Characteristics and mechanism of Al(H ₂ PO ₂ ) ₃ and C ₆ H ₉ N ₉ O ₃ inhibition on wheat dust explosion

Wheat dust is widely used in industry and daily life, and its suspended clouds easily explode when exposed to open flames. Selected phosphorus-based aluminum hypophosphite (AHP) and nitrogen-based melamine cyanurate (MCA) as two suppressants, and studied the thermal properties of wheat dust and suppressants. Investigated the effect of the two suppressants on the explosion characteristics, analyzed the changes in the functional groups of the AHP and MCA on the explosion inhibition process, combined with CHEMKIN simulation, revealing the explosion suppression mechanism. The experimental findings showed that wheat dust exhibited a 75% mass loss with a major exothermic DSC peak, suggesting that wheat dust explosion is gas-phase dominant. The maximum explosive power occurred at 500 g/m3. The minimum completely inert concentration (MCIC) of AHP and MCA to achieve suppression was 90 wt% and 30 wt%. After explosion, Al/P groups increased with AHP addition; –OH and C–O–C peaked at 30 wt% MCA. Elementary reactions R29 and R32 are key to affecting the radical yield. AHP achieves solid-phase suppression through thermal decomposition-generated phosphoric acid products covering combustible surfaces. And MCA provides a superior suppression effect by using NH3, CO2, and other gases for suppression of the gas phase.