Claims
- 1. A process for the purification of phosphoric acid obtained from the digestion of phosphate bearing rock containing metal impurities which comprise calcium, magnesium, aluminum, ferric iron, and ferrous iron, which process comprises:
- (a) contacting high alumina phosphate pebble rock having a bone phosphate of lime value less than about 68 with aqueous phosphoric acid containing from about 10% up to about 35% P.sub.2 O.sub.5 at an elevated temperature of from about 140.degree. F. to about 220.degree. F. to form a reaction mass containing extracted phosphate values from the phosphate pebble rock in the form of monocalcium phosphate and a residual solid phosphate pebble rock gangue;
- (b) contacting the reaction mass with concentrated sulfuric acid comprising from about 90% to about 100% H.sub.2 SO.sub.4 at an elevated temperature of from about 140.degree. F. to about 220.degree. F. to convert the monocalcium phosphate to solid calcium sulfate and phosphoric acid and form a crude phosphoric acid containing solid calcium sulfate, metal impurities selected from the group consisting of calcium, magnesium, aluminum, ferric iron and ferrous iron and solid phosphate pebble rock gangue;
- (c) separating the crude phosphoric acid containing the ionic metal impurities from the solid phosphate pebble rock gangue and the solid calcium sulfate;
- (d) contacting the crude phosphoric acid containing ionic metal impurities with a water-immiscible organic solvent containing a water-immiscible organic sulfonic acid compound selected from the group consisting of alkylaryl, polyalkylaryl, alkanoylaryl, polyalkanoylaryl sulfonic acids and aromatic ring-substituted derivatives thereof wherein the substituent is selected from fluoro, bromo, chloro, iodo, hydroxy, alkoxy and omegacarboxyalkoxy groups to extract ionic metal impurities and form:
- (i) a water-immiscible organic phase containing the organic sulfonic acid compound containing extracted ionic metal impurities; and
- (ii) an aqueous phase containing a purified phosphoric acid; and
- (e) separating the aqueous phase containing the purified phosphoric acid from the water-immiscible organic phase containing the organic sulfonic acid compound containing extracted ionic metal impurities.
- 2. The process of claim 1 including the following steps:
- (f) regenerating the water-immiscible organic sulfonic acid compound containing extracted metallic impurities by contacting the water-immiscible phase containing the organic sulfonic acid compound containing extracted ionic metal impurities from step (e) with a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, and nitric acid to form metallic salts of said mineral acids and the water-immiscible phase containing the water-immiscible sulfonic acid compound in the free acid form; and
- (g) separating the water-immiscible organic phase containing the organic sulfonic acid compound in free-acid form, from the metallic salts of said mineral acid.
- 3. The process of claim 1 wherein said high alumina phosphate rock pebble contains at least about 2.0% by weight Al.sub.2 O.sub.3.
- 4. The process of claim 3 wherein said high alumina phosphate rock pebble contains at least about 2.5% by weight Al.sub.2 O.sub.3.
- 5. The process of claim 1 wherein the total of the analysis of Al.sub.2 O.sub.3 and Fe.sub.2 O.sub.3 of said high alumina phosphate pebble rock is at least about 3.2 weight %.
- 6. The process as recited in claim 1 in which the P.sub.2 O.sub.5 content of the phosphoric acid used in the first contacting step (a) is from about 25% to about 35%.
- 7. The process as recited in claim 1 in which the weight ratio of the phosphate pebble rock to the phosphoric acid gives a slurry density of about 20% to about 45% by weight.
- 8. The process as recited in claim 1 in which the weight ratio of the phosphate pebble rock to the phosphoric acid gives a slurry density of about 30% by weight.
- 9. The process as recited in claim 1 in which the phosphate pebble rock is contacted with the phosphoric acid at from about 140.degree. F. to about 170.degree. F. and the reaction mass is contacted with sulfuric acid at from about 140.degree. F. to about 170.degree. F.
- 10. The process as recited in claim 1 in which the phosphate pebble rock is contacted with the phosphoric acid at about 155.degree. F. to about 170.degree. F. and the reaction mass is contacted with sulfuric acid at about 155.degree. F. to about 170.degree. F.
- 11. The process as recited in claim 1 in which the phosphate pebble rock is contacted with the phosphoric acid at about 180.degree. F. to about 220.degree. F. and the resulting reaction mass is contacted with sulfuric acid at about 180.degree. F. to about 220.degree. F., whereby said calcium sulfate in steps (b) and (c) comprises calcium sulfate hemihydrate and wherein in step (d) said crude phosphoric acid contains from about 40% to about 47% P.sub.2 O.sub.5.
- 12. The process as recited in claim 11 in which the phosphate pebble rock is contacted with the phosphoric acid at about 190.degree. F. to about 210.degree. F. and the reaction mass is contacted with sulfuric acid at about 190.degree. F. to about 210.degree. F.
- 13. The process of claim 1 in which the phosphate pebble rock is comminuted to -60 mesh prior to said contacting with phosphoric acid.
- 14. The process as recited in claim 1 in which the water-immiscible organic sulfonic acid compound contains at least 12 carbon atoms.
- 15. The process as recited in claim 1 in which the water-immiscible organic sulfonic acid compound contains from about 14 carbon atoms up to about 30 carbon atoms.
- 16. The process as recited in claim 1 in which the water-immiscible organic sulfonic acid compound is dissolved in a water-immiscible organic solvent.
- 17. The process as recited in claim 16 in which the water-immiscible organic solvent for the water-immiscible organic sulfonic acid compound is a saturated hydrocarbon having a boiling point of about 120.degree. C. up to about 230.degree. C., a flash point of about 15.degree. C. up to about 70.degree. C., a viscosity of about 1.5 to about 1.7 centipoise and a density below the density of the crude phosphoric acid.
- 18. The process as recited in claim 16 in which the water-immiscible organic sulfonic acid compound is dissolved in a water-immiscible organic solvent selected from the group consisting of kerosene, mineral spirits, benzene, naphtha, xylene, toluene, nitrobenzene, methylene chloride, isooctane and heptane at a concentration of the water-immiscible organic sulfonic acid compound dissolved in the water-immiscible organic solvent of from about 0.1 molar to about 1.0 molar.
- 19. The process as recited in claim 18 in which from about 0.1% up to about 20% by weight of a phase separator adjunct compound is dissolved in the solution of the water-immiscible organic sulfonic acid compound in a water-immiscible solvent.
- 20. The process as recited in claim 19 in which the phase separator adjunct compound is selected from water-immiscible aliphatic alcohols.
- 21. The process as recited in claim 20 in which the phase separator adjunct compound comprises isodecanol.
- 22. The process as recited in claim 1 in which the volumetric ratio of the water-immiscible organic phase to the phosphate pebble acid is from about 2 to 1 up to about 12 to 1.
- 23. The process as recited in claim 1 in which the volumetric ratio of the water-immiscible organic phase to the phosphate pebble acid is from about 4 to 1 up to about 8 to 1.
- 24. The process as recited in claim 1 in which the water-immiscible organic sulfonic acid compound is selected from the group consisting of dinonylnaphthalenesulfonic acid, 5-dodecanoyl-2-chlorobenzenesulfonic acid, 5-nonyl-2-ethoxybenzenesulfonic acid, 3,5-di-t-octyl-2-(alphacarboxymethoxy)benzenesulfonic acid, and 3,5-di-t-octyl-2-hydroxybenzenesulfonic acid.
- 25. The process of claim 1 wherein said phosphate pebble rock has a bone phosphate of lime value in the range of about 68 to about 38 and analyzes in the range of about 17.8-31.2% P.sub.2 O.sub.5.
- 26. The process of claim 25 wherein said bone phosphate of lime value is no greater than about 58.
- 27. A process for the production of high purity phosphoric acid from phosphate-bearing, high alumina pebble having a bone phosphate of lime value less than about 68 and containing metal impurities comprising calcium, magnesium, aluminum, ferric iron and ferrous iron, said process comprising:
- (a) contacting the pebble with dilute aqueous phosphoric acid at a temperature of from about 140.degree. F. to about 170.degree. F. to form a reaction mass containing extracted phosphate values from the pebble in the form of dissolved calcium monophosphate;
- (b) contacting the reaction mass with sulfuric acid at a temperature of from about 140.degree. F. to about 170.degree. F. to convert the calcium monophosphate to solid gypsum and phosphoric acid and to form dilute crude phosphoric acid containing solid pebble gangue and at least one of said ionic metal impurities comprising calcium, magnesium, aluminum, ferric iron and ferrous iron;
- (c) separating the dilute, crude phosphoric acid containing the ionic metal impurities from the pebble gangue;
- (d) contacting the dilute, crude phosphoric acid with at least one water-immiscible liquid organic sulfonic acid compound selected from alkyl sulfonic acids, alkylaryl sulfonic acids and polyalkylaryl sulfonic acids and mixtures thereof, said sulfonic acids having at least 12 carbon atoms, said members of the group consisting of alkoxy, alkanonyl, halo, hydroxy, and nitro groups; to extract ionic metal impurities and form:
- (i) an organic phase containing the liquid organic sulfonic acid compound and extracted ionic metal impurities;
- (ii) an aqueous phase containing purified dilute aqueous phosphoric acid;
- (e) separating the aqueous phase containing the purified dilute aqueous phosphoric acid from the water-immisible organic phase;
- (f) regenerating the liquid organic sulfonic compound by contact with a mineral acid for recycle; and
- (g) concentrating the purified dilute phosphoric acid.
- 28. The process of claim 27 in which the phosphate pebble rock having a mesh size greater than about 14 is comminuted to a suitable size range prior to contacting with phosphoric acid.
- 29. The process of claim 28 in which the phosphate pebble rock is comminuted to -60 mesh prior to contacting with phosphoric acid.
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part of my pending U.S. application Ser. No. 676,559 filed Apr. 13, 1976 (now abandoned) which is a continuation-in-part of my pending U.S. application Ser. No. 583,687 filed on June 4, 1975 (now abandoned) which is a continuation application of my U.S. application Ser. No. 301,085 filed on Oct. 26, 1972 (now abandoned) which is a continuation-in-part of my U.S. application Ser. No. 204,670 filed on Dec. 3, 1971 (now abandoned).
US Referenced Citations (5)
Foreign Referenced Citations (1)
Number |
Date |
Country |
39-1201 |
Feb 1964 |
JPX |
Non-Patent Literature Citations (1)
Entry |
van Dalen et al., "Proceedings of the International Solvent Extraction Conference", The Hague, 1971, vol. II, pp. 1096-1100. |
Continuations (1)
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Number |
Date |
Country |
Parent |
301085 |
Oct 1972 |
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Continuation in Parts (3)
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Number |
Date |
Country |
Parent |
676559 |
Apr 1976 |
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Parent |
583687 |
Jun 1975 |
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Parent |
204670 |
Dec 1971 |
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