Study On The Effect Of Air Leakage In Goaf On Coal Spontaneous Combustion Characteristics

The spontaneous combustion of coal in the goaf is one of the most common disasters in the coal mine.In recent years,more and more mines have been spontaneous combustion of coal,which poses a serious threat to the safety of mine production and personnel health.Among them,it is found that the spontaneous combustion of coal in many mines has a direct relationship with the air leakage in goaf.The air leakage in goaf is closely related to the ventilation of the mine.Therefore,it is very necessary to study and analyze the mine ventilation such as air leakage in goaf and the spontaneous combustion of coal in the goaf.Through theoretical analysis of the subject,The causes of air leakage in goaf,the theory of gas seepage and the causes and influencing factors of spontaneous combustion of coal are obtained,and the influence of air leakage on the spontaneous combustion of coal in goaf is theoretically analyzed.In order to study the influence of different working face ventilation system of air leakage and coal spontaneous combustion in goaf,field measurement and numerical simulation results data of a mine in this paper,a comparative analysis of U type and U+L type ventilation system,found that under the same conditions,U type ventilation system is more conducive to the prevention of goaf coal spontaneous combustion.Using Fluent simulation software to establish a geometric model for the actual situation of 702 working face of Baojishan coal mine,and numerical simulation of leakage flow field and oxygen concentration field distribution in goaf,according to oxygen concentration index,the "three zones" of spontaneous combustion of coal in goaf are divided.The width of the oxidation zone on the intake side of the goaf is about 68～110m,and the width of the oxidation zone on the return air side is about 10～35m.And according to the distribution range of the air volume in the 702 working face,we simulate the distribution of oxygen concentration in the goaf under different air volume,and get the influence of different air volume on the dangerous area of the coal spontaneous combustion disaster in the goaf.The gas monitoring points are arranged in the goaf of the working face,and gas is pumped through the buried tube,and the gas chromatograph is used to analyze it.The distribution of oxygen concentration,CO concentration and air leakage strength in the goaf is obtained,and the width of the inlet zone is about 70～115m.The width of the oxidation zone on the return air side is about 20～40m,which is close to the numerical simulation results.By collecting the CO concentration data of the upper corner of the working face and the return air side of the goaf and air leakage volume of the working face,the relationship between them is analyzed,and the rule that the coal spontaneous combustion risk of the 702 working face is affected by air leakage is obtained.Finally,according to the actual conditions of the mine,the measures for prevention and control of air leakage and spontaneous combustion of coal in the goaf are put forward in terms of mine ventilation and fire prevention and extinguishing technology.