Determination and assessment of spontaneous combustion zone of coal at gobs of the fully-mechanized top-coal caving face

Based on the heat output of coal and the rate of oxygen consumption tested by the big coal spontaneous combustion experimental unit, and through determining oxygen concentration distribution in a gob, the rule of distribution for air leak intensity in gob is deduced. In view ofthe conservation principle of energy and real distributions, such as coal thickness, air leak intensity, oxygen concentration, the terminal parameters resulting in coal self ignition are calculated, and the necessary conditions determining the dangerous zone of coal self ignition is established. According to the width of temperature-rising zone and the shortest period of coal self ignition, the least mining velocity resulting in coal self ignition can be calculated, and the sufficient conditions determining the dangerous zone of coal self ignition is established. The shortest period of coal self ignition is obtained under actual mining conditions in the dangerous zone, of coal self ignition in a gob.