Influence of Additives on Bath Analysis in Aluminum Electrolysis

In this study, the phase compositions of a solid cryolitic electrolyte based on the Na 3 AlF 6 -AlF 3 -KF-LiF-CaF 2 -Al 2 O 3 system have been investigated. Using x-ray diffraction (XRD) and fluoride ion selective electrode analysis (FISEA) techniques, the molar ratio of NaF-AlF 3 of the cryolitic electrolyte has been determined. The influence of the acidity of the additive electrolytes on the phase compositions of the cryolitic electrolyte has been discussed to gain fundamental insights into understanding the role of additives in such systems. Moreover, an improved XRD-based industrial bath analysis method has been introduced to analyze the composition of the complex cryolitic electrolytes. Finally, based on these results, a new equation has been derived that can be used for FISEA to complement such composition analyses.