Inhibition of different types of inert dust on aluminum powder explosion

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:Na H2PO4,(NH4)2HPO4,NH4H2PO4,KHCO3 and Na HCO3 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%Na H2PO4 can totally inert the aluminum explosion,and 50%(NH4)2HPO4or 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.

Simulation of Double-Front Detonation of Suspended Mixed Cyclotrimethylenetrinitramine and Aluminum Dust in Air

The two-phase detonation of suspended mixed cyclotrimethylenetrinitramine （i.e., RDX） and aluminum dust in air is simulated with a two-phase flow model. The parameters of the mixed RDX-AI dust detonation wave are obtained. The double-front detonation and steady state of detonation wave of the mixed dust are analyzed. For the dust mixed RDX with density of 0.565kg/m3 and radius of 10μm as well as aluminum with density of 0.145kg/m3 and radius of 4μm, the detonation wave will reach a steady state at 23m. The effects of the size of aluminum on the detonation are analyzed. For constant radius of RDX particles with radius of 10μm, as the radius of aluminum particles is larger than 2.0 μm, the double-front detonation can be observed due to the different ignition distances and reaction rates of RDX and aluminum particles. As the radius of aluminum particles is larger, the velocity, pressure and temperature of detonation wave will be slower. The pressure at the Chapman-Jouguet （CJ） point also becomes lower. Comparing the detonation with single RDX dust, the pressure and temperature in the flow field of detonation of mixed dust are higher.

Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

The deflagration-to-detonation transitions (DDTs) for clouds of spherical aluminum dust (SAD) mixed with air or epoxypropane mist (EPM) and air were investigated in a 29.6-m-long experimental tube of 199 mm in diameter. The clouds formed through the injection of SAD and SAD/liquid epoxypropane samples into the experimental tube. Explosions of the SAD/air mixture were initiated using a 7-m-long EPM/air cloud explosion ignited by a 40-J electric spark. Explosions in SAD/EPM/air clouds were initiated using a 1.2-m EPM/air cloud explosion ignited by a 40-J electric spark initiated using a 40-J electric spark. Self-sustained detonation waves formed in SAD/EPM/air mixtures instead of in SAD/air mixtures. The stages and characteristics of the DDT process in SAD/air and SAD/EPM/air mixtures were studied and analyzed. Self-sustained detonation was evident from the existence of a transverse wave and a cellular structure. Moreover, a retonation wave formed during the DDT process in SAD/EPM/air clouds.

Pulmonary sarcoid-like granulomatosis induced by aluminum dust:report of a case and literature review

Awide range of pulmonary pathology is attributed to aluminum dust exposure, including interstitial fibrosis^1-5 desquamative interstitial pneumonia^6 and pulmonary alveolar proteinosis^7 To our knowledge, granulomatous lung disease induced by aluminum dust is rare, only two cases were reported in literatures^8.9 We had the opportunity to make a diagnosis of pulmonary sarcoid-like granulomatosis in a patient exposed to aluminum dust. Herein, we report the clinical history, radiographic and histopathological findings in this patient, and the detailed mineralogical analyses performed on lung tissue obtained by open lung biopsy.