Comprehensive treatments of aluminum dross in China: A critical review

Aluminum is an important lightweight and high-value metal that is widely used in the transportation, construction, and military industries. China is the largest producer of Al in the world, and vast quantities of Al dross (ash) are generated and stored every year. Aluminum dross contains fluoride and heavy metals, and easily reacts with water and acid to produce stimulating, toxic, and explosive gases. Owing to a lack of developed technologies, most of this dross cannot be safely treated, resulting in a waste of resources and serious environmental and ecological risks. This review briefly describes the distribution and proportions of bauxite deposits in China, the Al extraction process, and the hazardous solid waste that is generated. It also discusses the comprehensive treatments for Al dross, including the hydrometallurgy and pyrometallurgy recovery processes, and reuse of Al, Al2O3, SiO2, and chloride salts as a summarized comparison of their advantages and disadvantages. In particular, this review focuses on the efforts to analyze the relationship between existing processes and the attempts to establish a comprehensive technology to treat Al dross. Additionally, areas for future research are suggested, which may provide new ideas for the closed-loop treatment of Al dross.