Effects of Moisture and Associated Pyrite on the Microstructure of Anthracite Coal for Spontaneous Combustion

To explore the micromechanism of the structural changes of anthracite due to heat accumulation by water and pyrite, during oxidation, anthracite with coal samples was selected in this work from Baijiao Coalmine, Sichuan, China. The samples were added with water of 1, 5, 10, 15, and 20 mass % and pyrite of 1, 2, 4, and 6 mass % and were conducted to experimented torts. As compared with the raw coal sample, the effects of water and pyrite on the microstructure of anthracite were studied. The results indicate that the oxygen-containing functional group of coal increases with the addition of water. The content of the aromatic structure in coal was thought to be due to water and pyrite synergistic effects. The synergistic effect of water and pyrite accelerates the oxidation process of seven types of active groups in coal samples. The water content was 10-15 mass %, and the associated pyrite content was 2-4 mass %; the contribution to the oxidation activity of the main active groups of coal was the largest under oxidizing conditions.