A Review: Understanding the Science and the Impacts of Impurities upon the Electrolytic Bath of Hall–He ´roult Reduction Cells

This article presents an overview of impurities associated with alkali metals and alkaline earth elements found in smelter-grade alumina and other raw materials that are critical to the electrolyte in Hall-Héroult reduction cells. The objective is to suggest pathways for improved control of these impurities at primary aluminum smelters, detailing their effects on intermediate subprocesses, metal products, and overall cell conditions. Through a review of the current literature and scientific understanding, the authors aim to create a comprehensive reference that encompasses both the scientific mechanisms by which impurities interact in molten salt baths during electrolysis and the practical challenges related to impurity management in aluminum production. By integrating scientific insights with effective process engineering techniques, the study offers valuable guidance for stakeholders to better manage the impacts of impurities, thereby enhancing the performance and efficiency of aluminum smelting operations.