Effect of Water Evaporation on the Inhibition of Spontaneous Coal Combustion

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 O₂, CO, and CO₂ 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.