5
samples were taken to analyze REE conversion. 2mL of the
lixiviant was added to the leaching solution to compensate
for the 2 mL of the pregnant solution that was taken for
ICP analysis periodically. Figure 6 shows the color of the
leachate in different DES media, and Table 6 shows the
leaching parameters and sample IDs for the leaching exper-
iment. The REE concentrations in samples were used for
the calculation of the conversion of sphalerite according to
Equations 1:
%X C
C D.F 100
0
##(1)
where X is conversion, D.F is the dilution factor, C is the
concentration of REEs in the leachate (mg/L), and C0 is the
maximum amount of REEs that can be leached out (mg/L).
RESULTS AND DISCUSSION
Experiments and analyses for this research are still in prog-
ress, so this chapter will only cover the results obtained thus
far from the completed experiments.
Reline Leaching of REE from Its Ore
Figure 7 shows the conversion of cerium (Ce), lanthanum
(La), or neodymium (Nd), and praseodymium (Pr) in
Reline DES leaching at 80°C. Recovery was almost zero
from 1 hour and consistent until 6 hours, when it increased
sharply for the four REEs. Cerium had the highest recovery,
at about 15%. The sharp increase in recovery after 6 hours
indicates that recovery could increase for all elements
when the leaching time is increased. The higher recovery
in cerium can be attributed to its higher oxidation power,
which makes it separate from other REEs [28].
Figure 5. Elemental Composition of REEs in the Ore
Figure 6. Color of the leachate in DESs
Table 5. Leaching interval for sample-taking
Experiment no. t
0 t
1 t
2 t
3 t
4 t
5
Time/hours 0 1 2 4 6 8
samples were taken to analyze REE conversion. 2mL of the
lixiviant was added to the leaching solution to compensate
for the 2 mL of the pregnant solution that was taken for
ICP analysis periodically. Figure 6 shows the color of the
leachate in different DES media, and Table 6 shows the
leaching parameters and sample IDs for the leaching exper-
iment. The REE concentrations in samples were used for
the calculation of the conversion of sphalerite according to
Equations 1:
%X C
C D.F 100
0
##(1)
where X is conversion, D.F is the dilution factor, C is the
concentration of REEs in the leachate (mg/L), and C0 is the
maximum amount of REEs that can be leached out (mg/L).
RESULTS AND DISCUSSION
Experiments and analyses for this research are still in prog-
ress, so this chapter will only cover the results obtained thus
far from the completed experiments.
Reline Leaching of REE from Its Ore
Figure 7 shows the conversion of cerium (Ce), lanthanum
(La), or neodymium (Nd), and praseodymium (Pr) in
Reline DES leaching at 80°C. Recovery was almost zero
from 1 hour and consistent until 6 hours, when it increased
sharply for the four REEs. Cerium had the highest recovery,
at about 15%. The sharp increase in recovery after 6 hours
indicates that recovery could increase for all elements
when the leaching time is increased. The higher recovery
in cerium can be attributed to its higher oxidation power,
which makes it separate from other REEs [28].
Figure 5. Elemental Composition of REEs in the Ore
Figure 6. Color of the leachate in DESs
Table 5. Leaching interval for sample-taking
Experiment no. t
0 t
1 t
2 t
3 t
4 t
5
Time/hours 0 1 2 4 6 8