Study On Distribution Law Of Spontaneous Combustion"Three-Zone" In Goaf Of Fully Mechanized Caving Coal Face With Inflammable Extra-thick Seam

In the mining process of extremely thick coal seam, lots of coal which is not mined absolutely exist in the goaf. Because of hidden spontaneous combustion, it is not easy to determine the location and extend of combustion, which increase the difficulty of the mine fire prevention. Thus, it is significant to carry out research about the law of spontaneous combustion for this research is helpful to reduce mine accidents. Recently many researchers often determine the hazardous scope of goaf by spontaneous combustion "three-zone", which often focuses on2distribution law of coal thinner than8m.But the researches on extra-thick coal seam spontaneous combustion on3distribution is seldom. In order to control mine fire more effeciently, it is particularly important to determine the hazardous areas of extra-thick coal seam which is liable to spontaneous combustion.Through theoretical analysis, experimental analysis, numerical simulation and field measurement methods, to13204working surface of Maodi mine in Shanxi Province (Average thickness of coal seam is12.06m) as an example, this paper study distribution law of spontaneous combustion "three-zone" and spontaneous combustion prevention in goaf of fully mechanized top coal caving mining face with extra-thick coal seam.Firstly, in the view of the seepage flow rules, this paper states the theory for formation of voids in the fully mechanized goaf and remaining coal distribution status in space and the porosity distribution functions of goaf have been determined.Then, the secondary development of ANSYS FLUENT software is carried out through UDF port within the Visual Studio environment and three-dimensional goaf physical model is established. The distribution rules of air leakage velocity field and oxygen concentration field is found out for13204fully mechanized surface goaf of Maodi Mine. Through the division of self-ignition "triple zone" in three-dimensional goaf, it is also analyzed the effect on the self ignition "triple zone" distribution in goaf by the air leakage source position and wind-break wall. The results show that:l) Under normal conditions, the widest point of oxidized spontaneous combustion zone could reach68meters appearing near the inlet air of side base plate, while the width of return air side come second. One area similar like banana expand in the deep of goaf locating in the intake and return air with two dimensional planar. In vertical height, oxidation spontaneous combustion zone in goaf gradually become narrowed along with height increase. And its distribution scope is gradually moving closer to the working face.2) After the pile filling, the widest point become only31meters appearing near the base plate of middle goaf in the shape of oval.3)The widest point of oxidized spontaneous combustion in the different positions of air leakage is:the side roof plate of intake (117m)> the side roof plate of outlet (113m)> the side roof plate of middle goaf (87m), which is show that It is most dangerous when the air leakage happen in the side roof plate of intake.Finally, a ventilation resistance measurement has been done in13204working face aiming at the situation in13204fully mechanized top-coal caving face that buried in shallow. The results of measurement show air leakage happen in the upper goaf. A space governance scheme that mainly contain filling masonry、injection fluid of the inhibitor for the MEA、accelerating mining rate and so on, has been worked out for the prevention and control of spontaneous combustion, which has been applied in actual working face and received good effect. It has provided the reliable theory basis and practical experience for the fire preventing and extinguishing in fully mechanized top-coal caving face of goaf.