Experiment study on spontaneous combustion features of weathered coal under condition of high temperature oxidation

In order to master a development evolution law of a seam outcrop fire,a high temperature programming rising experiment system was applied to simulate the high temperature oxidized spontaneous combustion process of the weathered coal and the macro spontaneous combustion features and the characteristic paramete rs in the normal temperature to 650 °C high temperature oxidized process were obtained.The increased rate analysis method of the index gas was applied to set up the weathred coal characteristic temperature point of the high temperature oxidation.The results showed that under the condition of the high temperature and low oxygen Co ncentration,the weathered coal still could keep the oxidized reaction occurred and could release great heat to maintain the spontaneous combustion. The humic acid con tained in the weathered coal would steadily occur the thermal decomposition reaction with the coal temperature increased and would cause CO_ 2、CH_ _4、 C_ _2H_ 4 and C_ _2H_ 6 gas concentrations from the oxidation increased.Meanwhile,the CH_ 4、C_ _2H_ _4 and C_ 2H_ 6 gas concentrations would be similar to the coal temperature varia tion law.Due to the weathered coal affected by the chemical weathered function,those three gas concentrations would be low at the low temperature stage and then coul d be increased with the temperature increased.In addition,the CO gas concentration occurred from the high temperature oxidation of the coal sample with a particle size less than 0.9 mm would have a high CO concentration generally than other particle size.From 400~590 °C,when the particle size was 7~10 mm,CO concentration value f rom the high temperature oxidation of the coal sample would be minimum.