Coal dust combustion suppression via melamine polyphosphate and silica: Experiment and simulation

Coal is extensively utilised to provide thermal energy for various industrial processes, such as ironmaking and steelmaking. However, it poses a certain threat due to the potential risk of dust explosion during processing. To address this issue, this study evaluated the effectiveness of melamine polyphosphate (MPP) as a solid inhibitor in suppressing coal dust explosions, and the inhibitory effect was compared with that of silica (SiO₂). The experiments showed that flame propagation height and flame propagation velocity were suppressed with the increase of inhibitors. At a mass fraction of MPP of 0–25 mass%, the minimum ignition temperature increased from 540 to 640 °C, an increase of 18%. To reveal the mechanisms for the noticeable suppression of coal dust explosion by MPP, the evolution with potential energy, free radicals, and main gaseous products of coal and coal/MPP was simulated using reactive force field molecular dynamics (ReaxFF-MD). During combustion, the PO and PO₂ groups decomposed from MPP reacting with the OH and H and terminated the gaseous combustion chain reaction. Meanwhile, NH₃ decomposed by MPP diluted the concentration of oxygen. Finally, the suppression mechanisms of SiO₂ and MPP were investigated.