Experimental Study on the Characteristics of the Spontaneous Combustion of Coal at High Ground Temperatures

Understanding the influence of high ground temperatures on the characteristics of the spontaneous combustion of coal is important for increasing safety in deep mines, where high temperatures are encountered. In this experimental study, long flame coal samples were treated at a constant temperature of 30, 40, and 50 degrees C to simulate the high ground temperatures found in deep mines. By Fourier transform infrared spectroscopy, thermogravimetry, and gas chromatography, changes to the functional groups, gas generation, and characteristic temperatures resulting from the exposure to elevated temperatures were reported. The results demonstrate that as the ground temperature rises, the abundance of hydroxyl groups and oxygen-containing functional groups increases, and the coal becomes more reactive. Results from gas chromatography show that the quantity and rate of production of CO, C2H4, and C2H2 during oxidation all increased with increasing pretreatment temperature. Additionally, results from the thermal analysis indicate that the critical temperature, dry cracking temperature, and ignition temperature all decreased with increasing pretreatment temperature. These results all suggest that high ground temperatures can regularly increase the risk of spontaneous combustion of coal by enhancing the activity of functional groups.