XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3327
RESULTS AND DISCUSSION
DMS Testwork
The dense media separation test was done with specific
gravities of the media ranging from 2.70–3.00 for two par-
ticle size ranges between 1000/+850μm and 850/+500μm,
respectively. Figure 4 illustrates the correlation between the
media’s specific gravity and the grade-recovery performance
for these two size fractions. The best DMS performance
was obtained for a size fraction of 850/+500μm achieving a
lithium recovery of 31% and the highest lithia grade con-
tent of 7.05%. However, a decrease in the specific gravity
of the media led to a reduced spodumene concentrate grade
in both fractions. A significant change in mass recovery was
observed within a specific gravity range of 2.60 to 2.70.
This change is attributed to the inclusion of quartz and
feldspar in the sink fraction as the specific gravity of the
media fell below that of these minerals. As the highest SG
stage of the DMS directly controls the mass and lithium
reporting to the final tailing, a lower SG results in less mass
(and subsequently, less lithium) being reported to the tail-
ings (Gibson et al., 2021).
An XRD analysis was carried out to qualitatively iden-
tify the main mineralogical phases present in the DMS
product. Figure 5 shows the mineral distribution in the
sink fraction at each specific gravity. Notably, an increase
in the specific gravity to 2.60 led to a higher proportion of
silicate gangue minerals, particularly feldspar and quartz, in
the sink fraction, which correspondingly caused a decrease
in the lithium grade. Conversely, the highest spodumene
concentration was observed at the maximum specific grav-
ity of 3.00, with the lithium grade reaching 7.05% Li2O
(approximately 91% spodumene) in the 850/+500 µm size
fraction for the size fraction of 850/+500 µm. The sepa-
ration for the 1000/+850 µm size fraction yielded a mar-
ginally lower concentration (6.72% Li2O or around 87%
spodumene). The reduced recovery in the latter size frac-
tion can be attributed to the presence of non-liberated par-
ticles in the float products. Understanding the liberation
and association of these particles is critical for interpreting
flotation behavior and for evaluating flotation studies on
finer size fractions, as these factors significantly influence
the efficiency of the separation process.
This observation is closely linked to (Tadesse et
al., 2019) identification of three major challenges in
Feed
-74/+38 μm
NaOH and Depressants
Variable dosage
Stirring
pH regulator
Collector
Frother
3 min
Froth product
(concentrate)
Tank product
(tailings)
5 min
5 min
5 min
3 min
Figure 3. Process of the spodumene flotation test
0
20
40
60
80
100
2.60 2.70 2.80 2.90 3.00
S.G (g/cm3)
Mass Pull 1000/850 um
Recovery 1000/+850 um
Mass Pul 850/+500 um
Recovery 850/+500 um
0
2
4
6
8
2.60 2.70 2.80 2.90 3.00
S.G (g/cm3)
Grade 1000/850 um
Grade 850/+500 um
(a) (b)
Figure 4. Dense media separation cumulative sink results. (a) Li
2 O recovery and mass pull at a size fraction of 1000/+850 µm
and 850/+500 µm (b) Li
2 O grade at a size fraction of 1000/+850 µm and 850/+500 µm
LiO
2
Recovery
/
Mass
Pull
(%)
LiO
2
Grade
(%)
RESULTS AND DISCUSSION
DMS Testwork
The dense media separation test was done with specific
gravities of the media ranging from 2.70–3.00 for two par-
ticle size ranges between 1000/+850μm and 850/+500μm,
respectively. Figure 4 illustrates the correlation between the
media’s specific gravity and the grade-recovery performance
for these two size fractions. The best DMS performance
was obtained for a size fraction of 850/+500μm achieving a
lithium recovery of 31% and the highest lithia grade con-
tent of 7.05%. However, a decrease in the specific gravity
of the media led to a reduced spodumene concentrate grade
in both fractions. A significant change in mass recovery was
observed within a specific gravity range of 2.60 to 2.70.
This change is attributed to the inclusion of quartz and
feldspar in the sink fraction as the specific gravity of the
media fell below that of these minerals. As the highest SG
stage of the DMS directly controls the mass and lithium
reporting to the final tailing, a lower SG results in less mass
(and subsequently, less lithium) being reported to the tail-
ings (Gibson et al., 2021).
An XRD analysis was carried out to qualitatively iden-
tify the main mineralogical phases present in the DMS
product. Figure 5 shows the mineral distribution in the
sink fraction at each specific gravity. Notably, an increase
in the specific gravity to 2.60 led to a higher proportion of
silicate gangue minerals, particularly feldspar and quartz, in
the sink fraction, which correspondingly caused a decrease
in the lithium grade. Conversely, the highest spodumene
concentration was observed at the maximum specific grav-
ity of 3.00, with the lithium grade reaching 7.05% Li2O
(approximately 91% spodumene) in the 850/+500 µm size
fraction for the size fraction of 850/+500 µm. The sepa-
ration for the 1000/+850 µm size fraction yielded a mar-
ginally lower concentration (6.72% Li2O or around 87%
spodumene). The reduced recovery in the latter size frac-
tion can be attributed to the presence of non-liberated par-
ticles in the float products. Understanding the liberation
and association of these particles is critical for interpreting
flotation behavior and for evaluating flotation studies on
finer size fractions, as these factors significantly influence
the efficiency of the separation process.
This observation is closely linked to (Tadesse et
al., 2019) identification of three major challenges in
Feed
-74/+38 μm
NaOH and Depressants
Variable dosage
Stirring
pH regulator
Collector
Frother
3 min
Froth product
(concentrate)
Tank product
(tailings)
5 min
5 min
5 min
3 min
Figure 3. Process of the spodumene flotation test
0
20
40
60
80
100
2.60 2.70 2.80 2.90 3.00
S.G (g/cm3)
Mass Pull 1000/850 um
Recovery 1000/+850 um
Mass Pul 850/+500 um
Recovery 850/+500 um
0
2
4
6
8
2.60 2.70 2.80 2.90 3.00
S.G (g/cm3)
Grade 1000/850 um
Grade 850/+500 um
(a) (b)
Figure 4. Dense media separation cumulative sink results. (a) Li
2 O recovery and mass pull at a size fraction of 1000/+850 µm
and 850/+500 µm (b) Li
2 O grade at a size fraction of 1000/+850 µm and 850/+500 µm
LiO
2
Recovery
/
Mass
Pull
(%)
LiO
2
Grade
(%)