Patent US3721730A successfully refreshed from Google Patents.
US3721730A
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Alumina recovery from retorted oil shale residue
Assignee: Oil Shale Corp
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Filing: 1970-12-30
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Granted: 1973-03-20
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Expires: 1990-12-30
Abstract
Abstract Alumina is recovered from a dawsonite-bearing oil shale matrix by treatment of the retorted oil shale residue or spent shale containing fixed carbon with a dilute aqueous soda ash-caustic soda leach liquor having a concentration of from about 5 to about 20 grams per liter of soda ash and from about 8 to about 20 grams per liter of caustic soda in a mole ratio of soda ash to caustic soda of from about 0.1:1 to about 0.9:1 to provide ultimately a high yield of cell-grade alumina substantially free of silica contamination.
Inventors
- 👤 F Haas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:39
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/04; C01F7/06; C01F7/068
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
9 words
separating the shale oil vapors from the solids blend;
Claim 2
Dependent Claim
24 words
The process as defined by claim 1 wherein the pyrolysis step (1) is conducted at a temperature of from about 750*F. to about 975*F.
Claim 3
Dependent Claim
9 words
separating the shale oil vapors from the solids blend;
Claim 4
Dependent Claim
89 words
leaching the solids blend at a solids content of from about 5 percent to about 50 percent by weight with a dilute aqueous soda ash-caustic soda leach liquor having a concentration of from about 5 to about 20 grams per liter of soda ash and from about 8 to about 20 grams per liter of caustic soda in a mole ratio of soda ash to caustic soda of from about 0.1:1 to about 0.9:1 to extract the sodium aluminate from the solids blend and provide a sodium aluminate solution;
Claim 5
Dependent Claim
32 words
The process as defined by claim 1 wherein the leaching step (3) is conducted at a temperature of from about 70*F. to about 212*F. for from about 1 to about 60 minutes.
Claim 6
Dependent Claim
115 words
leaching the solids blend at a temperature of from about 120*F. to about 170*F. for from about 5 to about 15 minutes with a dilute aqueous soda ash-caustic soda leach liquor maintained at a pH of from about 11 to about 13 and having a concentration of from about 5 to about 20 grams per liter of soda ash and from about 8 to about 20 grams per liter of caustic soda in a mole ratio of soda ash to caustic soda of from about 0.2:1 to about 0.4:1, at from about 5 percent to about 50 percent solids content, to extract the sodium aluminate from the solids blend and provide a sodium aluminate solution;
Claim 7
Dependent Claim
10 words
separating the sodium aluminate solution from the spent shale solids;
Claim 8
Dependent Claim
37 words
The process as defined by claim 1 wherein the dilute aqueous soda ash-caustic soda leach liquor used in step (3) has a mole ratio of soda ash to caustic soda of from about 0.2:1 to about 0.4:1.
Claim 9
Dependent Claim
10 words
separating the sodium aluminate solution from the spent shale solids;
Claim 10
Dependent Claim
19 words
adding carbon dioxide to the sodium aluminate solution to form an alumina hydrate precipitate and a supernatant liquor; and
Claim 11
Dependent Claim
28 words
The process as defined by claim 1 wherein the pH of the leach liquor during the leaching step (3) is maintained at from about 11 to about 13.
Claim 12
Dependent Claim
19 words
adding carbon dioxide to the sodium aluminate solution to form an alumina hydrate precipitate and a supernatant liquor; and
Claim 13
Dependent Claim
9 words
separating the alumina hydrate precipitate from the supernatant liquor.
Claim 14
Dependent Claim
13 words
A process for recovering alumina from a dawsonite-bearing oil shale matrix which comprises:
Claim 15
Dependent Claim
9 words
separating the alumina hydrate precipitate from the supernatant liquor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |