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1. WO2011095978 - A METHOD FOR THE SEPARATION OF A NON-VOLATILE STRONG ACID FROM A SALT THEREOF AND COMPOSITIONS PRODUCED THEREBY

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[ EN ]

WHAT IS CLAIMED IS:

1. An organic phase composition comprising

(a) a first solvent (S1 ) characterized by water solubility of less than 10% and by at least one of (a1 ) having a polarity related component of Hoy's cohesion parameter (delta-P) between 5 and 10 MPa 2 and (b1 ) having a Hydrogen bonding related component of Hoy's cohesion parameter (delta-H) between 5 and 20 MPa1/2;

(b) a second solvent (S2) characterized by a water solubility of at least 30% and by at least one of (a2) having delta-P greater than 8 MPa1 2 and (b2) having delta-H greater than 12 MPa1/2;

(c) water

(d) a non-volatile strong acid, and

(e) a salt thereof.

2. The composition according to Claim 1 , wherein S2 is selected from the group consisting of C1 -C4 mono- or poly-alcohols, aldehydes and ketones.

3. The composition according to Claim 1 , wherein S1 is selected from the group consisting of alcohols, ketones and aldehydes having at least 5 carbon atoms.

4. The composition according to Claim 1 , wherein said non-volatile strong acid is selected from the group consisting of sulfuric acid, phosphoric acid and nitric acid.

5. The composition according to Claim 1 , wherein said salt is selected from the group consisting of salts of calcium and of heavy metals.

6. The composition according to Claim 1 , wherein the weight/weight ratio of S1/S2 is in the range between 10 and 0.5.

7. The composition according to Claim 1 , wherein the weight/weight ratio of acid/water is greater than 0.15.

8. The composition according to Claim 1 , wherein the weight/weight ratio of acid/salt is greater than 10.

9. The composition according to Claim 1 , wherein salt concentration is in a range between 0.01 %wt and 5%wt.

10. The composition according to Claim 1 , wherein S1 forms a heterogeneous azeotrope with water, wherein S2 forms a homogeneous azeotrope with water, or both.

1 1 . A method for the separation of a non-volatile strong acid from a salt thereof comprising:

(i) providing an aqueous feed solution comprising a non-volatile strong acid and a salt thereof;

(ii) bringing said aqueous feed solution into contact with a first extractant comprising a first solvent S1 characterized by a water solubility of less than 10% and by at least one of (a1) having a delta-P between 5 and 10 MPa1 2 and (b1 ) having a delta-H between 5 and 20 MPa1/2, whereupon acid selectively transfers to said first extractant to form an acid-carrying first extract and an acid-depleted aqueous feed;

(iii) bringing said acid-depleted aqueous feed solution into contact with a second extractant comprising S1 and a second solvent S2 characterized by water solubility of at least 30% and by at least one of (a2) having a delta-P greater than 8 MPa1/2 and (b2) having a delta-H greater than 12 MPa1 2, whereupon acid selectively transfers to said second extractant to form an organic composition according to any of claims 1 -10 and a further acid- depleted aqueous feed; and

(iv) recovering acid from said first extract.

12. The method according to Claim 11 , wherein said aqueous feed is a product of leaching a mineral with a non-volatile strong acid.

13. The method according to Claim 12, wherein said mineral is rich in titanium.

14. The method according to Claim 12, wherein said mineral is rich in phosphate.

15. The method according to Claim 11 , wherein at least one of said bringing in contact of step (ii) and said bringing in contact of step (iii) comprises multiple stage counter-current contacting.

16. The method according to Claim 11 , wherein S2 is selected from the group consisting of C1-C4 mono- or poly-alcohols, aldehydes and ketones.

17. The method according to Claim 11 , wherein S1 is selected from the group consisting of alcohols, ketones and aldehydes having at least 5 carbon atoms

18. The method according to Claim 11 , wherein delta-P of said second extractant is greater than delta-P of said first extractant by at least 0.2 MPa1 2.

19. The method according to Claim 11 , wherein said delta-H of said second extractant is greater than delta-P of said second extractant by at least 0.2 MPa1 2.

20. The method according to Claim 11 , wherein said first extractant comprises S2 and wherein S2/S1 ratio in said second extractant is greater than S2/S1 ratio in said first extractant by at least 10%.

21. The method according to Claim 20, wherein the first extractant is generated from the organic composition formed in step (iii) by removing S2 therefrom.

22. The method according to Claim 1 1 further comprising a step of removing S2 from the organic composition formed in step (iii), whereupon said first extract is formed.

23. The method according to Claim 22, whereupon on said removing of S2 a heavy aqueous phase is formed and said heavy phase is separated from said formed first extract.

24. The method according to Claim 23, wherein the acid/water ratio in said heavy phase is smaller than that ratio in the acid-depleted aqueous feed.

25. The method according to Claim 23, wherein the acid/salt ratio in said heavy phase is smaller than that ratio in the acid-depleted aqueous feed

26. The method according to Claim 1 1 , wherein the acid/water ratio in said first extract is greater than that ratio in the organic composition of step (iii) by at least 10%.

27. The method according to Claim 1 1 , wherein the acid/water ratio in said first extract is greater than that ratio in the aqueous feed by at least 10%.

28. The method according to Claim 1 1 , wherein the acid/salt ratio in said first extract is greater than that ratio in the organic composition of step (iii) by at least 10%.

29. The method according to Claim 1 1 , wherein said recovering comprises at least one of acid back-extraction with water or an aqueous solution, removal of S1 , S2 or both and addition of a solvent S3, which solvent is characterized by water solubility smaller than that of S1.

30. The method according to Claim 1 1 , said non-volatile strong acid is sulfuric acid and said step of acid recovery comprises contacting said first extract with sulfur trioxide.

31 . The method according to Claim 11 , wherein the acid/salt ratio in said further depleted aqueous feed is smaller than 0.05.

32. The method according to Claim 1 1 , wherein said provided aqueous feed comprises an impurity, wherein the impurity/salt ratio in said feed is R1 , wherein the impurity/salt ratio in said further depleted aqueous feed is R2 and wherein R1/R2 is greater than 1.5.

33. The method according to Claim 32 wherein said impurity is another acid.

The method according to Claim 32 wherein said impurity is another salt.