Study on Coal Spontaneous Combustion Law and Key Prevention Technology in Goaf under Condition of Gas Drainage

Author:Li Guang

Supervisor:liu wei zuo


Degree Year:2019





Coal production is also facing serious safety problems;with the extension of mining depth in China,gas and coal seam spontaneous combustion symbiotic disasters have an increasing trend,and gradually become a common pattern of serious and major accidents in China’s coal mines.With the increase of mining depth,the gas problem has gradually become prominent in some mines without gas problem.In order to solve the problem of gas exceeding limit in the process of working face mining,the method of goaf gas drainage is generally used to drain gas from goaf.Gas drainage in goaf leads to disorder of air leakage flow,increase of air leakage intensity and abnormal spontaneous combustion law in goaf.Around the core problem of spontaneous combustion law and prevention and control technology of coal in goaf under the condition of drainage,this paper takes 3418 working face of Liangbaosi Coal Mine with the condition of gas drainage in goaf as an example,studies the basic characteristics of spontaneous combustion of coal in this mining face,obtains the law of gas production and product in the process of temperature rise of coal sample,and analyzes the spontaneous combustion inclination of coal.The dynamic model of coal reaction is obtained by measuring and calculating the directivity.The spontaneous combustion characteristics of coal are analyzed from the microscopic structure of coal,which lays a foundation for studying the spontaneous combustion law of goaf under the condition of gas drainage.Aiming at the problems of unknown spontaneous combustion law and judgment of spontaneous combustion dangerous area under the condition of gas drainage in goaf,this paper measured the evolution process of oxygen,gas,carbon monoxide and other gases and temperature fields in goaf with the mining face by laying gas drainage pipeline and temperature sensor on site,based on the spontaneous combustion danger of coal.The theory of dangerous area determination divides the distribution characteristics of coal spontaneous combustion dangerous area under the condition of gas drainage in goaf;designs the physical simulation experiment scheme of the flow field characteristics in goaf under the condition of gas drainage,and constructs the simulation experiment platform;uses the theory of coal chemistry,mass transfer and computational fluid dynamics to construct the gas drainage.A mathematical model for spontaneous combustion in goaf is presented.The variation characteristics of gas flow field,gas and oxygen concentration field in goaf under different position and different drainage intensity were studied and analyzed by combining physical simulation with numerical simulation.From the point of view of preventing spontaneous combustion,the need of upper coner gas control was considered comprehensively to optimize the return air pre-buried pipe in goaf.The parameters such as drainage location and drainage intensity are also discussed.In view of the fact that gas drainage increases the risk of spontaneous combustion of coal,based on the technology of injecting CO2 into goaf,the method of gas replacement in goaf under the condition of gas drainage is put forward.Using numerical simulation technology,the inerting effect of CO2 injection in goaf is systematically analyzed under different drainage conditions,different perfusion rates and different perfusion positions.The parameters of CO2 injection in goaf are optimized.Based on the technology of high position drilling,large flow injection and fire prevention foam technology,a rapid treatment method for hidden danger of spontaneous combustion of coal in goaf is constructed.The above technology has been applied to the prevention and control of spontaneous combustion in goaf under the condition of gas drainage,and good results have been achieved.