Is acid treatment of secondary aluminum waste products prior to storage and disposal a viable option?

Abstract

Aluminum (Al) is a widely produced metal in the United Arab Emirates (UAE) particularly for the use in development and construction industries. The waste products of the aluminum industry are categorized as hazardous and generally enter municipal waste landfills in the form of aluminum dross and salt cakes. Hence, aluminum industries in the UAE are currently searching for alternative uses and disposal methods for these waste derivatives. This paper investigates the plausible impacts of the aluminum waste products such as dross and salt cakes, through material characterization and leaching studies at different reaction conditions. The salt cake and dross from UAE were characterized by Fourier transformation infrared spectroscopy (FTIR), cation exchange capacity (CEC) and scanning electron microscopy coupled with energy dispersive X-ray Spectroscopy (SEM–EDS). The CEC values for salt cake and dross were 425.8 and 408.8 meqH+/100 g sample, respectively. The FTIR spectra for both wastes showed clear bands for Al (OH)3 and organic functional groups. A treatment with acidic, neutral and basic aqueous solutions was performed to both waste products and the results showed that the acid leachate is accompanied with gas evolution and heavy metals, including high concentrations of Al. The findings of this study prove that aluminum dross and salt cakes could have hazardous implications not only in the landfill but also in the surrounding environments. A feasible treatment method using acid is suggested in light of the experimental results to reduce the negative implications of the landfill process while keeping up with guidelines and goals regarding environmental waste management of aluminum waste products in the UAE.