XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3337
columbo-tantalite, microlite, cassiterite, zircon, apatite,
rutile, sphalerite and phosphates such as herderite) are also
found in the same deposit (Cuney et al., 1992 Gourcerol
et al., 2019 Harlaux et al., 2017 Demeusy et al., 2023).
Lithium is mainly contained in lepidolite
(K(Li,Al)3(Si,Al)4O10(F,OH)2), which forms a solid solu-
tion with other micas, particularly muscovite. Minerals
of the columbo-tantalite series ((Fe,Mn)(Ta,Nb)2O6),
which are abundant with niobium and tantalum. These
elements are also found in the microlite-pyrochlore series
((Na,Ca)2Ta2O6(OH,F)). Tungsten occurs in minor quan-
tities in granite, while tin is found in the form of cassiterite
(SnO2). The mineral of beryllium is not well identified in
granite, and the main hosts are probably phosphates such as
herderite (CaBePO4(F,OH)). However, it is also found in
lepidolite, which may be due to the presence of phosphates
(fluorapatite) as inclusions or in the mineral as a second-
ary substitution. Small amounts of uranium are also found
in granite in the columbo-tantalite, microlite and uraninite
(UO2) mineral series.
PROCESSING ROUTES FOR THE
EXPLOITATION OF HARD ROCK
LITHIUM DEPOSITS
Several upgrading options have been reported for lithium
deposits, including gravity separation (dense media sepa-
ration spiral concentrator), flotation, magnetic separa-
tion (high-intensity wet magnetic separation) (Bulatovic,
2015 Filippov et al., 2019 Leißner et al., 2016 Moon
and Fuerstenau, 2003 Siame and Pascoe, 2011). However,
most research and industrial practice is limited to spodu-
mene, petalite and zinwaldite, which are the main lithium-
bearing minerals (Tadesse et al., 2019). The literature also
shows that the processing and mineralogy of lepidolite-rich
lithium deposits are not well documented.
Flotation is used for most mineral deposits as the main
separation method for recovering Li-bearing minerals
(Bulatovic, 2015 Filippov et al., 2019 Tadesse et al., 2019).
However, as a wet process, flotation enrichment requires
fine grinding (200 µm) and chemical reagents. There are
some alternative methods such as magnetic separation, elec-
trostatic separation and ore sorting for dry preconcentration
of lithium-containing minerals (Brandt and Haus, 2010
Iuga et al., 2004 Leißner et al., 2016). Furthermore, elec-
trostatic separation and mineral sorting are dry separation
methods that use both the conductivity and optical proper-
ties of particles to separate them from each other. Dense
media separation is also used to recover spodumene, whose
density (3.0 g/cm3) is slightly different from that of gangue
minerals (quartz, feldspars). However, there is no literature
on the application of these technologies to the preconcen-
tration of lepidolite-rich ore deposits. Similarly, optical
sorting of ores has seen technological advances (Lessard et
al., 2014), but there is little information in the literature
concerning Li-bearing ores (Sousa et al., 2019 Filippov et
al., 2022). Nevertheless, some studies have shown that elec-
trostatic separation may be suitable for mica concentration
(Iuga et al., 2004 Lindley and Rowson, 1996 Yuga et al.,
1995). It is therefore of interest to understand the process’
ability to separate lepidolite from a low grade ore.
Processing Routes for the Rare Metal Granite
Multiscale Liberation: Risk of Overgrinding
Flowsheet development should consider the selection of a
preconcentration strategy at a coarse size (gravity concen-
tration, sorting, flotation of coarse particles, …other) to
limit grinding and avoid overgrinding of the other critical
minerals.
In this work, the flotation study performed on the two
fractions of the rare metal granite samples showed a big dif-
ference in the concentrate grade. If the Li grade was high
(4.8 to 5.2 LiO2) for the coarse size fraction (250–500 µm)
the Li grade decreased to 3.8–3.92 for the size fraction
90–250 µm. However, the Li recovery in the coarse con-
centrate was limited to 40–50% only, while the Li recovery
for the size fraction 90–250 µm reached 82–90%. The rela-
tively low Li grade for the finer size fraction was attributed
to the geochemical variability of the lepidolite and the pres-
ence of mineral inclusions in the mica particles, while the
low recovery of the coarse particles was related to the hydro-
dynamics of the flotation process favoring the intensive par-
ticle detachment. Thus, the optimization of the degree of
liberation and the separate flotation of the fine and coarse
size fraction at optimized hydrodynamic conditions can be
considered as promising ways to reach improved metallurgi-
cal performance of the flotation of the lepidolite.
Combined Flow-Sheet for Recovering of Lithium and
Rare Metals (Ta, Nb, Sn)
Figure 1 presents the optimized flow-sheet for the pro-
cessing of Li minerals from rare metals granite from the
Beauvoir deposit. Each step of the flow sheet presented in
Fig 7 includes a number of challenges to overcome and
issues to solve. Lithium mineral liberation requires a staged
comminution approach to avoid overgrinding.
Thus, the optimization of the degree of liberation and
the separate flotation of the fine and coarse size fraction
at optimized hydrodynamic conditions can be considered
as promising ways to reach improved metallurgical perfor-
mances of the flotation of the lepidolite.
columbo-tantalite, microlite, cassiterite, zircon, apatite,
rutile, sphalerite and phosphates such as herderite) are also
found in the same deposit (Cuney et al., 1992 Gourcerol
et al., 2019 Harlaux et al., 2017 Demeusy et al., 2023).
Lithium is mainly contained in lepidolite
(K(Li,Al)3(Si,Al)4O10(F,OH)2), which forms a solid solu-
tion with other micas, particularly muscovite. Minerals
of the columbo-tantalite series ((Fe,Mn)(Ta,Nb)2O6),
which are abundant with niobium and tantalum. These
elements are also found in the microlite-pyrochlore series
((Na,Ca)2Ta2O6(OH,F)). Tungsten occurs in minor quan-
tities in granite, while tin is found in the form of cassiterite
(SnO2). The mineral of beryllium is not well identified in
granite, and the main hosts are probably phosphates such as
herderite (CaBePO4(F,OH)). However, it is also found in
lepidolite, which may be due to the presence of phosphates
(fluorapatite) as inclusions or in the mineral as a second-
ary substitution. Small amounts of uranium are also found
in granite in the columbo-tantalite, microlite and uraninite
(UO2) mineral series.
PROCESSING ROUTES FOR THE
EXPLOITATION OF HARD ROCK
LITHIUM DEPOSITS
Several upgrading options have been reported for lithium
deposits, including gravity separation (dense media sepa-
ration spiral concentrator), flotation, magnetic separa-
tion (high-intensity wet magnetic separation) (Bulatovic,
2015 Filippov et al., 2019 Leißner et al., 2016 Moon
and Fuerstenau, 2003 Siame and Pascoe, 2011). However,
most research and industrial practice is limited to spodu-
mene, petalite and zinwaldite, which are the main lithium-
bearing minerals (Tadesse et al., 2019). The literature also
shows that the processing and mineralogy of lepidolite-rich
lithium deposits are not well documented.
Flotation is used for most mineral deposits as the main
separation method for recovering Li-bearing minerals
(Bulatovic, 2015 Filippov et al., 2019 Tadesse et al., 2019).
However, as a wet process, flotation enrichment requires
fine grinding (200 µm) and chemical reagents. There are
some alternative methods such as magnetic separation, elec-
trostatic separation and ore sorting for dry preconcentration
of lithium-containing minerals (Brandt and Haus, 2010
Iuga et al., 2004 Leißner et al., 2016). Furthermore, elec-
trostatic separation and mineral sorting are dry separation
methods that use both the conductivity and optical proper-
ties of particles to separate them from each other. Dense
media separation is also used to recover spodumene, whose
density (3.0 g/cm3) is slightly different from that of gangue
minerals (quartz, feldspars). However, there is no literature
on the application of these technologies to the preconcen-
tration of lepidolite-rich ore deposits. Similarly, optical
sorting of ores has seen technological advances (Lessard et
al., 2014), but there is little information in the literature
concerning Li-bearing ores (Sousa et al., 2019 Filippov et
al., 2022). Nevertheless, some studies have shown that elec-
trostatic separation may be suitable for mica concentration
(Iuga et al., 2004 Lindley and Rowson, 1996 Yuga et al.,
1995). It is therefore of interest to understand the process’
ability to separate lepidolite from a low grade ore.
Processing Routes for the Rare Metal Granite
Multiscale Liberation: Risk of Overgrinding
Flowsheet development should consider the selection of a
preconcentration strategy at a coarse size (gravity concen-
tration, sorting, flotation of coarse particles, …other) to
limit grinding and avoid overgrinding of the other critical
minerals.
In this work, the flotation study performed on the two
fractions of the rare metal granite samples showed a big dif-
ference in the concentrate grade. If the Li grade was high
(4.8 to 5.2 LiO2) for the coarse size fraction (250–500 µm)
the Li grade decreased to 3.8–3.92 for the size fraction
90–250 µm. However, the Li recovery in the coarse con-
centrate was limited to 40–50% only, while the Li recovery
for the size fraction 90–250 µm reached 82–90%. The rela-
tively low Li grade for the finer size fraction was attributed
to the geochemical variability of the lepidolite and the pres-
ence of mineral inclusions in the mica particles, while the
low recovery of the coarse particles was related to the hydro-
dynamics of the flotation process favoring the intensive par-
ticle detachment. Thus, the optimization of the degree of
liberation and the separate flotation of the fine and coarse
size fraction at optimized hydrodynamic conditions can be
considered as promising ways to reach improved metallurgi-
cal performance of the flotation of the lepidolite.
Combined Flow-Sheet for Recovering of Lithium and
Rare Metals (Ta, Nb, Sn)
Figure 1 presents the optimized flow-sheet for the pro-
cessing of Li minerals from rare metals granite from the
Beauvoir deposit. Each step of the flow sheet presented in
Fig 7 includes a number of challenges to overcome and
issues to solve. Lithium mineral liberation requires a staged
comminution approach to avoid overgrinding.
Thus, the optimization of the degree of liberation and
the separate flotation of the fine and coarse size fraction
at optimized hydrodynamic conditions can be considered
as promising ways to reach improved metallurgical perfor-
mances of the flotation of the lepidolite.