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Borated graphite cathodes for low-temperature aluminum electrolysis

A. V. Rudenko, A. A. Kataev, M. M. Neupokoeva, O. Yu. Tkacheva

Abstract


Electrochemical boriding of the graphite plates in the potassium cryolite based electrolytes was studied. The boriding were carried out in a cell with vertical electrodes. The procedure included 2 stages: 1) electrolysis in the KF–AlF3–KBF4 melt (CR=1.3) at low current density (0.01–0.02 A/cm2), required for the boron reduction, at 700 and 750 °C; 2) electrolysis in the KF–AlF3–Al2O3 melt at higher current density (0.2 A/cm2), required for the aluminum reduction. The optimal conditions of electrodeposition for obtaining the borated wettable cathodes were determined. According to the SEM data, a continuous AlB2 layer with a thickness of 7–10 μm was formed on the graphite surface. The borated graphite was tested as a wetted cathode during the low-temperature aluminum electrolysis. Prolonged electrolysis in a vertical cell with the graphite anode and the borated graphite cathode was carried out in the KF–NaF(10 wt.%)–AlF3–Al2O3 electrolyte (CR=1.5) at 830 °C. After 100 h of electrolysis, the thickness of the AlB2 layer on the graphite surface was 5 μm, while the cathode surface was completely wetted with aluminum. Thus, we demonstrated the feasibility of using the borated graphite cathode as a wettable dripping cathode in the low-temperature aluminum electrolysis in the vertical cell.


Keywords


graphite cathode; boriding; cryolite; electrolysis

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DOI: https://doi.org/10.15826/chimtech.2022.9.2.08

Copyright (c) 2022 Rudenko A.V., Kataev A.A., Neupokoeva M.M., Tkacheva O.Yu.

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Chimica Techno Acta, 2014-2023
ISSN 2411-1414 (Online)
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