Evaluation of low-temperature cryolite-based electrolytes for aluminium smelting

Aluminium was smelted in a laboratory-scale cell at temperatures down to 850 deg C from cryolite-based electrolytes with bath ratios in the range 0.75-1.50. Electolyses were conducted for 1-2 h using a current density of 1 A cm exp -2 on 5 cm exp 2 electrodes with an anode-cathode distance of 2 cm....

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Bibliographic Details
Published in:Journal of applied electrochemistry 1995-12, Vol.25 (12), p.1098-1104
Main Authors: VECCHIO-SADUS, A. M, DORIN, R, FRAZER, E. J
Format: Article
Language:English
Subjects:
Applied sciences
Electrometallurgy
Exact sciences and technology
Metals. Metallurgy
Production of metals
Production of non ferrous metals. Process materials
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Summary:Aluminium was smelted in a laboratory-scale cell at temperatures down to 850 deg C from cryolite-based electrolytes with bath ratios in the range 0.75-1.50. Electolyses were conducted for 1-2 h using a current density of 1 A cm exp -2 on 5 cm exp 2 electrodes with an anode-cathode distance of 2 cm. Current efficiencies of up to 95% were recorded. In low bath ratio electrolytes, operation at alumina concentrations of > = 3 wt.% sometimes resulted in the Al deposit breaking into globules which clustered around the cathode. Under constant current conditions, the critical alumina concentration for the onset of the anode effect was found to be 2 wt.%. The bubble evolution characteristics (i.e. size and frequency) which affect mass transfer and cell voltage were also evaluated. Overall, low temperature cryolite-based electrolytes may offer a viable alternative to conventional compositions for Al smelting.
ISSN:0021-891X
1572-8838
DOI:10.1007/BF00242536