Intensified sequential recovery of rare earth elements and other critical metals from waste

Patent metadata

Field	Value
Publication number	US-2025340967-A1
Application number	US-202519198361-A
Country	US
Kind code	A1
Filing date	May 5, 2025
Priority date	May 3, 2024
Publication date	Nov 6, 2025
Grant date	—

Abstract

Disclosed herein are systems and methods for enhancing metal recovery and/or processing from a waste source.

First claim

What is claimed:

1 . A method for enhancing metal recovery and/or processing from a waste source, the method comprising:
receiving a pre-concentrated feedstock, wherein the pre-concentrated feedstock comprises a leachate of a waste material contacted with a chelating agent that has be subjected to a eutectic freeze crystallization (EFC) process; and selectively removing one or more target metals from the pre-concentrated feedstock by contacting the pre-concentrated feedstock with a precipitation agent to form a solid precipitate comprising at least one of the one or more target metal, and separating the solid precipitate from the pre-concentrated feedstock.

2 . The method of claim 1 , wherein the waste source comprises coal fly ash (CFA), municipal solid waste incineration ash (MSWIA), industrial solid waste incineration ash, or a combination thereof.

3 . The method of claim 1 , wherein selectively recovering the one or more target metals from the pre-concentrated feedstock comprises a sulfide precipitation, an alkaline precipitation, and/or an oxalate precipitation.

4 . The method of claim 1 , further comprising performing sequential precipitations using a plurality of precipitation agents to selectively remove a plurality of target metals.

5 . The method of claim 4 , further comprising:
predicting, via thermodynamic modeling, interactions between the plurality of target metals, the plurality of precipitation agents, and/or the chelating agent, to determine parameters of the sequential precipitations to optimize metal recovery.

6 . The method of claim 1 , wherein one or more target metals comprise a rare earth element (REE).

7 . The method of claim 1 , wherein a concentration factor of the one or more target metals in the pre-concentrated feedstock is 5.0 or more.

8 . The method of claim 1 , wherein an overall recovery of the one or more target metals is 75% or more.

9 . The method of claim 1 , wherein an enrichment factor of the one or more target metals compared to the waste material is 2.5 or more.

10 . The method of claim 1 , wherein the chelating agent comprises citric acid or a salt thereof.

11 . The method of claim 1 , further comprising subjecting a residual stream of the pre-concentrated feedstock following removal of the one or more target metals to a post-treatment step to process undesired metal materials.

12 . A method for enhancing metal recovery and/or processing from a waste source, the method comprising:
contacting a waste source containing a plurality of target metals with a chelating agent to form a leachate; subjecting the leachate to a eutectic freeze crystallization (EFC) process to concentrate the plurality of target metals in a concentrated feedstock; contacting the concentrated feedstock with a sulfide precipitation agent to selectively form a first precipitate comprising an insoluble metal-sulfide complex, and a residual mixture; separating the first precipitate from the residual mixture; contacting the residual mixture with an alkaline precipitation agent to selectively form a second precipitate comprising an insoluble metal-hydroxide, and a second residual mixture; separating the second precipitate from the second residual mixture; contacting the second residual mixture with an oxalate precipitation agent to selectively form a third precipitate comprising an insoluble metal-oxalate complex, and a third residual mixture; and separating the third precipitate from the third residual mixture.

13 . A system for enhancing metal recovery and/or processing from a waste source, the system comprising:
a preprocessing unit configured to receive a waste ash source and a chelating agent to thereby form a leachate comprising one or more target metals, and wherein the preprocessing unit is configured to form a concentrated filtrate via a eutectic freeze crystallization (EFC) process; and a metal separation unit configured to receive the concentrated filtrate and a precipitation agent, wherein, when contacted with the concentrated filtrate under conditions effective, the precipitation agent selectively forms a solid precipitate comprising an amount of the one or more target metals.

14 . The system of claim 13 , wherein the metal separation unit comprises:
a first precipitation unit configured to receive the concentrated filtrate and a first precipitation agent and to selectively form a first precipitate comprising an insoluble metal-sulfide complex, and a residual mixture, and to separate the first precipitate from the residual mixture; a second precipitation unit configured to receive the residual mixture and an alkaline precipitation agent to selectively form a second precipitate comprising an insoluble metal-hydroxide, and a second residual mixture, and to separate the second precipitate from the second residual mixture; and a third precipitation unit configured to receive the second residual mixture and an oxalate precipitation agent to selectively form a third precipitate comprising an insoluble metal-oxalate complex, and a third residual mixture; and to separate the third precipitate from the third residual mixture.

15 . The system of claim 13 , wherein the chelating agent comprises citric acid or a salt thereof.

16 . The system of claim 13 , wherein the waste source comprises coal fly ash (CFA), municipal solid waste incineration ash (MSWIA), industrial solid waste incineration ash, or a combination thereof.

17 . The system of claim 13 , wherein the one or more target metals comprises a rare earth element (REE).

18 . The system of claim 13 , wherein a concentration factor of the plurality of target metals in the concentrated feedstock is 5.0 or more.

19 . The system of claim 13 , wherein an overall recovery of the one or more target metals is 75% or more.

20 . The system of claim 13 , wherein an enrichment factor of the one or more target metals compared to the waste source is 2.5 or more.

Assignees

• Georgia Tech Res Inst

Inventors

• Tang Yuanzhi
• Wen Yinghao

Classifications

• C22B3/44

  by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) · CPC title

• C22B7/02

  Working-up flue dust · CPC title

• C22B3/46 Primary

  by substitution, e.g. by cementation · CPC title

• C22B3/22

  by physical processes, e.g. by filtration, by magnetic means {, or by thermal decomposition} (treatment or purification of solutions by liquid-liquid extraction C22B3/26) · CPC title

• C22B59/00

  Obtaining rare earth metals · CPC title