LABORATORY STUDY ON LOW-TEMPERATURE COAL SPONTANEOUS COMBUSTION IN THE AIR OF REDUCED OXYGEN AND LOW METHANE CONCENTRATION

Laboratory tests were conducted to study coal spontaneous combustion at low-temperature (30 divided by 200 degrees C) in the air of reduced oxygen (10 divided by 21 %) and low methane concentrations (0 divided by 3 %). The production of carbon monoxide in coal spontaneous combustion was analysed. The test results show that both oxygen and methane concentrations affect coal spontaneous combustion. At given oxygen concentration the methane concentration in air had a positive impact on coal spontaneous combustion and the impact increased with methane concentration. This impact was weakened and diminished with the rise of temperature. The initial carbon dioxide temperate at which carbon monoxide started to appear increased with the reduction of oxygen concentration in the air and the increase was somewhat negated by the presence of increased methane concentration in air. However, as the oxygen concentration reduced to a certain value, methane concentration showed little or no influence on coal spontaneous combustion. The low temperature sorption characteristics of oxygen and methane by coal were applied to explain the results. The findings in this study are particularly useful in the prediction and control of coal spontaneous combustion in gassy coal mines.