Sammendrag
In the authors' opinion, it is not likely that there will soon be an alternative to the Hall-Héroult process for making primary aluminium. The energy consumption in the traditional process is steadily decreasing, and there is still more room for improvement. The present paper discusses some opportunities for reducing the energy consumption, such as the use of copper inserts and reduced anode-cathode distance. The latter requires better alumina control for counteracting the perturbation of the metal-bath interface following anode changes. The heat losses must be reduced as the cell voltage is reduced, and this is a serious challenge. The environmental performance can be improved by better alumina feeding and control and somewhat higher alumina level, which can eliminate all anode effects. Currently, the main global environmental issue appears to be carbon dioxide evolution in the production of electric power for the process, which has increased by one order of magnitude during the last four decades.
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