XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3273
spatial separation of the gases, and the electrical connection
between the stages and current collectors for electrical con-
tact with the cell, often using a nickel mesh. The first step in
the process chain is therefore the disassembly, where these
three components are separated. The nickel mesh can be
directly reused as a raw material, while the metal intercon-
nects are reprocessed into stainless steel in a metallurgical
step due to coatings and adhering residues from the cell.
After disassembly, the cells need to be further processed
mechanically because they are made of layered composite
structures. Preferably, the cells are fed directly into a de-
coating process where the perovskites on the anode side
can be selectively liberated and separated with high purity
like described above (Kaiser et al., 2024). Due to the very
small cell thicknesses in the range of only 200 µm in some
cases, coupled with the high brittleness of the cells, they
can break during disassembly (Sarner et al., 2022, Al Assadi
et al., 2023). Handling these broken cell pieces of unpre-
dictable size and shape for ultrasonic de-coating could be a
challenge, as the alignment of the cell with the anode to the
sonotrode is crucial for de-coating. When cell breakage is
unavoidable, additional steps are required for effective recy-
cling. Therefore, the cell pieces are first coarsely crushed
and then sieved at approximately 100 µm. The fine frac-
tion is a mixture of all materials present in the cell, but
is characterized by an enrichment of perovskites. Thus, a
perovskite-enriched fraction can be separated (Figure 9 b)).
The remaining coarse particles are cell particles with a more
homogeneous particle size distribution and shape as well as
a partially intact layer structure. These particles can be de-
coated by ultrasound (Figure 5), as they are moved around
during the ultrasound exposure so that the anode is at least
temporarily aligned with the sonotrode. The de-coated cells
or cell particles are milled to destroy the last material com-
posites between the remaining layers and inside the cath-
ode. Separation, e.g., by magnetic separation, could be used
to separate the nickel from the remaining oxide material.
Figure 9. Flow-sheet of a recycling process for high temperature electrolyzer stacks (HT-stacks) with focus on the mechanical
recycling steps
spatial separation of the gases, and the electrical connection
between the stages and current collectors for electrical con-
tact with the cell, often using a nickel mesh. The first step in
the process chain is therefore the disassembly, where these
three components are separated. The nickel mesh can be
directly reused as a raw material, while the metal intercon-
nects are reprocessed into stainless steel in a metallurgical
step due to coatings and adhering residues from the cell.
After disassembly, the cells need to be further processed
mechanically because they are made of layered composite
structures. Preferably, the cells are fed directly into a de-
coating process where the perovskites on the anode side
can be selectively liberated and separated with high purity
like described above (Kaiser et al., 2024). Due to the very
small cell thicknesses in the range of only 200 µm in some
cases, coupled with the high brittleness of the cells, they
can break during disassembly (Sarner et al., 2022, Al Assadi
et al., 2023). Handling these broken cell pieces of unpre-
dictable size and shape for ultrasonic de-coating could be a
challenge, as the alignment of the cell with the anode to the
sonotrode is crucial for de-coating. When cell breakage is
unavoidable, additional steps are required for effective recy-
cling. Therefore, the cell pieces are first coarsely crushed
and then sieved at approximately 100 µm. The fine frac-
tion is a mixture of all materials present in the cell, but
is characterized by an enrichment of perovskites. Thus, a
perovskite-enriched fraction can be separated (Figure 9 b)).
The remaining coarse particles are cell particles with a more
homogeneous particle size distribution and shape as well as
a partially intact layer structure. These particles can be de-
coated by ultrasound (Figure 5), as they are moved around
during the ultrasound exposure so that the anode is at least
temporarily aligned with the sonotrode. The de-coated cells
or cell particles are milled to destroy the last material com-
posites between the remaining layers and inside the cath-
ode. Separation, e.g., by magnetic separation, could be used
to separate the nickel from the remaining oxide material.
Figure 9. Flow-sheet of a recycling process for high temperature electrolyzer stacks (HT-stacks) with focus on the mechanical
recycling steps