3288 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
plastics also act as a secondary fuel source to the smelting
process. In the smelting reduction zone, depending on the
composition of the feed, the material is smelted into alloys
of copper, nickel, cobalt, and iron becomes distributed to
the metal alloy and slag phase along with lithium, alumi-
num and manganese deport to the slag as oxides (Zhou.et
al.,2020).
A key focus of pyrometallurgical smelting options is
the management of slag chemistry such that the viscosity
is managed so as to maintain a low viscosity. Slag chem-
istry (adjustment of slag basicity) also affects the impurity
distributions between the slag and metal phases This will
allow the fine metal /matte droplets trapped in the slag to
disengage and report to the higher density liquid phase in
the smelter.
Today pyrometallurgical smelting recycling operations
are making use of top submerged lance (TSL) smelting,
electric arc furnaces and induction furnaces, allowing for
the production of either a metal–slag or matte–slag set of
products. Depending on the composition of the feed and
the process specifications, the metal alloy or matte product
can be sold as a secondary material or be further refined via
a hydrometallurgical processing to produce various metal
enriched product. The slag is traditionally used as construc-
tion filler material, e.g., in road construction, concrete,
breeze blocks, plaster sand etc. As a last resort the slag can
be deposited in landfills. The smelting processes produce off
gases, which can contain solids as well as toxic gas such as
carbon dioxide (CO2), dioxins, and furans. There are suffi-
cient mature off gas scrubbing technologies to deal with the
dioxins and furans. The CO2 if present in large enough vol-
umes can be processed to clean the CO2 and compress it for
use in green jet fuels and the production of urea fertilizer.
The pyrometallurgical roasting options include chlori-
nation roasting, sulphate roasting and caustic roasting. The
feed material of this route is black mass from the pre-treated
LIB (shown in Figure 1), which comprises the cathode
material and carbon in the form of fine powders. Unlike the
pyrometallurgical smelting route, where the lithium is lost
in slag, the roasting options followed by hydrometallurgical
option, such as water leach, provides an effective approach
to recover lithium from the spent LIBs. The pyrometallur-
gical roasting processing can also be utilized alone to pro-
duce intermediate products instead of final products, which
are subsequently refined by hydrometallurgical processes.
HYDROMETALLURGICAL PROCESSES
Hydrometallurgical process involves the use of aqueous
solutions to extract the desired metals from cathode mate-
rial. Currently, the favored option is to directly process
active material concentrates with a combination of mul-
tiple hydrometallurgical unit operations.
Figure 2 illustrates the various hydrometallurgical pro-
cessing routes for different LIB chemistries.
The processing can be subdivided into leaching, sol-
vent extraction, precipitation, purification, and recovering
of the metal salts. Various organic and inorganic acids have
been trialed as solvents often mixed with reducing agents to
increase the recovery rate.
Once dissolved, the metals are extracted from the sol-
vent by liquid–liquid extraction, ion exchange, or chemical
precipitation. If the resulting metal salts meet the quality
requirements of the corresponding raw materials, subse-
quent recovery can be forgone. Otherwise, further pre-
cipitation, crystallization, or electrochemical processes such
as extraction electrolysis or electro winning are used. The
metal compounds or impurities are separated selectively or
deposited on electrodes, respectively.
Hydrometallurgical processes require material prepara-
tion and size control provided by manual dismantling and/
or liberation and separation. The particle size distribution
and material composition are significantly influenced by
the type of processing, which in turn determines the met-
allurgical process and yield of recyclable materials. Other
impurities are residues of organic solvents, which influence
the pH value of the solution and the performance of other
solvent based processes. Therefore, these impurities have to
be considered in the design stage of hydrometallurgical pro-
cesses as well.
Typically hydrometallurgical processes require strong
inorganic acids and expensive additives producing consid-
erable amounts of waste liquids and harmful or toxic emis-
sions. In contrast, metals from the cathode coating can be
recovered in an energy efficient and selective way. A new
stream of leaching agents is the use of deep eutectic solvents
(DES) which will be discussed further in the paper.
The leaching reagent suite comprises an acid solution
(inorganic/mineral or organic) often coupled with a reduc-
ing agent (e.g., H2O2, NaHSO3, glucose, citric acid, etc.).
As an example Li+ is easily leached in solution with its effi-
ciency strongly correlated with the acidic strength (i.e., dis-
placement of Li+ with H+ )to induce solubilization (Or et
al., 2019).
However, cathode transition metals have low solu-
bilities as they exist in +3/+4 valence states in discharged
cathodes and are difficult to leach due to the strong M–O
bonds.
The reductant aids leaching by reducing the metals
toward a divalent state (M2+), which is critical in achiev-
ing high leaching efficiencies (95%), especially for Co and
plastics also act as a secondary fuel source to the smelting
process. In the smelting reduction zone, depending on the
composition of the feed, the material is smelted into alloys
of copper, nickel, cobalt, and iron becomes distributed to
the metal alloy and slag phase along with lithium, alumi-
num and manganese deport to the slag as oxides (Zhou.et
al.,2020).
A key focus of pyrometallurgical smelting options is
the management of slag chemistry such that the viscosity
is managed so as to maintain a low viscosity. Slag chem-
istry (adjustment of slag basicity) also affects the impurity
distributions between the slag and metal phases This will
allow the fine metal /matte droplets trapped in the slag to
disengage and report to the higher density liquid phase in
the smelter.
Today pyrometallurgical smelting recycling operations
are making use of top submerged lance (TSL) smelting,
electric arc furnaces and induction furnaces, allowing for
the production of either a metal–slag or matte–slag set of
products. Depending on the composition of the feed and
the process specifications, the metal alloy or matte product
can be sold as a secondary material or be further refined via
a hydrometallurgical processing to produce various metal
enriched product. The slag is traditionally used as construc-
tion filler material, e.g., in road construction, concrete,
breeze blocks, plaster sand etc. As a last resort the slag can
be deposited in landfills. The smelting processes produce off
gases, which can contain solids as well as toxic gas such as
carbon dioxide (CO2), dioxins, and furans. There are suffi-
cient mature off gas scrubbing technologies to deal with the
dioxins and furans. The CO2 if present in large enough vol-
umes can be processed to clean the CO2 and compress it for
use in green jet fuels and the production of urea fertilizer.
The pyrometallurgical roasting options include chlori-
nation roasting, sulphate roasting and caustic roasting. The
feed material of this route is black mass from the pre-treated
LIB (shown in Figure 1), which comprises the cathode
material and carbon in the form of fine powders. Unlike the
pyrometallurgical smelting route, where the lithium is lost
in slag, the roasting options followed by hydrometallurgical
option, such as water leach, provides an effective approach
to recover lithium from the spent LIBs. The pyrometallur-
gical roasting processing can also be utilized alone to pro-
duce intermediate products instead of final products, which
are subsequently refined by hydrometallurgical processes.
HYDROMETALLURGICAL PROCESSES
Hydrometallurgical process involves the use of aqueous
solutions to extract the desired metals from cathode mate-
rial. Currently, the favored option is to directly process
active material concentrates with a combination of mul-
tiple hydrometallurgical unit operations.
Figure 2 illustrates the various hydrometallurgical pro-
cessing routes for different LIB chemistries.
The processing can be subdivided into leaching, sol-
vent extraction, precipitation, purification, and recovering
of the metal salts. Various organic and inorganic acids have
been trialed as solvents often mixed with reducing agents to
increase the recovery rate.
Once dissolved, the metals are extracted from the sol-
vent by liquid–liquid extraction, ion exchange, or chemical
precipitation. If the resulting metal salts meet the quality
requirements of the corresponding raw materials, subse-
quent recovery can be forgone. Otherwise, further pre-
cipitation, crystallization, or electrochemical processes such
as extraction electrolysis or electro winning are used. The
metal compounds or impurities are separated selectively or
deposited on electrodes, respectively.
Hydrometallurgical processes require material prepara-
tion and size control provided by manual dismantling and/
or liberation and separation. The particle size distribution
and material composition are significantly influenced by
the type of processing, which in turn determines the met-
allurgical process and yield of recyclable materials. Other
impurities are residues of organic solvents, which influence
the pH value of the solution and the performance of other
solvent based processes. Therefore, these impurities have to
be considered in the design stage of hydrometallurgical pro-
cesses as well.
Typically hydrometallurgical processes require strong
inorganic acids and expensive additives producing consid-
erable amounts of waste liquids and harmful or toxic emis-
sions. In contrast, metals from the cathode coating can be
recovered in an energy efficient and selective way. A new
stream of leaching agents is the use of deep eutectic solvents
(DES) which will be discussed further in the paper.
The leaching reagent suite comprises an acid solution
(inorganic/mineral or organic) often coupled with a reduc-
ing agent (e.g., H2O2, NaHSO3, glucose, citric acid, etc.).
As an example Li+ is easily leached in solution with its effi-
ciency strongly correlated with the acidic strength (i.e., dis-
placement of Li+ with H+ )to induce solubilization (Or et
al., 2019).
However, cathode transition metals have low solu-
bilities as they exist in +3/+4 valence states in discharged
cathodes and are difficult to leach due to the strong M–O
bonds.
The reductant aids leaching by reducing the metals
toward a divalent state (M2+), which is critical in achiev-
ing high leaching efficiencies (95%), especially for Co and