Investigation of electrolytic bubble behaviour in aluminum smelting cell

Abstract

A 1/4th scale low temperature electrolytic model of the Hall-Heroult cell was constructed to investigate the electrolytic bubble formation mechanism, coalescence and movement under the horizontal anode surface. Geometric and dynamic similarity between the model and real cell was maintained through using similarity criteria. A 0.28M CuSO4+20%H2SO4 solution was selected as an electrolyte where Cu was deposited at the cathode and O2 bubbles were generated underneath the anode, similar to the phenomena of real cell. The bubble generation mechanism, movement, coalescence and detachment under the electrolytic medium were observed using a high speed camera. It was found that electrolytic bubbles generate uniformly under the whole anode surface and grow through gas diffusion and coalescence. At higher current density and higher anode inclination angles, bubbles escape quickly from underneath the anode surface. The bubble layer thickness and bubble sizes were also found to decrease with an increase in anode inclination angle.