LOW-TEMPERATURE ELECTROLYTIC PRODUCTION OF Al-REM ALLOYS IN CRYOLITE MELTS

A. V. Rudenko; Руденко А. В.; O. Yu. Tkacheva; Ткачева О. Ю.; A. A. Kataev; Катаев А. А.

doi:10.31857/S0235010623040060

LOW-TEMPERATURE ELECTROLYTIC PRODUCTION OF Al-REM ALLOYS IN CRYOLITE MELTS

Authors: Rudenko A.V.¹, Tkacheva O.Y.¹, Kataev A.A.¹
Affiliations:
1. Institute of High Temperature Electrochemistry, Ural Branch of the RAS
Issue: No 4 (2023)
Pages: 385-395
Section: Articles
URL: https://journals.rcsi.science/0235-0106/article/view/138734
DOI: https://doi.org/10.31857/S0235010623040060
EDN: https://elibrary.ru/XFTAJK
ID: 138734

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Abstract

The process of electrolytic production of Al–Y and Al–Sc alloys in an electrolyte based on potassium cryolite KF–NaF(10 wt %)–AlF₃ with a cryolite ratio (CR) of 1.5, containing Al₂O₃, Sc₂O₃, or Y₂O₃ oxides, in a cell with vertical electrodes has been studied. The Fe–Ni–Cu alloy served as an inert anode. The wetted cathode was a graphite plate coated with the aluminum diboride. The electrolysis was carried out at a cathode current density of 0.2 A/cm² and a temperature of 830°C. The Al₂O₃ mass was calculated based on the value of the current efficiency of 60%. The Sc₂O₃ additive was introduced into the melt in an amount of 1 wt %. The mass of the Y₂O₃ additive was chosen based on its solubility in the melt under study. For this, the influence of Y₂O₃ additives on the liquidus temperature of the quasi-binary mixture [KF–NaF(10 wt %)–AlF₃ (KO = 1.5)]–Y₂O₃ was determined and it was found that, in contrast to Sc₂O₃ additives, which lower the liquidus temperature of the cryolite melt, small additions of Y₂O₃ lead to its sharp increase. It has been found that the efficiency of the electrolytic reduction of Y₂O₃ is 10 times higher than that of the aluminothermic reduction. Other things being equal, the efficiency of the electrolytic reduction of Y₂O₃ is higher than that of Sc₂O₃. Alloys Al–Y and Al–Sc with a REM content of 0.6 wt % have been obtained. However, the time to reach the maximum recovery of yttrium significantly exceeds the time to recover scandium. Metallographic studies of the obtained alloys indicated the presence of Al₃Sc and Al₂Y intermetallic compounds. A conclusion is made about the fundamental possibility of low-temperature electrolytic production of Al-REM alloys in cryolite melts based on potassium cryolite in vertical cells with an inert metal anode and a wettable cathode.

Keywords

cryolite, melts, cryolite ratio, yttrium oxide, scandium oxide

References

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