3238 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
leaching step. The configuration reported in Figure 3a was
used to study lithium, cobalt, nickel and manganese recovery
from acidic sulfate media by electrodialysis with Neosepta ®
monovalent-selective cationic exchange membranes
Figure 3b shows lithium cannot be separated totally
from cobalt, nickel and manganese. However, the perm-
selectivity indexes of the Neosepta ® membrane for lith-
ium and the fluxes for lithium towards the other cations
are high enough to envisage that electrodialysis could be
used to extract selectively lithium in a continuous process
(PLi/Co=5.6, PLi/Ni=6.1, PLi/Mn=5.4 JLi=846 mmol m–2 s–1
whereas JCo=54, JNi=51, JMn=33 mmol m–2 s–1). The pH of
the feed solution has been increased to 2.8 to reach a faradic
efficiency for lithium of 67.1% (at lower pH, the faradic
efficiency was too low).
A greenish precipitate was observed inside the mem-
brane after operating the electrodialysis unit for 13.5 hours
at 12.5 mA cm–2 followed by 5 hours at 15 mA cm–2.
Therefore, the implementation of the electrodialysis just
after leaching cannot be envisaged because of the pres-
ence of cobalt, nickel and manganese which can precipitate
inside the membrane. These metals have to be extracted
before electrodialysis. For this goal, solvent extraction of
manganese, cobalt and nickel was investigated by using
DEHPA (bis-2-ethylhexyl phosphoric acid) and Cyanex
272 (bis-(2, 4, 4-trimethylpentyl) phosphinic acid) diluted
in kerosene.
Figure 4 shows the extraction curves of cobalt, nickel,
manganese and lithium from sulfate media as a function of
pH at a phase volume ratio O/A=1 and room temperature
by DEHPA and Cyanex 272. DEHPA can extract manga-
nese at pH 1.8 without extracting cobalt whereas Cyanex
272 cannot be used to separate cobalt and manganese.
However, DEHPA cannot extract cobalt without extracting
nickel. Conversely, Cyanex 272 is very interesting to extract
cobalt selectively towards nickel at pH 4.5. However, it
cannot be used to extract nickel at pH 7 because of lithium
co-extraction. Indeed, for both extractants, lithium extrac-
tion starts at pH greater than pH 6.5.
As a conclusion, DEHPA can be used to extract man-
ganese at pH 1.8 and Cyanex 272 can extract cobalt at pH
4.5 and nickel could be extracted by DEHPA at pH 5.5.
The resulting stream could then be processed by electrodi-
alysis in order to extract and concentrate lithium as well as
to produce high-grade lithium salt without traces of nickel,
cobalt and manganese. Finally, the following flowsheet
combining leaching, solvent extraction and electrodialysis
could be suggested:
CONCLUSION
Electrodialysis presents a promising avenue for integrat-
ing into hydrometallurgical processes for lithium-ion bat-
tery recycling, particularly if employed immediately after
leaching to facilitate early lithium extraction and prevent
subsequent lithium losses. Unfortunately, the occurrence of
cobalt, nickel, and/or manganese precipitation inside the
membrane hinders this direct implementation. As an alter-
native conceptual flowsheet has been proposed, integrating
leaching, solvent extraction using Cyanex 272 and DEHPA
for subsequent manganese, cobalt, and nickel extraction.
Following this, the resultant solution, containing lithium
and minimal transition metal traces, undergoes electrodi-
alysis. This process aims to selectively extract and concen-
trate lithium into lithium hydroxide. The Neosepta ® cation
Figure 3. (a) electrodialysis configuration (CEM:Neosepta® AEM: Neosepta® AMX) (b) Lithium, cobalt, nickel, and
manganese concentrations in the recovery compartment as a function of time (current density j=12 mA cm–2, Flowrate=100
mL min–1 in all compartments anodic and cathodic solution: 0.1M H
2 SO
4 pH 2.8)
leaching step. The configuration reported in Figure 3a was
used to study lithium, cobalt, nickel and manganese recovery
from acidic sulfate media by electrodialysis with Neosepta ®
monovalent-selective cationic exchange membranes
Figure 3b shows lithium cannot be separated totally
from cobalt, nickel and manganese. However, the perm-
selectivity indexes of the Neosepta ® membrane for lith-
ium and the fluxes for lithium towards the other cations
are high enough to envisage that electrodialysis could be
used to extract selectively lithium in a continuous process
(PLi/Co=5.6, PLi/Ni=6.1, PLi/Mn=5.4 JLi=846 mmol m–2 s–1
whereas JCo=54, JNi=51, JMn=33 mmol m–2 s–1). The pH of
the feed solution has been increased to 2.8 to reach a faradic
efficiency for lithium of 67.1% (at lower pH, the faradic
efficiency was too low).
A greenish precipitate was observed inside the mem-
brane after operating the electrodialysis unit for 13.5 hours
at 12.5 mA cm–2 followed by 5 hours at 15 mA cm–2.
Therefore, the implementation of the electrodialysis just
after leaching cannot be envisaged because of the pres-
ence of cobalt, nickel and manganese which can precipitate
inside the membrane. These metals have to be extracted
before electrodialysis. For this goal, solvent extraction of
manganese, cobalt and nickel was investigated by using
DEHPA (bis-2-ethylhexyl phosphoric acid) and Cyanex
272 (bis-(2, 4, 4-trimethylpentyl) phosphinic acid) diluted
in kerosene.
Figure 4 shows the extraction curves of cobalt, nickel,
manganese and lithium from sulfate media as a function of
pH at a phase volume ratio O/A=1 and room temperature
by DEHPA and Cyanex 272. DEHPA can extract manga-
nese at pH 1.8 without extracting cobalt whereas Cyanex
272 cannot be used to separate cobalt and manganese.
However, DEHPA cannot extract cobalt without extracting
nickel. Conversely, Cyanex 272 is very interesting to extract
cobalt selectively towards nickel at pH 4.5. However, it
cannot be used to extract nickel at pH 7 because of lithium
co-extraction. Indeed, for both extractants, lithium extrac-
tion starts at pH greater than pH 6.5.
As a conclusion, DEHPA can be used to extract man-
ganese at pH 1.8 and Cyanex 272 can extract cobalt at pH
4.5 and nickel could be extracted by DEHPA at pH 5.5.
The resulting stream could then be processed by electrodi-
alysis in order to extract and concentrate lithium as well as
to produce high-grade lithium salt without traces of nickel,
cobalt and manganese. Finally, the following flowsheet
combining leaching, solvent extraction and electrodialysis
could be suggested:
CONCLUSION
Electrodialysis presents a promising avenue for integrat-
ing into hydrometallurgical processes for lithium-ion bat-
tery recycling, particularly if employed immediately after
leaching to facilitate early lithium extraction and prevent
subsequent lithium losses. Unfortunately, the occurrence of
cobalt, nickel, and/or manganese precipitation inside the
membrane hinders this direct implementation. As an alter-
native conceptual flowsheet has been proposed, integrating
leaching, solvent extraction using Cyanex 272 and DEHPA
for subsequent manganese, cobalt, and nickel extraction.
Following this, the resultant solution, containing lithium
and minimal transition metal traces, undergoes electrodi-
alysis. This process aims to selectively extract and concen-
trate lithium into lithium hydroxide. The Neosepta ® cation
Figure 3. (a) electrodialysis configuration (CEM:Neosepta® AEM: Neosepta® AMX) (b) Lithium, cobalt, nickel, and
manganese concentrations in the recovery compartment as a function of time (current density j=12 mA cm–2, Flowrate=100
mL min–1 in all compartments anodic and cathodic solution: 0.1M H
2 SO
4 pH 2.8)