Methods for extracting rare earth elements from ion-adsorption clays

Patent metadata

Field	Value
Publication number	US-2024417827-A1
Application number	US-202418815220-A
Country	US
Kind code	A1
Filing date	Aug 26, 2024
Priority date	Feb 27, 2022
Publication date	Dec 19, 2024
Grant date	—

Abstract

Methods of extracting rare earth elements (REEs) from low-grade REE sources composed of clayey materials. In one aspect, the REE sources are the waste materials generated in the coal and kaolin clay industries during the courses of upgrading mined coal and kaolinite. The methods described herein include the steps of pre-concentrating REE-bearing minerals using physical separation methods to prepare high-grade feedstocks for the chemical extraction of high-value REEs and critical materials while minimizing both the capital and operating costs.

First claim

1 . A method of extracting one or more rare earth elements (REEs) from a clayey REE source comprising the steps of
subjecting the REE source to high-shear agitation in the presence of a polyelectrolyte to liberate REE-bearing minerals from the REE source; a) separating the liberated REE-bearing minerals by a physical separation method to obtain a preconcentrate enriched with REEs; and b) extracting REEs from the preconcentrate by a chemical extraction method.

2 . The method of claim 1 , wherein the clayey REE source comprises detrital kaolin clays deposited on a coastal plane.

3 . The method of claim 2 , wherein the clayey REE source further comprises a secondary rare earth mineral, residual primary rare earth minerals, or a combination thereof.

4 . The method of claim 1 , wherein the clayey REE source is present in a coal byproduct.

5 . The method of claim 1 , wherein the physical separation method comprises flotation, hydrophobic-hydrophilic separation (HHS), or a combination thereof.

6 . The method of claim 5 , wherein the physical separation method recovers particles less than 30 microns in diameter.

7 . The method of claim 5 , wherein the flotation and HHS processes comprise rendering the REE-bearing minerals hydrophobic using one or more hydrophobizing agents.

8 . The method of claim 7 , wherein the hydrophobizing agent is selected from alkyl and/or aryl hydroxamates and hydroxamic acids, cationic surfactant, anionic surfactant, fatty acids, non-ionic surfactant, or any combination thereof.

9 . The method of claim 1 , wherein the chemical extraction method comprises the steps of
a) admixing a preconcentrate with a base at a temperature less than or equal to 100° C. to displace the phosphate ions and produce REE oxides and hydroxides, and b) leaching the REE oxides and hydroxides by (i) acid leaching, or (ii) by ion exchange leaching comprising ammonium sulfate or other lixiviants.

10 . The method of claim 9 , wherein the base comprises sodium hydroxide, potassium hydroxide, sodium carbonate, lime, or any combination thereof.

11 . The method of claim 9 , wherein the base is used at concentrations of 1% to about 80% by volume.

12 . The method of claim 9 , wherein the acid leaching is conducted at concentrations in the range of 0.1 M to 5 M.

13 . The method of claim 9 , wherein ammonium sulfate is used in combination with a chelating agent, a complex agent, or a combination thereof.

14 . The method of claim 13 , wherein the chelating agent is selected from organic acid, diamine, polyamine, hydroxamic acid, polyol, dicarboxylic acid, and mixtures thereof.

15 . The method of claim 14 , wherein the dicarboxylic acid is selected from maleic acid, succinic acid, glutamic acid, or any combination thereof.

16 . The method of claim 13 , wherein the chelating agent is ethylenediamine-tetracetate (EDTA).

17 . The method of claim 13 , wherein the complexing agent is selected from a sulfate, a formate, carboxylic acid, and any combination thereof.

18 . The method of claim 1 , wherein a chelating agent is used in combination with a base in step (a).

19 . A method of extracting one or more rare earth elements (REEs) from a clayey REE source, comprising the steps of
a) subjecting the REE source to high-shear agitation in the presence of a polyelectrolyte to liberate REE-bearing minerals from the REE source; b) separating the liberated REE-bearing minerals by a physical separation method to obtain a preconcentrate enriched with REEs; and c) treating the preconcentrate with a phosphate solubilizing microorganism.

20 . The method of claim 19 , wherein the phosphate solubilizing microorganism is selected from bacteria comprising Atrophaeus, Paenibacillus macerans, Vibrio proteolyticus, Xanthobacter agilis, Pantoea aananatis, P. putida, Brevibacillus agri, B. subtilis , or Bacillus megaterium.

21 . The method of claim 19 , wherein the phosphate solubilizing microorganism is selected from fungi comprising Aspergillus niger or Aspergillus terreus.

22 . A method of extracting one or more rare earth elements (REEs) from a clayey REE source, comprising the steps of:
a) subjecting the REE source to a physical separation process to obtain an enriched preconcentrate; b) contacting the preconcentrate with concentrated sulfuric acid at a temperature above 150° C. to produce an acid-treated concentrate; and c) contacting the acid-treated preconcentrate with water to extract both light and heavy rare earth elements into water to produce a leach liquor enriched with both light and heavy rare earth elements.

23 . The method of claim 22 , wherein the clayey REE source comprises anatase, wherein titanium ions and REE ions present in the leach liquor are separated from the leach liquor comprising the following steps:
a) adding a base to the leach liquor until the pH is raised to less than 5, wherein a precipitate comprising titanium dioxide is formed and a solution; and b) separating the solution from the precipitate, wherein the solution is enriched with rare earth elements.

24 . A method of extracting one or more rare earth elements (REEs) from a clayey REE source, comprising the steps of:
a) subjecting the REE source to high-shear agitation in the presence of a polyelectrolyte to liberate REE-bearing minerals from the REE source; b) separating the liberated REE-bearing minerals by a physical separation method to obtain a preconcentrate enriched with REEs; c) admixing a preconcentrate with a base at a temperature less than or equal to 100° C. to displace the phosphate ions and produce a first composition comprising REE oxides and hydroxides; d) leaching the first composition by (i) acid leaching or (ii) by ion exchange leaching to produce a first leach liquor enriched with light rare earth elements and a leach residue; e) contacting the leach residue with concentrated sulfuric acid at a temperature above 150° C. to produce an acid-treated product; f) contacting the acid-treated product with water to obtain a second leach liquor comprising heavy rare earth elements and titanium ions; and g) precipitating titanium dioxide by raising the pH to less than 5, leaving the second leach liquid enriched with heavy rare earth elements.

Assignees

• Virginia Tech Intellectual Properties Inc

Inventors

• Noble Christopher Aaron
• Yoon Roe-Hoan

Classifications

• C22B3/18

  with the aid of microorganisms or enzymes, e.g. bacteria or algae · CPC title

• C22B3/14

  containing ammonia or ammonium salts · CPC title

• C22B1/11

  Removing sulfur, phosphorus or arsenic other than by roasting · CPC title

• B03D2203/06

  Phosphate ores · CPC title

• B03D2201/02

  Collectors · CPC title