A comprehensive review of aluminium electrolysis and the waste generated by it

Abstract

Aluminium is produced by electrolysis using alumina (Al2O3) as raw material and cryolite (Na3AlF6) as electrolyte. In this Hall–Héroult process, the energy consumption is relatively large, and solid wastes such as spent anodes and spent pot liner, flue gas and waste heat are generated. Therefore, this article discusses from the perspective of high energy consumption and high pollution and summarizes the methods to reduce energy consumption and solve pollution problems. The functions of carbon anode, carbon cathode, refractory material and sidewall in aluminium electrolysis cells are discussed in detail. The process of aluminium electrolysis and the ways to improve the current efficiency of aluminium electrolysis cells and reduce their energy consumption are outlined. The causes and treatment methods of spent anodes, spent cathodes, spent refractories and spent spot liner are reviewed. The research progress of waste heat recovery and aluminium electrolysis flue gas purification are analysed. And the future research directions of aluminium electrolysis flue gas are provided.

Stable and fast Na-ion storage of recovered carbon from the spent carbon cathode of aluminum electrolysis

“…Spent carbon cathodes are a kind of solid waste generated in the Hall–Héroult aluminium electrolysis process, which contain a large amount of carbon, and several inorganic compounds, including fluoride, cyanide, aluminosilicates, silica, etc. 1 The used-to-be air storage method and landfill treatments threaten the environment and ecology seriously, because fluoride is soluble and cyanide is toxic, and their contents exceed the value defined in the national safety emission standard. 7000 tons of SCC would be generated by production of every 300 thousand tons of primary aluminium, and the production of SCC was up to 1.6 million tons in 2022, calculated from primary aluminium yield.…”