US3911087A
Expired / Lapsed
US
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Selective solvent extraction of sulfate impurities from phosphoric acid
Assignee: Freeport Minerals Co
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Filing: 1973-10-19
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Granted: 1975-10-07
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Expires: 1993-10-19
Abstract
Abstract While it is known that substantial amounts of the sulfate and fluorine impurities present in phosphoric acid can be concurrently extracted from the acid by treating it with a water immiscible amine enriched extractant, it has now been found that most of the sulfate can be extracted without concurrently extracting large amounts of the fluorine in the acid if a certain combination of treatment conditions is observed. Thus selective sulfate extraction surprisingly occurs when 35 to 44% P2O5 acid is treated with a water immiscible extractant containing about 1 to 3 moles of a tertiary organic amine per mole of sulfate in the acid. With the present invention, virtually all the sulfate present in the acid can be extracted while concurrently extracting only 25% of the fluorine. Selective sulfate extraction is an advantage whenever it is desirable to separately recover the fluorine in the acid in the conventional fluorine recovery systems of phosphoric acid manufacturing processes.
Inventors
- 👤 Miguel O Villarejos
- 👤 Tadeusz K Wiewiorowski
- 👤 Jr Willis L Thornsberry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:48
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/18; C01B25/234; C01B25/237; C01B25/2372; C01B25/2377
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
136 words
IN THE METHOD FOR SEPARATING FLUORINE AND SULFATE IMPURITIES FROM PHOSPHORIC ACID BY SOLVENT EXTRACTION WHICH COMPRISES CONTACTING THE ACID WITH AN EXTRACTANT COMPRISING A WAITER IMMISCIBLE ORGANIC LIQUID AND AN ORGANIC AMINE, AND SEPARATING THE ORGANIC EXTRACTANT PHASE CONTAINING THE FLUORINE AND SULFATE IMPURITIES FROM THE AQUEOUS ACID PHASE: THE IMPROVEMENT WHEREBY THE SULFATE IMPURITIES ARE SELECTIVELY SEPARATED FROM THE FLUORINE IMPURITIES IN THE FINAL PRODUCT ACID OF THE SOLVENT EXTRACTION, WITH THE FLUORINE IMPURITIES REMAINING IN THE PRODUCT ACID, WHICH COMPRISES CONTACTING A PHOSPHORIC ACID CONTAINING FLUORINE AND SULFATE IMPURITIES AND WHOSE P2O5 CONCENTRATION IS ABOUT 35 TO 44% BY WEIGHT WITH AN EXTRACTANT COMPRISING A WATER IMMISCIBLE ORGANIC LIQUID AND ABOUT 1 TO 3 MOLES OF A TERTIARY AMINE PER MOLE OF SULFATE PRESENT IN THE ACID, THE TERTIARY AMINE HAVING THE FORMULA:
Claim 2
Dependent Claim
136 words
IN THE METHOD FOR SEPARATING FLUORINE AND SULFATE IMPURITIES FROM PHOSPHORIC ACID BY SOLVENT EXTRACTION WHICH COMPRISES CONTACTING THE ACID WITH AN EXTRACTANT COMPRISING A WAITER IMMISCIBLE ORGANIC LIQUID AND AN ORGANIC AMINE, AND SEPARATING THE ORGANIC EXTRACTANT PHASE CONTAINING THE FLUORINE AND SULFATE IMPURITIES FROM THE AQUEOUS ACID PHASE: THE IMPROVEMENT WHEREBY THE SULFATE IMPURITIES ARE SELECTIVELY SEPARATED FROM THE FLUORINE IMPURITIES IN THE FINAL PRODUCT ACID OF THE SOLVENT EXTRACTION, WITH THE FLUORINE IMPURITIES REMAINING IN THE PRODUCT ACID, WHICH COMPRISES CONTACTING A PHOSPHORIC ACID CONTAINING FLUORINE AND SULFATE IMPURITIES AND WHOSE P2O5 CONCENTRATION IS ABOUT 35 TO 44% BY WEIGHT WITH AN EXTRACTANT COMPRISING A WATER IMMISCIBLE ORGANIC LIQUID AND ABOUT 1 TO 3 MOLES OF A TERTIARY AMINE PER MOLE OF SULFATE PRESENT IN THE ACID, THE TERTIARY AMINE HAVING THE FORMULA:
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the P2O5 concentration of the treated acid is about 39 to 43%.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein the extractant contains about 1.5 to 2.5 moles of tertiary amine per mole of sulfate present in the acid.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the tertiary amine is selected from the group consisting of tricaprylyl amine and tridodecyl amine.
Claim 6
Dependent Claim
18 words
The method of claim 1 wherein the acid is clarified before treatment with the extractant to remove solids.
Claim 7
Dependent Claim
63 words
The method of claim 1 wherein the treated acid is wet process acid, further including the step of stripping the sulfate loaded extractant with an aqueous solution capable of transferring the sulfate impurities from the extractant into the aqueous solution, and returning the stripped sulfate impurities to the attack zone of the process for elimination through the filtration steps of the wet process.
Claim 8
Dependent Claim
55 words
The method of claim 1 wherein the P2O5 concentration of the treated acid is about 39 to 43%, the extractant contains about 1.5 to 2.5 moles of tertiary amine per mole of sulfate present in the acid, and each R1, R2 and R3 group of the tertiary amine contains from 6 to 20 carbon atoms.
Claim 9
Dependent Claim
140 words
In the method for separating fluorine and sulfate impurities from phosphoric acid by solvent extraction which comprises contacting the acid with an extractant comprising a water immiscible organic liquid and an organic amine, and separating the organic extractant phase containing the fluorine and sulfate impurities from the aqueous acid phase: the improvement whereby the sulfate impurities are selectively separated from the fluorine impurities in the final product acid of the solvent extraction, with the fluorine impurities remaining in the product acid, which comprises contacting a substantially solids free wet process phosphoric acid containing fluorine and sulfate impurities and having a concentration of about 39 to 43% with an extractant comprising a water immiscible organic liquid containing about 1.5 to 2.5 moles of a tertiary amine per mole of sulfate present in the treated acid, the tertiary amine having the formula:
Claim 10
Dependent Claim
140 words
In the method for separating fluorine and sulfate impurities from phosphoric acid by solvent extraction which comprises contacting the acid with an extractant comprising a water immiscible organic liquid and an organic amine, and separating the organic extractant phase containing the fluorine and sulfate impurities from the aqueous acid phase: the improvement whereby the sulfate impurities are selectively separated from the fluorine impurities in the final product acid of the solvent extraction, with the fluorine impurities remaining in the product acid, which comprises contacting a substantially solids free wet process phosphoric acid containing fluorine and sulfate impurities and having a concentration of about 39 to 43% with an extractant comprising a water immiscible organic liquid containing about 1.5 to 2.5 moles of a tertiary amine per mole of sulfate present in the treated acid, the tertiary amine having the formula:
Claim 11
Dependent Claim
54 words
The method of claim 8 further including the step of stripping the sulfate loaded extractant with an aqueous solution capable of transferring the sulfate from the extractant into the aqueous solution, and returning the stripped sulfate impurities to the attack zone of the process for elimination through the filtration steps of the wet process.
Claim 12
Dependent Claim
20 words
The method of claim 1 wherein said product acid contains only about 1 to 6% of its original sulfate content.
Claim 13
Dependent Claim
36 words
The method of claim 3 wherein said product acid contains only about 1 to 6% of its original sulfate content, and wherein the tertiary amine is selected from the group consisting of tricaprylyl amine and tridodecylamine.
Claim 14
Dependent Claim
20 words
The method of claim 7 wherein said product acid contains only about 1 to 6% of its original sulfate content.
Claim 15
Dependent Claim
20 words
The method of claim 8 wherein said product acid contaIns only about 1 to 6% of its original sulfate content.
Claim 16
Dependent Claim
136 words
In the method for separating fluorine and sulfate impurities from phosphoric acid by solvent extraction which comprises contacting the acid with an extractant comprising a water immiscible organic liquid and an organic amine, and separating the organic extractant phase containing the fluorine and sulfate impurities from the aqueous acid phase: the improvement whereby the sulfate impurities are selectively separated from the fluorine impurities in the final product acid of the solvent extraction, with the fluorine impurities remaining in the product acid, which comprises contacting a phosphoric acid containing fluorine and sulfate impurities and whose P2O5 concentration is about 35 to 44% by weight with an extractant comprising a water immiscible organic liquid and about 1 to 3 moles of a tertiary amine per mole of sulfate present in the acid, the tertiary amine having the formula:
Claim 17
Dependent Claim
136 words
In the method for separating fluorine and sulfate impurities from phosphoric acid by solvent extraction which comprises contacting the acid with an extractant comprising a water immiscible organic liquid and an organic amine, and separating the organic extractant phase containing the fluorine and sulfate impurities from the aqueous acid phase: the improvement whereby the sulfate impurities are selectively separated from the fluorine impurities in the final product acid of the solvent extraction, with the fluorine impurities remaining in the product acid, which comprises contacting a phosphoric acid containing fluorine and sulfate impurities and whose P2O5 concentration is about 35 to 44% by weight with an extractant comprising a water immiscible organic liquid and about 1 to 3 moles of a tertiary amine per mole of sulfate present in the acid, the tertiary amine having the formula:
Claim 18
Dependent Claim
17 words
The method of claim 14 wherein the P2O5 concentration of the acid is about 39 to 43%.
Claim 19
Dependent Claim
25 words
The method of claim 14 wherein the extractant contains about 1.5 to 2.5 moles of tertiary amine per mole of sulfate present in the acid.
Claim 20
Dependent Claim
20 words
The method of claim 14 wherein the tertiary amine is selected from the group consisting of tricaprylyl amine and tridodecylamine.
Claim 21
Dependent Claim
136 words
In the method for separating fluorine and sulfate impurities from phosphoric acid by solvent extraction which comprises contacting the acid with an extractant comprising a water immiscible organic liquid and an organic amine, and separating the organic extractant phase containing the fluorine and sulfate impurities from the aqueous acid phase: the improvement whereby the sulfate impurities are selectively separated from the fluorine impurities in the final product acid of the solvent extraction, with the fluorine impurities remaining in the product acid, which comprises contacting a phosphoric acid containing fluorine and sulfate impurities and whose P2O5 concentration is about 35 to 44% by weight with an extractant comprising a water immiscible organic liquid and about 1 to 3 moles of a tertiary amine per mole of sulfate present in the acid, the tertiary amine having the formula:
Claim 22
Dependent Claim
136 words
In the method for separating fluorine and sulfate impurities from phosphoric acid by solvent extraction which comprises contacting the acid with an extractant comprising a water immiscible organic liquid and an organic amine, and separating the organic extractant phase containing the fluorine and sulfate impurities from the aqueous acid phase: the improvement whereby the sulfate impurities are selectively separated from the fluorine impurities in the final product acid of the solvent extraction, with the fluorine impurities remaining in the product acid, which comprises contacting a phosphoric acid containing fluorine and sulfate impurities and whose P2O5 concentration is about 35 to 44% by weight with an extractant comprising a water immiscible organic liquid and about 1 to 3 moles of a tertiary amine per mole of sulfate present in the acid, the tertiary amine having the formula:
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) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |