Effect of Water Evaporation on the Inhibition of Spontaneous Coal Combustion

Abstract

Spontaneous coal combustion is the primary cause of coal mine fires. During the production process, spontaneous coal combustion in the goaf is often affected by air leakage, which weakens or annuls the effect of inhibitors and leads to secondary oxidation. However, the action mechanism of inhibitors on secondary oxidation spontaneous coal combustion remains unclear. Thus, this study analyzes the influence of moisture evaporation on the performance of a high-water-content physical inhibitor (HWPI) using the Carbolite temperature-programmed experiment, differential scanning calorimetry, scanning electron microscopy, and a MINI MR test. The results demonstrate that as the moisture content of the inhibitor decreased, after being treated with the HWPI and drying for 24 h, the concentrations of O 2 , CO, and CO 2 were found to be lower than the gas concentration of raw coal, which showed that although the moisture content is reduced, the treated coal sample still has a lower spontaneous combustion tendency than the raw coal. The apparent activation energy was reduced, and the heat absorption per unit time decreased, which eventually weakened or annulled the effect of the HWPI. Future research should further improve existing inhibitor types to reduce the impact of secondary oxidation on spontaneous coal combustion caused by water evaporation.

Mining Polyethylene Glycol-Based Thermosensitive Hydrogel Materials: Preparation and Flame Retardant Properties

“…Once these materials are injected into the goaf, the moisture in the materials frequently starts to evaporate at the low-temperature stage of the coal due to air leakage of the goaf. The anti-extinguishing efficacy significantly diminished and even disappeared ineffectively after the protracted process of low-temperature oxidation and heating. − Thus, it is crucial to search for new and effective mining anti-fire extinguishing materials. Such materials should be able to continuously maintain good fluidity and fire-extinguishing activity in the low-temperature region of coal, gradually undergo a phase change, and weaken fluidity in the high-temperature region of coal, which causes them to gather in the high-temperature region, achieving the effective prevention and control of spontaneous combustion fires in the goaf and getting a multiplier effect.…”

Spontaneous Combustion Characteristics of Activated Carbon Modified via Liquid Phase Impregnation during Drying

“…The combustion in the process of modifying activated carbon is related to the properties of activated carbon, solvent properties of modified chemicals, drying gas, drying temperature and time, atmosphere flow, fluidization, and dust and moisture emissions in the drying process. − Spontaneous combustion of activated carbon generally occurs when its surface undergoes an exothermic reaction due to oxidation . Onifade’s study indicated that the spontaneous combustion of coal and coal-derived activated carbons is the results of carbon oxidation .…”