Research on the Reignition Characteristics and Key Functional Groups of Pre-Oxidized Coal
In order to study the reignition characteristics of coal body and the change law of key functional groups in the closed fire zone,the long-flame coal from the comprehensive excavation face was collected,and the coal samples were treated with programmed heating at different atmospheres(nitrogen and dry air)and pre-oxidation temperatures(80 ℃,120 ℃,160 ℃ and 220 ℃)with oxidation time of 4 h.And then the thermogravimetric analysis(TG-DTG)and infrared analysis(FTIR)were carried out with raw coal as comparison set.The change patterns of three characteristic temperatures(T1,T2,T3)of coal samples were analyzed by TG-DTG,and the combustion performance of coal samples were analyzed by combining with the comprehensive combustion index formula.The changes of hydroxyl groups of coal samples under different atmospheres and pre-oxidation temperatures were analyzed by FTIR.The results show that T1 and T3 of pre-oxidized coal are lower than that of raw coal and negatively correlated with pre-oxidation temperature,T2 increases and then decreases with pre-oxidation temperature and reaches the peak at 120 ℃.The pre-oxidized coal is more prone to spontaneous combustion than raw coal,and the nitrogen atmosphere is safer than the dry air atmosphere.The maximum weight loss rate,Cb and S of pre-oxidized coal are higher than that of the raw coal,and Hf is smaller than that of the raw coal,and the oxidative combustion of coal is more stable after pre-oxidation.After pre-oxidation treatment under different atmospheres,the types of functional groups in coal do not change,but the hydroxyl content increases first and then decreases.With the pre-oxidation temperature higher than 160 ℃,the fatty side chains in the coal reacts with oxygen to produce new hydroxyl groups,and the hydroxyl content increases in the dry-air atmosphere.The research results can provide some reference for the re-mining of the relic coal.
Pre-oxidized coalCharacteristic temperatureCombustion indexInfrared spectrumHydroxyl group
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维普
