Inhibition of different types of inert dust on aluminum powder explosion

Abstract

Aluminum powder explosion accidents occurred frequently, but the mechanism of aluminum powder explosion is unclear. Therefore, the inhibitive effect of aluminum powder explosion plays a key role. To evaluate the inhibition capacity of different kinds of carbonates and phosphates: NaH2PO4, (NH4)2HPO4, NH4H2PO4, KHCO3 and NaHCO3 on aluminum deflagrations, a standard 20-L spherical chamber was used to determine the explosion severity, characterized by the maximum explosion pressure (Pmax). New parameters have been proposed: the minimum significant inert concentration (MSIC) and the minimum complete inert concentration (MCIC), which characterized the effect of inert. Experimental results showed that from the minimum significant inert concentration (MSIC) and the minimum complete inert concentration (MCIC), phosphate can have a significant inhibiting effect. 40% NaH2PO4 can totally inert the aluminum explosion, and 50% (NH4)2HPO4 or 50% NH4H2PO4 can also suppress the explosion. Through simulation, phosphate mainly acts via a chemical inhibition pathway, which inhibits the reaction of aluminum powder and oxygen by catalyzing the recombination of H atoms and O atoms. Carbonate performs inhibition in chemically, producing CO2, diluting the oxygen around the aluminum powder. Studies indicated that the explosion pressure of the mixture decreases as the concentration of inert dust increases. However, when the concentration of carbonates was low, SEEP (suppressant enhanced explosion parameter) phenomenon was found. This research work has a potential industrial application in high hazard aluminum working condition, which can help decrease the explosion pressure and reduce the accident loss.