US 12,221,672 B2
Step-leaching process of rare earth elements from ash materials using mild inorganic acids at ambient conditions
Mengling Stuckman, Bethel Park, PA (US); Christina L. Lopano, Bethel Park, PA (US); and Thomas Tarka, Pittsburgh, PA (US)
Assigned to United States Department of Energy, Washington, DC (US)
Filed by United States Department of Energy, Washington, DC (US)
Filed on Jul. 15, 2021, as Appl. No. 17/376,715.
Claims priority of provisional application 63/053,925, filed on Jul. 20, 2020.
Prior Publication US 2022/0017992 A1, Jan. 20, 2022
Int. Cl. C22B 59/00 (2006.01); C22B 7/00 (2006.01)
CPC C22B 59/00 (2013.01) [C22B 7/007 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method for leaching REEs from ash material comprising:
contacting an ash material containing REEs with a first acid solution to generate a first leachate having a pH between approximately 5.0 and approximately 5.5, wherein the first leachate comprises calcium but not REEs;
contacting the ash material with a second acid solution to generate a second leachate having a second pH between approximately 2.8 and approximately 3.5,wherein the second leachate comprises at least 80% of the REEs originally contained in the ash material; and
contacting the ash material with a third acid solution to generate a third leachate having a third pH between approximately −0.6 and approximately 0.5.