US 12,392,014 B2
Low-cost selective precipitation circuit for recovery of rare earth elements from acid leachate of coal waste
Wencai Zhang, Lexington, KY (US); and Rick Q. Honaker, Lexington, KY (US)
Assigned to University of Kentucky Research Foundation, Lexington, KY (US)
Filed by University of Kentucky Research Foundation, Lexington, KY (US)
Filed on Sep. 9, 2021, as Appl. No. 17/470,690.
Application 17/470,690 is a continuation of application No. 16/185,120, filed on Nov. 9, 2018, granted, now 11,155,897.
Claims priority of provisional application 62/583,644, filed on Nov. 9, 2017.
Prior Publication US 2022/0064759 A1, Mar. 3, 2022
Int. Cl. C22B 59/00 (2006.01); C22B 3/22 (2006.01); C22B 3/44 (2006.01)
CPC C22B 59/00 (2013.01) [C22B 3/22 (2013.01); C22B 3/44 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for concentrating rare earth materials from a feed stock, the method comprising:
a) mixing the feed stock with an acid in a solution;
b) increasing the pH of the solution incrementally to precipitate contaminants and removing the precipitated contaminants from the solution;
c) further increasing the pH incrementally to precipitate rare earth metals and separating the precipitated rare earth metals from a resulting filtrate;
d) re-dissolving the precipitated rare earth metals in a smaller volume of the filtrate; and
e) transferring the re-dissolved filtrate to an acid solution.