XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2211
and refining stages of the concentrate (Forbes et al., 2024
Moslemi &Gharabaghi, 2017).
Flotation is a remarkable mineral processing method
employed for the selective separation of valuable minerals
from gangue minerals (Bilal et al., 2022 Tang et al., 2023).
In copper flotation plants, the typical approach involves
the recovery of copper-bearing minerals during the rougher
stage, followed either by additional elimination of iron sul-
fides at the cleaner stage or rougher concentrate cleaning
following regrinding (Castellón et al., 2022). Pyrite, along
with other gangue minerals is transferred to the tailing
stream. Copper-bearing minerals are separated from pyrite
using selective collectors: xanthates, dithiophosphates, fatty
acids, etc, and depressants at pH 11–12.5 (Castellón et al.,
2022 Mu et al., 2016).
Critical elements such as bismuth (Bi), selenium (Se),
antimony (Sb) gallium (Ga), germanium (Ge), indium (In),
and tellurium (Te) inherently exist within sulfide minerals
in the form of micron or submicron inclusions (Benites et
al., 2021 Steadman et al., 2021 Liu et al., 2019 Sahlström
et al., 2017 Altun, 2010). During the processing of copper
sulfide ores, a potential exists for an augmentation in the
concentration of these critical minerals, or conversely, their
loss to the tailings (Corchado-Albelo, 2023 2024 Nakhaei
at al., 2024). Pyrite in flotation tailings is a primary carrier
of some precious metals (gold and silver) and critical ele-
ments such as Te.
Tellurium is a critical element as listed by the
Department of Energy in the US, as it plays a significant
role in clean solar energy systems. Te is used in combination
with cadmium to produce cadmium telluride semiconduc-
tors used in the manufacturing of solar panels (Corchado-
Albelo, 2023 Makuei &Senanayake, 2018). Recent
mineralogical studies have revealed that the pyrite in the
tailings generated during porphyry copper flotation is the
main host of Te which is present in form of telluride inclu-
sions in pyrite (Corchado-Albelo, 2023 Nakhaei at al.,
2024). Moreover, Nassar et al., (2022) showed that almost
90% of the Te is lost to the tailings during the copper flota-
tion process. Despite this loss, these sources currently make
only a minor contribution to the overall global Te supply.
Addressing both the supply risk of Te, and the prob-
lem of tailing pollution via acid mine drainage requires the
development of viable, efficient, and cost-effective technol-
ogies for Te recovery from pyrite in mine tailings, specially
tellurides that are hosted within pyrite minerals. Therefore,
this review aims to provide a comprehensive understand-
ing of the mechanisms of pyrite flotation and discusses
the existing technologies that are suitable for the recovery
of pyrite from tailings generated by sulfide ore processing
operations.
PROPERTIES, STRUCTURE, AND
CHEMICAL COMPOSITION OF PYRITE
Pyrite, a naturally occurring iron disulfide (FeS2), is the
most common sulfide gangue mineral in the Earth’s crust
and is found in hydrothermal veins, igneous, sedimentary,
or metamorphic rocks, and is usually associated with other
sulfides or oxide minerals (Can et al., 2021). Additionally,
it is present in coal reserves as a major sulfur source. In
some cases, pyrite is concentrated to recover valuable metals
(e.g., Au) associated with it (Abraitis et al., 2004 Bicak et
al., 2007 Güler et al., 2009).
Pyrite consists of a face-centered cubic lattice of iron
atoms embedded with sulfur ions (Dos Santos et al., 2017).
The iron atoms are surrounded closely by six sulfur atoms,
creating a distorted octahedral shape, and despite its chemi-
cal formula, the iron in pyrite exists as low-spin divalent
iron due to the arrangement of sulfur ions that alters the
electronic structure (Chen et al., 2020). Pyrite exhibits
diamagnetic and semiconducting properties attributed to
the combination of low-spin iron and the closed electron
shells of sulfur ions (Chen et al., 2020). A notable feature of
pyrite is the absence of a center of inversion at sulfur sites,
influencing its crystallographic and physical properties
(Chen et al., 2020). This absence leads to the crystal elec-
tric field effect, polarizing the sulfur ions within the lattice
and contributing to pyrite’s unique characteristics. Moreso,
depending on the ore genesis, the iron (Fe) atoms in the
pyrite crystal lattice can be substituted by other elements,
nickel (Ni), cobalt (Co), lead (Pb), gold (Au) and arsenic
(As) which add to its variable behavior (Can et al., 2021).
Pyrite is a chemically active mineral and can easily be
oxidized despite having the highest rest potential of all the
sulfides (Dos Santos et al., 2017). Therefore, zeta potential
of pyrite changes depending on the surface state: isoelectric
point (iep) of unoxidized pyrite is typically around pH=2.
However, it has been measured at around pH= 6.4 in
various research studies, a deviation attributed to surface
oxidation. (Fuerstenau et al., 2009). Güler et al., (2009)
confirmed that pyrite undergoes oxidation in an electro-
chemically active flotation pulp leading to its surface being
covered with ferric species. Research has also shown that
the, iep of ferric species ranges between 5.2 and 8.6 (Parks,
1965) justifying shifting of the iep to higher pH ranges.
Pyrite is widely variable in terms of its properties, and
as such this variability has been shown to affect both its
electrochemical properties and behavior during flotation
(Jefferson et al., 2023 Moslemi &Gharabaghi, 2017).
and refining stages of the concentrate (Forbes et al., 2024
Moslemi &Gharabaghi, 2017).
Flotation is a remarkable mineral processing method
employed for the selective separation of valuable minerals
from gangue minerals (Bilal et al., 2022 Tang et al., 2023).
In copper flotation plants, the typical approach involves
the recovery of copper-bearing minerals during the rougher
stage, followed either by additional elimination of iron sul-
fides at the cleaner stage or rougher concentrate cleaning
following regrinding (Castellón et al., 2022). Pyrite, along
with other gangue minerals is transferred to the tailing
stream. Copper-bearing minerals are separated from pyrite
using selective collectors: xanthates, dithiophosphates, fatty
acids, etc, and depressants at pH 11–12.5 (Castellón et al.,
2022 Mu et al., 2016).
Critical elements such as bismuth (Bi), selenium (Se),
antimony (Sb) gallium (Ga), germanium (Ge), indium (In),
and tellurium (Te) inherently exist within sulfide minerals
in the form of micron or submicron inclusions (Benites et
al., 2021 Steadman et al., 2021 Liu et al., 2019 Sahlström
et al., 2017 Altun, 2010). During the processing of copper
sulfide ores, a potential exists for an augmentation in the
concentration of these critical minerals, or conversely, their
loss to the tailings (Corchado-Albelo, 2023 2024 Nakhaei
at al., 2024). Pyrite in flotation tailings is a primary carrier
of some precious metals (gold and silver) and critical ele-
ments such as Te.
Tellurium is a critical element as listed by the
Department of Energy in the US, as it plays a significant
role in clean solar energy systems. Te is used in combination
with cadmium to produce cadmium telluride semiconduc-
tors used in the manufacturing of solar panels (Corchado-
Albelo, 2023 Makuei &Senanayake, 2018). Recent
mineralogical studies have revealed that the pyrite in the
tailings generated during porphyry copper flotation is the
main host of Te which is present in form of telluride inclu-
sions in pyrite (Corchado-Albelo, 2023 Nakhaei at al.,
2024). Moreover, Nassar et al., (2022) showed that almost
90% of the Te is lost to the tailings during the copper flota-
tion process. Despite this loss, these sources currently make
only a minor contribution to the overall global Te supply.
Addressing both the supply risk of Te, and the prob-
lem of tailing pollution via acid mine drainage requires the
development of viable, efficient, and cost-effective technol-
ogies for Te recovery from pyrite in mine tailings, specially
tellurides that are hosted within pyrite minerals. Therefore,
this review aims to provide a comprehensive understand-
ing of the mechanisms of pyrite flotation and discusses
the existing technologies that are suitable for the recovery
of pyrite from tailings generated by sulfide ore processing
operations.
PROPERTIES, STRUCTURE, AND
CHEMICAL COMPOSITION OF PYRITE
Pyrite, a naturally occurring iron disulfide (FeS2), is the
most common sulfide gangue mineral in the Earth’s crust
and is found in hydrothermal veins, igneous, sedimentary,
or metamorphic rocks, and is usually associated with other
sulfides or oxide minerals (Can et al., 2021). Additionally,
it is present in coal reserves as a major sulfur source. In
some cases, pyrite is concentrated to recover valuable metals
(e.g., Au) associated with it (Abraitis et al., 2004 Bicak et
al., 2007 Güler et al., 2009).
Pyrite consists of a face-centered cubic lattice of iron
atoms embedded with sulfur ions (Dos Santos et al., 2017).
The iron atoms are surrounded closely by six sulfur atoms,
creating a distorted octahedral shape, and despite its chemi-
cal formula, the iron in pyrite exists as low-spin divalent
iron due to the arrangement of sulfur ions that alters the
electronic structure (Chen et al., 2020). Pyrite exhibits
diamagnetic and semiconducting properties attributed to
the combination of low-spin iron and the closed electron
shells of sulfur ions (Chen et al., 2020). A notable feature of
pyrite is the absence of a center of inversion at sulfur sites,
influencing its crystallographic and physical properties
(Chen et al., 2020). This absence leads to the crystal elec-
tric field effect, polarizing the sulfur ions within the lattice
and contributing to pyrite’s unique characteristics. Moreso,
depending on the ore genesis, the iron (Fe) atoms in the
pyrite crystal lattice can be substituted by other elements,
nickel (Ni), cobalt (Co), lead (Pb), gold (Au) and arsenic
(As) which add to its variable behavior (Can et al., 2021).
Pyrite is a chemically active mineral and can easily be
oxidized despite having the highest rest potential of all the
sulfides (Dos Santos et al., 2017). Therefore, zeta potential
of pyrite changes depending on the surface state: isoelectric
point (iep) of unoxidized pyrite is typically around pH=2.
However, it has been measured at around pH= 6.4 in
various research studies, a deviation attributed to surface
oxidation. (Fuerstenau et al., 2009). Güler et al., (2009)
confirmed that pyrite undergoes oxidation in an electro-
chemically active flotation pulp leading to its surface being
covered with ferric species. Research has also shown that
the, iep of ferric species ranges between 5.2 and 8.6 (Parks,
1965) justifying shifting of the iep to higher pH ranges.
Pyrite is widely variable in terms of its properties, and
as such this variability has been shown to affect both its
electrochemical properties and behavior during flotation
(Jefferson et al., 2023 Moslemi &Gharabaghi, 2017).