The impact of alumina quality on current efficiency and energy efficiency in aluminum reduction

Abstract

Current efficiency and energy efficiency are the two most important metrics for assessing the overall performance of a given potline. The influence of alumina quality on these parameters is however poorly understood although likely influential. This interplay is considered here with the construction of multiple regression models from daily data of test groups of 60 cells each for a number of important parameters, pertinent alumina properties from detailed materials characterization of judiciously chosen aluminas and relevant weather parameters for approximately 20 months of effective sampling. The concentration of a-Al203 in the fines is found to be the single most influential parameter affecting current efficiency and energy efficiency. Models of superheat and noise indicate that this is predominantly due to issues associated with alumina dissolution. Energy efficiency is also correlated with gibbsite content of the fines, likely due to the added energy required for the phase transformation from hydroxide to sesquioxide.