Harmless treatment and recycling of secondary aluminum dross: a review

Aluminum dross (AD) has become a severe problem for the environment and public health due to the great prosperity of the aluminum industry because it contains Al, AlN, Al4C3, fluoride salts, and various metal cations. In this review, the source and characterization of AD are introduced, and the differences between primary aluminum dross (PAD) and secondary aluminum dross (SAD) are analyzed. Then, the harmless treatment and utilization of AD are studied. Relative to the mature PAD recycling industry, the treatment of SAD is still in the small-scale experimental stage. The pyrometallurgical and hydrometallurgical routes are discussed as SAD processing methods, and the removal rate of hazardous content of SAD can reach 90%. Based on the high removal rate, high-purity Al, Al2O3, and other products can be prepared from SAD. Certain products, such as foaming materials, refractory materials, admixtures, and aluminum hydroxide gel material can be prepared by SAD. Finally, the economic and environmental values of the treatment and utilization of SAD are discussed. The environmental and economic assessment of SAD treatment behaves well in both life cycle assessment and life cycle cost calculations. A comprehensive display of SAD lifecycle treatment may promote the sustainable development of the aluminum industry.