SOM’s Effect on Coal Spontaneous Combustion and Its Inhibition Efficiency

Abstract

ABSTRACTAs an important part of coal, the existence of soluble organic matters (SOMs) has its own impact on the number of active groups within coal and its pore and fracture structure, which have influence on both spontaneous combustion and inhibitory effect of coal. But some in-depth researches are still lacking on this matter. On the basis of testing the composition of SOMs and analyzing the change of coal’s pore and fracture structure, we conducted an oxidation experiment on model compounds stimulating SOMs, and coal’s spontaneous combustion inhibition experiment before and after extraction. By testing characterization parameters like oxygen consumption rate, activation energy, inhibition rate, and the crossing point temperature, we analyzed how SOMs make a difference on spontaneous combustion and inhibitory effect of coal. It shows that, after the extraction of SOMs, both the amount and rate of oxygen consumption of coal goes down, while the activation energy of coal ascends after extraction. Once being added with model compounds stimulating SOMs, coal’s oxidation degree increases. Between 50°C and 140°C, the inhibition rates of ZHCM, ZHYM, and CTM range from 50.7% to 71.2%, 40.1% to 52.0%, and 18.1% to 27.6%, respectively, and residual coals’ inhibition rates surpass raw coals’ inhibition rates. The crossing point temperature of ZHCM reached 122.5°C, 35.2°C higher compared to that of YM. This shows that adding inhibitors after extract can have a strong effect on restraining coal’s spontaneous combustion. Through free radical reaction and oxidation reaction, SOMs would release the heat to hasten the coal’s oxidation process. After extraction, coal’s permeability increases, which makes it easier for an inhibitor to seep into coal, thereby restraining the intensity of coal’s oxidation.