Methods and systems for recovering rare earth elements

Patent metadata

Field	Value
Publication number	US-9376735-B2
Application number	US-201414211120-A
Country	US
Kind code	B2
Filing date	Mar 14, 2014
Priority date	Mar 15, 2013
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

Methods and systems for recovering or extracting rare earth elements under mild conditions include subjecting a material including rare earth element to a rare earth element crystallization medium under solvothermal conditions sufficient to form rare earth element crystals capable of gravity separation and purification.

First claim

We claim:

1. A composition comprising:
a material including rare earth elements, a rare earth element crystallization medium, and rare earth metal crystals,
where the rare earth metal crystals comprise rare earth metal formates or rare earth metal oxides and where the crystallization medium comprises 80 vol. % to 100 vol. % of at least one amide, 0 vol. % to 10 vol. % of at least one organic acid, and 0 vol. % to 10 vol. % water.

2. The composition of claim 1 , wherein the at least one amide is selected from the group consisting of formamide, an N-carbylformamide, an N,N-dicarbylformamide, and mixtures or combinations thereof, where the carbyl group are the same or different and are selected from the group consisting of linear or branched alkyl groups having between 1 and 6 carbon atoms, aryl groups, araalkyl groups, alkaaryl group, or mixture thereof and wherein the at least one organic acid is selected from the group consisting of formic acid, acetic acid, propanoic acid and mixtures or combinations thereof.

3. The composition of claim 1 , wherein the crystallization medium comprises formamide, formic acid and water.

4. The composition of claim 3 , wherein a volume ratio of the formamide to formic acid to water is 10:0.25:0.25.

5. A method for recovering rare earth elements from a material including containing rare earth elements comprising:
adding the material and a rare earth element crystallization medium into a temperature and pressure controlled vessel under solvothermal conditions sufficient to selectively crystallize the rare earth elements to form a rare earth metal crystals capable of being gravity separated,
where the crystallization medium comprises 80 vol. % to 100 vol. % of at least one amide, 0 vol. % to 10 vol. % of at least one organic acid, and 0 vol. % to 10 vol. % water.

6. The method of clam 5 , further comprising:
gravity separating the rare earth metal crystals to form a rare earth crystalline solid composition.

7. The method of clam 6 , further comprising:
purifying the rare earth metal crystalline solid composition.

8. The method of claim 7 , further comprising:
post-calcining the rare earth crystalline solid composition into purified rare earth metal oxides.

9. The method of claim 5 , further comprising:
pre-calcining the material prior to adding the material to the temperature and pressure controlled vessel.

10. The method of claim 5 , wherein the at least one amide is selected from the group consisting of formamide, an N-carbylformamide, anN,N-dicarbylformamide, and mixtures or combinations thereof, where the carbyl group are the same or different and are selected from the group consisting of linear or branched alkyl groups having between 1 and 6 carbon atoms, aryl groups, araalkyl groups, alkaaryl group, or mixture thereof and wherein the at least one organic acid is selected from the group consisting of formic acid, acetic acid, propanoic acid and mixtures or combinations thereof.

11. The method of claim 5 , wherein the crystallization medium comprises formamide, formic acid and water.

12. The method of claim 11 , wherein a volume ratio of the formamide to formic acid to water is 10:0.25:0.25.

13. A method for recovering rare earth elements from a material including containing rare earth elements comprising:
mixing the material with a rare earth element crystallization medium in a temperature and pressure controlled vessel under solvothermal conditions sufficient to selectively crystallize the rare earth elements to form rare earth metal crystals capable of being gravity separated, and
gravity separating the rare earth metal crystals to form a rare earth crystalline solid composition,
where the crystallization medium comprises 80 vol. % to 100 vol. % of at least one amide, 0 vol. % to 10 vol. % of at least one organic acid, and 0 vol. % to 10 vol. % water.

14. The method of clam 13 , further comprising:
purifying the rare earth metal crystalline solid composition.

15. The method of claim 14 , further comprising:
post-calcining the rare earth crystalline solid composition into purified rare earth metal oxides.

16. The method of claim 13 , further comprising:
pre-calcining the material prior to adding the material to the temperature and pressure controlled vessel.

17. The method of claim 13 , wherein the at least one amide is selected from the group consisting of formamide, an N-carbylformamide, an N,N-dicarbylformamide, and mixtures or combinations thereof, where the carbyl group are the same or different and are selected from the group consisting of linear or branched alkyl groups having between 1and 6 carbon atoms, aryl groups, araalkyl groups, alkaaryl group, or mixture thereof and wherein the at least one organic acid is selected from the group consisting of formic acid, acetic acid, propanoic acid and mixtures or combinations thereof.

18. The method of claim 13 , wherein the crystallization medium comprises formamide, formic acid and water.

19. The method of claim 18 , wherein a volume ratio of the formamide to formic acid to water is 10:0.25:0.25.

20. A process for recovering rare earth elements from cathode ray tube (CRT) phosphors comprising:
obtaining CRT monitors,
removing phosphor material from CRT lenses to form a powered phosphor material,
calcining the powered phosphor material to form a calcined phosphor material,
reacting the calcined phosphor material with a rare earth element crystallization medium,
solid/liquid separating in a solid/liquid separator to form a solid material,
separating the solid material in a solid/solid density separator using a density separation medium, and
separating the solid material into a residual solid material and a rare earth element containing solid material,
where the crystallization medium comprises 80 vol. % to 100 vol. % of at least one amide, 0 vol. % to 10 vol. % of at least one organic acid, and 0 vol. % to 10 vol. % water.

21. The method of claim 19 , further comprising:
separating the density separation medium into its constituents for reuse.

22. The process of claim 20 , wherein the crystallization medium comprises formamide, formic acid and water.

23. The process of claim 22 , wherein a volume ratio of the formamide to formic acid to water is 10:0.25:0.25.

24. A process for recovering rare earth elements from a mercury free waste phosphor material comprising:
obtaining a mercury free waste phosphor material,
separating the mercury free waste phosphor material in a solid/solid density separator using a density separation medium into a rare earth element rich, mercury free waste phosphor material,
calcining the rare earth element rich, mercury free waste phosphor material to form a calcined rare earth element rich, mercury free waste phosphor material,
reacting the calcined rare earth element rich, mercury free waste phosphor material with a rare earth element crystallization medium to form rare earth element crystals,
solid/liquid separating in a solid/liquid separator to form a solid material, and
separating the solid material in a solid/solid density separator using a density separation medium to form a rare earth element containing solid material,
where the crystallization medium comprises 80 vol. % to 100 vol. % of at least one amide, 0 vol. % to 10 vol. % of at least one organic acid, and 0 vol. % to 10 vol. % water.

25. The process of claim 24 , further comprising:
separating the

Assignees

• Univ Houston System
• Univ Houston System

Inventors

• Jacobson Allan J
• Samarasekere Pradeep

Classifications

• C01F17/206

  oxide or hydroxide being the only anion · CPC title

• C22B3/1658

  Leaching with acyclic or carbocyclic agents of different types in admixture, e.g. with organic acids added to oximes · CPC title

• C22B59/00 Primary

  Obtaining rare earth metals · CPC title

• C22B3/02

  Apparatus therefor · CPC title

• C22B7/007

  by acid leaching · CPC title