US3899571A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the removal of organic substances from sodium aluminate solution
Assignee: Sumitomo Chemical Co Ltd
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Filing: 1973-12-04
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Granted: 1975-08-12
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Expires: 1993-12-04
Abstract
Abstract The present invention relates to a method for the removal of organic substances from a sodium aluminate solution in the production of alumina from bauxite in accordance with the Bayer process, the improvement which involves adding sodium oxalate crystals as seeds to a sodium aluminate solution for a time period which spans from after the aluminum hydroxide step to before the dissolution step, thereby precipitating organic substances mainly composed of sodium oxalate in the said sodium aluminate solution; separating the crystals of organic substances from the sodium aluminate solution, washing the said separated crystals with an aqueous solution to remove most of the organic substances newly deposited on the seeds from the separated crystals and recycling the sodium oxalate crystals as seeds for precipitating organic substances after the removal of substantially all of the newly deposited organic substances.
Inventors
- 👤 Koichi Yamada
- 👤 Tadanori Hashimoto
- 👤 Kazuhiko Nakano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:55
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/46; C01F7/47; C01F7/473
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
142 words
A METHOD FOR THE REMOVAL OF ORGANIC SUBSTANCES FROM A SODIUM ALUMINATE SOLUTION IN THE PRODUCTION OF ALUMINA FROM BAUXITE IN ACCORDANCE WITH THE BAYER PROCESS OR IMPROVED PROCESSES THEREOF, CHARACTERIZED BY ADDING SODIUM OXALATE CRYSTAL AS SEEDS TO A SODIUM ALUMINATE SOLUTION DURING THE TIME PERIOD EXTENDING FROM AFTER THE ALUMINATE HYDROXIDE PRECIPITATION STEP TO BEFORE THE DISSOLUTION STEP, THEREBY PRECIPITATING ORGANIC SUBSTANCES MAINLY COMPOSED OF SODIUM OXALATE IN SAID SODIUM ALUMINATE SOLUTION, SEPARATING THE CRYSTALS OF ORGANIC SUBSTANCES FROM THE SODIUM ALUMINATE SOLUTION, WASHING THE SAID SEPARATED CRYSTALS WITH AN AQUEOUS SOLUTION HAVING A PH OF 5 TO 12 TO REMOVE SUBSTANTIALLY ALL OF THE ORGANIC SUBSTANCES NEWLY DEPOSITED ON THE SEEDS FROM THE SEPARATED CRYSTALS, AND RECYCLING THE SODIUM OXALATE CRYSTALS AS SEEDS FOR PRECIPITATING ORGANIC SUBSTANCES AFTER THE REMOVAL OF SUBSTANTIALLY ALL OF THE NEWLY DEPOSITED ORGANIC SUBSTANCES.
Claim 2
Independent Claim
142 words
A METHOD FOR THE REMOVAL OF ORGANIC SUBSTANCES FROM A SODIUM ALUMINATE SOLUTION IN THE PRODUCTION OF ALUMINA FROM BAUXITE IN ACCORDANCE WITH THE BAYER PROCESS OR IMPROVED PROCESSES THEREOF, CHARACTERIZED BY ADDING SODIUM OXALATE CRYSTAL AS SEEDS TO A SODIUM ALUMINATE SOLUTION DURING THE TIME PERIOD EXTENDING FROM AFTER THE ALUMINATE HYDROXIDE PRECIPITATION STEP TO BEFORE THE DISSOLUTION STEP, THEREBY PRECIPITATING ORGANIC SUBSTANCES MAINLY COMPOSED OF SODIUM OXALATE IN SAID SODIUM ALUMINATE SOLUTION, SEPARATING THE CRYSTALS OF ORGANIC SUBSTANCES FROM THE SODIUM ALUMINATE SOLUTION, WASHING THE SAID SEPARATED CRYSTALS WITH AN AQUEOUS SOLUTION HAVING A PH OF 5 TO 12 TO REMOVE SUBSTANTIALLY ALL OF THE ORGANIC SUBSTANCES NEWLY DEPOSITED ON THE SEEDS FROM THE SEPARATED CRYSTALS, AND RECYCLING THE SODIUM OXALATE CRYSTALS AS SEEDS FOR PRECIPITATING ORGANIC SUBSTANCES AFTER THE REMOVAL OF SUBSTANTIALLY ALL OF THE NEWLY DEPOSITED ORGANIC SUBSTANCES.
Claim 3
Dependent Claim
24 words
The method according to claim 1, wherein the precipitating procedure of the organic substances is carried out at a temperature from 0*C. to 75*C.
Claim 4
Dependent Claim
35 words
The method according to claim 1, wherein the amount of the addition of sodium oxalate seed crystals is about 50-30,000 weight percent based on the amount of the sodium oxalate in said sodium aluminate solution.
Claim 5
Dependent Claim
28 words
The method according to claim 1, wherein the sodium aluminate solution after the addition of sodium oxalate seed crystals is maintained under stirring 30 minutes to 10 hours.
Claim 6
Dependent Claim
12 words
The method according to claim 1, wherein said washing solution is water.
Claim 7
Dependent Claim
65 words
The method according to claim 1, wherein the amount of said separated crystals removed during washing ranges from an amount such that the seed after the removal of substantially all of the newly deposited organic substances have a seed activity to an amount such that all the amount of the newly deposited organic substances plus 50 weight percent of the initial seed crystals are removed.
Claim 8
Dependent Claim
21 words
The method according to claim 1, wherein the washing of said separated crystals is carried out at a temperature below 100*C.
Claim 9
Dependent Claim
31 words
The method according to claim 1, wherein the washing is carried out by spraying the washing solution onto the separated crystals or by immersing the separated crystals into the washing solution.
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) | 1978-08-11 | 1979-02-10 | 1979-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-11 | 1983-02-10 | 1983-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-11 | 1987-02-10 | 1987-08-12 | $7700.00 | Window Closed / Lapsed |