Methods of recovering an elemental rare earth metal, and methods of forming a rare earth metal

Patent metadata

Field	Value
Publication number	US-11788171-B2
Application number	US-202117249283-A
Country	US
Kind code	B2
Filing date	Feb 25, 2021
Priority date	Mar 19, 2020
Publication date	Oct 17, 2023
Grant date	Oct 17, 2023

Abstract

A method of recovering an elemental rare earth metal comprises placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprising an ionic liquid or a eutectic mixture, reducing the rare earth metal with the reducing agent to form a metallic rare earth metal and cations of the reducing agent, transferring the cations of the reducing agent from the reaction solution to an electrochemical cell through an ion exchange membrane, and reducing the cations of the reducing agent in the electrochemical cell. Related methods of forming an elemental rare earth metal, and related systems are disclosed.

First claim

What is claimed is:

1. A method of recovering an elemental rare earth metal, the method comprising:
placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprising an ionic liquid;
reducing the rare earth metal with the reducing agent to form a metallic rare earth metal and cations of the reducing agent;
transferring the cations of the reducing agent from the reaction solution to an electrochemical cell through an ion exchange membrane; and
reducing the cations of the reducing agent in the electrochemical cell.

2. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprises placing a rare earth-containing material in the reaction solution having a temperature less than about 300° C.

3. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprising an ionic liquid comprises placing a rare earth-containing material in the reaction solution having temperature less than about 100° C.

4. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprising an ionic liquid comprises placing a rare earth-containing material in a reaction solution comprising an ionic liquid comprising a eutectic mixture at a temperature greater than about 100° C.

5. The method of claim 1 , further comprising adding, to the reaction solution, a compound formulated to facilitate transfer of electrons between the reducing agent and the rare earth-containing material.

6. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprises placing, in the reaction solution, a rare earth-containing material comprising a rare earth metal-ligand complex selected from the group consisting of one or more of beta-diketones, carboxylic acids, tertiary amines, thiocarbomates, and organophosphates.

7. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprises placing, in the reaction solution, a rare earth-containing material comprising one or more of a rare earth fluoride, a rare earth chloride, a rare earth nitrate, a rare earth triflate, a rare earth carbonate, and a rare earth bistriflimide.

8. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing the rare earth-containing material in the reaction solution comprising a reducing agent comprising a Group IA element or a Group IIA element.

9. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing the rare earth-containing material in the reaction solution comprising a reducing agent comprising one of lithium, sodium, potassium, calcium, magnesium, or lanthanum.

10. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing the rare earth-containing material in the reaction solution comprising an ionic liquid comprising one or more pyrrolidiniums selected from the group consisting of N-ethyl-N-methylpyrrolidinium, N-methyl-N-propylpyrrolidinium, N-methyl-N-isopropylpyrrolidinium, N-butyl-N-methylpyrrolidinium, N-isobutyl-N-methylpyrrolidinium, N-secbutyl-N-methylpyrrolidinium, N-methyl-N-pentylpyrrolidinium, N-hexyl-N-methylpyrrolidinium, N-heptyl-N-methylpyrrolidinium, N-methyl-N-octylpyrrolidinium, and 1-n-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide.

11. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing the rare earth-containing material in the reaction solution comprising an ionic liquid comprising one or more of a piperidinium, a tetra alkyl ammonium, bis(trifluoromethanesulfonyl)imide, trifluoromethanesulfonate, dicyanimide, methyltributylammonium bis(trifluoromethylsulfonyl)imide, imidazolium chlorides (e.g., 1-ethyl-3-methylimidazolium chloride), tricaprylmethylammonium thiocyanate, and n-butylpyridinium chloride.

12. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing the rare earth-containing material in the reaction solution comprising an ionic liquid comprising one or more phosphoniums selected from the group consisting of trihexyl(tetradecyl)phosphonium, tetradecyl(trioctyl)phosphonium, triethyl-pentyl-phosphonium, triethyl-octyl-phosphonium, triethyl-dodecyl-phosphonium, trihexyl(tetradecyl)phosphonium dicyanamide, trihexyl(tetradecyl)phosphinium bis(trifluoromethylsulfonyl) amide, trihexyl(tetradecyl)phosphinium bis(2,4,4-trimethylpentyl phosphinate), trihexyl(tetradecyl)phosphinium bromide, trihexyl(tetradecyl)phosphinium chloride, and trihexyl(tetradecyl)phosphinium decanoate.

13. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing the rare earth-containing material in the reaction solution comprising a eutectic mixture selected from the group consisting of one or more of mixtures of choline bromide and xylitol, mixtures of choline and urea, and mixtures of choline chloride and lactic acid.

14. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprising a reducing agent and a non-aqueous solvent comprises placing a rare earth-containing material comprising a rare earth oxide or a rare earth salt in the reaction solution.

15. The method of claim 1 , wherein reducing the cations of the reducing agent in the electrochemical cell comprises reducing lithium in the electrochemical cell.

16. The method of claim 1 , further comprising recycling, to the reaction solution, the reduced cations of the reducing agent.

17. The method of claim 1 , wherein placing a rare earth-containing material comprising a rare earth metal in a reaction solution comprises placing the rare earth-containing material in a hydrophobic reaction solution.

18. The method of claim 1 , further comprising adding a viscosity-reducing material to the reaction solution.

19. A method of forming an elemental rare earth metal, the method comprising:
reducing a rare earth metal of a rare earth-containing material in a reaction chamber comprising a reaction solution including the rare earth-containing material, a reducing agent, and a non-aqueous solvent comprising an ionic liquid to form an elemental rare earth metal and cations of the reducing agent; and
reducing the cations of the reducing agent to regenerate the reducing agent in an electrochemical cell isolated from the rare earth-containing material.

20. The method of claim 19 , further comprising passing the cations of the reducing agent through a cation exchange membrane configured to selectively p

Assignees

• Battelle Energy Alliance Llc

Inventors

• Case Mary E
• Fox Robert V
• Baek Donna L

Classifications

• C22B59/00 Primary

  Obtaining rare earth metals · CPC title

• C01F17/10

  Preparation or treatment, e.g. separation or purification · CPC title

• C25C1/22

  of metals not provided for in groups C25C1/02 - C25C1/20 · CPC title

• C25C3/00

  Electrolytic production, recovery or refining of metals by electrolysis of melts (C25C5/00 takes precedence) · CPC title

• C25C3/34

  of metals not provided for in groups C25C3/02 - C25C3/32 · CPC title