US4466995A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of ledge formation in aluminum cell operation
Assignee: Rio Tinto Aluminium Ltd
•
Filing: 1982-07-22
•
Granted: 1984-08-21
•
Expires: 2002-07-22
Abstract
Abstract The application of a Refractory Hard Material coating composition to selected areas of the surface of an aluminum cell cathode permits tailoring or control of ledge formation during cell operation. Cell voltage improvements are also noted, resulting in more efficient cell performance.
Inventors
- 👤 Larry G. Boxall
- 👤 Douglas W. Townsend
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:45
CPC Classifications
C; C25; C25C; C25C3/00; C25C3/06; C25C3/08
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
93 words
A method for the control of ledge formation in a Hall-Heroult electrolytic cell for the production of aluminum, which method consisting essentially of applying to a limited defined area of the cathode surface directly below the anode of said cell a coating composition comprising Refractory Hard Material, thermosetting binder, a mix liquid, carbonaceous filler, and carbonaceous additive, and curing and carbonizing said composition to produce an adherent coating composition comprising Refractory Hard Material in a carbonaceous matrix bonded by amorphous carbon on said limited defined area of the cathode surface below the anode.
Claim 2
Independent Claim
93 words
A method for the control of ledge formation in a Hall-Heroult electrolytic cell for the production of aluminum, which method consisting essentially of applying to a limited defined area of the cathode surface directly below the anode of said cell a coating composition comprising Refractory Hard Material, thermosetting binder, a mix liquid, carbonaceous filler, and carbonaceous additive, and curing and carbonizing said composition to produce an adherent coating composition comprising Refractory Hard Material in a carbonaceous matrix bonded by amorphous carbon on said limited defined area of the cathode surface below the anode.
Claim 3
Dependent Claim
31 words
A method as set forth in claim 1, wherein the area of said coating constitutes from 50 percent to 100 percent of the cathode area beneath the anodes of said cell.
Claim 4
Dependent Claim
31 words
A method as set forth in claim 1, wherein the area of said coating constitutes from 70 percent to 100 percent of the cathode area beneath the anodes of said cell.
Claim 5
Dependent Claim
27 words
A method as set forth in claim 3, wherein said coating is characterized by an expansion of less than 0.2 percent between 800° C. and 1000° C.
Claim 6
Dependent Claim
38 words
A method as set forth in claim 4, wherein said carbon matrix has an ablation rate essentially equal to the combined rate of wear and dissolution of said Refractory Hard Material in the environment of said aluminum cell.
Claim 7
Dependent Claim
31 words
A method as set forth in claim 5, wherein said Refractory Hard Material is selected from the group consisting of titanium diboride, titanium carbide, zirconium diboride, zirconium carbide, and alloys thereof.
Claim 8
Dependent Claim
21 words
A method as set forth in claim 6, wherein said coating composition is applied to said cathode surface within said cell.
Claim 9
Dependent Claim
21 words
A method as set forth in claim 5, wherein said coating composition is applied to said cathode surface within said cell.
Claim 10
Dependent Claim
29 words
A method as set forth in claim 8, wherein the area of said coating constitutes at least 90 percent of the cathode area beneath the anodes of said cell.
Claim 11
Dependent Claim
16 words
A method as set forth in claim 9, wherein said Refractory Hard Material is titanium diboride.
References Cited (Backward Citations)
US3429759A
Cited
US3400061A
Cited
US3492208A
Cited
US3661736A
Cited
US3657592A
Cited
US4308114A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-08-21 | 1988-02-20 | 1988-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-21 | 1992-02-20 | 1992-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-21 | 1996-02-20 | 1996-08-21 | $7700.00 | Window Closed / Lapsed |