Study On Fire Management Technology Of Sealed Fire Area In High Gas Fully Mechanized Face Of Tengda Coal Mine

The method of fully mechanized top coal caving mining has been widely used in the field.With the promotion of high-yield and high-efficiency intensive production,the adaptability of fire-prevention technology is also facing new challenges.As the dangers develops rapidly after a hidden danger of spontaneous combustion and the direct fire-fighting measures are ineffective,sealing measures must be taken.There is a risk of explosion after the sealing.If no effective treatment measures are taken after the sealing of the fire area,the reopening of the fire area will have to be sealed again.There are great risks in this process,especially for the high-gas methane work face,which can easily lead to disasters.At present,the control effect of such sealed fire areas is still difficult to meet the needs of safe and efficient production.This article mainly takes the sealed fire zone treatment of the 1701 face of Tengda Coal Mine as the carrier.Combined with the experience of the treatment of the fire zone in the site,the theoretical analysis,laboratory experiments and field engineering practices are used to systematically control the sealed fire area of the high-gas methane in Tengda Mine.Systematic management was studied and the main results and conclusions obtained were as follows:The spontaneous combustion law of residual coal in the 1701 fully mechanized goaf and the cause of ignition were studied.The large amount of residual coal in the gob of 1701 fully mechanized caving face is in a “concave” shape,which provides a material basis for the spontaneous combustion of coal.The complex air leakage is a continuous supply of oxygen for the sealed fire zone;the vicinity of the upper and lower ends and the two lanes,the residual coal at the bottom of large lump coal gangue and the floating coal area around the ground conducting cracks are prone to igniting;The large amount of residual coal,serious air leakage,ineffective fire protection measures,and slow advancing speed result in the firing of 1701 workface.A method for determining the combustion state of the 1701 sealed fire area is proposed.Through the B7 coal seam temperature programming experimental system,the law of coal oxidizing gas products was studied,the coal spontaneous combustion index gas was explored,and various influencing factors in the determination of the combustion status in the sealed fire area were analyzed,and the gas sample reliability judgment method was found out.The results show that the ratio of alkanes before 200°C and the ratio of alkenes after 200 °C increase monotonously with the increase of temperature,which can predict the spontaneous combustion of coal.When the same CO is produced in different oxygen atmospheres,the temperature varies greatly,There is a hysteresis effect in the determination of the combustion state at the sealed fire area;the CO yield is proportional to the ambient oxygen concentration.The Graham’s coefficient can be used to determine the combustion state of the high gas sealed fire area.The Graham coefficient correction index can more accurately determine the combustion state under any oxygen concentration conditions.The determination method of multi-parameter change trends in the fire area can effectively solve the reignition problem in the fire area.A high-efficiency treatment technology system for the sealed fire area in the highmechanized fully-mechanized caving face was proposed.The treatment technology was studied through laboratory experiments and field experiments.The research shows that the fire area detection method combined with on-site evidence analysis and along-thehole drilling parameter analysis can effectively detect high-temperature areas;the sealed fire area inert gas can be rapidly inerted,but it can not eliminate the fire source;blocking air leakage can effectively reduce the supply of oxygen in the fire area;continuous perfusion three-phase foam can achieve rapidly cooling of the fire area,dynamic variable parameter perfusion three-phase foam process can achieve high temperature area of high efficiency fire cooling.The oxidation law of coal before and after unsealing was studied,and the technical measures for preventing re-ignition after unsealing were proposed.After the unsealing of the sealed fire zone,the residual coal is easier to oxidize at lower temperatures than the original coal,and the natural pyrolysis cycle becomes shorter.After the unsealing,the anti-resurrection technology system can exert a good prevention and control effect on the on-site fire prevention in the goaf.Coal spontaneous combustion does not occur afterwards.The successful management of the sealed fire area in the high-mechanized fully mechanized top-coal caving face of Tengda Mine shows that the management technology system has a good applicability on the site,and this set of management technology system has very good promotion value for the treatment of the same sealed fire area.