Primary Production of Aluminium and Its Alloys in Molten Salts with Oxygen Evolving Anodes: Overview

Abstract

Due to environmental and economic concerns, carbon-free aluminium production has been an ultimate target for aluminium industries. For the last few decades, a considerable amount of research has been conducted to find a suitable inert anode that could replace the consumable carbon anodes for aluminium electrolysis. Material types such as metals, ceramics and cermets have been studied extensively. All the anode materials have their advantages and disadvantages. However, metallic alloys have been considered attractive anode material candidates due to their high electrical conductivity, thermal stability and easy fabrication and machining properties. For a successful adaptation of metallic anodes into the aluminium electrolysis cell, an electrolyte with a low-operating temperature and high alumina solubility is required. Another significant component of the carbon-free aluminium electrolysis cell is a wettable cathode. This overview discusses the research progress on inert anodes, wettable cathodes and electrolytes.

Electrowinning of Aluminum —Challenges and Possibilities for Reducing the Carbon Footprint—

“…A lot of research has been done in this area. 4 Tin oxide was found to be a good candidate inert anode in the 1980's. However, very small contents of tin in produced aluminium is detrimental for the properties.…”

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

“…For the KF-AlF 3 -Al 2 O 3 based melts, the regularities of the cathode process on tungsten and glassy carbon, 24,25 as well as those of the anode process on glassy carbon, 26,27 and the anode behavior of various candidate materials of oxygen-evolving anodes (Cu, Ni, Cu-Al, Cu-Fe-Ni, Cu-Fe-Ni-Al, NiFe 2 O 4 et al) were studied earlier. [4][5][6][7][28][29][30] The interpretation of the mechanism and determination of anode process parameters according to the available results is challenging due to the superposition of chemical and electrochemical dissolution of the above oxygen-evolving anode materials, as well as the variability of the electrical resistance of the surface layer of the anode. To obtain new fundamental results for the purpose of their practical application, it is necessary to study the anode process on more stable materials (e.g., Pt, Au, Ir).…”