Method for recovering rare earth elements and other products from ash

Patent metadata

Field	Value
Publication number	US-2025171879-A1
Application number	US-202318836636-A
Country	US
Kind code	A1
Filing date	Feb 6, 2023
Priority date	Feb 7, 2022
Publication date	May 29, 2025
Grant date	—

Abstract

Disclosed herein are systems and methods relating to simultaneous waste processing and recovery of rare earth elements from a waste ash source. In some examples, the method includes contacting a REE-containing waste ash source with a chelating agent, thereby forming a leachate comprising one or more REE and a first residual material; contacting a precipitation agent with the leachate to form a second residual material and a solid precipitate comprising an amount of the one or more REE; separating the solid precipitate from the second residual material; and hydrothermally treating (e.g., using recycled heat or new heat) the first and/or second residual materials under conditions effective to yield a processed material comprising zeolites.

First claim

What is claimed is:

1 . A method for recovering rare earth elements (REE) from a waste ash source, the method comprising:
contacting a REE-containing waste ash source with a chelating agent, thereby forming a leachate comprising one or more REE and a first residual material; contacting a precipitation agent with the leachate to form a second residual material and a solid precipitate comprising an amount of the one or more REE; separating the solid precipitate from the second residual material; and hydrothermally treating the first and/or second residual materials under conditions effective to yield a processed material comprising zeolites.

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

3 . The method of any of claims 1-2 , wherein the REE-containing waste ash source comprises coal fly ash (CFA).

4 . The method of any of claims 1-3 , wherein the REE-containing waste ash source comprises 5% or more SiO 2 by weight.

5 . The method of any of claims 1-4 , wherein the chelating agent comprises an acid or salt thereof.

6 . The method of any of claims 1-5 , wherein the chelating agent comprises citric acid or a salt thereof.

7 . The method of claim 6 , wherein the citric acid or salt thereof is contacted with the REE-containing waste ash source at a concentration of 25 mM to 150 mM.

8 . The method of any of claims 1-7 , wherein the REE-containing waste ash source is contacted with the chelating agent at a pH of 7.0 or less.

9 . The method of any of claims 1-8 , wherein the precipitation agent comprises an organic ligand.

10 . The method of any of claims 1-9 , wherein the solid precipitate comprises an REE-oxalate.

11 . The method of any of claims 1-10 , further comprising contacting the first residual material with the second residual material prior to or during hydrothermal treatment.

12 . The method of any of claims 1-11 , wherein the first and/or second residual material are contacted with an alkaline solution prior to or during hydrothermal treatment.

13 . The method of any of claims 1-12 , wherein the hydrothermal treating of the first and/or second residual material occurs at a temperature of from 50° C. to 300° C.

14 . The method of any of claims 1-13 , further comprising substantially separating the zeolites from the processed material to form a zeolite-rich product and a depleted waste material.

15 . The method of claim 14 , wherein the zeolite-rich product comprises 75% or more zeolites by weight.

16 . The method of any of claims 1-15 , further comprising substantially separating a purified REE-product from the solid precipitate.

17 . The method of claim 16 , wherein the step of substantially separating the purified REE-product comprises dissolving the solid precipitate comprising the amount of one or more REE in a solvent and recovering the purified REE-product.

18 . The method claim 17 , wherein the purified REE-product is adsorbed using functionalized magnetic mesoporous silica particles.

19 . The method of any of claims 1-18 , wherein the method is performed continuously or semi-continuously.

20 . The method of any of claims 1-18 , wherein the method is performed batchwise.

21 . A method for processing a residual waste ash material, the method comprising:
hydrothermally treating a residual waste ash material comprising a concentration of aluminosilicates under conditions effective to yield a processed waste ash material comprising zeolites, wherein the residual waste ash material was collected as a byproduct from the removal of a heavy metal from a prior process; and substantially separating the zeolites from the processed waste material, thereby forming a zeolite-rich product and a depleted waste material.

22 . A method for recovering rare earth elements (REE) from a waste ash source, the method comprising:
contacting a REE-containing waste ash source with a chelating agent, thereby forming a leachate comprising one or more REE and a first residual material; adding a precipitation agent to the leachate to form a second residual material and a solid precipitate comprising an amount of the one or more REE; separating the solid precipitate from the second residual material; and using the first and/or second residual materials to produce porous metal oxide particles.

23 . A system comprising: components to perform the method of any of claims 1-22 .

24 . A system for recovering rare earth elements from a REE-containing waste source, the system comprising:
a first reactor configured to receive the REE-containing waste ash source and a chelating agent, and wherein the first reactor is configured to produce a leachate comprising one or more REE and a first residual material; and a second reactor configured to receive the leachate and a precipitation agent, wherein the second reactor is configured to produce a second residual material and a solid precipitate comprising an amount of the one or more REE.

25 . The system of claim 24 , further comprising a third reactor configured to receive the first and/or second residual materials, wherein the third reactor operates under conditions effective to produce a processed waste material comprising zeolites.

26 . The system of any of claims 24-25 , wherein the REE-containing waste ash source comprises coal fly ash (CFA), municipal solid waste incineration (MSWI) ash, or a combination thereof.

27 . The system of any of claims 24-26 , wherein the REE-containing waste ash source comprises coal fly ash (CFA).

28 . The system of any of claims 24-27 , wherein the REE-containing waste ash source comprises 5% or more SiO 2 by weight.

29 . The system of any of claims 24-28 , wherein the chelating agent comprises an acid.

30 . The system of any of claims 24-29 , wherein the chelating agent comprises citric acid or a salt thereof.

31 . The system of claim 30 , wherein a concentration of citric acid or salt thereof in the first reactor is from 25 mM to 150 mM.

32 . The system of any of claims 24-31 , wherein the first reactor is configured to operate at a pH of 7.0 or less.

33 . The system of any of claims 24-32 , wherein the precipitation agent comprises an organic ligand.

34 . The system of any of claims 24-33 , wherein the solid precipitate comprises an REE-oxalate.

35 . The system of any of claims 25-34 , wherein the third reactor is configured to operate at a temperature of 50° C. to 300° C.

36 . The system of any of claims 24-35 , further comprising a separation unit configured to receive the solid precipitate and a solvent, wherein the separation unit produces a purified REE-product and a third residual material.

37 . The system of claim 36 , wherein the separation unit comprises an adsorption column or reactor comprising an adsorbent.

38 . The system of any of claims 36-37 , wherein the third reactor is configured to receive the first, second, and third residual materials.

39 . The system of any of claims 24-38 , wherein the system is configured to

Assignees

• Georgia Tech Res Inst

Inventors

• Tang Yuanzhi
• Liu Pan

Classifications

• C22B7/007

  by acid leaching · CPC title

• C22B3/44

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

• C22B3/24

  by adsorption on solid substances, e.g. by extraction with solid resins · CPC title

• C22B3/02

  Apparatus therefor · CPC title

• C01P2004/03

  obtained by SEM · CPC title