An Investigation into the impact of water immersion behavior of coarse coal particles on their propensity for spontaneous combustion

İngilizce (OpenAlex)

This study investigates the influence of long-term water immersion on the spontaneous combustion behavior of bituminous coal across four particle size ranges (0.5–1, 3–5, 6–9, and 9–12 cm). To simulate underground goaf conditions, samples were immersed in water for three years. Combustion characteristics were assessed using Crossing Point Temperature (CPT), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). Raw coal showed the highest susceptibility, with a CPT of 145°C and an IFCC index of 11.85 min−1. Water immersion increased ignition thresholds, especially in coarse samples: CPT values rose to 168°C for 6–9 cm and 166°C for 9–12 cm, placing them in the low-risk category. Activation energy values supported this trend, increasing from 85.32 kJ/mol in raw coal to 110.3 kJ/mol in fine immersed coal and up to 119.0 kJ/mol in larger particles, indicating enhanced thermal stability. SEM results showed that fine particles retained a porous structure that facilitates oxygen uptake, whereas coarse samples developed smoother, agglomerated surfaces that restricted diffusion. Overall, long-term immersion increased reactivity in fine coal but significantly reduced the spontaneous combustion propensity of coarse particles. These findings highlight the importance of particle size management in reducing combustion hazards in submerged or collapsed coal environments.