XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3353
leaching (Setoudeh et al., 2019), acid digestion (Vieceli
et al., 2018), or direct leaching process (Lee, 2015). The
mechanochemical-assisted process in lepidolite processing
is known to improve the following pyro- or hydrometal-
lurgical process by:
• Amorphization of crystalline structure and short-
ening contact distance between target element and
reagent
• In-situ formation of water-soluble compounds by
solid-solid reaction and/or
• Increase the penetration depth of the leaching
solution.
However, there is limited information about the effect of
mechanochemical-assisted process, either mechanical acti-
vation or mechanochemical reaction, on lepidolite. As a
fundamental study on applying the mechanochemical-
assisted process on Li mineral, this study introduced the
mechanical activation mode for lepidolite processing fol-
lowed by 20% sulfuric acid (H2SO4) leaching, a commonly
used reagent in commercial applications. The variables
tested throughout the experimental program were grinding
time and leaching time.
EXPERIMENTAL
The X-ray diffraction (XRD) analysis was conducted using
D8 Advance XRD (X-ray diffractometer, Bruker, USA)
with Cu Kα radiation (λ =0.15406 nm), with 0.02° at
1.25s of scanning speed. The XRD result of the lepidolite
concentrate feed used in this study is presented in Figure 1.
The lepidolite concentrate was crushed in a jaw crusher,
and the particle size was reduced to under 1.0 mm (sieve
aperture size) before the mechanical activation test. The
PM-100 planetary ball mill (Retsch Inc., Germany) with
a single grinding jar and counter-weight was employed to
transfer the high energy into the feed material.
Throughout the experiments, 10 g of lepidolite con-
centrate and 200 g of 5 mm diameter zirconia (ZrO2) balls
were charged in the 250 mL of zirconia chamber (equiva-
lent to 20:1 (g:g) of ball-to-feed (BTF) weight ratio). The
grinding time varied from 10 minutes to 60 minutes dur-
ing the mechanical activation test. For 30 and 60 minutes
of mechanical activation, mechanical activation test paused
for 10 minutes after every 10 minutes of grinding time to
minimize the accumulation of generated heat while the
grinding speed was fixed at 400 rpm.
The un-activated lepidolite, which is only pulverized
only for 15 seconds in a ring mill (C+PB, ROCKLAB
Ltd.), and mechanically activated lepidolite were leached
in 20% sulfuric acid within 24 hours after the mechanical
activation process. The sample was leached in a 150 mL
Erlenmeyer flask on the hotplate with a magnetic stirrer
for 180 minutes of leaching time at the solid-liquid ratio of
10% (5 g/50 mL) and at the leaching temperature of 25 °C.
The leaching solution was filtered using a 0.22 μm syringe
membrane filter to obtain the clear filtrate solution, and
then it was diluted using 2% nitric acid (HNO3). The con-
centration of Li, aluminum (Al), and silica (Si) was mea-
sured with Agilent Technologies 5100 ICP-OES (Agilent
Technologies Inc., USA). The element’s leaching efficiency
was calculated using the following equation: where LE is
leaching efficiency, MSolution is the concentration of an ele-
ment in the filtrate, and MFeed is the concentration of an
element in the feed material (Table 1).
L MFeed
M
100^%h
E
Solution #=
Figure 1. X-ray diffractogram (XRD) of lepidolite concentrate feed used in this study (L: lepidolite, M:
muscovite, Q: quartz)
leaching (Setoudeh et al., 2019), acid digestion (Vieceli
et al., 2018), or direct leaching process (Lee, 2015). The
mechanochemical-assisted process in lepidolite processing
is known to improve the following pyro- or hydrometal-
lurgical process by:
• Amorphization of crystalline structure and short-
ening contact distance between target element and
reagent
• In-situ formation of water-soluble compounds by
solid-solid reaction and/or
• Increase the penetration depth of the leaching
solution.
However, there is limited information about the effect of
mechanochemical-assisted process, either mechanical acti-
vation or mechanochemical reaction, on lepidolite. As a
fundamental study on applying the mechanochemical-
assisted process on Li mineral, this study introduced the
mechanical activation mode for lepidolite processing fol-
lowed by 20% sulfuric acid (H2SO4) leaching, a commonly
used reagent in commercial applications. The variables
tested throughout the experimental program were grinding
time and leaching time.
EXPERIMENTAL
The X-ray diffraction (XRD) analysis was conducted using
D8 Advance XRD (X-ray diffractometer, Bruker, USA)
with Cu Kα radiation (λ =0.15406 nm), with 0.02° at
1.25s of scanning speed. The XRD result of the lepidolite
concentrate feed used in this study is presented in Figure 1.
The lepidolite concentrate was crushed in a jaw crusher,
and the particle size was reduced to under 1.0 mm (sieve
aperture size) before the mechanical activation test. The
PM-100 planetary ball mill (Retsch Inc., Germany) with
a single grinding jar and counter-weight was employed to
transfer the high energy into the feed material.
Throughout the experiments, 10 g of lepidolite con-
centrate and 200 g of 5 mm diameter zirconia (ZrO2) balls
were charged in the 250 mL of zirconia chamber (equiva-
lent to 20:1 (g:g) of ball-to-feed (BTF) weight ratio). The
grinding time varied from 10 minutes to 60 minutes dur-
ing the mechanical activation test. For 30 and 60 minutes
of mechanical activation, mechanical activation test paused
for 10 minutes after every 10 minutes of grinding time to
minimize the accumulation of generated heat while the
grinding speed was fixed at 400 rpm.
The un-activated lepidolite, which is only pulverized
only for 15 seconds in a ring mill (C+PB, ROCKLAB
Ltd.), and mechanically activated lepidolite were leached
in 20% sulfuric acid within 24 hours after the mechanical
activation process. The sample was leached in a 150 mL
Erlenmeyer flask on the hotplate with a magnetic stirrer
for 180 minutes of leaching time at the solid-liquid ratio of
10% (5 g/50 mL) and at the leaching temperature of 25 °C.
The leaching solution was filtered using a 0.22 μm syringe
membrane filter to obtain the clear filtrate solution, and
then it was diluted using 2% nitric acid (HNO3). The con-
centration of Li, aluminum (Al), and silica (Si) was mea-
sured with Agilent Technologies 5100 ICP-OES (Agilent
Technologies Inc., USA). The element’s leaching efficiency
was calculated using the following equation: where LE is
leaching efficiency, MSolution is the concentration of an ele-
ment in the filtrate, and MFeed is the concentration of an
element in the feed material (Table 1).
L MFeed
M
100^%h
E
Solution #=
Figure 1. X-ray diffractogram (XRD) of lepidolite concentrate feed used in this study (L: lepidolite, M:
muscovite, Q: quartz)