US3906084A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precipitation of alumina trihydrate from bayer pregnant liquors
Assignee: Alcan Research and Development Ltd
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Filing: 1971-09-21
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Granted: 1975-09-16
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Expires: 1991-09-21
Abstract
Abstract In the operation wherein fine seed alumina trihydrate is added as a precipitating agent to Bayer pregnant liquor for the precipitation of alumina trihydrate therefrom there is precipitated a coarser alumina trihydrate, as evidenced by the percentage of precipitated alumina trihydrate having a particle size greater than 325 mesh, by carrying out the precipitation of the alumina trihydrate from said Bayer pregnant liquor in the presence of added calcium carbonate. The increase in the amount of the resulting precipitated alumina trihydrate having a particle size greater than 325 mesh when precipitated in the presence of calcium carbonate is especially evident when the Bayer pregnant liquor has a caustic content measured as Na2CO3 in the range from about 180 grams per liter to about 200 grams per liter and the calcium carbonate is present in the pregnant liquor in an amount in the range from about 0.05 to about 0.10 grams per liter based on the Bayer pregnant liquor.
Inventors
- 👤 Bohdan Gnyra
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:58
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/04; C01F7/14; C01F7/144; C01F7/145; C01P; C01P2004/00; C01P2004/60; C01P2004/61
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
147 words
A METHOD OF PRECIPITATING ALUMINA TRIHYDRATE FROM FILTERED BAYER PREGNANT LIQUOR SATURATED WITH RESPECT TO ALUMINA TRIHYDRATE AND HAVING A CAUSTIC CONTENT ABOVE ABOUT 160 GPL CAUSTIC MEASURED AS NA2CO3 TO INCREASE THE AMOUNT OF ALUMINATRIHYDRATE HAVING A PARTICLE SIZE GREATER THAN 325 MESH, WHICH COMPRISES ADDING TO SAID FILTERED LAYER PREGNANT LIQUOR FINE SEED ALUMINA TRIHYDRATE AS A PRECIPITATING AGENT FOR THE PRECIPITATION OF ALUMINA TRIHYDRATE FROM SAID FILTERED BAYER PREGNANT LIQUOR AND SUBSTANTIALLY SIMULTANEOUSLY WITH THE ADDITION OF SAID FINE SEED ALUMINA TRIHYDRATE TO SAID FILTERED BAYER PREGNANT LIQUOR ADDING AN AMOUNT OF FINELY DIVIDED SOLID CALCIUM CARBONATE IN THE RANGE ABOUT 0.02-0.2 GPL OF SAID FILTERED BAYER PREGNANT LIQUOR WHEREBY THE PRECIPITATED ALUMINA TRIHYDRATE HAS AN INCREASED AMOUNT OF ALUMINA TRIHYDRATE HAVING A PARTICLE SIZE GREATER THAN 325 MESH AS COMPARED WITH THE ALUMINA TRIHYDRATE PRECIPITATED IN THE ABSENCE OF SAID ADDED CALCIUM CARBONATE.
Claim 2
Independent Claim
147 words
A METHOD OF PRECIPITATING ALUMINA TRIHYDRATE FROM FILTERED BAYER PREGNANT LIQUOR SATURATED WITH RESPECT TO ALUMINA TRIHYDRATE AND HAVING A CAUSTIC CONTENT ABOVE ABOUT 160 GPL CAUSTIC MEASURED AS NA2CO3 TO INCREASE THE AMOUNT OF ALUMINATRIHYDRATE HAVING A PARTICLE SIZE GREATER THAN 325 MESH, WHICH COMPRISES ADDING TO SAID FILTERED LAYER PREGNANT LIQUOR FINE SEED ALUMINA TRIHYDRATE AS A PRECIPITATING AGENT FOR THE PRECIPITATION OF ALUMINA TRIHYDRATE FROM SAID FILTERED BAYER PREGNANT LIQUOR AND SUBSTANTIALLY SIMULTANEOUSLY WITH THE ADDITION OF SAID FINE SEED ALUMINA TRIHYDRATE TO SAID FILTERED BAYER PREGNANT LIQUOR ADDING AN AMOUNT OF FINELY DIVIDED SOLID CALCIUM CARBONATE IN THE RANGE ABOUT 0.02-0.2 GPL OF SAID FILTERED BAYER PREGNANT LIQUOR WHEREBY THE PRECIPITATED ALUMINA TRIHYDRATE HAS AN INCREASED AMOUNT OF ALUMINA TRIHYDRATE HAVING A PARTICLE SIZE GREATER THAN 325 MESH AS COMPARED WITH THE ALUMINA TRIHYDRATE PRECIPITATED IN THE ABSENCE OF SAID ADDED CALCIUM CARBONATE.
Claim 3
Dependent Claim
49 words
A method in accordance with claim 1 wherein the fine seed alumina trihydrate employed as a precipitating agent for the precipitation of alumina trihydrate from Bayer pregnant liquor has a particle size such that at least about 60% by weight of said alumina trihydrate is smaller than 325 mesh.
Claim 4
Dependent Claim
32 words
A method in accordance with claim 1 wherein said calcium carbonate is added in an amount in the range from about 0.05 to about 0.1 gpl based on said Bayer pregnant liquor.
Claim 5
Dependent Claim
31 words
A method in accordance with claim 1 wherein the caustic content of said Bayer pregnant liquor measured as Na2CO3 is in the range from about 180 gpl to about 220 gpl.
Claim 6
Dependent Claim
27 words
A method in accordance with claim 1 wherein said fine seed alumina trihydrate is added in an amount above about 50 gpl of said Bayer pregnant liquor.
Claim 7
Dependent Claim
35 words
A method in accordance with claim 1 wherein said fine seed alumina trihydrate is added in an amount in the range from about 50 gpl to about 90 gpl based on said Bayer pregnant liquor.
Claim 8
Dependent Claim
53 words
A method in accordance with claim 1 wherein said fine seed alumina trihydrate is added in an amount above about 50 gpl of said Bayer pregnant liquor, said fine seed alumina trihydrate having a particle size such that at least about 60% by weight of said alumina trihydrate is smaller than 325 mesh.
References Cited (Backward Citations)
US2283849A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |