Gas Evolution on Graphite and Oxygen Evolving Anodes During Aluminium Electrolysis

Abstract

Anode gas evolution, growth and flow behaviour during aluminium electrolysis have been investigated using various experimental techniques, including water modelling, X-ray visualization and direct observation. Video recordings of oxygenevolving anodes (SnO2, Cu, Cu-Ni) and carbon anodes were performed in laboratory electrolysis cells of various scales. The water model also investigated the effects of slotted anodes on the gas escape from beneath large anodes. Beneath large horizontal anodes, individual bubbles form and are then subsequently swept away by large sweeping bubbles flowing rapidly beneath the bottom surface. The gas behaviour on oxygen evolving anodes was very different from that with carbon, with the formation of very small bubbles that released very quickly from the anode due to improved wetting of the anode by the electrolyte.