The process of aluminum powder production could cause the emission of large amounts of aluminum dust into the air. This process has in the past sometimes proven dangerous and even catastrophic. The dangers that come with the production of aluminum dust often manifest themselves in form of severe dust fires, explosion accidents or health concerns for the workers. These safety concerns are what have inadvertently led to the need to not only come up with a dust removal system, but also the need to put in place adequate preventive and protective measures. Among the most prevalent methods of dust removal techniques is the immersion of aluminum dust into water. However, this method runs the risk of the water reacting with the aluminum dust to produce hydrogen gas which is extremely flammable.
Professor Qingsheng Wang at Oklahoma State University in collaboration with Professor Kaili Xu at Northeastern University in China with their joint PhD students Yantong Wang and Beibei Wang conducted a series of studies to determine how utilizing Cr(NO3)3·9H2O solution could be an effective Hydrogen Inhibition Method.
The hydrogen inhibition experiment involved the collection of dust from the dust section hole. Cr(NO3)3·9H2O and deionized water were then used to prepare a concentration of the required solution. The researchers carried out the experiments in an aluminum and water reaction tester.
Following the experiment, the researchers then collected and analyzed the results accordingly. The researchers noted that the reaction between the aluminum dust and the Cr(NO3)3·9H2O solution did not start immediately due to a passive oxide film. The onset of the experiment saw the production of hydrogen gas which became less and less as the solutions’ concentration became higher. By the time the concentration of Cr(NO3)3·9H2O solution reached 5.32 g/L, the amount of hydrogen gas being produced had almost completely subsided and the reaction between the water and aluminum dust had been completely inhibited. Moreover, the reactants produced very little Al(OH)3 and Cr(OH)3. These results thus showed that when aluminum dust was introduced into a Cr(NO3)3·9H2O solution that had a concentration equal to or greater than 5.32 g/L, the production of hydrogen gas due to the reaction of aluminum and water was inhibited.
Based on the observations made in the course of the experiment, the research team arrived at some conclusions. They realized that the presence of hydrogen gas in a wet dust removal system was a fire and explosion hazard. They also concluded that concentrations of Cr(NO3)3·9H2O solution that were higher than 5.32 g/L inhibited the production of hydrogen gas in the system. Finally, the researchers noted that this Hydrogen Inhibition Method could potentially remedy fire and explosions caused by the presence of hydrogen gas as a result of the reactions. The research team would like to see the practice of this method in the industry soon.
The significance of their study was therefore proving that regulated concentrations of Cr(NO3)3·9H2O solution were an effective way of inhibiting hydrogen production in the wet dust removal system for the treatment of aluminum dust.
Wang Yantong, Xu Kaili, Wang Beibei, Wang Qingsheng. Hydrogen inhibition by using Cr(NO3)3· 9H2O in the wet dust removal system for the treatment of aluminum dust. International Journal of Hydrogen Energy, Volume 43, Issue 4, 25 January 2018, Pages 2514-2523
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