Suppression performance and flame-blocking mechanisms of industrial-grade hydrotalcite for the safety control of Mg–Al alloy dust explosions

Dust explosions pose a severe threat to industrial production. Mg–Al alloy powder, a significant industrial product, is highly reactive owing to its chemical properties; thus, it is prone to explosive incidents. Therefore, effective safety protection measures are urgently needed. In this study, the explosion suppression effects of industrial-grade MgAl-layered double hydroxides (LDHs) on Mg–Al alloy dust explosions are investigated using on a novel dual-channel 20-L spherical explosion vessel and a dual-channel Hartmann tube, focusing on both explosion pressure and flame propagation. The results indicate that MgAl-LDHs exhibit significantly superior suppression effects compared with suppressants such as CaCO₃ and NaHCO₃. Moreover, if the amount of MgAl-LDHs added to the Mg–Al alloy exceeds 100% and the suppressant release time is less than 10 ms, the explosions can be effectively controlled. Analysis of explosive products and chemical kinetics models indicates that the suppression mechanism of MgAl-LDHs includes the adsorption and isolation of oxygen, endothermic physical decomposition, and radical scavenging. Notably, the concentration of oxygen free radicals is significantly reduced during the explosion process of Mg–Al alloys. This work establishes a theoretical framework and provides new insights into solving practical problems in the production process of Mg–Al alloys.