Fundamental Loss of Current Efficiency During Aluminium Electrolysis and Its Correlation with Sodium Content Dissolved in the Aluminium

Primary aluminiumPrimary aluminium producers are inclined to maximize the cellsCell’ current efficiencyCurrent efficiency in order to enhance metal production and reduce production cost. For timely decisions, sodium contentSodium content of the cathodic aluminiumAluminium has been used as a performance indicator related to individual cellCell performances. This paper pinpoints the straightforward quantitative theoretical relation which exists between sodium contentSodium content and current efficiencyCurrent efficiency. This relation is based on the fundamental thermodynamics of the changing bath composition in the boundary layers and on mass transfers at the anodic and cathodic interfaces. Few simplifying hypotheses are used to predict the cellCell’s optimal current efficiencyCurrent efficiency under a specific set of operating conditions. The proposed calculation methodology is described and a critical discussion is performed to highlight the impact of different factors on the current efficiencyCurrent efficiency along with future considerations necessary to improve the current efficiencyCurrent efficiency estimations.