Use of Ionic Liquids as Innovative Solvents in Primary Aluminum Production

Today, the primary aluminum production is based on two processes: (a) the Bayer process and (b) the Hall–Heroult process. Both processes deal with several economic and environmental drawbacks. The production of aluminum is an energy intensive process, consuming 53–61 GJ/t of aluminum, while huge amount of red mud and gaseous emissions are inevitably produced through the whole process. The utilization of a new family of solvents called ionic liquids (ILs) in the primary aluminum production is the subject of this paper, which examines the possibility of dissolving metallurgical alumina, hydrated alumina, and bauxites in 1-ethyl-3-methyl-imidazolium hydrogen sulfate ([Emim]HSO₄). The results show that hydrated alumina can be dissolved relatively easily at 210°C, forming a melt that contains 9% w/w of dissolved alumina, which is higher than the alumina content in Hall–Heroult melts. Bauxites can also be directly dissolved in this IL with iron presenting higher dissolution than aluminum, while silicon dissolution is negligible.