Thanks for your question. We contacted Chem Supply about the SDS for their aluminium powder and they confirmed that their supplier has classified this chemical as non hazardous according to Regulation (EC) No. 1272/2008 and not a dangerous good. The SDS states:
‘This grade of aluminium atomised powder has been tested by an independent authority in accordance with the test procedures laid out in the ADG Code. The criteria for the ‘dangerous when wet’ classification is NOT met by this aluminium atomised powder, and accordingly has not been classified as a Dangerous Good. The decreased sensitivity to moisture and reactive nature of finely divided metal powders is due to a protective oxide layer.’
We also had a look into the gas atomisation process for generating aluminium powder and found that, typically, the process involves the introduction of a small percentage of oxygen into the atomisation gas so that a protective layer of aluminium oxide is formed on surface of the metal. The aluminium powder is thus ‘passified’ to reduce its explosion hazard and is rendered less reactive to water.
However, taking into consideration the ability of aluminium powder to liberate hydrogen on reaction with water, and the associated risk of powder ignition, as well as its incompatibility with acids, alkalis, oxidising agents and halogenated hydrocarbons, ASSIST is in agreement with the RTG (Regional Technicians Group, W.A. Department of Education) that the most appropriate place in a school Chemstore to store aluminium powder is with Class 4.3 chemicals (substances which in contact with water emit flammable gases).
Chem-Supply, Material Safety Data Sheet cs:1.4.95, Aluminium Powder, https://www.chemsupply.com.au/documents/AL0301CH0S.pdf, issue date September 2011, accessed September 2014.
Gopienko, Victor G., Production of Aluminum and Aluminum Alloy Powders, Chapter 12 in Handbook of Non-Ferrous Metal Powders: Technologies and Applications (authors: Oleg D. Neikov, Stanislav Naboychenko, Irina B. Mourachova, Victor G. Gopienko, Irina V. Frishberg, Dina V. Lotsko), Burlington: Elsevier Science, 2009, pp. 268-271.
Tang, F., Anderson, I.E., and Biner, S.B., Journal of Light Metals 2, 2002, p. 201.
Neikov, Oleg D., Safety Engineering in the Production of Powders, Chapter 24 in Handbook of Non-Ferrous Metal Powders: Technologies and Applications (authors: Oleg D. Neikov, Stanislav Naboychenko, Irina B. Mourachova, Victor G. Gopienko, Irina V. Frishberg, Dina V. Lotsko), Burlington: Elsevier Science, 2009, pp. 554-558.