Patent US10669610

Rare earth element extraction from coal
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US10669610

1. A method comprising: (10) (2)

contacting a coal feedstock with an acidic solution to form a residual coal and a leachate; and

separating the residual coal from the leachate, wherein the leachate contains rare earth elements, and wherein the residual coal has preserved organic content and reduced inorganic content such that an ash content of the residual coal will be reduced during combustion.

2. The method of claim 1, further comprising: (0) (1)

3. The method of claim 1, wherein the acidic solution comprises an acid selected from the group consisting of HCl, H₃PO₄, H₂SO₄, HNO₃, H₂CO₃, carboxylic acids, halogen oxoacids and combinations thereof. (0)

4. The method of claim 1, wherein the acidic solution comprises an acid at a molarity between 0.1M and 5M. (0)

5. The method of claim 1, further comprising: (2) (1)

contacting the coal feedstock with ammonium acetate or other ion exchange solution prior to contacting the coal feedstock with the acidic solution.

6. The method of claim 5, further comprising: (0) (1)

17. The method of claim 5, wherein the ammonium acetate removes a portion of alkali, alkaline earth, and transition metal elements from the coal feedstock to form an ammonium acetate leachate, and further comprising separating the ammonium acetate leachate from the coal feedstock. (0)

7. The method of claim 1, wherein the coal feedstock is contacted with the acidic solution for a period of time between about 1 hour and about 60 hours at a temperature between about 20° C. and about 70° C. (1) (0)

9. The method of claim 1, wherein the coal feedstock is selected from the group consisting of brown coal, lignite, leonardite, sub-bituminous coal and combinations thereof. (1) (0)

11. The method of claim 1, further comprising: (1) (1)

12. The method of claim 1, further comprising: (1) (2)

14. The method of claim 1, wherein the coal feedstock is contacted with the acidic solution at a ratio between about 0.5:1 and about 1:4 by weight. (1) (0)

18. The method of claim 1, wherein the coal feedstock is contacted with the acidic solution for a period of time that is less than 1 hour at a temperature between about 20° C. and about 70° C. (0)

19. A method comprising: (1) (3)

contacting a coal feedstock with ammonium acetate or other ion exchange solution;

contacting the coal feedstock with an acidic solution to form a residual coal and a leachate; and

20. The method of claim 19, wherein the ammonium acetate removes a portion of alkali, alkaline earth, and transition metal elements from the coal feedstock to form an ammonium acetate leachate, and further comprising separating the ammonium acetate leachate from the coal feedstock. (0)

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Patent US10669610

Rare earth element extraction from coal

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