Effect of alkali doping on the preparation of calcium aluminate by aluminum dross calcification process

• Published in: Environmental technology & innovation Vol. 32; p. 103312
• Main Authors: Xie, Mingzhuang, Lv, Han, An, Huilong, Liu, Fengqin, Zhao, Hongliang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2023
• Subjects: Alkali doping; Aluminum dross; Calcium aluminate; Detoxification; Phase transition; Aluminum dross; Alkali doping; Calcium aluminate; Detoxification; Phase transition
• ISSN: 2352-1864; 2352-1864
• DOI: 10.1016/j.eti.2023.103312

The emission of hazardous aluminum dross is increasing with the rapid development of China’s aluminum industry. It is not only a waste of valuable aluminum resources, but also a serious ecological problem. Aluminum dross, calcium based additives, and trace alkaline additives are used for roasting reactions to achieve high-temperature synergistic detoxification. A new method for extracting valuable aluminum elements from aluminum dross has been proposed. The research results indicate that a small amount of sodium carbonate added to the aluminum dross calcination system can enable Na2O to solidly dissolve in 12CaO⋅7Al2O3 (C12A7). The crystal plane spacing and cell volume of C12A7 are increased, the structural activity of the crystal is improved, and the leaching performance of C12A7 is strengthened. High quality aluminum sources can be extracted and separated from other impurities that are insoluble in alkaline solution. Under the optimal roasting conditions, the aluminum leaching rate is 95.84%, and the removal rates of nitrogen, chlorine, and soluble fluorine elements all exceed 99%. The toxic components in aluminum dross are efficiently removed during the roasting process. The leaching reaction of calcium aluminate conforms to the unreacted core model controlled by internal diffusion. The crystal structure activity of calcium aluminate was enhanced by alkali doping, and the activation energy of the leaching reaction was 15.50 kJ mol−1. [Display omitted] •A method for detoxification of aluminum dross by calcification has been proposed.•The doping of alkali enhances the leaching performance of 12CaO⋅7Al2O3 (C12A7).•The removal rates of nitrogen, chlorine, and soluble fluorine elements all exceed 99%.