3268 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
For electrolyzers, the manual or automated disassembly
aims at the re-use of components, e.g., the bipolar plates,
since the life times of the catalytic material is supposed to
be significantly shorter than that of the more robust com-
ponents of the stacks. After manual or automated disassem-
bly of the setups to mechanical processing can be applied,
which starts with a liberation comminution of the mem-
brane electrode assemblies (MEA) of electrolyzers, of the
cells or smaller modules of batteries respectively.
Legislative boundary conditions
The legislation in several countries acts to make secondary
materials from batteries a tradable good. This includes a
material passport, which allows to trace the (critical) mate-
rials of a battery over the entire life cycle. With the 2023
battery directive the EU is on the forefront of regulations to
drive battery recycling. This directive defines both recycling
rates for individual (critical) elements as well as mandatory
direct reuse rates for individual elements i.e., a certain per-
centage e.g., 15% of nickel (Ni). has come from recycling
by 2031 in new batteries. This framework aims at stimulat-
ing a real circular economy. The electrolyzers are still out-
side of material specific recycling regulations, but the mere
material value, especially regarding the platinum group
metals (PGM) drives already the recycling effort. Here we
are speaking of recycling rates above 99% for Pt, Ir and Ru.
1st Comminution/Liberation Step
Shredding of Battery Cells
Li-ion battery cells are typically crushed by rotary shears
(Diekmann et al., 2018). Tearing and shearing forces are
applied to open up the cells and to liberate the individual
components from each other (Werner et al., 2020). The
crushing can be done in 1 or 2 crushing steps (Diekmann
et al., 2018). The size of the crushing product is controlled
by a discharge grid underneath the crusher. Wuschke et al.
(Wuschke et al., 2019) showed that a maximum grid of
30 mm should be used to have a sufficient liberation for
the subsequent separation step. Figure 1 shows rotor shears
applied for the first (a) and second (c) crushing step and
their crushing products (b and d). Four particle size distri-
butions of crushing products are shown in Figure 2. The
size distributions vary depending of the durability of the
coating of the electrode foils, since the de-coating efficiency
determines the share of particles smaller than 1 mm (Wilke
et al., 2023a).
The use of new battery materials, such as solid-state
electrolytes (SSE), presents several additional challenges.
Polymer-based SSEs can be challenging to separate from
current collectors in dry processes due to their flexibility and
adhesive properties (Azhari et al., 2020, Wu et al., 2023).
Therefore, it is necessary to adapt or extend the processes
developed for conventional LIB accordingly. Thermal pro-
cesses can burn the polymer electrolyte, allowing for further
processing of the exposed materials, but resulting in the loss
of the polymer solid electrolyte (Doose et al., 2021, Wu et
al., 2023). Alternatively, complex wet-chemical processes
can be employed. The electrolyte is dissolved in a suit-
able solvent, and the polymer can be recovered during the
process (Azhari et al., 2020, Doose et al., 2021, Wu et al.,
2023). This example demonstrates that recycling processes
for conventional LIBs cannot be directly applied to cells
with solid-state electrolytes because of their unique chemi-
cal and material properties (Schwich et al., 2020).
Comminution of MEA of PEM-electrolyzers
Comminution tests are performed to recover the precious
metal catalysts from the coated PEM, the coated catalyst
membrane (CCM), which is the core of the MEA. Due to
the limited availability of MEA and the low thickness of
the component resulting in a low surface weight of about
40 mg/cm2, the tests have to be performed on the smallest
scale. The hammer mill on the machine platform Picoline
(Hosokawa Alpine, Germany) is suitable for grinding less
than 100 mg due to its small grinding chamber diameter
of 4 cm, easy access to the grinding chamber for effective
cleaning, and adjustable discharge screen. A labeled image
of the hammer mill is shown in Figure 3 a).
Figure 1. a) Rotor shear for 1st crushing step, b) Product after 1st crushing step, c) Rotor shear for 2nd crushing step, d)
product after 2nd crushing step (© TUBAF)
For electrolyzers, the manual or automated disassembly
aims at the re-use of components, e.g., the bipolar plates,
since the life times of the catalytic material is supposed to
be significantly shorter than that of the more robust com-
ponents of the stacks. After manual or automated disassem-
bly of the setups to mechanical processing can be applied,
which starts with a liberation comminution of the mem-
brane electrode assemblies (MEA) of electrolyzers, of the
cells or smaller modules of batteries respectively.
Legislative boundary conditions
The legislation in several countries acts to make secondary
materials from batteries a tradable good. This includes a
material passport, which allows to trace the (critical) mate-
rials of a battery over the entire life cycle. With the 2023
battery directive the EU is on the forefront of regulations to
drive battery recycling. This directive defines both recycling
rates for individual (critical) elements as well as mandatory
direct reuse rates for individual elements i.e., a certain per-
centage e.g., 15% of nickel (Ni). has come from recycling
by 2031 in new batteries. This framework aims at stimulat-
ing a real circular economy. The electrolyzers are still out-
side of material specific recycling regulations, but the mere
material value, especially regarding the platinum group
metals (PGM) drives already the recycling effort. Here we
are speaking of recycling rates above 99% for Pt, Ir and Ru.
1st Comminution/Liberation Step
Shredding of Battery Cells
Li-ion battery cells are typically crushed by rotary shears
(Diekmann et al., 2018). Tearing and shearing forces are
applied to open up the cells and to liberate the individual
components from each other (Werner et al., 2020). The
crushing can be done in 1 or 2 crushing steps (Diekmann
et al., 2018). The size of the crushing product is controlled
by a discharge grid underneath the crusher. Wuschke et al.
(Wuschke et al., 2019) showed that a maximum grid of
30 mm should be used to have a sufficient liberation for
the subsequent separation step. Figure 1 shows rotor shears
applied for the first (a) and second (c) crushing step and
their crushing products (b and d). Four particle size distri-
butions of crushing products are shown in Figure 2. The
size distributions vary depending of the durability of the
coating of the electrode foils, since the de-coating efficiency
determines the share of particles smaller than 1 mm (Wilke
et al., 2023a).
The use of new battery materials, such as solid-state
electrolytes (SSE), presents several additional challenges.
Polymer-based SSEs can be challenging to separate from
current collectors in dry processes due to their flexibility and
adhesive properties (Azhari et al., 2020, Wu et al., 2023).
Therefore, it is necessary to adapt or extend the processes
developed for conventional LIB accordingly. Thermal pro-
cesses can burn the polymer electrolyte, allowing for further
processing of the exposed materials, but resulting in the loss
of the polymer solid electrolyte (Doose et al., 2021, Wu et
al., 2023). Alternatively, complex wet-chemical processes
can be employed. The electrolyte is dissolved in a suit-
able solvent, and the polymer can be recovered during the
process (Azhari et al., 2020, Doose et al., 2021, Wu et al.,
2023). This example demonstrates that recycling processes
for conventional LIBs cannot be directly applied to cells
with solid-state electrolytes because of their unique chemi-
cal and material properties (Schwich et al., 2020).
Comminution of MEA of PEM-electrolyzers
Comminution tests are performed to recover the precious
metal catalysts from the coated PEM, the coated catalyst
membrane (CCM), which is the core of the MEA. Due to
the limited availability of MEA and the low thickness of
the component resulting in a low surface weight of about
40 mg/cm2, the tests have to be performed on the smallest
scale. The hammer mill on the machine platform Picoline
(Hosokawa Alpine, Germany) is suitable for grinding less
than 100 mg due to its small grinding chamber diameter
of 4 cm, easy access to the grinding chamber for effective
cleaning, and adjustable discharge screen. A labeled image
of the hammer mill is shown in Figure 3 a).
Figure 1. a) Rotor shear for 1st crushing step, b) Product after 1st crushing step, c) Rotor shear for 2nd crushing step, d)
product after 2nd crushing step (© TUBAF)