XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3339
The fractions coarser than 840 µm had a higher lithium
content than the average feed (2.02% Li), reaching 2.35%
Li for the fraction 2 mm. Lithium content decreased with
decreasing particle size, and was found to be 1% Li2O
(0.93%) in the ultrafine fraction (–0.063 mm). Maximum
Li2O distribution occurred in the coarsest particle range.
This finding further supports the recovery of lepidolite at
coarse liberation sizes as a potentially cost-effective separa-
tion method that avoids the use of fine grinding.
These results have led to the consideration of optical
sorting as a pre-concentration method at the crushing stage
as a promising approach (Souza et al., 2020 Filippov et
al., 2022). Furthermore, preconcentration of muscovite-
type minerals in pegmatite is achievable using an electro-
static separation method (Yuga et al., 1994 Iuga et al.,
2004). Muscovite has stronger insulating properties than
quartz and feldspar. Due to the mineralogical similarities
between muscovite and lepidolite, it was deduced that both
minerals would behave in the same way during electro-
static separation and that this technique could therefore be
implemented as a pre-concentration step.
Electrostatic separation was applied to the fraction
210 µm, as a pre-concentration step prior to the flotation
step. Three size fractions were tested: [2–0.84 mm], [0.84–
0.42 mm] and [0.42–0.21 mm]. Finally, the 200 mm
fraction was processed by flotation at a pH range of 2–5,
using an etheramine reagent as flotation collector. The
studies carried out resulted in the proposal of a processing
circuit for aplitic pegmatites combining dry preconcentra-
tion methods and flotation as the main process for recover-
ing lepidolite from pegmatite (Figure 3).
The flotation separation process yielded very interest-
ing and promising results, both in terms of the quality of
the Li concentrate (4.0%) and the level of recovery, reach-
ing 77% .
Processing Challenges for LCT Pegmatite Ore
Spodumene in Lithium-Cerium-Tantalum (LCT is) peg-
matite recovered by flotation with anionic collector but it
is inefficient (Filippov et al., 2019). Process optimization
requires the use of collector blends and preliminary acti-
vation with the metallic cations.Literature provides exten-
sive information about the crystal structure of spodumene
during grinding. The total broken bond strength per unit
cell area varies according to the plans between 4.7 to 9.75
× 1018 valence per m2 according to the series (Moon and
Fuerstenau, 2003):
{110 }{010 }{001} {100 }
The comminution of the LCT pegmatite leads to the
exposure of the {110} of spodumene planes where the den-
sity of Al sites in the unit cell area is higher except the {001}
plane and defines carboxylate collector adsorption and effi-
cient flotation. However, collector adsorption efficiency is
not sufficient for efficient flotation with carboxylate collec-
tor alone. The flotation process is performed with a prelimi-
nary activation by the Ca2+ cation (Figure 6).
It was demonstrated that activated spodumene has a
much higher recovery than the non-activated sample when
either NaOH or Na2CO3 is used. This suggests that CaCl2
has an activating effect on spodumene in flotation, even if
a depressant (i.e., Na2CO3 in the current case) is present.
0.97
1.39
1.73 1.80 1.88
2.16
2.35
0
0.5
1
1.5i2O
2
2.5
0
10
20
30
40
50
63 63 106 210 420 840 2000
Size (μm)
Recovery
Figure 2. Lithium grade and deportment according to size distribution of crushed and ground
sample of Gonçalo pegmatite ore (adapted from Filippov et al., 2022)
Grade
L
%Distribution
LiO
2
%
The fractions coarser than 840 µm had a higher lithium
content than the average feed (2.02% Li), reaching 2.35%
Li for the fraction 2 mm. Lithium content decreased with
decreasing particle size, and was found to be 1% Li2O
(0.93%) in the ultrafine fraction (–0.063 mm). Maximum
Li2O distribution occurred in the coarsest particle range.
This finding further supports the recovery of lepidolite at
coarse liberation sizes as a potentially cost-effective separa-
tion method that avoids the use of fine grinding.
These results have led to the consideration of optical
sorting as a pre-concentration method at the crushing stage
as a promising approach (Souza et al., 2020 Filippov et
al., 2022). Furthermore, preconcentration of muscovite-
type minerals in pegmatite is achievable using an electro-
static separation method (Yuga et al., 1994 Iuga et al.,
2004). Muscovite has stronger insulating properties than
quartz and feldspar. Due to the mineralogical similarities
between muscovite and lepidolite, it was deduced that both
minerals would behave in the same way during electro-
static separation and that this technique could therefore be
implemented as a pre-concentration step.
Electrostatic separation was applied to the fraction
210 µm, as a pre-concentration step prior to the flotation
step. Three size fractions were tested: [2–0.84 mm], [0.84–
0.42 mm] and [0.42–0.21 mm]. Finally, the 200 mm
fraction was processed by flotation at a pH range of 2–5,
using an etheramine reagent as flotation collector. The
studies carried out resulted in the proposal of a processing
circuit for aplitic pegmatites combining dry preconcentra-
tion methods and flotation as the main process for recover-
ing lepidolite from pegmatite (Figure 3).
The flotation separation process yielded very interest-
ing and promising results, both in terms of the quality of
the Li concentrate (4.0%) and the level of recovery, reach-
ing 77% .
Processing Challenges for LCT Pegmatite Ore
Spodumene in Lithium-Cerium-Tantalum (LCT is) peg-
matite recovered by flotation with anionic collector but it
is inefficient (Filippov et al., 2019). Process optimization
requires the use of collector blends and preliminary acti-
vation with the metallic cations.Literature provides exten-
sive information about the crystal structure of spodumene
during grinding. The total broken bond strength per unit
cell area varies according to the plans between 4.7 to 9.75
× 1018 valence per m2 according to the series (Moon and
Fuerstenau, 2003):
{110 }{010 }{001} {100 }
The comminution of the LCT pegmatite leads to the
exposure of the {110} of spodumene planes where the den-
sity of Al sites in the unit cell area is higher except the {001}
plane and defines carboxylate collector adsorption and effi-
cient flotation. However, collector adsorption efficiency is
not sufficient for efficient flotation with carboxylate collec-
tor alone. The flotation process is performed with a prelimi-
nary activation by the Ca2+ cation (Figure 6).
It was demonstrated that activated spodumene has a
much higher recovery than the non-activated sample when
either NaOH or Na2CO3 is used. This suggests that CaCl2
has an activating effect on spodumene in flotation, even if
a depressant (i.e., Na2CO3 in the current case) is present.
0.97
1.39
1.73 1.80 1.88
2.16
2.35
0
0.5
1
1.5i2O
2
2.5
0
10
20
30
40
50
63 63 106 210 420 840 2000
Size (μm)
Recovery
Figure 2. Lithium grade and deportment according to size distribution of crushed and ground
sample of Gonçalo pegmatite ore (adapted from Filippov et al., 2022)
Grade
L
%Distribution
LiO
2
%