3354 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
RESULTS
Li is sandwiched by two sheets of silicate minerals in lepid-
olite. Thereby, the pre-treatment method, commonly ther-
mal treatment, is required to liberate Li from its structure
and maximize the Li leaching efficiency in the following
metal extraction stage (Choubey et al., 2016). Through the
leaching test using mechanically activated samples at differ-
ent times, we investigated the effectiveness of mechanical
activation and its role in the liberation of alkaline metals
from the layered silicate structure.
Figure 2 shows the leaching efficiency of Al, Li, and
Si from un-activated (0 minutes) or mechanically activated
lepidolite (10 to 60 minutes) using 20% sulfuric acid.
The Li and Al leaching efficiencies gradually increases
as mechanical activation time increases. The highest Li
leaching efficiency achieved was 78.4% (60 minutes acti-
vated) at 180 minutes of leaching time, while less than 1%
of Li was leached with un-activated lepidolite concentrate.
The Al shows a similar increasing trend, and the highest
leaching efficiency of Al achieved was 77.0% after 60 min-
utes of mechanical activation. From the XRD analysis, a
dramatic decrease in crystallinity was observed. The crys-
tallinity decreased from 65.9% (un-activated) to 51.4%
(10 minutes activated) and 18.5% (60 minutes activated),
and this is assumed as the main reason for the enhancement
of leaching efficiencies. However, Al is the major impurity
in the following purification and concentration process for
Li production. On the other hand, the leaching efficiency of
Si was kept below 3% throughout the entire leaching test.
Figure 3 shows the leaching efficiency of (a) Al and Li
and (b) Si from mechanically activated lepidolite for 60
minutes by leaching time.
As shown in Figure 3(a), the leaching efficiency of
alkaline metals, Al and Li, reached the plateau within 60
minutes of leaching time, and the leaching efficiency was
75.5% Al and 75.4% Li, respectively. From 60 minutes of
leaching time, Al and Li leaching efficiency was enhanced
slightly. In the previous study by Liu et al. (2019), the high-
est Li leaching efficiency was less than 60.0% at 77 °C of
leaching temperature and using 50% H2SO4, but without
Table 1. Chemical composition of lepidolite concentrate
(feed material)
Elements Wt.%
Aluminum (Al) 15.35
Iron (Fe) 0.04
Potassium (K) 7.80
Lithium (Li) 1.77
Silica (Si) 23.90
Manganese (Mn) 0.65
Figure 2. Al, Li, and Si leaching efficiency from un-activated
(0 minute) and mechanically activated (10 to 60 minutes)
lepidolite under the leaching conditions of 180 minutes of
leaching time, temperature at 25 °C, and 10%(w/v) pulp
density using 20% concentration of sulfuric acid
Figure 3. The trend of (a) Al and Li leaching efficiency and (b) Si leaching efficiency by leaching time (0 – 180 minutes) from
mechanically activated lepidolite for 60 minutes under the leaching conditions of temperature at 25 °C and 10%(w/v) pulp
density using 20% sulfuric acid
RESULTS
Li is sandwiched by two sheets of silicate minerals in lepid-
olite. Thereby, the pre-treatment method, commonly ther-
mal treatment, is required to liberate Li from its structure
and maximize the Li leaching efficiency in the following
metal extraction stage (Choubey et al., 2016). Through the
leaching test using mechanically activated samples at differ-
ent times, we investigated the effectiveness of mechanical
activation and its role in the liberation of alkaline metals
from the layered silicate structure.
Figure 2 shows the leaching efficiency of Al, Li, and
Si from un-activated (0 minutes) or mechanically activated
lepidolite (10 to 60 minutes) using 20% sulfuric acid.
The Li and Al leaching efficiencies gradually increases
as mechanical activation time increases. The highest Li
leaching efficiency achieved was 78.4% (60 minutes acti-
vated) at 180 minutes of leaching time, while less than 1%
of Li was leached with un-activated lepidolite concentrate.
The Al shows a similar increasing trend, and the highest
leaching efficiency of Al achieved was 77.0% after 60 min-
utes of mechanical activation. From the XRD analysis, a
dramatic decrease in crystallinity was observed. The crys-
tallinity decreased from 65.9% (un-activated) to 51.4%
(10 minutes activated) and 18.5% (60 minutes activated),
and this is assumed as the main reason for the enhancement
of leaching efficiencies. However, Al is the major impurity
in the following purification and concentration process for
Li production. On the other hand, the leaching efficiency of
Si was kept below 3% throughout the entire leaching test.
Figure 3 shows the leaching efficiency of (a) Al and Li
and (b) Si from mechanically activated lepidolite for 60
minutes by leaching time.
As shown in Figure 3(a), the leaching efficiency of
alkaline metals, Al and Li, reached the plateau within 60
minutes of leaching time, and the leaching efficiency was
75.5% Al and 75.4% Li, respectively. From 60 minutes of
leaching time, Al and Li leaching efficiency was enhanced
slightly. In the previous study by Liu et al. (2019), the high-
est Li leaching efficiency was less than 60.0% at 77 °C of
leaching temperature and using 50% H2SO4, but without
Table 1. Chemical composition of lepidolite concentrate
(feed material)
Elements Wt.%
Aluminum (Al) 15.35
Iron (Fe) 0.04
Potassium (K) 7.80
Lithium (Li) 1.77
Silica (Si) 23.90
Manganese (Mn) 0.65
Figure 2. Al, Li, and Si leaching efficiency from un-activated
(0 minute) and mechanically activated (10 to 60 minutes)
lepidolite under the leaching conditions of 180 minutes of
leaching time, temperature at 25 °C, and 10%(w/v) pulp
density using 20% concentration of sulfuric acid
Figure 3. The trend of (a) Al and Li leaching efficiency and (b) Si leaching efficiency by leaching time (0 – 180 minutes) from
mechanically activated lepidolite for 60 minutes under the leaching conditions of temperature at 25 °C and 10%(w/v) pulp
density using 20% sulfuric acid