1288 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
In the chemical process, rare earth elements are leached
from the physically separated coal ash into a heated nitric
acid solution. The slurry is then filtered, the remaining solid
coal ash is washed for evaluation as a cement ingredient. The
liquid leachate is then fed to a solvent extraction system,
the aqueous leachate feed is mixed with an organic phase
extractant that selectively uptakes the rare earth elements.
Agitation is used to increase contact surface area between
the two phases which are then allowed to phase separate.
The REE-enriched organic phase is then contacted with DI
water to strip the REEs into an aqueous phase. The aqueous
Figure 2. Map of the United States indicating Rare Earth Element deposits with 500 ppm total REE
content and Heavy to Light REE (HREE/LREE) ratio 10%. Information was gathered from the
COALQUAL database maintained by the U.S.G.S. (Palmer 2015)
Figure 3. Physical Separation Pilot Plant (0.4 tpd capacity)
In the chemical process, rare earth elements are leached
from the physically separated coal ash into a heated nitric
acid solution. The slurry is then filtered, the remaining solid
coal ash is washed for evaluation as a cement ingredient. The
liquid leachate is then fed to a solvent extraction system,
the aqueous leachate feed is mixed with an organic phase
extractant that selectively uptakes the rare earth elements.
Agitation is used to increase contact surface area between
the two phases which are then allowed to phase separate.
The REE-enriched organic phase is then contacted with DI
water to strip the REEs into an aqueous phase. The aqueous
Figure 2. Map of the United States indicating Rare Earth Element deposits with 500 ppm total REE
content and Heavy to Light REE (HREE/LREE) ratio 10%. Information was gathered from the
COALQUAL database maintained by the U.S.G.S. (Palmer 2015)
Figure 3. Physical Separation Pilot Plant (0.4 tpd capacity)