Abstract
The effects of anode dopants and alumina bath content on the wetting properties of the anode/bath interface in an aluminium electrolysis cell have been investigated in this study. Increasing the wettability of the carbon anode maximises the anode surface area and prevents a sudden increase in current density that polarises the anode leading to the discharge of fluoride ions and the onset of anode effect. From the contact angle measurements presented in this study, it is clear that the presence of carbonate salts inside and at the surface of the substrate greatly increases the wettability of the graphite substrate/cryolitic melt interface. The higher the carbonate salt content of the substrate, up to a dopant levels of 6 wt%, the better the wetting properties. Furthermore, alumina appears to act as a surface-active component when present in the electrolyte in contact with a pure graphite anode, but these properties diminish when carbonate is present in the anode.
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Acknowledgements
This project was supported by a grant from the “Laboratoire des Recherches et Fabrications” (LRF) of Aluminium Pechiney (now Rio Tinto). The authors gratefully acknowledge Pierre Homsi and Claude Vanvoren for their support.
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Meunier, P., Welch, B., Skyllas-Kazacos, M. et al. Effect of dopants on wetting properties and electrochemical behaviour of graphite anodes in molten Al2O3-cryolite melts. J Appl Electrochem 39, 837–847 (2009). https://doi.org/10.1007/s10800-008-9730-0
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DOI: https://doi.org/10.1007/s10800-008-9730-0