Method for separating zirconium and hafnium

• US 20090185965A1
• Filed: 10/07/2005
• Published: 07/23/2009
• Est. Priority Date: 10/11/2004
• Status: Abandoned Application

• Current Assignee: Compagnie Europeenne Du Zirconium Cezu (AES Corporation), Autoliv AB (Autoliv Incorporated)
• Original Assignee: Autoliv AB (Autoliv Incorporated)
• Inventors: Poriel, Ludovic, Lagarde, Stéphane, Pellet-Rostaing, Stéphane, Favre-Reguillon, Alain, Lemaire, Marc, Delons, Laurence
• Application Number:
  US11/665,526
• Publication Number:
  US 20090185965A1
• Time in Patent Office: Days
• US Class Current: 423/70
• CPC Class Codes: B01J 41/04 Processes using organic exchangers
• CPC Class Codes: C01G 25/003 Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange
• CPC Class Codes: C01G 25/04 Halides
• CPC Class Codes: C01G 27/003 Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange
• CPC Class Codes: C01G 27/04 Halides

Abstract

A method for separating zirconium and hafnium from a mixture of ZrCl₄ and HfCl₄ containing 3 wt. % or less of Hf based on Zr+Hf, the method includes the following steps: 1) hydrolyzing a mixture of ZrCl₄ and HfCl₄ in an aqueous solution of strong inorganic acid, so as to form an aqueous solution having 7 to 12 moles of acid per liter; 2) passing the solution obtained at step 1) in an anion exchanging resin; 3) optionally eluting a fraction of said aqueous solution having 7 to 12 moles of acid per liter, enriched in hafnium; 4) removing the resin of the acid solution containing Zr and Hf; 5) passing in the resin an aqueous solution to detach the zirconium compounds fixed to the resin, and recovering a zirconium-enriched fraction.

Claims

1. Method for separating zirconium from hafnium in a mixture of ZrCl₄ and HfCl₄ containing 3% Hf by weight, expressed with respect to Zr+Hf, or less, the method comprising the following steps:

(1) hydrolysing the mixture of ZrCl₄ and HfCl₄ in an aqueous solution of a strong inorganic acid, to form an aqueous acid solution having 7 to 12 moles of acid per liter;

(2) passing the solution obtained in step (1) through an anion exchange resin;

(3) optionally, eluting a hafnium-enriched fraction of the solution obtained in step (1);

(4) removing an aqueous acid solution containing Zr and Hf from the resin;

then

(5) passing an aqueous solution through the resin in order to release the zirconium compounds fixed to the resin, and recovering a zirconium-enriched fraction.

2. Method according to claim 1, wherein in step (2), the resin is conditioned in advance with a strong inorganic acid solution having from 7 to 12 moles of acid per liter.

3. Method according to claim 1, wherein the strong inorganic acid is selected from the group consisting of HCl and H₂SO₄.

4. Method according to claim 3, wherein the strong inorganic acid is HCl.

5. Method according to claim 1, wherein the aqueous acid solution has from 7.5 to 9.5 moles of acid per liter.

6. Method according to claim 1, wherein the anion exchange resin includes amine, ammonium or azine groups.

7. Method according to claim 1, wherein in step (5), the aqueous solution contains from 0 to 7 moles of acid per liter, and this molar concentration is less than the molar concentration of the inorganic acid solution used in step (1).

8. Method according to claim 7, wherein the aqueous solution is water.

9. Method according to claim 7, wherein step (5) further comprises passing at least one additional aqueous solution with a decreasing acid concentration through the resin in succession.

10. Method according to claim 9, wherein the last aqueous solution passed through the resin in step (5) is water.

11. Method according to claim 1, wherein in step (4), the resin is rinsed with a strong inorganic acid solution having from 7 to 12 moles of acid per liter, and having a number of moles of acid per liter substantially identical to or greater than the solution obtained in step (1).

12. Method according to claim 1, wherein, in step (4), the liquid content of the resin is removed.

13. Method according to claim 1, wherein the hafnium-enriched fraction is recovered in step (3).

14. Method according to claim 2, wherein the strong inorganic acid is selected from the group consisting of HCl and H₂SO₄.

15. Method according to claim 14, wherein the aqueous acid solution has from 7.5 to 9.5 moles of acid per liter.

16. Method according to claim 14, wherein the anion exchange resin includes amine, ammonium or azine groups.

17. Method according to claim 14, wherein in step (5), the aqueous solution contains from 0 to 7 moles of acid per liter, and this molar concentration is less than the molar concentration of the inorganic acid solution used in step (1).

18. Method according to claim 14, wherein in step (4), the resin is rinsed with a strong inorganic acid solution having from 7 to 12 moles of acid per liter, and having a number of moles of acid per liter substantially identical to or greater than the solution obtained in step (1).

19. Method according to claim 11, wherein in step (4), the liquid content of the resin is removed.

20. Method according to claim 14, wherein the hafnium-enriched fraction is recovered in step (3).