Effect of Coke Properties on the Bubble Formation at the Anodes During Aluminium Electrolysis in Laboratory Scale

Abstract

The anodic reaction of aluminium electrolysis cells leads to the formation of CO 2 bubbles, which partly screen the anode surface and leads to an increase in the cell voltage. An advantage of these bubbles is that the formation and release contribute to the stirring of the electrolyte, however, the screening of the surface increase the irreversible energy losses. In this work the voltage and current oscillation due to bubbles evolution during electrolysis in laboratory cell were presented. A comparison of different carbon anode materials in terms of coke impurities (mainly sulphur content) and grain sizes were investigated. Anodes with finer coke fraction showed lower oscillations than coarser fraction equivalents. Additionally, influence of current density on amplitude of anode potentials was measured. A 64 % increase of current density caused an increase of anode potential oscillations from 79 to 179 %.

Study on the Inter-Electrode Process of Aluminum Electrolysis (Ⅱ)—Digital Analysis of the Anode Gas Distribution Patterns on the Anode Surface Using A See-Through Cell

“…The bubble evolution behavior on several carbon materials has been reported in other investigations [18][19][20]. Combined research should be carried out in the future to understand the relationship between the bubble behavior and the material properties, with the aim of improving the performance of industrial anode.…”

Optical and Electrochemical Characterisation of Carbon Anodes with Varying Porosity and Coke Quality

“…Similarly, the current oscillations using the constant voltage measurements can be used to calculate the bubble screening, Equation 3. Since the anode is small, the maximum current Imax is assuming the anode is completely free for bubbles [10,13].…”

“…In laboratory studies the different contributions to the cell potential can be investigated separately by suitably adapting the anode assembly. A horizontal anode assembly [12,13] will maximise the bubble formation, and can be used to investigate the effect of hyperpolarisation. A vertical anode assembly [11,14,15] will minimise the bubble screening of the surface, and the reaction overpotential can be investigated without the effect of hyperpolarisation.…”