Process and apparatus for low temperature electrolysis of oxides
AssigneeAluminum Company of America
InventorsAlfred F. La Camera, Kathleen M. Tomaswick, Siba P. Ray, Donald P. Ziegler
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Abstract
A process for electrowinning metal in a low temperature melt is disclosed. The process utilizes an inert anode for the production of metal such as aluminum using low surface area anodes at high current densities.
Claims29
A process for electrowinning metal in a low temperature melt comprising passing a current between a cermet anode and a cathode in an essentially nonslurry molten salt bath containing an oxide of said metal, wherein oxygen is evolved at said anode, said anode having an active surface area of about 0.7 to 1.3 times the active surface area of said cathode, said molten salt bath comprising an alkali metal fluoride and at least one other metal fluoride for electrolyzing said oxide to metal and oxygen while maintaining said molten salt bath at a temperature less than about 900.degree. C.
A process for electrowinning aluminum in a low temperature melt comprising passing a current between a cermet anode and a cathode in a molten salt bath containing alumina, said anode having an actual surface area about 0.7 to 1.3 times the actual surface area of said cathode, said molten salt bath comprising a eutectic of NaF and AlF.sub.3, essentially devoid of lithium said cermet anode comprising a Cu-Ni-Fe cermet;
- maintaining said molten salt bath at a temperature less than about 900.degree. C.;
- and
- recovering aluminum from said molten salt bath and generating oxygen at said cermet anode.
An apparatus for electrowinning aluminum comprising:
- a crucible containing an essentially nonslurry molten salt bath consisting essentially of a eutectic of NaF and AlF.sub.3 and alumina in solution therewith;
- a cathode positioned within said crucible for collecting said aluminum;
- and
- an anode, spaced from said cathode within said crucible, said anode comprising about 12-25% by weight copper metal and about 75-88% by weight oxide, said oxide comprising about 50-60 mole % NiO and about 40-50 mole % Fe.sub.2 O.sub.3 ;
- and
- means providing current between said cathode and said anode.
A process for electrowinning aluminum in a low temperature melt containing alumina dissolved therein essentially without a slurry, comprising passing a current between a cermet anode consisting essentially of about 12-25% by weight Cu and about 75-88% by weight oxide, said oxide comprising about 50-60 mole % NiO and about 40-50 mole % Fe.sub.2 O.sub.3, said low temperature melt comprising a eutectic mixture of NaF and AlF.sub.3 ;
- maintaining said melt at a temperature less than about 900.degree. C.;
- and recovering molten aluminum from said melt and generating oxygen at said anode.
The process of calm 27, wherein said anode and cathode are moved relative to one another to vary the extent of cross-sectional area for current flow through said molten salt bath between said anode and cathode and therefore regulate current density at said anode.
Dependencies are inferred from the claim text.