Suppression characteristics of methane/coal dust explosions by active explosion suppression system in the large mining tunnel

To enhance intelligent prevention and control of methane/coal dust explosions in coal mines, the active explosion suppressor was developed. Methane/coal dust explosion suppression experiments were carried out in an 896-m mining tunnel. The suppression mechanism of NH₄H₂PO₄ powder during methane/coal dust explosions was elucidated. The results indicated that the device effectively prevented flame propagation within a 40 m radius by propelling NH₄H₂PO₄ powder using high-pressure nitrogen. There was a significant reduction in the intensity and destructiveness of the overpressure, with a maximum decrease of 61.43 %. The phosphorus-containing material produced by NH₄H₂PO₄ consumed free radicals through catalytic cycles of HOPO ⇔ PO₂ and HOPO ⇔ HPO₃⇔PO(OH)₂, weakening and interrupting the reactions, and suppressing flame development. NH₄H₂PO₄ reduced peak concentrations of CO and NO₂. Guidelines for explosion suppression of CH₄/coal dust explosions in large mining tunnel were presented. The findings provide technical and theoretical support for the prevention and control of methane/coal dust explosions in coal mines.