Patent US4572827A successfully refreshed from Google Patents.
US4572827A
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Process for preparing finely-divided silicon dioxide in good yield
Assignee: Individual
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Filing: 1984-10-18
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Granted: 1986-02-25
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Expires: 2004-10-18
Abstract
Abstract Process and apparatus are provided for preparing finely-divided silicon dioxide in good yield by reaction of silicon fluoride in the vapor phase with water vapor, combustible gas and free oxygen-containing gas in a flame reaction zone to form hydrogen fluoride and silicon dioxide entrained in a gaseous reaction mixture; withdrawing the gaseous reaction mixture from the flame reaction zone; and then immediately and rapidly cooling the gaseous reaction mixture and entrained silicon dioxide to a temperature below 700° C. by passing the gaseous reaction mixture in a turbulent flow at a Reynolds number above 300 under constraint through a straight narrow passage in alignment with the gas flow, the passage having a diameter within the range from about 20 to about 150 mm and smooth walls constituting a cooling surface.
Inventors
- 👤 Gosta Flemmert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:33
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/18; C01B33/181; C01B33/183; C01B33/184; B; B01; B01J; B01J12/00; B01J12/005; C01B7/00; C01B7/19; C01B7/191; C01B7/193; C01P; C01P2006/00; C01P2006/12; C01P2006/22; C01P2006/80
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
133 words
A process for preparing finely-divided silicon dioxide in good yield which comprises reacting a silicon fluoride in the vapor phase with water vapor, combustible gas and free oxygen-containing gas in a flame reaction zone to form hydrogen fluoride and silicon dioxide entrained in a gaseous reaction mixture; withdrawing the gaseous reaction mixture from the flame reaction zone; and then immediately and rapidly cooling the gaseous reaction mixture and entrained silicon dioxide to a temperature below 700° C. by passing the gaseous reaction mixture in turbulent flow at a Reynolds number above 300 under constraint through a plurality of passages all of which consist of straight passages in alignment with the gas flow, the passages having a diameter within the range from about 20 to about 150 mm and smooth walls constituting cooling surfaces.
Claim 2
Dependent Claim
133 words
A process for preparing finely-divided silicon dioxide in good yield which comprises reacting a silicon fluoride in the vapor phase with water vapor, combustible gas and free oxygen-containing gas in a flame reaction zone to form hydrogen fluoride and silicon dioxide entrained in a gaseous reaction mixture; withdrawing the gaseous reaction mixture from the flame reaction zone; and then immediately and rapidly cooling the gaseous reaction mixture and entrained silicon dioxide to a temperature below 700° C. by passing the gaseous reaction mixture in turbulent flow at a Reynolds number above 300 under constraint through a plurality of passages all of which consist of straight passages in alignment with the gas flow, the passages having a diameter within the range from about 20 to about 150 mm and smooth walls constituting cooling surfaces.
Claim 3
Dependent Claim
14 words
A process according to claim 1 in which the silicon fluoride is silicon tetrafluoride.
Claim 4
Dependent Claim
12 words
A process according to claim 1 in which the passages are tubular.
Claim 5
Dependent Claim
15 words
A process according to claim 1 in which the passages are defined by parallel plates.
Claim 6
Dependent Claim
25 words
A process according to claim 1 in which the gaseous reaction mixture passes through the passages in a transit time of less than ten seconds.
Claim 7
Dependent Claim
25 words
A process according to claim 1 in which the gaseous reaction mixture passes through the passages in a transit time of less than one second.
Claim 8
Dependent Claim
17 words
A process according to claim 1 in which the cooling surface is cooled by circulating boiling water.
References Cited (Backward Citations)
US3645684A
Cited
US4036938A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-24 | 1989-08-26 | 1990-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-24 | 1993-08-26 | 1994-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-24 | 1997-08-26 | 1998-02-25 | $7700.00 | Window Closed / Lapsed |