US4057480A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inconsumable electrodes
Assignee: Rio Tinto Switzerland AG
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Filing: 1976-01-19
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Granted: 1977-11-08
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Expires: 1996-01-19
Abstract
Abstract Process for operating a cell for the electrolysis of a molten charge, in particular aluminum oxide, with one or more anodes the working surfaces of which are of ceramic oxide material, and anode for carrying out the process.
Inventors
- 👤 Hanspeter Alder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:20
CPC Classifications
C; C25; C25C; C25C3/00; C25C3/06; C25C3/08; C25C3/12
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
135 words
In an inconsumable anode comprising an electrode composed of ceramic oxide material, for use in electrolytic recovery of aluminum from a molten charge electrolyte containing aluminum oxide during which electrolytic recovery a predetermined minimum current density is maintained over that portion of the surface of the electrode in contact with the electrolyte to retard the reaction between the electrode and the electrolyte, the improvement comprising: a protective ring composed of electrically insulating material which is also resistant against reaction with the electrolyte, said protective ring being disposed on the surface of the electrode at least at the portion of the electrode which during use, normally forms a three phase zone by simultaneous contact with the atmosphere and the electrolyte, whereby said protective ring provides protection to the anode from reaction at the three phase zone.
Claim 2
Dependent Claim
135 words
In an inconsumable anode comprising an electrode composed of ceramic oxide material, for use in electrolytic recovery of aluminum from a molten charge electrolyte containing aluminum oxide during which electrolytic recovery a predetermined minimum current density is maintained over that portion of the surface of the electrode in contact with the electrolyte to retard the reaction between the electrode and the electrolyte, the improvement comprising: a protective ring composed of electrically insulating material which is also resistant against reaction with the electrolyte, said protective ring being disposed on the surface of the electrode at least at the portion of the electrode which during use, normally forms a three phase zone by simultaneous contact with the atmosphere and the electrolyte, whereby said protective ring provides protection to the anode from reaction at the three phase zone.
Claim 3
Dependent Claim
22 words
In an anode, as claimed in claim 1 wherein the protective ring is supplied to the electrode before it goes into service.
Claim 4
Dependent Claim
17 words
In an anode, as claimed in claim 1 wherein said ring comprises a crust of solidified electrolyte.
Claim 5
Dependent Claim
48 words
In an anode as claimed in claim 1, further including a current distributor composed of electrical conductive material having an electrical resistance less than that of the ceramic oxide material and which does not enter into a reaction with the ceramic oxide layer at temperatures around 1000° C.
Claim 6
Dependent Claim
28 words
In an anode according to claim 2, in which the protective ring consists of densely sintered Al 2 O 3 , electromelted MgO or poorly conducting refractory nitrides.
Claim 7
Dependent Claim
39 words
In an anode as claimed in claim 5, said current distributor including a part projecting out of the anode to serve as a conductor for the electrical power supplied to the anode for use in electrolytic recovery of aluminum.
Claim 8
Dependent Claim
24 words
In an anode, as claimed in claim 13, wherein said current distributor consists of a metal or an electrically conductor carbide, nitride or boride.
Claim 9
Dependent Claim
24 words
In an anode as claimed in claim 7, wherein said current distributor consists of a metal which is nickel, silver, copper, cobalt or molybdenum.
Claim 10
Dependent Claim
60 words
In an anode, as claimed in claim 1, said anode including a bottom surface and wherein at least a part of said bottom surface of the anode consists of a ceramic oxide based on SnO 2 , Fe 2 O 3 , Fe 3 O 4 , Cr 2 O 3 , Co 3 O 4 , NiO or ZnO.
Claim 11
Dependent Claim
55 words
An anode as claimed in claim 9, in which the ceramic oxide base material is used as an oxide doped with at least one metal oxide in which the metallic component is selected from the group consisting of Fe, Sb, Cu, Mn, Nb, Zn, Co, W, Cd, Zr, Ta, In, Ni, Ca, Ba, and Bi.
Claim 12
Dependent Claim
33 words
An anode as claimed in claim 10, in which the ceramic oxide base material consists of SnO 2 and at least one of said metal oxides in a concentration of 0.01 - 20%.
Claim 13
Dependent Claim
20 words
An anode as claimed in claim 11, in which the concentration of each metal oxide added is 0.05 - 2%.
Claim 14
Dependent Claim
23 words
An anode, as claimed in claim 12 wherein the anode has a specific resistivity at 1000° C of 0.0004 ohm. cm or less.
Claim 15
Dependent Claim
27 words
An anode, as claimed in claim 13, wherein said ceramic oxide is doped with 0.5 - 2% CuO and 0.5 - 2% Sb 2 O 3 .
Claim 16
Dependent Claim
39 words
In an anode, as claimed in claim 1, wherein said electrode has side surfaces and a bottom surface, the bottom surface substantially facing the lower part of the charge; said protective ring being provided substantially over the side surfaces.
Claim 17
Dependent Claim
135 words
An anode, as claimed in claim 1, further including: a current distributor disposed in the anode composed of an electrically conductive material having a lower electrical resistance than that of the ceramic oxide material and which is substantially unreactive toward the ceramic oxide material at temperatures of about 1000° C., and said ceramic oxide material comprising a base material chosen from group consisting of SnO 2 , Fe 2 O 3 , Fe 3 O 4 , Cr 2 O 3 , Co 3 O 4 , NiO and ZnO doped with at least one metal oxide in a concentration of about 0.01% to about 20%, chosen from the oxides consisting of the oxides of Fe, Sb, Cu, Mn, Nb, Zn, Co, W, Cd, Zr, Ta, In, Ni, Ca, Ba, Bi or a combination thereof.
Claim 18
Dependent Claim
84 words
An inconsumable anode, for use in connection with a molten electrolyte containing aluminum oxide, said anode comprising, in combination, a body composed of ceramic oxide material adapted to be extended into said electrolyte, and a protective ring connected to said body and being composed of electrically, insulating material which is resistant to attack by the electrolyte, said protective ring being during use of the anode normally disposed at the three phase zone defined at the interface between the atmosphere, the electrolyte and the anode.
Claim 19
Dependent Claim
84 words
An inconsumable anode, for use in connection with a molten electrolyte containing aluminum oxide, said anode comprising, in combination, a body composed of ceramic oxide material adapted to be extended into said electrolyte, and a protective ring connected to said body and being composed of electrically, insulating material which is resistant to attack by the electrolyte, said protective ring being during use of the anode normally disposed at the three phase zone defined at the interface between the atmosphere, the electrolyte and the anode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-07 | 1981-05-09 | 1981-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-07 | 1985-05-09 | 1985-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-07 | 1989-05-09 | 1989-11-08 | $7700.00 | Window Closed / Lapsed |