Study on the Distribution of Three Zones of Spontaneous Combustion in Air Mining Zone Based on Concentration and Temperature Characteristics

In order to reduce the risk of spontaneous combustion in the air pocket, the concentration changes and temperature characteristics of O₂, CO and CH₄ in the air pocket were analyzed through on-site measurements, so as to study the distribution law of spontaneous combustion in the three zones in the air pocket. The results show that when the working face advances more than 80m, the compaction of the coal body leads to the decrease of oxygen concentration, which restricts the oxidized warming of the remaining coal, and the concentration of CO stabilizes at 18×10⁻⁶; the concentration of CH₄ increases and then stabilizes with the advancing distance, with the maximum value of 1.14%, and it gradually decreases from the middle of the working face to the two sides; the calculation of the method of analyzing and indexing the concentration of oxygen indicates that the scattering belt x1＜39.1 m, and oxidation warming belt x₂ The range is from 39.1 to 82.3 m, the asphyxiation zone x₃＞82.3 m, and the minimum safe advancing speed of the working face is 0.73m/d, so the spontaneous combustion of coal left in the airspace zone will not occur during the period of mining back.