Combustion Characteristics of Coal Dust Containing Oil in the Oxygen-enriched Environment

An oily coal dust that is difficult to remove is easily formed on the surface of coal mining equipment. However, high-power equipment generates a higher surface temperature, which can promote spontaneous combustion of coal, especially in the oxygen-enriched environment of the refuge chamber. This study investigated the effects of lubricating oil on coal spontaneous combustion under different oxygen concentrations using a temperature-programmed experiment, Fourier transform infrared spectroscopy and thermogravimetry-differential scanning calorimetry. The results show that the activation energy is inversely proportional to the lubricating oil content during the low-temperature oxidation stage. With a mass ratio of coal to lubricating oil of 2:1, compared with raw coal, the activation energy was reduced by 6.46 KJ/mol. With a higher lubricating oil content of coal and an increased oxygen concentration, the absorption peak intensities of -CH₃, -CH₂, -OH were lower and the C-O absorption peak intensity was higher. Therefore, lubricating oil promotes coal spontaneous combustion and the promoting effect is proportional to the lubricating oil content and oxygen concentration. Furthermore, the difference in heat released indicates that the effect of lubricating oil on coal spontaneous combustion is the result of the interaction between coal oxidation and lubricating oil oxidation.