Abstract
The aluminium industry is concerned by the predicted
quality changes in available petroleum cokes used for
prebaked carbon anodes. The knowledge on the effects of
high-sulfur cokes on the electrochemical performance is
limited in the industry. In this study, the electrochemical
performance related to voltage oscillations caused by
bubble formation on the horizontal surface of the anode is
investigated with respect to both coke quality and anode
properties. Pilot anodes made from five industrial cokes,
ranging in sulfur content from 1.4 to 5.5 wt% were
studied. For anodes produced with anisotropic cokes,
voltage oscillations are observed in the range of 0.25–
0.36 V, with the maximum screening due to the bubbles
in the 40–50% range. These values correlate with the
anode properties, rather than differences between the
anisotropic cokes. Among the anisotropic anodes, the
most permeable anode resulted in the lowest voltage
oscillations, similar to the observations for the anode
made from isotropic coke. The positive effect on electrochemical
behaviour related to bubbles for the isotropic
anode is likely an indirect effect of the coke quality and
characteristics.