4A zeolite-loaded bicarbonate as an anti-caking dust explosion inhibitor

This study aims to improve the explosion suppression performance of bicarbonate powders (KHCO₃ and NaHCO₃) against combustible dust and enhance their anti-caking properties by loading bicarbonate onto the surface of 4A zeolite. Using wet impregnation and evaporative crystallization, KHCO₃ and NaHCO₃ particles were successfully attached to the tetrahedral structure of 4A zeolite, resulting in composite dust explosion inhibitors, Zeolite-KHCO₃ and Zeolite-NaHCO₃, with large specific surface areas. The inhibition efficiencies of bicarbonate and 4A zeolite-loaded bicarbonate on wheat starch explosions were tested using a 150 cm Hartmann tube. The anti-caking properties of the composite were also evaluated under high humidity conditions. Results showed that Zeolite-KHCO₃ exhibited enhanced explosion suppression efficiency compared to KHCO₃, with a minimum complete inerting ratio (MIR) of 0.05, while Zeolite-NaHCO₃ exhibited an MIR of 0.12, consistent with NaHCO₃. The accelerated caking tests revealed that in contrast to KHCO₃ and NaHCO₃, Zeolite-KHCO₃ and Zeolite-NaHCO₃ exhibited superior anti-caking properties due to the drying effect of zeolite, with a caking rate of less than 0.1. These findings indicate that 4A zeolite-loaded bicarbonates can drastically reduce the caking tendency of bicarbonate while maintaining or enhancing its explosion suppression efficiency.