Blast furnace slag/KH₂PO₄ composite deflagration inhibitor for aluminum dust explosion suppression

This study investigates the explosion suppression mechanism of a novel composite deflagration inhibitor (SK), synthesized from industrial waste blast furnace slag (S105) and KH₂PO₄, for the suppression of aluminum dust explosions. By employing a liquid-phase chemical coating method, SK integrates S105 (a low-cost, high-strength matrix) and KH₂PO₄ (a chemically active carrier) into a core–shell structure, achieving synergistic suppression effects. Explosion suppression effect were evaluated using a dual-channel 20 L spherical explosion vessel and a Hartmann tube, revealing that SK reduced the maximum explosion pressure by 23.9%, the pressure rise rate by 70.7%, and the flame propagation speed by 67.3%. These results indicate that SK outperforms individual components (S105 and KH₂PO₄) as well as conventional inhibitors (e.g., NaHCO₃). Thermogravimetry–differential scanning calorimetry (TG–DSC) and microstructure characterization techniques, such as scanning electron microscopy (SEM) and X-ray diffraction (XRD), elucidate the dual inhibition mechanisms: (1) Physical inhibition, through endothermic decomposition and release of H₂O to dilute oxygen and form a physical barrier; (2) Chemical inhibition, which suppresses explosions by scavenging radicals and terminating chain reactions. S105 is more cost-effective than its components, primarily due to the ultra-low cost of slag. This work not only promotes the sustainable use of industrial waste resources but also provides a scalable and efficient solution for industrial explosion safety, aligning with global circular economy goals.