Summary
Increasing prices and the shortage of large blocks of electrical energy have given greater impetus to the search for viable alternative processes for aluminum production. These include electrolysis of aluminum chloride, sulfide, and nitride; carbothermal reduction of either the ore or alumina; and disproportioning reactions of either aluminum sulfide or the monochloride route. Common to all these processes are the starting material—an ore containing aluminum oxide—and the final product—the metal. Thus, the thermodynamic cycle will invariably dictate similar theoretical energy requirements for the three processes. In practice, however, the achievable efficiencies and, more noticeably, the proportion of electrical to carbothermal energy required for the various stages of operation can vary.
The present status of these alternative processes indicates that while alternative routes, such as the Alcoa-AlCl3-Smelting Process, show distinct potential for reducing electrical energy requirements, they offer little chance of reducing overall energy requirements. Furthermore, because of more stringent purity requirements, any gains made may be at the expense of production costs.
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References
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Kai Grjothelm received his Diploma in chemistry in 1950 and his Dr. Techn. In 1956 from the Technical University of Norway (NTH), Trondheim. He has been professor of inorganic chemistry at the University of Oslo, Norway since 1973. He previously held the same position at this Alma Mater in Trondheim, where he also served as head of the Department of Chemistry. Professor Grjotheim’s main area of research is fused salt chemistry and its application to industrial problems. He has published numerous papers in this area and has authored a recent book, Aluminum Electrolysis. The Chemistry of the Hall-Héroult Process. He has received several international awards for his work. including the Italian “Guido Donegadi” gold medal and “La Medaille Sant-Clair Deville” of the French Metallurgical Society. He has been a frequent speaker at AIME Annual Meetings.
Barry Welch is professor of chemical and materials engineering and head of the Department of Chemical and Materials Engineering with the School of Engineering at the University of Auckland. He received his MSc and PhD from the University of New Zealand. He was recently awarded a DSc for his contributions to applied electrochemistry by the University of Auckland. He first developed his research interest in aluminum smelter technology while working with Reynolds Metals Research Division in 1960–1963. This continued to be the central theme of his research group while on the staff of the University of New South Wales, Australia. His collaboration with Kai Grjotheim extends over 12 years and includes coauthoring the book Aluminum Smelter Technology — A Pure and Applied Approach, as well as numerous other publications.
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Grjotheim, K., Welch, B. Impact of Alternative Processes for Aluminum Production on Energy Requirements. JOM 33, 26–32 (1981). https://doi.org/10.1007/BF03339491
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DOI: https://doi.org/10.1007/BF03339491