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US4011301A
Expired / Lapsed
US
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Ammonium phosphate production and the reduction of fluorine and silicon emissions
Assignee: Union Oil Company of California
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Filing: 1975-10-23
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Granted: 1977-03-08
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Expires: 1995-10-23
Abstract
Abstract Ammonium phosphates are produced from wet-process phosphoric acids containing silicon and fluorine compounds by preconcentrating the acid and evolving some of the water, silicon and fluorine compounds as a vapor phase, maintaining it at a temperature above about 50° C., neutralizing the liquid acid concentrate with ammonia, and absorbing the isolated vapor phase from the evaporation zone in a relatively cool, neutralized ammonium phosphate solution at a pH of at least about 5.5.
Inventors
- 👤 Donald C. Young
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:16
CPC Classifications
C; C05; C05B; C05B13/00; C05B13/06; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/28; C01B25/38; C01B25/40; C01B25/405; C05B7/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
183 words
The method of converting wet-process phosphoric acid containing silicon and fluorine as soluble compounds thereof to ammonium phosphates and reducing the emission of said compounds to the atmosphere, including the steps of (a) heating said wet-process acid feed to a temperature of at least about 120° C. sufficient to vaporize a portion of the water from said acid, concentrate said acid and form a vapor phase containing vaporized water and a portion of said silicon and fluorine; (b) separating said vapor phase from the concentrated acid, (c) maintaining said vapor phase at a temperature of at least about 50°° C. until said vapor phase is contacted with the ammonium phosphate solution hereinafter defined; (d) at least partially neutralizing at least 5 percent of said concentrated acid with ammonia to form said ammonium phosphates; and (e) contacting said vapor phase with said ammonium phosphates in the liquid phase at a liquid phase temperature below about 110° C., a vapor phase temperature of at least about 50° C., and a pH of at least 5.5, and absorbing said vapor phase in said ammonium phosphate solution.
Claim 2
Independent Claim
183 words
The method of converting wet-process phosphoric acid containing silicon and fluorine as soluble compounds thereof to ammonium phosphates and reducing the emission of said compounds to the atmosphere, including the steps of (a) heating said wet-process acid feed to a temperature of at least about 120° C. sufficient to vaporize a portion of the water from said acid, concentrate said acid and form a vapor phase containing vaporized water and a portion of said silicon and fluorine; (b) separating said vapor phase from the concentrated acid, (c) maintaining said vapor phase at a temperature of at least about 50°° C. until said vapor phase is contacted with the ammonium phosphate solution hereinafter defined; (d) at least partially neutralizing at least 5 percent of said concentrated acid with ammonia to form said ammonium phosphates; and (e) contacting said vapor phase with said ammonium phosphates in the liquid phase at a liquid phase temperature below about 110° C., a vapor phase temperature of at least about 50° C., and a pH of at least 5.5, and absorbing said vapor phase in said ammonium phosphate solution.
Claim 3
Dependent Claim
98 words
The method of claim 1 wherein said wet-process acid feed contains at least about 20 weight percent P 2 O 5 , said feed is heated at a temperature of about 120° to about 350° C. for a period of time sufficient to drive off at least 5 percent of the water contained in said wet-process acid, said vapor phase removed from said liquid phase is maintained at a temperature of at least about 80° C. prior to contacting with said ammonium phosphate solution and is contacted with said solution at a solution temperature below about 100° C.
Claim 4
Dependent Claim
197 words
The method of claim 1 wherein said wet-process acid feed has a P 2 O 5 content of about 20 to about 60 weight percent, a silicon content of at least about 0.1 weight percent determined as SiO 2 , and a fluorine content of at least about 0.1 weight percent determined as the element, including the steps of heating said wet-process acid in step (a) to a temperature and for a period of time sufficient to reduce the H 2 O/P 2 O 5 molar ratio thereof at least to about 6.5, reacting the resultant acid with ammonia, and heating the same to a temperature of at least about 290° C. sufficient to convert at least 10 percent of the P 2 O 5 content thereof to polyphosphates, diluting, quenching and neutralizing the resultant ammonium phosphates to a P 2 O 5 content of less than about 40 weight percent, a temperature of less than about 100° C., and a pH of at least about 6, respectively, and contacting at least 5 percent of the solution thus formed with said vapor removed from said concentrating step under conditions sufficient to absorb said vapor in said solution.
Claim 5
Dependent Claim
58 words
The method of claim 1 including the steps of removing a portion of the heated and concentrated acid from the system after separation from said resultant vapor phase in step (b) and before said neutralization in step (d) and recovering said acid portion as concentrated, purified phosphoric acid having a higher elemental P/F weight ratio than said feed.
Claim 6
Dependent Claim
19 words
The method of claim 4 wherein said concentrated, purified acid is converted to ammonium phosphate by neutralization with ammonia.
Claim 7
Dependent Claim
65 words
The method of claim 1 including the steps of withdrawing from the system a portion of said neutralized acid from step (d) prior to said contacting with said vapor phase of step (e), isolating the thus withdrawn portion of partially neutralized acid from said vapor phase, and recovering said withdrawn portion as purified ammonium phosphate having a higher elemental P/F weight ratio than said feed.
Claim 8
Dependent Claim
38 words
The method of claim 6 including the steps of quenching said withdrawn portion of ammonium phosphate in an aqueous ammonium phosphate solution at a temperature below about 110° C. and at a pH of at least about 5.5.
Claim 9
Dependent Claim
56 words
The method of claim 3 including the steps of withdrawing from said system a portion of said polyphosphates prior to said contacting of said solution with said vapor, isolating said withdrawn polyphosphates from said vapors, and recovering said portion of said polyphosphates as purified ammonium polyphosphates having a higher P/F elemental weight ratios than said feed.
Claim 10
Dependent Claim
107 words
The method of claim 1 wherein said wet-process acid feed contains at least about 20 and less than about 65 weight percent P 2 O 5 , has an H 2 O/P 2 O 5 molar ratio of at least about 4.5, and contains about 1 to about 20 weight percent total cogeneric impurities and at least about 0.1 weight percent silicon expressed as SiO 2 and at least about 0.1 weight percent fluorine expressed as the element, and all of said vapor phase recovered from said concentrated acid is absorbed in said ammonium phosphate solution in the absence of any net vapor effluent from said absorption.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-07 | 1980-09-06 | 1981-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-07 | 1984-09-06 | 1985-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-07 | 1988-09-06 | 1989-03-08 | $7700.00 | Window Closed / Lapsed |