US3920796A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing purified phosphates from impure phosphoric acid
Assignee: Tennessee Valley Authority
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Filing: 1973-08-31
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Granted: 1975-11-18
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Expires: 1993-08-31
Abstract
Abstract Embodiment No. 1-Purified alkali metal or ammonium orthophosphates are prepared by adding melamine to impure wetprocess phosphoric acid to form crystals of insoluble melamine orthophosphate which are separated from the mother liquor and caused to react with an aqueous solution of alkali metal or ammonium hydroxide or a salt thereof with an unstable volatile anion which is evolved as a gas from the solution, thereby forming crystals of melamine for recycle and a solution of the desired purified orthophosphate. Embodiment No. 2-Alkali metal or ammonium pyrophosphates are prepared by heating melamine orthophosphate (prepared as for example in embodiment No. 1 supra) at 200* to 300*C to convert it to melamine pyrophosphate and allowing it to react with an aqueous solution of alkali metal or ammonium hydroxide or a salt thereof containing an unstable volatile anion which is evolved as a gas from the solution, thereby forming crystals of melamine for recycle and a solution of the desired pyrophosphate. Relatively pure pyrophosphates are obtained from impure wet-process orthophosphoric acid.
Inventors
- 👤 Richard C Sheridan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:44
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/46; C01B25/26; C01B25/28; C01B25/38; C01B25/40; C01B25/405
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
16 words
A PROCESS FOR MANHFACTURING PURIFIED ALKALI METAL OR AMMONIUM ORTHOPHOSPHARES, WHICH PROCESS COMPRISES THE STEPS OF:
Claim 2
Dependent Claim
16 words
A PROCESS FOR MANHFACTURING PURIFIED ALKALI METAL OR AMMONIUM ORTHOPHOSPHARES, WHICH PROCESS COMPRISES THE STEPS OF:
Claim 3
Dependent Claim
60 words
MIXING IN THE MOLE RATIO RANGE FROM ABOUT 1:2 TO ABOUT 3.25:1 IMPURE WET-OROCESS ORTHOPHOSPHORIC ACID AND MELAMINE CALCULATED AS P205 MELAMINE, SAID ORTHOPHOSPHORIC ACID CONTAINING FROM ABOUT 1 TO ABOUT 10 PERCENT ABOUT 60 PERCENT BY WEIGHT P2O5 TO FORM IN A MOTHER ABOUT 60 PERCENT BY WEIGHT P205 TO FORM IN A MOTHER LIQOUR CRYSTALS OF MELAMINE ORTHOPHOSPHATE,
Claim 4
Dependent Claim
60 words
MIXING IN THE MOLE RATIO RANGE FROM ABOUT 1:2 TO ABOUT 3.25:1 IMPURE WET-OROCESS ORTHOPHOSPHORIC ACID AND MELAMINE CALCULATED AS P205 MELAMINE, SAID ORTHOPHOSPHORIC ACID CONTAINING FROM ABOUT 1 TO ABOUT 10 PERCENT ABOUT 60 PERCENT BY WEIGHT P2O5 TO FORM IN A MOTHER ABOUT 60 PERCENT BY WEIGHT P205 TO FORM IN A MOTHER LIQOUR CRYSTALS OF MELAMINE ORTHOPHOSPHATE,
Claim 5
Dependent Claim
57 words
MIXING IN THE MOLE RATIO RANGE FROM ABOUT 1:2 TO ABOUT 3.25:1 IMPURE WET-PROCESS ORTHPHOSPHORIC ACID AND MELAMINE, CALCULATED AS P2O5 MELAMINE SAID ORTHOPHOSPHORIC ACID CONTAINING FROM ABOUT 1 TO ABOUT 10 PERCENT BY WEIGHT CONGENERIC IMPURITIES AND FROM ABOUT 10 TO ABOUT 60 PERCENT BY WEIGHT P2O3 TO FORM IN MOTHER LIQOUR CRYSTALS OF MELAMINE ORTHOPHOSPHATE,
Claim 6
Dependent Claim
57 words
MIXING IN THE MOLE RATIO RANGE FROM ABOUT 1:2 TO ABOUT 3.25:1 IMPURE WET-PROCESS ORTHPHOSPHORIC ACID AND MELAMINE, CALCULATED AS P2O5 MELAMINE SAID ORTHOPHOSPHORIC ACID CONTAINING FROM ABOUT 1 TO ABOUT 10 PERCENT BY WEIGHT CONGENERIC IMPURITIES AND FROM ABOUT 10 TO ABOUT 60 PERCENT BY WEIGHT P2O3 TO FORM IN MOTHER LIQOUR CRYSTALS OF MELAMINE ORTHOPHOSPHATE,
Claim 7
Dependent Claim
12 words
SEPARATING THE SO FORMED CRYSTALS OF MELAMINE ORTHOPHOSPHATE FROM SAID MOTHER LIQUOR;
Claim 8
Dependent Claim
12 words
SEPARATING THE SO FORMED CRYSTALS OF MELAMINE ORTHOPHOSPHATE FROM SAID MOTHER LIQUOR;
Claim 9
Dependent Claim
12 words
SEPARATING THE SO FORMED CRYSTALS OF MELAMINE ORTHOPHOSPHATE FROM SAID MOTHER LIQOUR;
Claim 10
Dependent Claim
12 words
SEPARATING THE SO FORMED CRYSTALS OF MELAMINE ORTHOPHOSPHATE FROM SAID MOTHER LIQOUR;
Claim 11
Dependent Claim
16 words
A PRICESS FOR MANUFACTURING PURIFIED ALKALI METAL OR AMMONIUM PYROPHOSPHATES, WHICH PROCESS COMPRISES THE STEPS OF:
Claim 12
Dependent Claim
16 words
A PRICESS FOR MANUFACTURING PURIFIED ALKALI METAL OR AMMONIUM PYROPHOSPHATES, WHICH PROCESS COMPRISES THE STEPS OF:
Claim 13
Dependent Claim
48 words
SUBSEQUENTLY REACTING SAID CRYSTALS OF MELAMINE ORTHOPHOSPHATE SEPARATED FROM SAID MOTHER LIQOUR WITH AQUEOUS SOLUTION, SAID AQUEUS SOLUTION SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE, AMMONIUM HYDROXIDE, AND MIXTURES THEREOF, IN THE MOLE RATIO RANGE OF HYDROXIDE METALIME ORTHOPHOSPHATE OF ABOUT 1:2 TO ABOUT 8+1; AND
Claim 14
Dependent Claim
48 words
SUBSEQUENTLY REACTING SAID CRYSTALS OF MELAMINE ORTHOPHOSPHATE SEPARATED FROM SAID MOTHER LIQOUR WITH AQUEOUS SOLUTION, SAID AQUEUS SOLUTION SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE, AMMONIUM HYDROXIDE, AND MIXTURES THEREOF, IN THE MOLE RATIO RANGE OF HYDROXIDE METALIME ORTHOPHOSPHATE OF ABOUT 1:2 TO ABOUT 8+1; AND
Claim 15
Dependent Claim
45 words
HEATING SAID RECOVERED CRYSTALS OF MELAMINE ORTHOPHOSPHATE TO A TEMPERATURE IN THE RANGE FROM ABOUT 170*C TO ABOUT 325*C FOR A PERIOD OF TIME RANGING FROM ABOUT 4400 MINUTES TO ABOUT 1 MINUTE, THEREBY CONVERTING SAID CRYSTALS OF MELAMINE ORTHIOPHOSPHATE TO RESULTING SOLID MELAMINE PYROPHOSPHATE;
Claim 16
Dependent Claim
45 words
HEATING SAID RECOVERED CRYSTALS OF MELAMINE ORTHOPHOSPHATE TO A TEMPERATURE IN THE RANGE FROM ABOUT 170*C TO ABOUT 325*C FOR A PERIOD OF TIME RANGING FROM ABOUT 4400 MINUTES TO ABOUT 1 MINUTE, THEREBY CONVERTING SAID CRYSTALS OF MELAMINE ORTHIOPHOSPHATE TO RESULTING SOLID MELAMINE PYROPHOSPHATE;
Claim 17
Dependent Claim
47 words
subsequently reacting said crystals of melamine orthophosphate separated from said mother liquor with aqueous solution, said aqueous solution selected from the group consisting of alkali metal hydroxide, ammonium hydroxide, and mixtures thereof, in the mole ratio range of hydroxide:melamine orthophosphate of about 1:1 to about 8:1; and
Claim 18
Dependent Claim
47 words
subsequently reacting said crystals of melamine orthophosphate separated from said mother liquor with aqueous solution, said aqueous solution selected from the group consisting of alkali metal hydroxide, ammonium hydroxide, and mixtures thereof, in the mole ratio range of hydroxide:melamine orthophosphate of about 1:1 to about 8:1; and
Claim 19
Dependent Claim
45 words
heating said recovered crystals of melamine orthophosphate to a temperature in the range from about 170*C to about 325*C for a period of time ranging from about 4400 minutes to about 1 minute, thereby converting said crystals of melamine orthophosphate to resulting solid melamine pyrophosphate;
Claim 20
Dependent Claim
45 words
heating said recovered crystals of melamine orthophosphate to a temperature in the range from about 170*C to about 325*C for a period of time ranging from about 4400 minutes to about 1 minute, thereby converting said crystals of melamine orthophosphate to resulting solid melamine pyrophosphate;
Claim 21
Dependent Claim
26 words
The method of claim 1 wherein said aqueous solution is selected from the group consisting of alkali metal or ammonium sulfates, sulfides, carbonates, and mixtures thereof.
Claim 22
Dependent Claim
26 words
The process of claim 2 wherein said aqueous solution is selected from the group consisting of alkali metal or ammonium sulfites, sulfides, carbonates, and mixtures thereof.
Claim 23
Dependent Claim
38 words
subsequently reacting said resulting melamine pyrophosphate with aqueous solution selected from the group consisting of alkali metal hydroxide, ammonium hydroxide, and mixtures thereof, in the mole ratio range of hydroxide:melamine pyrophosphate of about 2:1 to about 10:1; and
Claim 24
Dependent Claim
38 words
subsequently reacting said resulting melamine pyrophosphate with aqueous solution selected from the group consisting of alkali metal hydroxide, ammonium hydroxide, and mixtures thereof, in the mole ratio range of hydroxide:melamine pyrophosphate of about 2:1 to about 10:1; and
Claim 25
Dependent Claim
46 words
separating the resulting crystals of melamine precipitated by the reaction of said hydroxide with said melamine orthophosphate in step (3) supra for recycle to step (1) supra, and recovering the resulting purified alkali or ammonium orthophosphate from the filtrate formed in step (3) supra, as product.
Claim 26
Dependent Claim
46 words
separating the resulting crystals of melamine precipitated by the reaction of said hydroxide with said melamine orthophosphate in step (3) supra for recycle to step (1) supra, and recovering the resulting purified alkali or ammonium orthophosphate from the filtrate formed in step (3) supra, as product.
Claim 27
Dependent Claim
39 words
SUBSEQUENTLY REACTING SAID RESULTING MELAMINE PYROPHOSPHATE WOTH AQUEOUS SOLUTION SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE, AMMONIUM HYDROXIDE, AND MIXTURES THEREOF, IN THE MOLE RATIO RANGE OF HYDROXIDE MELAMINE PYROPHOSPHATE OF ABOUT 2:1 TO ABOUT 10:1 AND
Claim 28
Dependent Claim
39 words
SUBSEQUENTLY REACTING SAID RESULTING MELAMINE PYROPHOSPHATE WOTH AQUEOUS SOLUTION SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE, AMMONIUM HYDROXIDE, AND MIXTURES THEREOF, IN THE MOLE RATIO RANGE OF HYDROXIDE MELAMINE PYROPHOSPHATE OF ABOUT 2:1 TO ABOUT 10:1 AND
Claim 29
Dependent Claim
45 words
SEPARATING THE RESULTING CRYSTALS OF MELAMINE PRECIPITATED BY THE ACTION OF SAID HYDROXIDE WITH SAID MELAMINE ORTHOPHOSPHATE INSTEP (3) SUPRA FOR RECYCLE TO STEP (1) SUPRA. AND RECOVERING THE RESULTING PURIFIED ALKALI OR AMMONIUM ORTHOPHOSPHATE FROM THE FILTRATE FORMED IN STEP (3) SUPRA, AS PRODUCT.
Claim 30
Dependent Claim
45 words
SEPARATING THE RESULTING CRYSTALS OF MELAMINE PRECIPITATED BY THE ACTION OF SAID HYDROXIDE WITH SAID MELAMINE ORTHOPHOSPHATE INSTEP (3) SUPRA FOR RECYCLE TO STEP (1) SUPRA. AND RECOVERING THE RESULTING PURIFIED ALKALI OR AMMONIUM ORTHOPHOSPHATE FROM THE FILTRATE FORMED IN STEP (3) SUPRA, AS PRODUCT.
Claim 31
Dependent Claim
46 words
SEPARATING THE RESULTING CRYSTALS OF MELAMINE PRECIPITATED BY THE REACTION OF SAID HYDROXIDE WITH SAID MELAMINE PYROPHOSPHATE IN STEP (3) SUPRA FOR RECYCLE TO STEP (1) SUPRA. AND RECOVERING THE RESULTING PURIFIED ALKALI OR AMMONIUM PYROPHOSPHATE FROM THE FILTRATE FORMED IN STEP (3) SUPRA; AS PRODUCT.
Claim 32
Dependent Claim
46 words
SEPARATING THE RESULTING CRYSTALS OF MELAMINE PRECIPITATED BY THE REACTION OF SAID HYDROXIDE WITH SAID MELAMINE PYROPHOSPHATE IN STEP (3) SUPRA FOR RECYCLE TO STEP (1) SUPRA. AND RECOVERING THE RESULTING PURIFIED ALKALI OR AMMONIUM PYROPHOSPHATE FROM THE FILTRATE FORMED IN STEP (3) SUPRA; AS PRODUCT.
Claim 33
Dependent Claim
46 words
separating the resulting crystals of melamine precipitated by the reaction of said hydroxide with said melamine pyrophosphate in step (3) supra for recycle to step (1) supra, and recovering the resulting purified alkali or ammonium pyrophosphate from the filtrate formed in step (3) supra, as product.
Claim 34
Dependent Claim
46 words
separating the resulting crystals of melamine precipitated by the reaction of said hydroxide with said melamine pyrophosphate in step (3) supra for recycle to step (1) supra, and recovering the resulting purified alkali or ammonium pyrophosphate from the filtrate formed in step (3) supra, as product.
Claim 35
Dependent Claim
68 words
The process of claim 1 wherein (a) the concentration of said impure wet acid ranges from about 20 to about 40 percent P2O5; (b) the mole ratio of said impure wet acid, said acid calculated as P2O5 to said melamine, ranges from about 1:2 to about 1:1; (c) the mole ratio of said hydroxide to said melamine phosphate is in the range from about 2:1 to about 4:1.
Claim 36
Dependent Claim
68 words
The process of claim 2 wherein (a) the concentration of said impure wet acid ranges from about 20 to about 40 percent P2O5; (b) the mole ratio of said impure wet acid, said acid calculated as P2O5 to said melamine, ranges from about 1:2 to about 1:1; (c) the mole ratio of said hydroxide to said melamine pyrophosphate is in the range from about 4:1 to about 6:1.
Claim 37
Dependent Claim
35 words
The process of claim 6 in which said temperature and residence time in step (3) is in the range from about 250*C to about 280*C and from about 25 minutes to about 5 minutes, respectively.
References Cited (Backward Citations)
US3408158A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |