US3993733A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Food grade alkali metal phosphates from wet process H3 PO4
Assignee: Stauffer Chemical Co
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Filing: 1975-08-14
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Granted: 1976-11-23
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Expires: 1995-08-14
Abstract
Abstract A process for converting wet process phosphoric acid to food grade alkali metal phosphates by a sequence of steps including extraction of the wet process acid, partial neutralization, dilution with water, contact with activated carbon, neutralization to a pH of from about 5 to about 9, contact with activated carbon, contact with insoluble alkaline earth metal phosphate salts and recovery of the dissolved alkali metal phosphate product in solution.
Inventors
- 👤 Mazin R. Irani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:24
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/46; C01B25/26; C01B25/30; C01B25/301; C01B25/303
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
164 words
A process for the preparation of high purity alkali phosphate solutions from wet process phosphoric acid which comprises: a. contacting a wet process phosphoric acid with an organic solvent capable of extracting said acid to form a solvent-acid phase, and a raffinate phase; b. partially neutralizing the solvent-acid phase by contacting with a concentrated alkali in amounts sufficient to precipitate impurities, and separating said impurities; c. diluting said partially neutralized solvent-acid phase with water to strip a dilute aqueous phosphoric acid phase from said solvent phase, and separating said phosphoric acid phase; d. neutralizing the aqueous phosphoric acid to a pH of between about 5 and about 9, thereby forming a solution of soluble salts of phosphoric acid and a precipitate, and separating said precipitate; e. contacting said solution of soluble salts with activated carbon; f. contacting said solution of soluble salts with an insoluble alkaline earth metal phosphate salt and separating said insoluble salt to thereby produce a high purity alkali phosphate solution.
Claim 2
Dependent Claim
164 words
A process for the preparation of high purity alkali phosphate solutions from wet process phosphoric acid which comprises: a. contacting a wet process phosphoric acid with an organic solvent capable of extracting said acid to form a solvent-acid phase, and a raffinate phase; b. partially neutralizing the solvent-acid phase by contacting with a concentrated alkali in amounts sufficient to precipitate impurities, and separating said impurities; c. diluting said partially neutralized solvent-acid phase with water to strip a dilute aqueous phosphoric acid phase from said solvent phase, and separating said phosphoric acid phase; d. neutralizing the aqueous phosphoric acid to a pH of between about 5 and about 9, thereby forming a solution of soluble salts of phosphoric acid and a precipitate, and separating said precipitate; e. contacting said solution of soluble salts with activated carbon; f. contacting said solution of soluble salts with an insoluble alkaline earth metal phosphate salt and separating said insoluble salt to thereby produce a high purity alkali phosphate solution.
Claim 3
Dependent Claim
19 words
The process of claim 1, step (a), wherein said solvent is an alcohol containing 5 to 8 carbon atoms.
Claim 4
Dependent Claim
17 words
The process of claim 1, step (a), wherein the raffinate phase is separated prior to partial neutralization.
Claim 5
Dependent Claim
39 words
The process of claim 1, step (b), wherein said alkali is selected from the group consisting of sodium hydroxide, sodium carbonate, and mixtures thereof; potassium hydroxide, potassium carbonate, and mixtures thereof; ammonia, ammonium hydroxide, ammonium carbonate, and mixtures thereof.
Claim 6
Dependent Claim
22 words
The process of claim 4 wherein said alkali is selected from the group consisting of sodium hydroxide, sodium carbonate and mixtures thereof.
Claim 7
Dependent Claim
23 words
The process of claim 1, step (c), wherein said aqueous phosphoric acid phase, after separating said solvent phase, is contacted with activated carbon.
Claim 8
Dependent Claim
53 words
The process of claim 1, step (d) wherein said neutralization is accomplished by contacting said acid wih an alkali selected from the group consisting of sodium hydroxide, sodium carbonate, sodium bicarbonate, and mixtures thereof; potassium hydroxide, potassium carbonate, potassium bicarbonate, and mixtures thereof; ammonia, ammonium hydroxide, ammonium bicarbonate, ammonium carbonate, and mixtures thereof.
Claim 9
Dependent Claim
24 words
The process of claim 7 wherein said alkali is selected from the group consisting of sodium hydroxide, sodium carbonate, sodium bicarbonate and mixtures thereof.
Claim 10
Dependent Claim
37 words
The process of claim 1, step (d) wherein said neutralization is accomplished by contacting said acid with an ion exchange resin loaded with an alkali metal cation selected from the group consisting of sodium, potassium, and ammonium.
Claim 11
Dependent Claim
17 words
The process of claim 1, step (d), wherein said pH varies from about 6 to about 8.
Claim 12
Dependent Claim
16 words
The process of claim 1, step (d) wherein said neutralization is accomplished by means of electrodialysis.
Claim 13
Dependent Claim
26 words
The process of claim 1, step (f), wherein said alkaline earth metal phosphate salt is selected from the group consisting of calcium, magnesium and mixtures thereof.
Claim 14
Dependent Claim
29 words
The process of claim 12 wherein said insoluble alkaline earth metal phosphate salt has an alkaline earth metal to phosphorus mole ratio varying from about 1.4:1 to about 1.8:1.
Claim 15
Dependent Claim
28 words
The process of claim 13 wherein said alkaline earth metal phosphate is a calcium salt selected from the group consisting of hydroxy apatite, tricalcium phosphate, and mixtures thereof.
Claim 16
Dependent Claim
24 words
The process of claim 1 wherein the supernatant liquid from the residues of steps (a), (b), and (d) is recycled to the solvent-acid contacting.
Claim 17
Dependent Claim
21 words
The process of claim 1, step (d), wherein said soluble salts undergo a phase separation prior to the activated carbon contacting.
Claim 18
Dependent Claim
28 words
The process of claim 1, step (d) wherein said acid has been diluted to a concentration varying from about 5% to about 30% P 2 O 5 .
Claim 19
Dependent Claim
17 words
The process of claim 1, step (c), wherein said solvent phase is recycled to the solvent supply.
Claim 20
Dependent Claim
25 words
The process of claim 2 wherein said solvent is selected from the group consisting of amyl alcohol, 2-methyl-1-butanol, hexanol, heptanol, octanol, isomers, and mixtures thereof.
Claim 21
Dependent Claim
17 words
The process of claim 1, step (d), wherein said pH varies from about 6 to about 8.
Claim 22
Dependent Claim
15 words
The process of claim 1 wherein said alkali phosphate solution complies with food grade requirements.
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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) | 1979-11-23 | 1980-05-24 | 1980-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-23 | 1984-05-24 | 1984-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-23 | 1988-05-24 | 1988-11-23 | $7700.00 | Window Closed / Lapsed |