US3800031A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing silica hydrogel
Assignee: WR Grace and Co Conn
•
Filing: 1972-04-06
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Granted: 1974-03-26
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Expires: 1992-04-06
Abstract
Abstract An improved and rapid process for purifying a silica hydrogel of soluble contaminants which comprises reducing the hydrogel to a controlled particle size range and thereafter treating the sized hydrogel in a continuous three-step operation. Treatment involves first dewatering a hydrogel slurry, washing the resulting hydrogel with acidified water, followed by washing with ammoniated water. All treatment steps are carried out on a moving belt maintained under a vacuum.
Inventors
- 👤 C Doyle
- 👤 H Sale
- 👤 A Delgado
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:59
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/14; C01B33/157; C01B33/158
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
21 words
A process according to claim 1 wherein said vacuum consists of a pressure of about 1 to 300 mm of Hg.
Claim 2
Dependent Claim
18 words
A process according to claim 2 wherein the acidified water contains .5 to 5 percent of sulphuric acid.
Claim 3
Dependent Claim
18 words
A process according to claim 3 wherein the acidified water contains 1.5 to 2.5 percent of sulphuric acid.
Claim 4
Dependent Claim
14 words
A process according to claim 3 wherein the aqueous alkaline solution is ammoniated water.
Claim 5
Dependent Claim
18 words
A process according to claim 5 wherein the ammoniated water has a pH ranging between 8.0 and 10.
Claim 6
Dependent Claim
18 words
A process according to claim 6 wherein the ammoniated water has a pH of between 9.0 and 9.5.
Claim 7
Dependent Claim
26 words
A process according to claim 6 wherein said silica hydrogel is prepared by reacting an aqueous solution of an alkali metal silicate and a mineral acid.
Claim 8
Dependent Claim
18 words
A process according to claim 8 wherein the silicate is sodium silicate and the acid is sulphuric acid.
Claim 9
Dependent Claim
21 words
A process according to claim 8 wherein said silica hydrogel is ammonia solution treated prior to depositing on said moving belt.
Claim 10
Dependent Claim
25 words
A process according to claim 6 wherein said silica hydrogel is prepared by reacting an aqueous solution of an alkali metal silicate with carbon dioxide.
References Cited (Backward Citations)
CA541212A
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US2358201A
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US2424232A
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US2462236A
Cited
US2871099A
Cited
US3243262A
Cited
US3453077A
Cited
US3716493A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-25 | 1977-09-24 | 1978-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-25 | 1981-09-24 | 1982-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-25 | 1985-09-24 | 1986-03-26 | $7700.00 | Window Closed / Lapsed |