A Study of Bubble Behavior and Anode Effect on the Graphite and Industrial Carbon Anode in a See-Through Furnace During Aluminium Electrolysis

Abstract

Anode gas bubble behavior and anode effect on graphite and industrial carbon rod-shaped anode in a cryolite melt have been studied using a see-through furnace. The different carbon materials have different properties which can affect bubble behavior and electrochemical properties. Industrial carbon is more inhomogeneous with respect to structure, pore, aggregates and impurities in comparison to the graphite. More bubbles were nucleated on the industrial carbon than on the graphite for the same current density. The time related to the coalescence process for both anodes was found to be in interval 16 to 24 ms and independent of the current densities. Bubbles detached from the horizontal surface of the anode have similar average diameter value for both anodes for current densities < 1.0 A cm−2, while for current densities > 1.0 A cm−2, the average diameter is lower for the industrial carbon anode. The onset of the anode effect occurred faster on the graphite than on the industrial anode. The PFC-containing gas layer appeared to be thicker and more stable on the graphite anode than on the industrial carbon anode.

Numerical simulation study of the effect of anodic bubble behavior in aluminum electrolysis cell

“…The simulation results showed that the bubble would not be detached immediately when they approached the anode edge, but would be longitudinally thickened by shaking from side to side at the horizontal surface of the anode and released immediately when they reached the electrode edge. The shape changes of the bubble growing at the horizontal surface of the anode and releasing along the side wall of the electrode are shown in Figure 1, which is consistent with the experiment observed by Stanic et al [8] .…”