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Combination for electrolytic reduction of alumina

United States Patent

April 30, 2002
View the Complete Patent at the US Patent & Trademark Office
An electrolytic bath for use during the electrolytic reduction of alumina to aluminum. The bath comprises molten electrolyte having the following ingredients: AlF.sub.3 and at least one salt selected from the group consisting of NaF, KF, and LiF; and about 0.004 wt. % to about 0.2 wt. %, based on total weight of the molten electrolyte, of at least one transition metal or at least one compound of the metal or both. The compound is, a fluoride; oxide, or carbonate. The metal is nickel, iron, copper, cobalt, or molybdenum. The bath is employed in a combination including a vessel for containing the bath and at least one non-consumable anode and at least one dimensionally stable cathode in the bath. Employing the instant bath during electrolytic reduction of alumina to aluminum improves the wetting of aluminum on a cathode by reducing or eliminating the formation of non-metallic deposits on the cathode.
Brown; Craig W. (Seattle, WA), Brooks; Richard J. (Seattle, WA), Frizzle; Patrick B. (Lynnwood, WA), Juric; Drago D. (Bulleen, AU)
Northwest Aluminum Technology (The Dalles, OR)
09/ 721,846
November 25, 2000
The work described herein was partially funded by Pacific Northwest National Laboratory, a unit of the U.S. Department of Energy, operated by Battelle Northwest; the contract number is 310468-A-UF.