US3800029A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for recovering sodium fluosilicate from wet process phosphoric acid
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1971-02-17
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Granted: 1974-03-26
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Expires: 1991-02-17
Abstract
Abstract Sodium fluosilicate of high quality is recovered from wet process phosphoric acid by adding a sodium compound to phosphoric acid not containing substantial amount of fluosilicic acid dissolved therein to form an aqueous solution containing phosphoric acid and sodium dihydrogen-phosphate, adding said aqueous solution to wet process phosphoric acid containing fluosilicic acid dissolved therein and separating the resulting sodium fluosilicate crystals from the defluorinated phosphoric acid.
Inventors
- 👤 L Pavia
- 👤 T Yazaki
- 👤 T Omoto
- 👤 T Inoue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:39
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/18; C01B25/234; C01B25/237; C01B25/2372; C01B25/2375; C01B33/00; C01B33/08; C01B33/10; C01B33/103
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
38 words
A process as claimed in claim 1 wherein said sodium compound added to said first of said portions is a member selected from the group consisting of caustic soda, sodium carbonate, sodium silicate, sodium chloride and sodium sulfate.
Claim 2
Dependent Claim
26 words
A process according to claim 1 wherein the contained fluosilicate crystals are separated from said first of said portions prior to addition of said sodium compound.
Claim 3
Dependent Claim
28 words
A process as claimed in claim 1 wherein said first of said portions is the overflow from hydraulic classification of said defluorinated phosphoric acid containing sodium fluosilicate crystals.
Claim 4
Dependent Claim
40 words
A process as claimed in claim 1 wherein the amount of phosphoric acid in said solution containing phosphoric acid and sodium dihydrogen phosphate is from about 10 to about 40 percent by weight of said additional wet process phosphoric acid.
Claim 5
Dependent Claim
34 words
A process as claimed in claim 5 wherein said solution is neutralized to a pH of less than about 1.5 with a member selected from the group consisting of caustic soda and sodium carbonate.
Claim 6
Dependent Claim
85 words
A process for recovering sodium fluosilicate having high purity and large crystal size from wet process phosphoric acid containing fluosilicic acid, which process comprises: adding to phosphoric acid substantially free of fluosilicic acid a sodium compound to form a solution having a pH of less than about 1.5 and containing phosphoric acid and sodium dihydrogen phosphate; adding said solution to said wet process phosphoric acid in an amount sufficient to precipitate fluosilicic acid contained therein as sodium fluosilicate crystals; and recovering said sodium fluosilicate crystals.
References Cited (Backward Citations)
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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) | 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 |