve our understanding of gas control disasters in the working face of the deep mine with roof cutting and self-retained roadway considering the prevention and control of coal residue in goaf,and provide a reference for the prevention and treatment of gas disasters in the goaf spontaneous coal seam in the future.Figure 43;table 5;reference 56...