Maintaining molten salt electrolyte concentration in aluminum-producing electrolytic cell
AssigneeNorthwest Aluminum Technologies
InventorsRobert J. Barnett, Michael B. Mezner, Donald R. Bradford
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Abstract
A method of maintaining molten salt concentration in a low temperature electrolytic cell used for production of aluminum from alumina dissolved in a molten salt electrolyte contained in a cell free of frozen crust wherein volatile material is vented from the cell and contacted and captured on alumina being added to the cell. The captured volatile material is returned with alumina to cell to maintain the concentration of the molten salt.
Claims20
A method of maintaining concentration in a low temperature electrolytic cell used for the production of aluminum from alumina dissolved in a molten salt electrolyte contained in a cell free of frozen crust, the method comprising:
- (a) providing a molten salt electrolyte at a temperature less than 900° C.;
- (b) providing a plurality of anodes and cathodes disposed in said electrolyte;
- (c) venting volatile material from said cell through a conduit;
- (d) adding alumina to said cell through said conduit;
- (e) capturing said volatile material on said alumina;
- and
- (f) returning said captured volatile material to said electrolyte with said alumina thereby maintaining the concentration in said molten salt electrolyte.
A method of maintaining fluoride concentration in a low temperature electrolytic cell during electrolytic production of aluminum from alumina dissolved in a fluoride-based molten salt electrolyte contained in a cell substantially free of a frozen crust, the method comprising:
- (a) providing a fluoride-based molten salt electrolyte at a temperature less than 900° C., the electrolyte comprised of one or more alkali metal fluorides and at least one metal fluoride;
- (b) providing a plurality of anodes and cathodes in said molten electrolyte containing inert dissolved alumina;
- (c) passing electrical current from said anodes through said electrolyte to said cathodes and depositing aluminum at said cathode;
- (d) venting fluorides containing volatile material from said cell;
- (e) adding alumina to said cell substantially continuously and contacting said fluoride containing volatile material with said alumina;
- (f) capturing volatile material on said alumina;
- and
- (g) returning said fluorides containing volatile material to said electrolyte with said alumina to maintain the fluoride concentration in said molten salt electrolyte.
Dependencies are inferred from the claim text.