1348 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
be subjected to ICP-OES to find the concentration of the
dissolved elements.
Ethaline
Ethaline is a eutectic mixture of ChCl and ethylene glycol
(EG) at a 1:2 molar ratio. The reported eutectic transfor-
mation temperature for this solvent is –66°C. The solution
was formed at a slower rate however, heating the solution
helped fasten the solvent formation. This solvent was less
viscous than reline, and the reported viscosity values are 36
cP at 20°C (Zhang et al. 2012). Hence, solid-liquid separa-
tion was comparatively easy. The same experimental design
was used for this solvent as well. The solution sample was
centrifuged for 10–15 minutes at 4000 rpm and then sepa-
rated using a syringe filter. The pregnant liquor was then
subjected to ICP-OES, and the obtained results are pre-
sented in Table 3.
As seen in Table 3, the elemental dissolution for dif-
ferent feeds was very low. The maximum dissolution was
achieved in the first 24 hours, and the elements tended to
drop out of the solution with time. However, a 23.75%
Ca dissolution was observed in Ore B. This is to be further
studied as it was not observed with the other feeds. This
solvent will have to be further explored to extract the ele-
ments from the primary sources efficiently. Even though
solid-liquid separation was achieved, the conditions in
which it was obtained do not tend to be economical or
practical.
Behaviour of the Feeds in Other Leach Systems
A two-stage leach process was carried out for the feeds using
oxalic acid and EDTA. The reactivity of the feeds was much
different to that observed here. The results obtained from
the oxalic acid leach stage are presented in Figure 2 for
context.
The above data shows that the feed samples behave
differently from one another, but they are quite reactive.
The ACL tailings were found to be highly soluble, and the
tested deep eutectic solvents could not dissolve it either.
CONCLUSION
Deep Eutectic Solvents are a new class of green solvents,
primarily used in extraction from secondary sources in the
past decade. These solvents have garnered attention due
to their increased selectivity to certain metals, low toxic-
ity, and low cost. This work was carried out as a scoping
test to investigate the applicability of these solvents for
primary ores and mine tailings. The main concern with
using this solvent is its highly viscous nature. In the case of
reline, a solid-liquid separation technique must be devised
Figure 1. Different stages of eutectic mixture formation in reline
Table 3. Elemental dissolution of the samples (80°C, 24 h, S/L ratio =1:10, 250 rpm)
Elemental
Dissolution (%)Al Ca Ce Fe La Mn Nd P Pr Th T-REE
Ore A 0.09 8.68 0.03 0.02 0.03 1.39 0.03 0.03 0.03 0.02 0.03
Ore B 0.15 23.75 0.10 0.03 0.10 0.15 0.10 0.13 0.10 0.04 0.10
Float Tails 0.08 2.87 0.03 0.01 0.05 0.91 0.03 0.03 0.04 0.02 0.04
ACL Tails 0.04 0.31 0.19 0.51 0.15 0.49 0.23 0.03 0.21 0.31 0.20
be subjected to ICP-OES to find the concentration of the
dissolved elements.
Ethaline
Ethaline is a eutectic mixture of ChCl and ethylene glycol
(EG) at a 1:2 molar ratio. The reported eutectic transfor-
mation temperature for this solvent is –66°C. The solution
was formed at a slower rate however, heating the solution
helped fasten the solvent formation. This solvent was less
viscous than reline, and the reported viscosity values are 36
cP at 20°C (Zhang et al. 2012). Hence, solid-liquid separa-
tion was comparatively easy. The same experimental design
was used for this solvent as well. The solution sample was
centrifuged for 10–15 minutes at 4000 rpm and then sepa-
rated using a syringe filter. The pregnant liquor was then
subjected to ICP-OES, and the obtained results are pre-
sented in Table 3.
As seen in Table 3, the elemental dissolution for dif-
ferent feeds was very low. The maximum dissolution was
achieved in the first 24 hours, and the elements tended to
drop out of the solution with time. However, a 23.75%
Ca dissolution was observed in Ore B. This is to be further
studied as it was not observed with the other feeds. This
solvent will have to be further explored to extract the ele-
ments from the primary sources efficiently. Even though
solid-liquid separation was achieved, the conditions in
which it was obtained do not tend to be economical or
practical.
Behaviour of the Feeds in Other Leach Systems
A two-stage leach process was carried out for the feeds using
oxalic acid and EDTA. The reactivity of the feeds was much
different to that observed here. The results obtained from
the oxalic acid leach stage are presented in Figure 2 for
context.
The above data shows that the feed samples behave
differently from one another, but they are quite reactive.
The ACL tailings were found to be highly soluble, and the
tested deep eutectic solvents could not dissolve it either.
CONCLUSION
Deep Eutectic Solvents are a new class of green solvents,
primarily used in extraction from secondary sources in the
past decade. These solvents have garnered attention due
to their increased selectivity to certain metals, low toxic-
ity, and low cost. This work was carried out as a scoping
test to investigate the applicability of these solvents for
primary ores and mine tailings. The main concern with
using this solvent is its highly viscous nature. In the case of
reline, a solid-liquid separation technique must be devised
Figure 1. Different stages of eutectic mixture formation in reline
Table 3. Elemental dissolution of the samples (80°C, 24 h, S/L ratio =1:10, 250 rpm)
Elemental
Dissolution (%)Al Ca Ce Fe La Mn Nd P Pr Th T-REE
Ore A 0.09 8.68 0.03 0.02 0.03 1.39 0.03 0.03 0.03 0.02 0.03
Ore B 0.15 23.75 0.10 0.03 0.10 0.15 0.10 0.13 0.10 0.04 0.10
Float Tails 0.08 2.87 0.03 0.01 0.05 0.91 0.03 0.03 0.04 0.02 0.04
ACL Tails 0.04 0.31 0.19 0.51 0.15 0.49 0.23 0.03 0.21 0.31 0.20