Abstract
Current efficiency as high as 92% was obtained in bench scale electrolysis of alumina in sodium fluoride - aluminum fluoride bath with weight ratios from 0.65 to 0.80 at temperatures from about 730 to 900°C. Special aluminas calcined at low temperatures had to be used to obtain rapid solution of the alumina at these temperatures. A solid cryolite layer slowly deposited on the cathode unless the bath temperature was maintained about 100°C above the liquidus temperature of the bulk sodium fluoride - aluminum fluoride composition. The carbon anodes were attacked during anode effect, sometimes swelling, dusting, and evolving larger than normal quantities of carbon tetrafluoride. Addition of 5 wt. % LiF to the bath gave more normal anode effects. Carbon consumption approached the theoretical 0.33 g C/g Al when the alumina content was maintained at high levels and moisture additions were made to the cell atmosphere.
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References
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© 2016 The Minerals, Metals & Materials Society
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Sleppy, W.C., Cochran, C.N. (2016). Bench Scale Electrolysis of Alumina in Sodium Fluoride - Aluminum Fluoride Melts Below 900°C. In: Bearne, G., Dupuis, M., Tarcy, G. (eds) Essential Readings in Light Metals. Springer, Cham. https://doi.org/10.1007/978-3-319-48156-2_159
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DOI: https://doi.org/10.1007/978-3-319-48156-2_159
Publisher Name: Springer, Cham
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