3272 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
(Vanderbruggen et al., 2022). Flotation needs a further
liberation of the coating debris and the removal of the
residues of the low volatile organic electrolyte, since the
latter effect the hydrophobicity of the particle surfaces. To
separate the particles of the current collector foils, it is pos-
sible to apply different methods. One option is again the
zig-zag air classifier as the difference of the settling veloci-
ties of the particles is now great enough. Another method
using the settling velocity is the hydro-upstream separation
(Wuschke, 2018). Here, the separation efficiency can even
be higher. However, a drawback is lower throughput and
the additional process water treatment (Kaas et al., 2022b).
Next on, an eddy current separation can be applied to sepa-
rate the aluminum and copper particles from each other
(Gaun and Elwert, 2017).
Flow-Sheet PEM-Electrolyzer
There are established recycling processes for PEM elec-
trolyzers, mainly based on hydro- and pyrometallurgical
processes (Moschovi et al., 2021). More recent approaches
suggest processing via alcohol dissolving of the MEA
(Haque et al., 2023), recovering the electrodes and PFSA
membrane, but a flowsheet focusing on mechanical de-
coating has not yet been described, yet. A possible simpli-
fied flow sheet is shown in Figure 8.
Manual or automatic disassembly first separates the
end plates with the tensioning elements and de-stacks the
bipolar plates and MEAs (Al Assadi et al., 2023). Next, the
porous transport layers must be removed from the coated
membrane so that the electrode layers containing precious
metals are accessible. This can be done also in a second
disassembly step where the layers are peeled off. If this is
not possible, shredding with subsequent sorting of porous
transport layer must be performed.
Since the coated membrane is in the form of a
large polymeric film after removal of the transport lay-
ers (Figure 8), it has to be cut into smaller pieces before
de-coating. A granulator type mill capable of shredding
visco-plastic membranes must be used. The resulting mem-
brane fragments can be liberated from the electrode layers
by mechanical de-coating in a hammer mill as described
above. The resulting products are each shown in an indi-
vidual picture in Figure 8 b).
The de-coated membrane can now be dissolved in an
alcohol-water mixture, cleaned, and then reused as an iono-
mer solution to produce new membranes (Xu et al., 2002).
The electrode powder is further processed in hydrometal-
lurgical processes to recover the catalysts used (Moschovi
et al., 2021).
Flow-Sheet High-Temperature (HT) Electrolyzer
As HT-electrolyzers have just recently reached TRL 8 (IEA,
2023), there are only a few published approaches to recy-
cling as this technology is just starting to be commercialized.
A possible approach for a process chain for the recycling
of HT electrolyzers is shown in Figure 9. HT-electrolyzer
stacks consist of repeating layered components: the elec-
trochemically active cell, metallic interconnects for
Figure 8. Flow-sheet of the recycling process of PEM-electrolyzers with focus on the mechanical recycling steps
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Extracted Text (may have errors)

3272 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
(Vanderbruggen et al., 2022). Flotation needs a further
liberation of the coating debris and the removal of the
residues of the low volatile organic electrolyte, since the
latter effect the hydrophobicity of the particle surfaces. To
separate the particles of the current collector foils, it is pos-
sible to apply different methods. One option is again the
zig-zag air classifier as the difference of the settling veloci-
ties of the particles is now great enough. Another method
using the settling velocity is the hydro-upstream separation
(Wuschke, 2018). Here, the separation efficiency can even
be higher. However, a drawback is lower throughput and
the additional process water treatment (Kaas et al., 2022b).
Next on, an eddy current separation can be applied to sepa-
rate the aluminum and copper particles from each other
(Gaun and Elwert, 2017).
Flow-Sheet PEM-Electrolyzer
There are established recycling processes for PEM elec-
trolyzers, mainly based on hydro- and pyrometallurgical
processes (Moschovi et al., 2021). More recent approaches
suggest processing via alcohol dissolving of the MEA
(Haque et al., 2023), recovering the electrodes and PFSA
membrane, but a flowsheet focusing on mechanical de-
coating has not yet been described, yet. A possible simpli-
fied flow sheet is shown in Figure 8.
Manual or automatic disassembly first separates the
end plates with the tensioning elements and de-stacks the
bipolar plates and MEAs (Al Assadi et al., 2023). Next, the
porous transport layers must be removed from the coated
membrane so that the electrode layers containing precious
metals are accessible. This can be done also in a second
disassembly step where the layers are peeled off. If this is
not possible, shredding with subsequent sorting of porous
transport layer must be performed.
Since the coated membrane is in the form of a
large polymeric film after removal of the transport lay-
ers (Figure 8), it has to be cut into smaller pieces before
de-coating. A granulator type mill capable of shredding
visco-plastic membranes must be used. The resulting mem-
brane fragments can be liberated from the electrode layers
by mechanical de-coating in a hammer mill as described
above. The resulting products are each shown in an indi-
vidual picture in Figure 8 b).
The de-coated membrane can now be dissolved in an
alcohol-water mixture, cleaned, and then reused as an iono-
mer solution to produce new membranes (Xu et al., 2002).
The electrode powder is further processed in hydrometal-
lurgical processes to recover the catalysts used (Moschovi
et al., 2021).
Flow-Sheet High-Temperature (HT) Electrolyzer
As HT-electrolyzers have just recently reached TRL 8 (IEA,
2023), there are only a few published approaches to recy-
cling as this technology is just starting to be commercialized.
A possible approach for a process chain for the recycling
of HT electrolyzers is shown in Figure 9. HT-electrolyzer
stacks consist of repeating layered components: the elec-
trochemically active cell, metallic interconnects for
Figure 8. Flow-sheet of the recycling process of PEM-electrolyzers with focus on the mechanical recycling steps

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