The United States of America as Represented by the Department of Energy

Thomas J Tarka

Jonathan Yang

Christina L Lopano

Mark L McKoy

Scott Montross

Circe Verba

Mengling Stuckman

The invention provides a method for extracting REEs from ash having the steps of contacting ash with a first acid solution to generate leachate having a pH between approximately 5.0 and approximately 5.5; contacting the ash with a second acid solution to generate leachate having a pH between approximately 2.8 and approximately 3.5; and contacting the ash with a third acid solution to generate leachate having a pH between approximately −0.6 and approximately 0.5. The invention also provides a method for leaching REEs from ash having the steps of: contacting ash with a first amount of acid sufficient to leach Ca and AJ from the ash without leaching REEs; contacting the ash with a second amount of acid sufficient to leach REEs from the ash without leaching Fe and Sc; and contacting ash with a third amount of acid sufficient to leach Fe and Sc from the ash.

Step-leaching process of rare earth elements from ash materials using mild inorganic acids at ambient conditions

One or more embodiments relates to a process for extracting Rare Earth Elements (REEs) from REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal. In at least one embodiment the process includes contacting the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal with an Organic Acid Solution (OAS) comprising at least one organic acid and at least one ionic salt at a predetermined ambient temperature and predetermined pH; and separating the REE from the REE-bearing underclays, claystones, shales, coal-mining waste, and waste coal, forming REE+Yttrium (REY) concentrate.

Organic acid solution having at least one ionic salt and at least one organic acid which is used for rare earth extraction

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Pittsburgh, PA, United States of America

Thomas J Tarka