Magnesium powder explosion suppression: high-performance carbonate-intercalated calcium-iron layered double hydroxide as an advanced suppressant

Magnesium powder, a widely used high-energy metallic material, poses significant explosion risks during production, necessitating the urgent development of highly efficient and targeted explosion suppressants. In this study, a novel high-performance suppressant, carbonate-intercalated calcium-iron layered double hydroxide (CaFe-LDHs-CO₃), possessing a unique layered structure, was successfully synthesized via a co-precipitation method. Its suppression effectiveness on magnesium powder explosions was systematically investigated through flame propagation experiments in a vertical combustion tube and pressure tests in a 20 L spherical explosion device. Experimental results demonstrated that the addition of over 33.3 wt% CaFe-LDHs-CO₃ led to a discrete and dimmed flame morphology, with the flame height at 140 ms was reduced by 25% compared to that of pure magnesium powder explosions. In the 20 L sphere, a 20 wt% addition was sufficient to reduce the maximum explosion pressure (Pmax) by 64.7%, while a 42.9 wt% addition achieved an 82.6% reduction in P_max and a 95.1% reduction in the maximum rate of pressure rise ((dP/dt)_max). Combining characterization results from SEM, XRD, and TG-DSC with numerical simulations using Chemkin software, the core suppression mechanism was elucidated: CaFe-LDHs-CO₃ achieves a synergistic physical–chemical suppression effect through endothermic decomposition, physical encapsulation, inert gas dilution, and the cooperative scavenging of key radicals by metal cations and interlayer anions. This work reveals the significant advantages of this material over traditional suppressants, offering new insights for safety protection in high-risk metallic dust explosion environments.