US4224288A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alumina production
Assignee: Monash University
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Filing: 1979-02-06
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Granted: 1980-09-23
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Expires: 1999-02-06
Abstract
Abstract In a process for the production of alumina which comprises the steps of digesting bauxite to produce a precipitate of alumina trihydrate containing uncombined moisture, drying the alumina trihydrate to reduce the uncombined moisture content thereof, and feeding the dried alumina trihydrate to a calciner to convert the alumina trihydrate to alumina, improved economy is achieved by drying the alumina trihydrate in a fluidized bed in which the fluidized mass is heated indirectly by means of steam which is available from the digestion and recovery system. Drying of the alumina trihydrate in this manner prior to feeding it to the calciner also reduces the fuel requirement in the calciner and enables the throughput of the calciner to be increased.
Inventors
- 👤 Owen E. Potter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:44
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/44; C01F7/441; C01F7/445; F; F26; F26B; F26B3/00; F26B3/02; F26B3/06; F26B3/08; F26B3/084; Y; Y10; Y10S; Y10S423/00; Y10S423/09; Y10S423/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
137 words
A process for the production of alumina which comprises the steps of digesting bauxite by dissolving it in caustic liquors at 140° C. to 250° C. under pressure, and cooling and seeding the resulting solution to produce a precipitate of alumina trihydrate containing uncombined moisture, drying the alumina trihydrate to reduce the uncombined moisture content thereof, and feeding the dried alumina trihydrate to a calciner to convert the alumina trihydrate to alumina, characterized in that the alumina trihydrate is dried by feeding it to a fluidized bed apparatus in which the fluidized mass is alumina trihydrate and in which the fluidized mass is heated indirectly by means of steam from the digestion and caustic recovery system, said steam used for indirect heating being saturated stem having a temperature in the range from 125° C. to 250° C.
Claim 2
Dependent Claim
137 words
A process for the production of alumina which comprises the steps of digesting bauxite by dissolving it in caustic liquors at 140° C. to 250° C. under pressure, and cooling and seeding the resulting solution to produce a precipitate of alumina trihydrate containing uncombined moisture, drying the alumina trihydrate to reduce the uncombined moisture content thereof, and feeding the dried alumina trihydrate to a calciner to convert the alumina trihydrate to alumina, characterized in that the alumina trihydrate is dried by feeding it to a fluidized bed apparatus in which the fluidized mass is alumina trihydrate and in which the fluidized mass is heated indirectly by means of steam from the digestion and caustic recovery system, said steam used for indirect heating being saturated stem having a temperature in the range from 125° C. to 250° C.
Claim 3
Dependent Claim
23 words
A process according to claim 1 in which the temperature of the steam is in the range from 150° C. to 190° C.
Claim 4
Dependent Claim
18 words
A process as claimed in claim 1 in which the fluidizing medium for the fluidized mass is steam.
Claim 5
Dependent Claim
29 words
A process as claimed in claim 3 in which the product vapour is passed to a separator to remove entrained alumina trihydrate, and is then used for process heating.
Claim 6
Dependent Claim
30 words
A process as claimed in claim 1 in which the fluidizing medium for the fluidized mass is air and product vapour from the fluidized bed is air saturated with steam.
References Cited (Backward Citations)
US3336109A
Cited
US3227521A
Cited
US3265465A
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US3408745A
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US3408159A
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US3565408A
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US3529356A
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US3864461A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-23 | 1984-03-24 | 1984-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-23 | 1988-03-24 | 1988-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-23 | 1992-03-24 | 1992-09-23 | $7700.00 | Window Closed / Lapsed |