Effect of Coal Dust Content on the Low-temperature Oxidation of Silo Coal

Coal's low-temperature oxidation (LTO) poses a significant threat to the safety of storing coal in silos. This study investigates the impact of coal dust content on the LTO characteristics of silo coal samples. The results indicate that the larger the coal dust content the higher the oxygen (O2) consumption rate and carbon monoxide (CO) generation rate and the stronger the LTO capacity. To clear the mechanism of the impact, the thermal physical characteristics were studied and thermogravimetric and differential thermal analysis (TG-DTA) experiments were performed on various coal samples. The results show that, first, with the increase of coal dust content, the thermal conductivity of the silo coal samples initially increased and then decreased, whereas the thermal diffusion and heat capacity decreased and increased linearly, respectively. This indicates that the heat storage capacity of the silo coal sample is enhanced with the increase of the coal dust content. Second, the maximum oxygen absorption rate and differential thermal reduction value of the coal samples increased linearly with the decrease in their particle size; this result verifies that decreasing the particle size of silo coal can advance its LTO process. The study findings indicate that the risk of LTO and spontaneous combustion of silo coal can be effectively reduced by controlling the coal dust content (fine coal particles).