Dissolution of Al2O3 in KF–AlF3

• Published in: Russian metallurgy Metally Vol. 2021; no. 2; pp. 213 - 218
• Main Authors: Pershin, P. S., Suzdaltsev, A. V., Zaikov, Yu. P.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-02-2021; Springer Nature B.V
• Subjects: Aluminum fluorides; Aluminum oxide; Carbothermic reactions; Chemistry and Materials Science; Dissolution; Electrodes; Electrolysis; Electrolytic cells; Empirical analysis; Materials Science; Melts; Metallic Materials; dissolution rate; alumina; voltammetry; dissolution; KF–AlF; Al; electrolysis of aluminum; O
• ISSN: 0036-0295; 1555-6255; 1531-8648
• DOI: 10.1134/S0036029521020191

KF–AlF
3
–Al
2
O
3
-based melts are promising media for the electrolytic production of aluminum in next-generation energy efficient cells. This work analyzes the dissolution of Al
2
O
3
in the KF–AlF
3
melt with a mole ratio [KF]/[AlF
3
] = 1.5 mol/mol at 785°C using cyclic voltammetry and the carbothermic reduction of melt samples using a LECO analyzer. The measurements are performed by a cell consisting of a carbon glass working electrode, a CO/CO
2
gas reference electrode, and a graphite counter electrode. During measurements, the current response peak on voltammograms is recorded as a function of the potential scan rate, the dissolution time of the next alumina sample, and the alumina content in the melt. The current response peak is shown to linearly depend on the Al
2
O
3
content in the melt, and the oxide dissolution rate is from 2.4 × 10
–3
to 5.45 × 10
–5
mol/s as a function of the oxide content in the melt. The obtained results demonstrate general possibility of operating nondestructive control of the alumina (Al
2
O
3
) content during the electrolysis of KF–AlF
3
–Al
2
O
3
–based melts. It includes the recording of a current response peak in current–voltage curves and the determination of the current alumina content in a melt using the obtained empirical dependence.