Review—Synthesis of Aluminum Master Alloys in Oxide-Fluoride Melts: A Review

Abstract

A review of the existing methods for producing aluminum master alloys with silicon, zirconium, scandium and boron are given. Basic parameters, advantages and disadvantages of the existing methods are analyzed, indicating the need to develop new more energy-efficient technologies. The prospects of obtaining aluminum master alloys in the electrolysis of melts based on the KF-NaF-AlF 3 -Al 2 O 3 -MeO (MeO = SiO 2, ZrO 2 , Sc 2 O 3 , and B 2 O 3 ) system are considered. For this purpose, the results of physical and chemical measurements in these melts are presented, including data on the solubility of Al 2 O 3 , SiO 2, ZrO 2 , Sc 2 O 3 , and B 2 O 3 oxides in KF-NaF-AlF 3 melts, data on the effect of oxide additives on the liquidus temperature of studied melts, as well as data on the kinetics of electrowinning of aluminum and alloying element from KF-AlF 3 -Al 2 O 3 -MeO melts. Based on the measurements, the parameters were selected and electrolysis tests were carried out for obtaining aluminum master alloys with silicon, zirconium, scandium, and boron from its oxides. The composition and structure of the obtained master alloys were studied.

Selective Scandium (Sc) Extraction from Bauxite Residue (Red Mud) Obtained by Alkali Fusion-Leaching Method

“…The Sc demand annually increases as it is used in lasers glass, catalysts, electronic components, halide lamps, fuel cells, and non-ferrous metallurgy [17]. The most relevant application is the production of Al-Sc alloys with high strength and low weight [18]. The Sc content in different types of RM (more than 100 mg kg −1 ) is higher than the average abundance in the Earth's crust (22 mg kg −1 ) [19].…”

Electrochemical Sensor for Monitoring the Alumina Dissolution and Concentration in a Cryolite-Alumina Melt

“…-visual method (based on the presence of alumina suspension in the melt). [29][30][31] The alumina concentration measurement and interpretation of its dissolution in conditions of an industrial electrolysis cell is complicated by the magneto-hydrodynamic phenomena as well as the high aggressivity of the cryolite-alumina melt. However, the methods and devices for measuring the alumina concentration directly in an industrial bath are proposed in the patent literature.…”

Anode Process on Platinum in Low Temperature KF-AlF3-Al2O3 Based Melts: An Update

“…This is justified, since NaF practically does not affect the anode overvoltage, and the KF-NaF-AlF 3 -Al 2 O 3 melts have an improved combination of physicochemical properties. [17][18][19][20][21] In order to avoid significant overheating, measurements were carried out in two Al…”

“…[10][11][12][13][14][15][16] During the electrolysis of the KF-AlF 3 -Al 2 O 3 based melts, the consumption of carbon or oxygen-evolving anodes can be reduced both by effecting a decrease in temperature and increasing the Al 2 O 3 dissolution rate. [17][18][19][20] Nevertheless, the use of oxygen-evolving anodes for the electrolytic production of pure aluminum requires a radical change in the design of the electrolyzer and adjustment of the electrolysis parameters. This firstly concerns the need to separate the anolyte and catholyte using Al 2 O 3 suspension or ceramic diaphragms.…”