XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2659
The exploitation of lithium from hard rock pegma-
tites is primarily from spodumene (LiAlSi2O6) contain-
ing 4.5–8.0% Li2O while petalite (Li,Na)AlSi4O11) with
2.0–4.0% Li2O, lepidolite (KLi1.5Al1.5[Si3AlO10][F,OH]2,
with 1.2–5.9% Li2O, and amblygonite LiAlPO4(F,OH)
with 8–9.5% Li2O also play an important role (Bulatovic,
2015). Other lithium-bearing minerals include zinnwaldite,
eucryptite and other lithium-bearing clays. The benefi-
ciation of lithium-bearing pegmatites is typically done by
physical separation methods that include sorting, dense
media separation, magnetic separation, and froth flotation.
The choice of a flowsheet depends on the mineralogical
properties and the target product grade and recovery. Froth
flotation is the most dominant method to concentrate lith-
ium-bearing minerals, especially spodumene (Bulatovic,
2015, Oliazadeh et al., 2018, Filippov et al., 2019). This
is partly because froth flotation can efficiently handle com-
plex and low-grade ores that require fine grinding and still
achieve high concentrate grades at relatively high recoveries
of lithium when compared to other methods (Menendez
et al., 2004). Consequently, froth flotation is the focus of
this work.
Lithium Flotation
The recovery of lithium-bearing minerals from pegmatites
using froth flotation is complicated by the similarities in
the mineralogy of the gangue minerals (quartz, feldspar,
mica) and the lithium minerals. Both direct and reverse
flotation are typically used to recover lithium resulting in
several flowsheet configurations.
Flotation of Spodumene
Several options can be adopted depending on mineralogy.
Spodumene can be floated directly using anionic collec-
tors, alternatively, cationic collectors are used to float the
gangue minerals while the spodumene concentrate is col-
lected in the tailings (Bulatovic, 2015, Oliazadeh et al.,
2018). The choice of reagent and flotation conditions is
heavily anchored on the mineralogy and process objectives.
Where direct flotation is used, fatty acids at pH 8–9 such as
oleic acid or their salt form e.g., sodium oleate are typically
used especially in academic research. In contrast, TOFAs
are commonly used in industry (Cook and Gibson, 2023).
Sulfonated, and phosphorated fatty acids are also used as
spodumene collectors (Gibson et al., 2017). The success of
these anionic collectors to recover spodumene despite its
overall negative surface charge (isoelectric point (i.e.p) at
pH of 2 (Filippov et al., 2019)) was extensively discussed
by Moon and Fuerstenau (2003). They concluded that the
surface crystal chemistry of spodumene plays a major role
in its selective recovery by sodium oleate when compared
to associated aluminosilicates. This is because it has surface
Al3+ sites whereas those of other aluminosilicates are buried
in the crystallographic unit cell. These Al3+ sites were found
to be favourable for the chemisorption of oleate. Filippov
et al. (2019) also arrived at a similar conclusion. The use of
fatty acids as collectors for spodumene has not been with-
out challenges. Cook and Gibson (2023) summarised these
challenges and they include (i) strong collecting power
but poor selectivity (ii) poor recovery of fine sizes i.e., -
19 microns (e.g., Xu et al. (2016)), (iii) excessive foaming
which may result in poor selectivity and (iv) sensitivity to
pulp temperature and pH which leads to poor selectivity.
Xie et al. (2020) suggested the use of collector mixtures to
overcome some of these although the collectors they dis-
cussed are combinations of cationic and anionic collectors.
As stated previously spodumene can also be upgraded
through reverse flotation where the gangue minerals typi-
cally mica and talc are floated ahead of spodumene using
cationic collectors (amines) at pH 2.5 -3 (Bulatovic, 2015).
In the paper, we will explore the use of proprietary col-
lectors and collector mixtures to improve the flotation of
spodumene.
Flotation of Lepidolite, Zinnwaldite
Direct flotation of lepidolite (lithium mica), can be achieved
by using cationic collectors including primary amines, ter-
tiary amines, etheramines and quaternary ammonium salts
(Liu, 2023). The surface charge of lepidolite is negative over
a wide range of pH (Ney 1973), consequently, its flotation
is also typically performed over a wide pH range 2.5–11
with a pulp density of 25% providing optimum results
(Bulatovic, 2015). Choi et al. (2012) obtained optimum
performance at pH 2.7 using a quaternary ammonium salt
as a collector. They, however, observed the pH dependence
of grade and recovery i.e., grade increased while recovery
decreased as pH was decreased. Korbel et al. (2023) deduced
that the observation by Choi et al. may indicate a loss in
selectivity as pH is increased. Ether amines can also be used
effectively as lepidolite collectors. Filippov et al. (2022)
obtained good lithia (Li2O) grade and recovery after using
an ether monoamine they obtained 4.5% Li2O grade and
up to 90% recovery at a total dosage of 165g/t added step-
wise. Sousa et al. (2018) obtained a Li2O grade of 3.56%
and a recovery of 69% using an ether monoamine. Mixed
collectors are also gaining traction as alternatives for the
recovery of lithium. Combinations of cationic and anionic
collectors have been reported especially for lepidolite e.g.,
Zhang and Zhang (2021) where it was found to overcome
excessive foaming.
The exploitation of lithium from hard rock pegma-
tites is primarily from spodumene (LiAlSi2O6) contain-
ing 4.5–8.0% Li2O while petalite (Li,Na)AlSi4O11) with
2.0–4.0% Li2O, lepidolite (KLi1.5Al1.5[Si3AlO10][F,OH]2,
with 1.2–5.9% Li2O, and amblygonite LiAlPO4(F,OH)
with 8–9.5% Li2O also play an important role (Bulatovic,
2015). Other lithium-bearing minerals include zinnwaldite,
eucryptite and other lithium-bearing clays. The benefi-
ciation of lithium-bearing pegmatites is typically done by
physical separation methods that include sorting, dense
media separation, magnetic separation, and froth flotation.
The choice of a flowsheet depends on the mineralogical
properties and the target product grade and recovery. Froth
flotation is the most dominant method to concentrate lith-
ium-bearing minerals, especially spodumene (Bulatovic,
2015, Oliazadeh et al., 2018, Filippov et al., 2019). This
is partly because froth flotation can efficiently handle com-
plex and low-grade ores that require fine grinding and still
achieve high concentrate grades at relatively high recoveries
of lithium when compared to other methods (Menendez
et al., 2004). Consequently, froth flotation is the focus of
this work.
Lithium Flotation
The recovery of lithium-bearing minerals from pegmatites
using froth flotation is complicated by the similarities in
the mineralogy of the gangue minerals (quartz, feldspar,
mica) and the lithium minerals. Both direct and reverse
flotation are typically used to recover lithium resulting in
several flowsheet configurations.
Flotation of Spodumene
Several options can be adopted depending on mineralogy.
Spodumene can be floated directly using anionic collec-
tors, alternatively, cationic collectors are used to float the
gangue minerals while the spodumene concentrate is col-
lected in the tailings (Bulatovic, 2015, Oliazadeh et al.,
2018). The choice of reagent and flotation conditions is
heavily anchored on the mineralogy and process objectives.
Where direct flotation is used, fatty acids at pH 8–9 such as
oleic acid or their salt form e.g., sodium oleate are typically
used especially in academic research. In contrast, TOFAs
are commonly used in industry (Cook and Gibson, 2023).
Sulfonated, and phosphorated fatty acids are also used as
spodumene collectors (Gibson et al., 2017). The success of
these anionic collectors to recover spodumene despite its
overall negative surface charge (isoelectric point (i.e.p) at
pH of 2 (Filippov et al., 2019)) was extensively discussed
by Moon and Fuerstenau (2003). They concluded that the
surface crystal chemistry of spodumene plays a major role
in its selective recovery by sodium oleate when compared
to associated aluminosilicates. This is because it has surface
Al3+ sites whereas those of other aluminosilicates are buried
in the crystallographic unit cell. These Al3+ sites were found
to be favourable for the chemisorption of oleate. Filippov
et al. (2019) also arrived at a similar conclusion. The use of
fatty acids as collectors for spodumene has not been with-
out challenges. Cook and Gibson (2023) summarised these
challenges and they include (i) strong collecting power
but poor selectivity (ii) poor recovery of fine sizes i.e., -
19 microns (e.g., Xu et al. (2016)), (iii) excessive foaming
which may result in poor selectivity and (iv) sensitivity to
pulp temperature and pH which leads to poor selectivity.
Xie et al. (2020) suggested the use of collector mixtures to
overcome some of these although the collectors they dis-
cussed are combinations of cationic and anionic collectors.
As stated previously spodumene can also be upgraded
through reverse flotation where the gangue minerals typi-
cally mica and talc are floated ahead of spodumene using
cationic collectors (amines) at pH 2.5 -3 (Bulatovic, 2015).
In the paper, we will explore the use of proprietary col-
lectors and collector mixtures to improve the flotation of
spodumene.
Flotation of Lepidolite, Zinnwaldite
Direct flotation of lepidolite (lithium mica), can be achieved
by using cationic collectors including primary amines, ter-
tiary amines, etheramines and quaternary ammonium salts
(Liu, 2023). The surface charge of lepidolite is negative over
a wide range of pH (Ney 1973), consequently, its flotation
is also typically performed over a wide pH range 2.5–11
with a pulp density of 25% providing optimum results
(Bulatovic, 2015). Choi et al. (2012) obtained optimum
performance at pH 2.7 using a quaternary ammonium salt
as a collector. They, however, observed the pH dependence
of grade and recovery i.e., grade increased while recovery
decreased as pH was decreased. Korbel et al. (2023) deduced
that the observation by Choi et al. may indicate a loss in
selectivity as pH is increased. Ether amines can also be used
effectively as lepidolite collectors. Filippov et al. (2022)
obtained good lithia (Li2O) grade and recovery after using
an ether monoamine they obtained 4.5% Li2O grade and
up to 90% recovery at a total dosage of 165g/t added step-
wise. Sousa et al. (2018) obtained a Li2O grade of 3.56%
and a recovery of 69% using an ether monoamine. Mixed
collectors are also gaining traction as alternatives for the
recovery of lithium. Combinations of cationic and anionic
collectors have been reported especially for lepidolite e.g.,
Zhang and Zhang (2021) where it was found to overcome
excessive foaming.