3194 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
et al., 2022). The globally growing demand of LIBs gives
more attention of the huge need for the large amounts of
critical valuable metals (Li, Co, Ni, Mn, Cu, Al, Fe), and
anode materials (Zhang et al., 2022).
A LIB is composed of an anode, a cathode, electrolytes,
a separator and an outer shell (Yao et al., 2018). China had
750,000 tonnes of LIBs processed in 2022 (Tong et al.,
2023). The chemical compositions of spent LIBs include
5–7 wt.% of lithium (Li), 5–10 wt.% of nickel (Ni), 5–20
wt.% of cobalt (Co), 5–10 wt.% other metals (copper (Cu),
aluminum (Al), iron (Fe), etc.), 15 wt.% of organic com-
pounds, and 7 wt.% of plastics, which varies slightly with
different manufacturers (Ordoñez et al., 2016). It is notable
that the critical metal content (Li, Ni, and Co) of LIBs are
normally even higher than that in natural ores (Sattar et al.,
2019). Recycling precious metal resources in spent LIBs is
an important pathway to alleviate the current situation of
resource depletion and develop a circular economic path
for LIBs (Jena et al., 2021 Jena et al., 2022). Meanwhile,
the spent LIBs contain toxic materials such as electrolytes,
heavy metals, which poses a special threat to ecosystems
and human health (Zhan et al., 2018). Thus, the recycling
of spent LIBs can respond to the attention on potential
environmental concerns related to their production and
disposal (Peters et al., 2017).
Cathode and anode materials account for about 50%
in the cost composition of LIBs (Wentker et al., 2019).
Graphite materials (natural and synthetic) have occupied
the majority share of the anode materials (Liu et al., 2022).
Cathode materials for the LIB industry can be selected
from LCO (LiCoO2), NCA (Li-Ni-Co-Al), NMC (Li-Ni-
Mn-Co), LFP (LiFePO4) and LMO (LiMn2O4). In gen-
eral, the pristine states of graphite materials and lithium
transition metal oxides are hydrophobic and hydrophilic,
respectively (Nazari et al., 2022). Froth flotation is a physic-
chemical separation process based on the attachment of
hydrophobic particles to air bubbles, and the hydrophobic
particles to sink to the bottom of the flotation cell (Gao
et al., 2023). It is demonstrated that the flotation is effi-
cient to separate lithium metal oxides and graphite materi-
als based on their difference in wettability (Verdugo et al.,
2022). The anode is a composite of graphite materials and
polymer binder which are coated by a Cu foil. Meanwhile,
the cathode consists of carbon powder, polymer binder, and
lithium metal oxides. After the liberation of electrode mate-
rials from metal foils, the presence of the residual organic
binder (e.g., PVDF and CMC/SBR) and electrolyte resi-
dues (with C-C/C-H structures) coatings on the surfaces
of cathode and anode electrode materials in the spent LIBs
leads to the hydrophobic difference of between lithium
metal oxides and graphite materials (Han et al., 2022).
Thus, in conventional flotation, it is difficult to efficiently
separate the cathode and anode particles because of the
entrainment of Li metal oxide particles covered by organic
polymers in the flotation concentrate (Cheng et al., 2022).
Prior to flotation, some treatment methods were pro-
posed to overcome these drawbacks such as Fenton reaction
(He et al., 2017), (cryogenic) grinding (Liu et al., 2020),
attrition (Vanderbruggen et al., 2022), roasting (Nazari et
al., 2023), and pyrolysis (Zhang et al., 2021). Grinding an
environmentally friendly method, while the mechanical
force leads to a low efficiency of removing the organic film
on the surface of the electrode material and a low cathode
purity of flotation product (Vanderbruggen et al., 2022).
The use Liquid nitrogen can further increase the grinding-
flotation separation efficiency, while the cryogenic grinding
device has high cost (Liu et al., 2020). The introduction
of Fe2+ by the “Fenton reaction” method makes the sub-
sequent utilization process of electrode materials more
complex (Vanderbruggen et al., 2022). Heating methods
(including pyrolysis and roasting) with high temperature
poses problems such as high energy consumption, second-
ary pollution of toxic gases generated by organic mem-
brane decomposition, and high equipment costs (Roy et
al., 2022).
Plasma technology is an environment-friendly, and
easy-to-operate surface modification, which is widely used
for the treatments of textile and leather materials (Tudoran
et al., 2020), starch (Okyere et al., 2022), carbon materials
(Huang et al., 2021), polymers (Vesel and Mozetic, 2017),
and wastewater pollutants (Kyere-Yeboah et al., 2023), etc.
Recently, some attempts have been made to enhance the
hydrophobic difference between different materials /min-
erals by plasma treatment, which is help for the improve-
ment in flotation separation selectivity. The plasma surface
modification method was applied to achieve the selec-
tive flotation separation of sulfide ores (Ran et al., 2023),
waste plastics (Zhao et al., 2021), zircon (from oil sands)
(Marshall et al., 2014), and low-rank coal (reverse flota-
tion) (Wang et al., 2018). In addition, the oxidation treat-
ment of non-polar oil by the plasma oxidation method is
efficient to enhance the flotation performance of low-rank
coal (Wang et al., 2019). Discharge power, exposure time
and gas types are the main factors involved in the related
work on applications of plasma treatment in mineral flota-
tion. Furthermore, there is no report on the application of
plasma pretreatment in the modification of surface hydro-
phobicity of electrode materials of spent LIBs.
To fill the gap, differences in the flotation recovery
difference between anode and cathode materials in the
et al., 2022). The globally growing demand of LIBs gives
more attention of the huge need for the large amounts of
critical valuable metals (Li, Co, Ni, Mn, Cu, Al, Fe), and
anode materials (Zhang et al., 2022).
A LIB is composed of an anode, a cathode, electrolytes,
a separator and an outer shell (Yao et al., 2018). China had
750,000 tonnes of LIBs processed in 2022 (Tong et al.,
2023). The chemical compositions of spent LIBs include
5–7 wt.% of lithium (Li), 5–10 wt.% of nickel (Ni), 5–20
wt.% of cobalt (Co), 5–10 wt.% other metals (copper (Cu),
aluminum (Al), iron (Fe), etc.), 15 wt.% of organic com-
pounds, and 7 wt.% of plastics, which varies slightly with
different manufacturers (Ordoñez et al., 2016). It is notable
that the critical metal content (Li, Ni, and Co) of LIBs are
normally even higher than that in natural ores (Sattar et al.,
2019). Recycling precious metal resources in spent LIBs is
an important pathway to alleviate the current situation of
resource depletion and develop a circular economic path
for LIBs (Jena et al., 2021 Jena et al., 2022). Meanwhile,
the spent LIBs contain toxic materials such as electrolytes,
heavy metals, which poses a special threat to ecosystems
and human health (Zhan et al., 2018). Thus, the recycling
of spent LIBs can respond to the attention on potential
environmental concerns related to their production and
disposal (Peters et al., 2017).
Cathode and anode materials account for about 50%
in the cost composition of LIBs (Wentker et al., 2019).
Graphite materials (natural and synthetic) have occupied
the majority share of the anode materials (Liu et al., 2022).
Cathode materials for the LIB industry can be selected
from LCO (LiCoO2), NCA (Li-Ni-Co-Al), NMC (Li-Ni-
Mn-Co), LFP (LiFePO4) and LMO (LiMn2O4). In gen-
eral, the pristine states of graphite materials and lithium
transition metal oxides are hydrophobic and hydrophilic,
respectively (Nazari et al., 2022). Froth flotation is a physic-
chemical separation process based on the attachment of
hydrophobic particles to air bubbles, and the hydrophobic
particles to sink to the bottom of the flotation cell (Gao
et al., 2023). It is demonstrated that the flotation is effi-
cient to separate lithium metal oxides and graphite materi-
als based on their difference in wettability (Verdugo et al.,
2022). The anode is a composite of graphite materials and
polymer binder which are coated by a Cu foil. Meanwhile,
the cathode consists of carbon powder, polymer binder, and
lithium metal oxides. After the liberation of electrode mate-
rials from metal foils, the presence of the residual organic
binder (e.g., PVDF and CMC/SBR) and electrolyte resi-
dues (with C-C/C-H structures) coatings on the surfaces
of cathode and anode electrode materials in the spent LIBs
leads to the hydrophobic difference of between lithium
metal oxides and graphite materials (Han et al., 2022).
Thus, in conventional flotation, it is difficult to efficiently
separate the cathode and anode particles because of the
entrainment of Li metal oxide particles covered by organic
polymers in the flotation concentrate (Cheng et al., 2022).
Prior to flotation, some treatment methods were pro-
posed to overcome these drawbacks such as Fenton reaction
(He et al., 2017), (cryogenic) grinding (Liu et al., 2020),
attrition (Vanderbruggen et al., 2022), roasting (Nazari et
al., 2023), and pyrolysis (Zhang et al., 2021). Grinding an
environmentally friendly method, while the mechanical
force leads to a low efficiency of removing the organic film
on the surface of the electrode material and a low cathode
purity of flotation product (Vanderbruggen et al., 2022).
The use Liquid nitrogen can further increase the grinding-
flotation separation efficiency, while the cryogenic grinding
device has high cost (Liu et al., 2020). The introduction
of Fe2+ by the “Fenton reaction” method makes the sub-
sequent utilization process of electrode materials more
complex (Vanderbruggen et al., 2022). Heating methods
(including pyrolysis and roasting) with high temperature
poses problems such as high energy consumption, second-
ary pollution of toxic gases generated by organic mem-
brane decomposition, and high equipment costs (Roy et
al., 2022).
Plasma technology is an environment-friendly, and
easy-to-operate surface modification, which is widely used
for the treatments of textile and leather materials (Tudoran
et al., 2020), starch (Okyere et al., 2022), carbon materials
(Huang et al., 2021), polymers (Vesel and Mozetic, 2017),
and wastewater pollutants (Kyere-Yeboah et al., 2023), etc.
Recently, some attempts have been made to enhance the
hydrophobic difference between different materials /min-
erals by plasma treatment, which is help for the improve-
ment in flotation separation selectivity. The plasma surface
modification method was applied to achieve the selec-
tive flotation separation of sulfide ores (Ran et al., 2023),
waste plastics (Zhao et al., 2021), zircon (from oil sands)
(Marshall et al., 2014), and low-rank coal (reverse flota-
tion) (Wang et al., 2018). In addition, the oxidation treat-
ment of non-polar oil by the plasma oxidation method is
efficient to enhance the flotation performance of low-rank
coal (Wang et al., 2019). Discharge power, exposure time
and gas types are the main factors involved in the related
work on applications of plasma treatment in mineral flota-
tion. Furthermore, there is no report on the application of
plasma pretreatment in the modification of surface hydro-
phobicity of electrode materials of spent LIBs.
To fill the gap, differences in the flotation recovery
difference between anode and cathode materials in the