Abstract
Like all metallurgical industries, aluminum smelting has been under pressure from two fronts—to give maximum return on investment to the shareholders and to comply with environmental regulations by reducing greenhouse emissions. The smelting process has advanced by improving efficiency and productivity while continuing to seek new ways to extend the cell life. Materials selection (particularly the use of more graphitized cathodic electrodes) has enabled lower energy consumption, while optimization of the process and controlling in a narrow band has enabled increases in productivity and operations at higher current densities. These changes have, in turn, severely stressed the materials used for cell construction, and new problems are emerging that are resulting in a reduction of cell life. The target for aluminum electro-winning has been to develop an oxygen-evolving electrode, rather than one that evolves substantial amounts of carbon dioxide. Such an electrode, when combined with suitable wettable cathode material developments, would reduce operating costs by eliminating the need for frequent electrode change and would enable more productive cell designs and reduce plant size. The materials specifications for developing these are, however, an extreme challenge. Those specifications include minimized corrosion rate of any electrode into the electrolyte, maintaining an electronically conducting oxidized surface that is of low electrical resistance, meeting the metal purity targets, and enabling variable operating current densities. Although the materials specifications can readily be written, the processing and production of the materials is the challenge.
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Editor’s Note: This was an invited plenary lecture for the symposium Processing Materials for Properties II, which was held in San Francisco, California, November 5–8, 2000.
For more information, contact B.J. Welch, University of Auckland, High Temperature Materials and Processes Group, School of Engineering, Private Bag 92019, Auckland, New Zealand; +649-373-7515; fax +649-521-9142; e-mail barry@barry.co.nz.
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Welch, B.J., Hyland, M.M. & James, B.J. Future materials requirements for the high-energy-intensity production of aluminum. JOM 53, 13–18 (2001). https://doi.org/10.1007/s11837-001-0114-8
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DOI: https://doi.org/10.1007/s11837-001-0114-8