XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1291
refining (which was outside the scope of this project). The
physical and chemical separation stages are described in the
following sections.
The primary products were REY-rich and Sc-rich con-
centrates. The key byproducts may include beneficiated ash
cement substitute, a magnetic ash product, cenospheres
and a carbon product used as a secondary fuel.
Ash from two eastern KY coal fire power plants was
recovered and used as process feedstocks. Analysis of both
ash sources (Ash C and D in Figure 7) by inductively cou-
pled plasma mass spectroscopy (ICP-MS) indicated sig-
nificant content of Nd (~180 ppm), Y (~50 ppm), and Sc
(~25 ppm) as well as reasonable (~10 ppm) content of Pr,
Gd, Dy elements. Ash C exhibited a darker color, due to a
higher carbon content (loss on ignition of ~12 wt.%). The
loss on ignition of Ash D was closer to 3 wt.%.
Approximately 20 tons of coal ash were processed
through the physical separation pilot plant (Figure 3) with
50% yield to produce ~10 tons of the fraction suitable
for chemical processing (carbon-removed, non-magnetic
ash with particle size 75 microns). Figure 8 shows pho-
tographs comparing the physical and chemical processing
feedstocks. Note that the color changes from dark black to
brown, indicating removal of carbon.
The physically processed ash was then shipped for fur-
ther REE-enrichment by the chemical process. To stream-
line the chemical pilot plant operations and reduce risk,
the project team developed a micropilot plant (0.5 kg/day
capacity), shown in Figure 4. Key micropilot unit operations
include digestion, filtration, pre-concentration, LLX feed
preparation, and liquid-liquid extraction and re-extraction.
The micropilot facility was successfully used for validating
and troubleshooting chemical pilot processes, demonstrat-
ing target yield and enrichment performance requirements.
Approximately 15 kg of coal ash was processed through the
PSI micropilot facility.
Figure 7. Ash feedstocks used for this research study and subsequent characterization
Figure 8. Photographic analysis of the physical and chemical processing feedstocks
refining (which was outside the scope of this project). The
physical and chemical separation stages are described in the
following sections.
The primary products were REY-rich and Sc-rich con-
centrates. The key byproducts may include beneficiated ash
cement substitute, a magnetic ash product, cenospheres
and a carbon product used as a secondary fuel.
Ash from two eastern KY coal fire power plants was
recovered and used as process feedstocks. Analysis of both
ash sources (Ash C and D in Figure 7) by inductively cou-
pled plasma mass spectroscopy (ICP-MS) indicated sig-
nificant content of Nd (~180 ppm), Y (~50 ppm), and Sc
(~25 ppm) as well as reasonable (~10 ppm) content of Pr,
Gd, Dy elements. Ash C exhibited a darker color, due to a
higher carbon content (loss on ignition of ~12 wt.%). The
loss on ignition of Ash D was closer to 3 wt.%.
Approximately 20 tons of coal ash were processed
through the physical separation pilot plant (Figure 3) with
50% yield to produce ~10 tons of the fraction suitable
for chemical processing (carbon-removed, non-magnetic
ash with particle size 75 microns). Figure 8 shows pho-
tographs comparing the physical and chemical processing
feedstocks. Note that the color changes from dark black to
brown, indicating removal of carbon.
The physically processed ash was then shipped for fur-
ther REE-enrichment by the chemical process. To stream-
line the chemical pilot plant operations and reduce risk,
the project team developed a micropilot plant (0.5 kg/day
capacity), shown in Figure 4. Key micropilot unit operations
include digestion, filtration, pre-concentration, LLX feed
preparation, and liquid-liquid extraction and re-extraction.
The micropilot facility was successfully used for validating
and troubleshooting chemical pilot processes, demonstrat-
ing target yield and enrichment performance requirements.
Approximately 15 kg of coal ash was processed through the
PSI micropilot facility.
Figure 7. Ash feedstocks used for this research study and subsequent characterization
Figure 8. Photographic analysis of the physical and chemical processing feedstocks