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US2659761A
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Fractional crystallization method
Assignee: Dow Chemical Co
•
Filing: 1948-08-23
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Granted: 1953-11-17
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Expires: 1968-08-23
Abstract
No abstract record available.
Inventors
- 👤 Ludo K Frevel
- 👤 Leonard J Kressley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:45
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/14; B; B01; B01D; B01D9/00; B01D9/0004; B01D9/0013; B01D9/004; C01; C01F; C01F11/00; C01F11/20; C01F11/24; C01F11/30; C07C17/00; C07C17/38; C07C17/392
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
118 words
A FRACTIONAL CRYSTALLIZATION METHOD WHICH COMPRISES BRINGING A MIXTURE TO A TEMPERATURE AT WHICH IT CONSISTS OF A SLURRY OF CRYSTALLINE AND LIQUID MATERIALS, CONTINUOUSLY LIFTING CRYSTALLINE MATERIAL FROM THE SLURRY UPWARD THROUGH A ZONE OF INCREASING TEMPERATURES SO AS TO CAUSE RECRYSTALLIZATION ANS PARTIAL MELTING OF THE CRYSTALLINE MATERIAL WITH A RESULTANT DOWNFLOW OF THE MELT OVER ASCENDING CRYSTALLINE MATERIAL AT LOWER POINTS BUT ABOVE SAID SLURRY, THE RATE OF MELTING BEING CONTROLLED SO AS TO AVOID COMPLETE IMMERSION OF A MAJOR PORTION OF THE ASCENDING CRYSTALLINE MATERIAL IN A CONTINUOUS BODY OF THE MELT AND GRADUALLY ELEVATING THE MATERIAL UNDERGOING RECRYSTALLIZATION THROUGH SAID ZONE AND DELIVERING THE RESULTANT RECRYSTALLIZED MATERIAL FROM THE TOP OF SAID ZONE.
Claim 2
Dependent Claim
118 words
A FRACTIONAL CRYSTALLIZATION METHOD WHICH COMPRISES BRINGING A MIXTURE TO A TEMPERATURE AT WHICH IT CONSISTS OF A SLURRY OF CRYSTALLINE AND LIQUID MATERIALS, CONTINUOUSLY LIFTING CRYSTALLINE MATERIAL FROM THE SLURRY UPWARD THROUGH A ZONE OF INCREASING TEMPERATURES SO AS TO CAUSE RECRYSTALLIZATION ANS PARTIAL MELTING OF THE CRYSTALLINE MATERIAL WITH A RESULTANT DOWNFLOW OF THE MELT OVER ASCENDING CRYSTALLINE MATERIAL AT LOWER POINTS BUT ABOVE SAID SLURRY, THE RATE OF MELTING BEING CONTROLLED SO AS TO AVOID COMPLETE IMMERSION OF A MAJOR PORTION OF THE ASCENDING CRYSTALLINE MATERIAL IN A CONTINUOUS BODY OF THE MELT AND GRADUALLY ELEVATING THE MATERIAL UNDERGOING RECRYSTALLIZATION THROUGH SAID ZONE AND DELIVERING THE RESULTANT RECRYSTALLIZED MATERIAL FROM THE TOP OF SAID ZONE.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-11-16 | 1957-05-18 | 1957-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-11-16 | 1961-05-18 | 1961-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-11-16 | 1965-05-18 | 1965-11-17 | $7700.00 | Window Closed / Lapsed |