Rare earth enrichment process by contacting raw material with a base at specific pH values

Patent metadata

Field	Value
Publication number	US-11827954-B2
Application number	US-202217876332-A
Country	US
Kind code	B2
Filing date	Jul 28, 2022
Priority date	Jul 17, 2019
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

Disclosed herein are methods for preparing a hydraulic pre-concentrate enriched in rare earth elements and critical minerals, the method comprising: (a) contacting a raw material with a first base in an amount sufficient to adjust the pH to a value from about 4.0 to about 6.0, thereby forming a mixture comprising a first aqueous phase and a first solid concentrate; (b) separating the first aqueous phase from the first solid concentrate; (c) contacting the first aqueous phase with a second base in an amount sufficient to adjust the pH to a value from about 7.0 to about 9.0, thereby forming a mixture comprising a second aqueous phase and the hydraulic pre-concentrate; (d) removing the second aqueous phase and collecting the hydraulic pre-concentrate; wherein the raw material comprises rare earth elements; and wherein the hydraulic pre-concentrate is enriched in rare earth elements.

First claim

What is claimed is:

1. A method for preparing a hydraulic pre-concentrate, the method comprising:
(a) contacting a raw material with a first base in an amount sufficient to adjust the pH to a value from about 4.0 to about 6.0, thereby forming a mixture comprising a first aqueous phase and a first solid concentrate;
(b) separating the first aqueous phase from the first solid concentrate, thereby forming a separated first aqueous phase;
(c) contacting the separated first aqueous phase with a second base in an amount sufficient to adjust the pH to a value from about 7.0 to about 9.0, thereby forming a mixture comprising a second aqueous phase and a hydraulic pre-concentrate;
(d) removing the second aqueous phase and collecting the hydraulic pre-concentrate;
wherein the raw material comprises rare earth elements; and
wherein the hydraulic pre-concentrate is enriched in rare earth elements and critical minerals.

2. The method of claim 1 , wherein the raw material comprises acid mine drainage associated with a coal mine, a hard rock mine, or combinations thereof.

3. The method of claim 2 , wherein the hydraulic pre-concentrate is prepared at or proximal to the coal mine, the hard rock mine, or combinations thereof.

4. The method of claim 1 , wherein the raw material comprises raw acid mine drainage (AMD), an AMD precipitate (AMDp), an enriched AMD precipitate (eAMDp), or combinations thereof.

5. The method of claim 1 , wherein the raw material has a pH less than about 4.0.

6. The method of claim 1 , wherein the first base comprises a base selected from ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, ammonium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, and a combination thereof.

7. The method of claim 6 , wherein the first base comprises calcium hydroxide.

8. The method of claim 1 , wherein the contacting the raw material with the first base is in an amount sufficient to adjust the pH to a value from about 4.0 to about 4.5.

9. The method of claim 1 , further comprising oxidation; and wherein oxidation is mechanical oxidation, electrochemical oxidation, chemical oxidation, or combinations thereof.

10. The method of claim 9 , wherein oxidation comprises adding an oxidizing agent to the raw material and the first base.

11. The method of claim 10 , wherein the oxidizing agent comprises a peroxide, ozone, a permanganate, or combinations thereof.

12. The method of claim 1 , wherein the second base comprises a base selected from ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, ammonium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, and a combination thereof.

13. The method of claim 12 , wherein the second base comprises calcium hydroxide.

14. The method of claim 1 , wherein the contacting the separated first aqueous phase with the second base is in an amount sufficient to adjust the pH to a value from about 8.0 to about 8.5.

15. The method of claim 1 , wherein the removing the second aqueous phase and collecting the hydraulic pre-concentrate carried out using a clarifier, a settlement basin, a flexible planar geotextile fabric of woven or nonwoven construction, or combinations thereof.

16. The method of claim 1 , further comprising:
(e) transferring the hydraulic pre-concentrate to a geosynthetic geobag; and
(f) conditioning the hydraulic pre-concentrate in a first conditioning tank for a period of time sufficient and a temperature suitable for the solids concentration in the geosynthetic geobag to increase from about 1.1-fold to about 15-fold compared to the solids concentration of the hydraulic pre-concentrate.

17. The method of claim 1 , further comprising:
(e) transferring the hydraulic pre-concentrate to a first conditioning tank; and
(f) conditioning the hydraulic pre-concentrate in the first conditioning tank for a period of time sufficient and a temperature suitable for the solids concentration in the lower sloped portion to increase from about 1.1-fold to about 15-fold compared to the solids concentration of the hydraulic pre-concentrate;
thereby forming in the lower portion of a conditioning tank a first conditioned hydraulic pre-concentrate.

18. The method of claim 17 , wherein the period of time sufficient and the temperature suitable for the solids concentration in the lower sloped portion to reach a first conditioned pre-hydraulic solids concentration; wherein the first conditioned pre-hydraulic solids concentration is increased from about 1.2-fold to about 10-fold compared to the solids concentration of the hydraulic pre-concentrate; wherein the period of time is from about 10 min to about 72 hours; and wherein the temperature is from about 5° C. to about 50° C.

19. The method of claim 1 , further comprising collecting the first conditioned hydraulic pre-concentrate; wherein the collecting further comprises:
(g) transferring the first condition hydraulic pre-concentrate to a second conditioning tank; and
(h) condition the first conditioned hydraulic pre-concentrate in the second conditioning tank for a period of time sufficient and at a temperature suitable for the solids concentration in the lower sloped portion to increase from about 1.1-fold to about 5-fold compared to the solids concentration of the first conditioned hydraulic pre-concentrate;
thereby forming in the lower portion of the second conditioning tank a second conditioned hydraulic pre-concentrate.

20. The method of claim 19 , wherein the period of time sufficient and the temperature suitable for the solids concentration in the lower sloped portion to increase from about 1.2-fold to about 5-fold compared to the solids concentration of the hydraulic pre-concentrate is a period of time from about 30 min to about 72 hours at a temperature from about 5° C. to about 50° C.

21. A method for preparing a pregnant leach solution, the method comprising:
transferring the first conditioned hydraulic pre-concentrate of claim 17 or the second conditioned hydraulic pre-concentrate of claim 19 to a mixing tank; and
adding a first acid to the mixing tank in an amount sufficient to adjust the pH from about 2.0 to about 4.0, thereby forming the pregnant leach solution;
wherein the first acid is mixed with the first conditioned hydraulic pre-concentrate or the second conditioned hydraulic pre-concentrate as the first acid is added.

22. The method of claim 21 , wherein the first acid is a mineral acid.

23. The method of claim 22 , wherein the mineral acid comprises a mineral acid selected from nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, sulfurous acid, and combinations thereof.

24. The method of claim 21 , further comprising adding a flocculating agent, coagulating agent, or combinations thereof to: (a) the first conditioned hydraulic pre-concentrate; and/or (b) the second conditioned hydraulic pre-concentrate.

25. The method of 21 , further comprising neutralizing the pregnant leach solution by contacting the pregnant leach solution with a third base in an amount sufficient to raise the pH of the pregnant leach solution to a pH of from about 4.5 to 5.0, thereby forming a neutralized pregnant leach solution.

26. The method of claim 1 , further comprising adding a flocculating agent, coagulating agent, or combinations thereof to:

Assignees

• West Virginia Univ Board Of Governors On Behalf Of West Virginia Univ
• Univ West Virginia

Inventors

• Ziemkiewicz Paul F
• Constant James
• Hoffman David K
• Quaranta John D

Classifications

• C22B3/065 Primary

  Nitric acids or salts thereof · CPC title

• C22B3/20

  Treatment or purification of solutions, e.g. obtained by leaching (C22B3/18 takes precedence) · CPC title

• C22B59/00

  Obtaining rare earth metals · CPC title

• Y02P10/20

  Recycling · CPC title

• C22B3/02

  Apparatus therefor · CPC title