Abstract
The operational characteristics of a laboratory-scale alumina reduction cell incorporating a wettable cathode were evaluated by electrolyses in a 10 wt% alumina/cryolite melt at 975° C. It was shown that as the anode—cathode distance (a.c.d.) decreased, the mass transfer rate increased and the current efficiency decreased. The contribution to cell resistance from the anode bubble-layer at small a.c.d.'s was found to be significant. The ohmically corrected cell voltage decreased with decreasing a.c.d., increasing anode immersion and increasing anode rotation rate, indicating a substantial influence of mass-transfer on cell operation. Digital analysis of cell voltage and resistance data was used to characterize bubble behaviour over a range of operating conditions. The frequency spectra varied over the course of a run due to the cessation of the regular formation and detachment of large bubbles. Bubble behaviour was strongly dependent on anode geometry, current density and anode rotation rate, tending towards smaller bubbles at high angles of inclination, low current density and high rotation rate.
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Dorin, R., Frazer, E.J. Operational characteristics of laboratory scale alumina reduction cells with wettable cathodes. J Appl Electrochem 23, 933–942 (1993). https://doi.org/10.1007/BF00251030
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DOI: https://doi.org/10.1007/BF00251030