Study on the Difference in Oxidation Characteristics of Coal and Gangue from the Same Coal Seam

Abstract

ABSTRACT The gangue hills and underground backfill mining gob where crushed coal and coal gangue coexist face severe risks of spontaneous combustion. Studying the differences in oxidation characteristics between coal and gangue from the same coal seam is beneficial for spontaneous combustion. This paper tested the changes in radicals, functional groups, and gas products during the oxidation of raw coal, raw gangue, and washed gangue and analyzed their differences. Finally, gray correlation analysis was used to calculate the correlation between active groups and gas. The results showed that raw coal contained a more significant initial radical concentration and g factor value than raw and washed gangue. Its aliphatic hydrocarbons and oxygen-containing functional groups content was also significantly higher. The growth rate of radical concentration in the early oxidation stage of washed gangue was larger than that of raw coal and raw gangue due to the high sulfur content. At the same time, the temperature at which the g factor started to increase rapidly and the temperature at which the aliphatic hydrocarbons decreased rapidly was lower than that of raw coal and raw gangue. Gray correlation analysis showed that the active groups closely related to oxygen consumption were CH3 and CH2, while the groups closely associated with CO generation were C=O, COOH, Ng, and g factor.