Patent US3764658A successfully refreshed from Google Patents.
US3764658A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of fluosilicic acid
Assignee: United States Steel Corp
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Filing: 1972-01-26
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Granted: 1973-10-09
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Expires: 1992-01-26
Abstract
Abstract An improved process for the recovery of fluosilicic acid from recycle streams in the manufacture of phosphoric acid by the sulfuric acid digestion of phosphate ore.
Inventors
- 👤 C Darwin
- 👤 J Nickerson
- 👤 J Parsons
- 👤 R Wiesboeck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:55
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/08; C01B33/10; C01B33/103
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
21 words
The process of claim 1 wherein from 0 to 15 weight percent steam is added to the mixture in step a.
Claim 2
Dependent Claim
32 words
The process of claim 1 wherein from 5 to 10 weight percent steam is added and the sulfuric acid concentration is elevated to a value of from 25 to 35 weight percent.
Claim 3
Dependent Claim
29 words
The process of claim 1 wherein sufficient reactive silica is added in step a to adjust the fluorine:silica molar ratio to from 5 to 1 to 6 to 1.
Claim 4
Dependent Claim
18 words
The process of claim 1 wherein a fluoride containing compound is added to the mixture of step a.
Claim 5
Dependent Claim
42 words
The process of claim 1 wherein from 30 to 75 percent of the washing liquor is contacted with the sulfuric acid in step a and the remaining portion of the washing liquor is introduced directly into the vacuum chamber in step c.
Claim 6
Dependent Claim
42 words
The process of claim 6 wherein from 50 to 65 percent of the washing liquor is contacted with the sulfuric acid in step a and the remaining portion of the washing liquor is introduced directly into the vacuum chamber in step c.
References Cited (Backward Citations)
US2933372A
Cited
US3615195A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |