Three-dimensional “three zones” observation of spontaneous combustion in goaf of fully mechanized top coal caving face in shallow buried and extra thick seam

In view of the fact that the 6# coal seam in 605 fully mechanized caving face of Dongchen company is an extremely thick spontaneous combustion coal seam, and the coal seam buried relatively shallow, under the influence of mining, there is a leakage channel between the working face and the surface, which increases the threat of spontaneous combustion in the working face. The three zones of spontaneous combustion in the goaf are observed by the analysis of the gas samples taken from the embedded beam tube in the working face. The results show that the distribution of the gas in the goaf is in a three-dimensional state. There are not only three zones of spontaneous combustion in the traditional horizontal direction, but also three zones of spontaneous combustion in the vertical direction; the oxidation zone in the horizontal direction is 38 m to 170 m in the air inlet side and 30 m to 150 m in the air return side; the oxidation zone in the vertical direction is 6 m to 52 m above the coal seam floor at the side of the transportation roadway and 4 m to 46 m above the coal seam floor at the side of the return air roadway. By measuring the distribution range of the “three zones” of spontaneous combustion in the goaf, the work of fire prevention and extinguishing in the working face can be targeted, so as to ensure the safe production of the working face.