XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1555
for “early gangue rejection.” Early gangue rejection involves
pre-concentration processing step designed to remove
gangue minerals in the early stage of minerals beneficia-
tion processes. This concept has significant benefits includ-
ing reduction in energy requirement in the comminution
process, provision of ‘rich’ feed/concentrate to downstream
processes at lower ore throughput with its associated han-
dling and operating cost benefits (G. B. Abaka-Wood et al.,
2022 Chen &Yin, 2022 Lessard et al., 2014 Shi et al.,
2015).
Essentially, spodumene separation is characterized by
multistage processes, due to similarities in the physical and
physicochemical properties of the spodumene and its asso-
ciated gangue minerals (Gibson et al., 2021). Typically, a
combination of gravity separation, magnetic separation,
de-sliming, and flotation processes are employed in spod-
umene beneficiation flowsheets. The selection of the unit
operations is dictated by the mineralogical composition
and characteristics of the ore. In the present study de-slim-
ing and magnetic separation processes may not be needed
due to the grain size and mineralogical composition of the
ore. Specifically, the absence of iron oxides or zinnwaldite
suggest that magnetic separation may not be beneficial in
processing the ore. Zinnwaldite is a lithium bearing min-
eral which has a very high magnetic susceptibility due to its
high iron content, making it amenable to magnetic benefi-
ciation (G. Abaka-Wood et al., 2022 Tadesse et al., 2019).
Gravity Separation
With silicate minerals making up the bulk of the ore and
occupying over 60% of the total mass, it is crucial to use
gravity separation methods to recover and upgrade spodu-
mene for subsequent lithium extraction. Promising results
have been reported for gravity separation studies carried
out on different lithium ores. Spodumene is slightly heavier
as compared to silicate gangue minerals in the ore includ-
ing quartz (2.65), feldspars (2.6), and micas (2.8–3.0).
Two possible spodumene gravity concentration routes may
be employed: (i) dense media separation (DMS) at coarse
grain size and (ii) knelson concentration after “controlled
milling” process. At such coarse grain size, gravity con-
centration via dense media separation may be employed
to recover and upgrade spodumene. Previous studies by
(Gibson et al., 2021) and (Kundu et al., 2023) have shown
that DMS is an effective preconcentration method for
rejecting silicate gangue minerals in spodumene benefi-
ciation. Bromoform (sg =2.89) and methyl iodide (sg =
2.28) are mainly used in heavy liquid separation (HLS) or
DMS process to recover spodumene (Gibson et al., 2021
Tadesse et al., 2019). However, DMS is not suitable for
ores wherein spodumene is finely disseminated and form
complex middlings with gangue minerals. Such ores require
aggressive comminution to generate a finer liberation size
to maximize the recovery of valuable spodumene minerals
from its associated gangues by adopting the froth flotation
technique (Kundu et al., 2023b).
With spodumene mainly liberated in the ore, con-
trolled milling may be considered to produce desired feed
particle size for subsequent processing via the knelson con-
centrator. The concept of controlled milling is to ensure
that ore particle reduction is achieved without producing
excessively fine/ultrafine particles in the process. Fine/
ultrafine particles tend to form slimes which have nega-
tive impacts on downstream beneficiation processes such as
gravity separation and froth flotation.
Froth Flotation
It is well documented in the literature that froth flotation is
the most widely accepted and proven practice of processing
spodumene. Froth flotation exploits the differences in the
physico-chemical properties of spodumene and its associ-
ated silicate gangue minerals. The process offers superior
performance in most cases producing higher-grade con-
centrates, which has made the process popular and con-
sequently a better option compared with DMS technique
(Kundu et al., 2023b). There are two possible spodumene
flotation routes: direct flotation with anionic collectors or
reverse flotation using cationic collectors. Typically, con-
centrates generated from DMS could further be processed
via froth flotation process (Tadesse et al., 2019). It is worth
noting that direct flotation is the common and preferred
option, where spodumene is recovered into the concen-
trate, whereas the gangue minerals are depressed as tailings.
Oleic acid, sodium oleate, and sulphonated and phospho-
rated fatty acids are common anionic collectors used in
the process, whereas sodium silicate, starch, and CMC are
used as depressants (Kundu et al., 2023b). On the other
hand, reverse flotation technique employs cationic col-
lectors including dodecyl amine-hydrochloride, dodecyl
trimethyl ammonium chloride (DTAC), and dodecylam-
ine (DDA) to recover the silicate gangue minerals (mica,
quartz, felspar) associated with spodumene (Luo et al.,
2022 Xu et al., 2016). To achieve the desired results in the
flotation process, controlled grinding is required to minize
slime production which could promote entarinment recov-
ery of undesired minerals into the concentrate. This could
decrease the concentrate grade thus requiring further pro-
cessing such as desliming.
for “early gangue rejection.” Early gangue rejection involves
pre-concentration processing step designed to remove
gangue minerals in the early stage of minerals beneficia-
tion processes. This concept has significant benefits includ-
ing reduction in energy requirement in the comminution
process, provision of ‘rich’ feed/concentrate to downstream
processes at lower ore throughput with its associated han-
dling and operating cost benefits (G. B. Abaka-Wood et al.,
2022 Chen &Yin, 2022 Lessard et al., 2014 Shi et al.,
2015).
Essentially, spodumene separation is characterized by
multistage processes, due to similarities in the physical and
physicochemical properties of the spodumene and its asso-
ciated gangue minerals (Gibson et al., 2021). Typically, a
combination of gravity separation, magnetic separation,
de-sliming, and flotation processes are employed in spod-
umene beneficiation flowsheets. The selection of the unit
operations is dictated by the mineralogical composition
and characteristics of the ore. In the present study de-slim-
ing and magnetic separation processes may not be needed
due to the grain size and mineralogical composition of the
ore. Specifically, the absence of iron oxides or zinnwaldite
suggest that magnetic separation may not be beneficial in
processing the ore. Zinnwaldite is a lithium bearing min-
eral which has a very high magnetic susceptibility due to its
high iron content, making it amenable to magnetic benefi-
ciation (G. Abaka-Wood et al., 2022 Tadesse et al., 2019).
Gravity Separation
With silicate minerals making up the bulk of the ore and
occupying over 60% of the total mass, it is crucial to use
gravity separation methods to recover and upgrade spodu-
mene for subsequent lithium extraction. Promising results
have been reported for gravity separation studies carried
out on different lithium ores. Spodumene is slightly heavier
as compared to silicate gangue minerals in the ore includ-
ing quartz (2.65), feldspars (2.6), and micas (2.8–3.0).
Two possible spodumene gravity concentration routes may
be employed: (i) dense media separation (DMS) at coarse
grain size and (ii) knelson concentration after “controlled
milling” process. At such coarse grain size, gravity con-
centration via dense media separation may be employed
to recover and upgrade spodumene. Previous studies by
(Gibson et al., 2021) and (Kundu et al., 2023) have shown
that DMS is an effective preconcentration method for
rejecting silicate gangue minerals in spodumene benefi-
ciation. Bromoform (sg =2.89) and methyl iodide (sg =
2.28) are mainly used in heavy liquid separation (HLS) or
DMS process to recover spodumene (Gibson et al., 2021
Tadesse et al., 2019). However, DMS is not suitable for
ores wherein spodumene is finely disseminated and form
complex middlings with gangue minerals. Such ores require
aggressive comminution to generate a finer liberation size
to maximize the recovery of valuable spodumene minerals
from its associated gangues by adopting the froth flotation
technique (Kundu et al., 2023b).
With spodumene mainly liberated in the ore, con-
trolled milling may be considered to produce desired feed
particle size for subsequent processing via the knelson con-
centrator. The concept of controlled milling is to ensure
that ore particle reduction is achieved without producing
excessively fine/ultrafine particles in the process. Fine/
ultrafine particles tend to form slimes which have nega-
tive impacts on downstream beneficiation processes such as
gravity separation and froth flotation.
Froth Flotation
It is well documented in the literature that froth flotation is
the most widely accepted and proven practice of processing
spodumene. Froth flotation exploits the differences in the
physico-chemical properties of spodumene and its associ-
ated silicate gangue minerals. The process offers superior
performance in most cases producing higher-grade con-
centrates, which has made the process popular and con-
sequently a better option compared with DMS technique
(Kundu et al., 2023b). There are two possible spodumene
flotation routes: direct flotation with anionic collectors or
reverse flotation using cationic collectors. Typically, con-
centrates generated from DMS could further be processed
via froth flotation process (Tadesse et al., 2019). It is worth
noting that direct flotation is the common and preferred
option, where spodumene is recovered into the concen-
trate, whereas the gangue minerals are depressed as tailings.
Oleic acid, sodium oleate, and sulphonated and phospho-
rated fatty acids are common anionic collectors used in
the process, whereas sodium silicate, starch, and CMC are
used as depressants (Kundu et al., 2023b). On the other
hand, reverse flotation technique employs cationic col-
lectors including dodecyl amine-hydrochloride, dodecyl
trimethyl ammonium chloride (DTAC), and dodecylam-
ine (DDA) to recover the silicate gangue minerals (mica,
quartz, felspar) associated with spodumene (Luo et al.,
2022 Xu et al., 2016). To achieve the desired results in the
flotation process, controlled grinding is required to minize
slime production which could promote entarinment recov-
ery of undesired minerals into the concentrate. This could
decrease the concentrate grade thus requiring further pro-
cessing such as desliming.