Effect of soaking process on spontaneous combustion characteristics of long-flame coal

In order to find out the spontaneous combustion characteristics and affecting mechanism of long term soaked long-flame coal,this paper analyzed the low temperature oxidation characteristics of long-flame raw coal and soaked and air-dried coal. The effect on the microcosmic structure,self-heating process,activation energy and so on was also analyzed. The results show that the coal soaked in water for a long time has a more developed surface pore structure, the average pore size,mesoporous volume and micro-pore volume increase at different degrees. Simultaneously,some of organic and inorganic substances on the coal surface will be dissolved in water,the concentration of free radical in coal increased and the group distribution has obvious change compared with the raw coal. After 90 and 180 days of water immersion,the amount and rate of gas production during the low temperature oxidation process are higher,the cross point temperature is reduced from 160. 9 ℃ to 157 ℃ and 151. 5 ℃ ,the activation energies decreased by 3. 84 kJ /mol and 4. 18 kJ / mol,respectively. And the soaked and air-dried coals have higher spontaneous combustion tendency. This study provides a scientific guidance for prevention and control of spontaneous combustion of the soaked and air- dried coal in shallow buried close distance coal seam group mining overlying coal goaf in western privinces.