US2939765A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reducing the silica content of alumina containing materials of the bauxite type
Assignee: Vereinigte Aluminium Werke AG
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Filing: 1958-03-07
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Granted: 1960-06-07
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Expires: 1978-03-07
Abstract
No abstract record available.
Inventors
- 👤 Schoenfelder Herbert
- 👤 Ginsberg Hans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:55
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/04; C01F7/06; C01F7/0613
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
177 words
A METHOD FOR REDUCING THE SILICA CONTENTS OF ALUMINA-CONTAINING MATERIALS OF THE BAUXITE TYPE HAVING A RELATIVELY HIGH SIO2-CONTENT OF AT LEAST ABOUT 10% AND WHEREIN THE ALUMINUM CONTENT OF SAID BAUXITE TYPE IS ESSENTIALLY ALUMINA, AND SIMULTANEOUSLY INCREASING THE CONTENT OF ALUMINA, COMPRISING (A) CALCINING A BAUXITE HAVING AN SIO2 CONTENT OF AT LEAST ABOUT 10% AND BEING FREE FROM ADDITIONS OF LIME AND SODA AT A TEMPERATURE OF ABOUT 900 TO 1100*C. FOR ABOUT ONE HOUR, SO AS TO CONVERT A MAJOR PORTION OF THE SIO2 PRESENT THEREIN INTO SOLUBLE SILICATE, THEREAFTER (B) DISSOLVING SAID SOLUBLE SILICATE FROM THE CALCINED MATERIAL WITH A SODIUM HYDROXIDE SOLUTION CONTAINING ABOVE 20% OF SODIUM HYDROXIDE AT A TEMPERATURE OF BETWEEN 70*C. TO THE BOILING TEMPERATURE OF SAID SOLUTION AND FOR A PERIOD OF ABOUT FIFTEEN TO THIRTY MINUTES, THEREBY LEAVING UNDISSOLVED A RESIDUE CONTAINING MAXIMALLY 10% OF SIO2 AND MORE THAN 50% OF AL2O3, AND THEN (C) SEPARATING THE SILICATE-CONTAINING SOLUTION FROM THE UNDISSOLVED RESIDUE CONTAINING THE AFORESAID INCREASED RATE OF ALUMINA AND THE REDUCED RATE OF SILICA.
Claim 2
Independent Claim
177 words
A METHOD FOR REDUCING THE SILICA CONTENTS OF ALUMINA-CONTAINING MATERIALS OF THE BAUXITE TYPE HAVING A RELATIVELY HIGH SIO2-CONTENT OF AT LEAST ABOUT 10% AND WHEREIN THE ALUMINUM CONTENT OF SAID BAUXITE TYPE IS ESSENTIALLY ALUMINA, AND SIMULTANEOUSLY INCREASING THE CONTENT OF ALUMINA, COMPRISING (A) CALCINING A BAUXITE HAVING AN SIO2 CONTENT OF AT LEAST ABOUT 10% AND BEING FREE FROM ADDITIONS OF LIME AND SODA AT A TEMPERATURE OF ABOUT 900 TO 1100*C. FOR ABOUT ONE HOUR, SO AS TO CONVERT A MAJOR PORTION OF THE SIO2 PRESENT THEREIN INTO SOLUBLE SILICATE, THEREAFTER (B) DISSOLVING SAID SOLUBLE SILICATE FROM THE CALCINED MATERIAL WITH A SODIUM HYDROXIDE SOLUTION CONTAINING ABOVE 20% OF SODIUM HYDROXIDE AT A TEMPERATURE OF BETWEEN 70*C. TO THE BOILING TEMPERATURE OF SAID SOLUTION AND FOR A PERIOD OF ABOUT FIFTEEN TO THIRTY MINUTES, THEREBY LEAVING UNDISSOLVED A RESIDUE CONTAINING MAXIMALLY 10% OF SIO2 AND MORE THAN 50% OF AL2O3, AND THEN (C) SEPARATING THE SILICATE-CONTAINING SOLUTION FROM THE UNDISSOLVED RESIDUE CONTAINING THE AFORESAID INCREASED RATE OF ALUMINA AND THE REDUCED RATE OF SILICA.
References Cited (Backward Citations)
US1971354A
Cited
GB552583A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-06-07 | 1963-12-07 | 1964-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-06-07 | 1967-12-07 | 1968-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-06-07 | 1971-12-07 | 1972-06-07 | $7700.00 | Window Closed / Lapsed |