3432 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
SOLVENT EXTRACTION
This section describes the first step of an attempt to use
solvent extraction (SX) in purifying the Mn from the PLS
after copper removal. There is no known operating Mn SX
plant and, although numerous studies on the SX of man-
ganese have been published, they invariably deal with feeds
of comparable concentrations to those of other transition
metals and often with manganese minor by-product only.
For example, in the case of nickel SX, which is another
transition metal with many chemical similarities to man-
ganese, the PLS feed to SX usually contains ~3–5 g/L only
of Ni. More recent studies involving SX of manganese have
been focused on the recycling of spent batteries particu-
larly Li-Ion batteries. The works of Keller, Hawitschka and
Bart (2022) and Vieceli et al. (2023) are two examples.
In the work of the former, the manganese in the feed was
only 4.96 g/L and is only one of the valuable metals in
the feed. The concentration of the manganese in the PLS
(63,630 g/L) post copper removal, however, was exception-
ally high compared to those commonly used in SX applica-
tions. Thus, the first step in this work was to explore the
extraction behaviour of Mn as well its associated impurity
ions when its concentration in the feed is exceptionally
high.
The solvent consisted of Ionquest 220 (20%) as extract-
ant with tributyl phosphate, TBP (5%) as modifier in
Escaid 110 diluent. The active component of Ionquest 220
is di(2-ethylhexyl)phosphoric acid (D2EHPA), which has
been the extractant of choice for manganese SX. For bet-
ter control of the pH, the extractant was saponified (40%).
Given the limited concentration of the extractant in the
solvent, which is dictated by its viscosity, it was decided
to dilute the feed 1:4. This resulted in a Mn concentra-
tion of about 12,276 mg/L and proportional decrease in
the concentrations of the impurity ions. This, preserves
their concentration ratios while allowing observation of
their extraction behaviour within a few extraction stages.
Details, including the concentrations of manganese as well
as associated impurities in the first three stripping stages of
the first extraction stage are shown in Table 8.
IX raf refers to the raffinate from the IX circuit, which is
the PLS post copper removal. Dil Feed refers to the diluted
IX raf and the feed to the SX. E labels refer to extraction
stage number while ‘Strip’ and number labels refer to the
stripping stage number. Thus, E1 Strip 1 is the loaded strip
solution from the first stripping stage of the first extraction
stage.
As in previous tables, a shaded value indicates that it
is below the detection limit of the instrument. Some val-
ues, even though unshaded, are clearly errors and can be
ignored. For example, lead was below detection limit in the
sample. So, its detection in the first two extraction stages
must be errors. Sulfur is part of the sulfate ion, which is
Table 6. Assay of the PLS from MnO2 re-leach
Item Assay (mg/L)
Al 10
Ba 0.5
Ca 25
Co 6
Cr 12
Cu 11
Fe 88
K 1590
Mg 2
Mn 64050
Na 28
Ni 11
P 10
SO3 0.5
S 58750
Si 4
Ti 1.0
V 1.4
Zn 5.8
Table 7. Results of the IX Test to remove the copper from the PLS of the MnO2 re-leach
Sample Description
Al Ba Ca Co Cr Cu Fe K Mg Mn
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
HY17081 t=0 SA 10.0 0.5 25.0 6.0 11 9.6 87.0 1600 2.0 64,550
HY17081 t=2 SA 10.0 0.5 25.0 6.0 11 1.4 86.0 1580 2.0 63,630
Sample ID
Na Ni P Pb S Si Ti V Zn
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
HY17081 t=0 SA 30.0 10.0 10 0.5 58,510 4.0 1.0 0.4 4.4
HY17081 t=2 SA 28.0 9.5 10 0.5 96,500 3.0 1.0 0.4 4.4
SOLVENT EXTRACTION
This section describes the first step of an attempt to use
solvent extraction (SX) in purifying the Mn from the PLS
after copper removal. There is no known operating Mn SX
plant and, although numerous studies on the SX of man-
ganese have been published, they invariably deal with feeds
of comparable concentrations to those of other transition
metals and often with manganese minor by-product only.
For example, in the case of nickel SX, which is another
transition metal with many chemical similarities to man-
ganese, the PLS feed to SX usually contains ~3–5 g/L only
of Ni. More recent studies involving SX of manganese have
been focused on the recycling of spent batteries particu-
larly Li-Ion batteries. The works of Keller, Hawitschka and
Bart (2022) and Vieceli et al. (2023) are two examples.
In the work of the former, the manganese in the feed was
only 4.96 g/L and is only one of the valuable metals in
the feed. The concentration of the manganese in the PLS
(63,630 g/L) post copper removal, however, was exception-
ally high compared to those commonly used in SX applica-
tions. Thus, the first step in this work was to explore the
extraction behaviour of Mn as well its associated impurity
ions when its concentration in the feed is exceptionally
high.
The solvent consisted of Ionquest 220 (20%) as extract-
ant with tributyl phosphate, TBP (5%) as modifier in
Escaid 110 diluent. The active component of Ionquest 220
is di(2-ethylhexyl)phosphoric acid (D2EHPA), which has
been the extractant of choice for manganese SX. For bet-
ter control of the pH, the extractant was saponified (40%).
Given the limited concentration of the extractant in the
solvent, which is dictated by its viscosity, it was decided
to dilute the feed 1:4. This resulted in a Mn concentra-
tion of about 12,276 mg/L and proportional decrease in
the concentrations of the impurity ions. This, preserves
their concentration ratios while allowing observation of
their extraction behaviour within a few extraction stages.
Details, including the concentrations of manganese as well
as associated impurities in the first three stripping stages of
the first extraction stage are shown in Table 8.
IX raf refers to the raffinate from the IX circuit, which is
the PLS post copper removal. Dil Feed refers to the diluted
IX raf and the feed to the SX. E labels refer to extraction
stage number while ‘Strip’ and number labels refer to the
stripping stage number. Thus, E1 Strip 1 is the loaded strip
solution from the first stripping stage of the first extraction
stage.
As in previous tables, a shaded value indicates that it
is below the detection limit of the instrument. Some val-
ues, even though unshaded, are clearly errors and can be
ignored. For example, lead was below detection limit in the
sample. So, its detection in the first two extraction stages
must be errors. Sulfur is part of the sulfate ion, which is
Table 6. Assay of the PLS from MnO2 re-leach
Item Assay (mg/L)
Al 10
Ba 0.5
Ca 25
Co 6
Cr 12
Cu 11
Fe 88
K 1590
Mg 2
Mn 64050
Na 28
Ni 11
P 10
SO3 0.5
S 58750
Si 4
Ti 1.0
V 1.4
Zn 5.8
Table 7. Results of the IX Test to remove the copper from the PLS of the MnO2 re-leach
Sample Description
Al Ba Ca Co Cr Cu Fe K Mg Mn
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
HY17081 t=0 SA 10.0 0.5 25.0 6.0 11 9.6 87.0 1600 2.0 64,550
HY17081 t=2 SA 10.0 0.5 25.0 6.0 11 1.4 86.0 1580 2.0 63,630
Sample ID
Na Ni P Pb S Si Ti V Zn
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
HY17081 t=0 SA 30.0 10.0 10 0.5 58,510 4.0 1.0 0.4 4.4
HY17081 t=2 SA 28.0 9.5 10 0.5 96,500 3.0 1.0 0.4 4.4