Patent US3635408A successfully refreshed from Google Patents.
US3635408A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of carbon lining from reduction cells
Assignee: Alcan Research and Development Ltd
•
Filing: 1970-08-25
•
Granted: 1972-01-18
•
Expires: 1990-08-25
Abstract
Abstract Carbon lining removed after long, chemical-accumulating use in an aluminum reduction cell is crushed and treated with dry steam at a temperature insufficient to destroy the carbon, so that unwanted carbides and nitrides are eliminated and the lining material is conditioned for recovery of useful values, advantageously by classification thereafter into a coarse fraction providing carbon in reusable form and a fine fraction in which chemical material is reclaimed, such as alumina and fluorides suitable for use in the fused bath of a reduction cell.
Inventors
- 👤 Merlyn Morris Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:03
CPC Classifications
C; C04; C04B; C04B33/00; C04B33/02; C04B33/04; C04B33/06; C04B33/30; C25; C25C; C25C3/00; C25C3/06; C25C3/08
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
28 words
A method as defined in claim 1, in which said steam treatment is effected at a temperature not higher than about 400* F. for at least several hours.
Claim 2
Dependent Claim
29 words
A method as defined in claim 2, in which said steam treatment is effected at a pressure of at least about 15 p.s.i. for at least about 4 hours.
Claim 3
Independent Claim
46 words
A method as defined in clam 2 in which said used lining, as subjected to said steam treatment, has particle sizes not greater than about 4 inches, and said steam treatment is effected for a period of time in a range up to about 10 hours.
Claim 4
Dependent Claim
25 words
A method as defined in claim 4, in which said steam treatment is effected at a temperature in the range of 250* to 400* F.
Claim 5
Dependent Claim
19 words
A method as defined in claim 1, in which said used lining is lining predominantly constituted of prebake blocks.
Claim 6
Dependent Claim
52 words
A method as defined in claim 1, in which sad used lining which is treated contains material of the class consisting of carbide and nitride, and said treating step is effective for reaction of said steam with said last-mentoned material to release gaseous product of the clasS consisting of hydrocarbon and ammonia.
Claim 7
Dependent Claim
34 words
A method as defined in claim 7, in which said used lining which is treated contains aluminum oxide, and said treating step is effective for hydration of at least some of said aluminum oxide.
Claim 8
Independent Claim
165 words
A method of treating used carbon lining of an aluminum reduction cell that has contained a molten bath, said used lining containing carbon, unwanted material of the class consisting of aluminum carbide and nitride, and chemical material of the class consisting of fluoride, oxide and hydroxide of aluminum, sodium and calcium, comprising crushing said used lining, treating the crushed lining in a confined region with dry steam for converting the unwanted material to gaseous product and to material which is of the class of aluminum oxide and hydroxide and which augments said chemical material in the crushed lining, while maintaining the crushed lining at a temperature insufficient for substantial reaction of carbon in the region and while withdrawing sad gaseous product from the region, to yield a substantially dry, particulate used lining product classifiable by particle size into a fine fraction, which contains chemical material of the aforesaid class, and a coarser fraction, which contains carbon in amount of at least about half its composition.
Claim 9
Dependent Claim
26 words
A method as defined in claim 9, in which said steam treatment is effected at superatmospheric pressure and a temperature not higher than about 400* F.
Claim 10
Dependent Claim
31 words
A method as defined in claim 10, in which said crushed lining has particle sizes less than about three-fourths inch and said steam treatment is effected for at least several hours.
Claim 11
Dependent Claim
29 words
A method as defined in claim 11, in which said steam treatment is effected at pressure of about 15 to 40 p.s.i. and for about 4 to 10 hours.
Claim 12
Dependent Claim
76 words
A method as defined in claim 10, in which said used lining which is treated contains at least about 50 percent carbon, and said steam treatment is effected for a sufficient time to yield said product classifiable into said fractions of which the fine fraction is suitable for employment as chemical addition in the molten bath of a reduction cell and the coarser fraction is suitable for incorporation in new carbon lining of a reduction cell.
Claim 13
Dependent Claim
27 words
A method as defined in claim 13, which includes the step of subjecting said product to classification by particle size to separate said fine and coarser fractions.
Claim 14
Dependent Claim
27 words
A method as defined in claim 14, in which said fine fraction consists of and is separated as material having particle size smaller than about one-sixteenth inch.
Claim 15
Dependent Claim
60 words
A method as defined in claim 9, in which said used lining which is treated contains at least about 50 percent carbon, and said steam treatment is effected at superatmospheric pressure for a sufficient time to yield said product classifiable into said fractions of which the coarser fraction is suitable for incorporation in new carbon lining of a reduction cell
Claim 16
Dependent Claim
100 words
In a method of treating used, chemical-containing, carbon lining of an aluminum reduction cell, the step of treating fragments of said used lining in a confined region with dry steam at a temperature insufficient for substantial reaction of carbon in the region, for sufficient time to exert disintegrating influence on said used lining and to convert same into form capable of treatment for classification by particle size to separate, from a coarser fraction, a fine, chemical-containing fraction having a substantially lower proportion of carbon and a substantially higher content of chemical material than said used carbon lining which was treated.
Claim 17
Dependent Claim
52 words
A method as defined in claim 17, in which said used lining which is treated contains material of the class consisting of carbide and nitride, and said treating step is effective for reaction of said steam with said last-mentioned material to release gaseous product of the class consisting of hydrocarbon and ammonia.
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) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |