XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3269
For the feasibility study, circles with a diameter of about
5 mm were punched out of the MEAs and subjected to dif-
ferent stressing speeds in the hammer mill with a discharge
screen diameter of 1 mm. The products of the comminu-
tion process are membrane fragments, which are torn and
de-coated to varying degrees depending on the stressing
rate, and an electrode powder containing precious metals.
Due to the low feed quantities too little electrode pow-
der is produced for reliable quantitative analysis. For this
reason, the decoating success is analyzed based on the de-
coated membrane fragments. Using micro-X-ray fluores-
cence analysis (µ-XRF), which makes the de-coated areas
and the remaining electrode layer visible by elemental
mapping, the area-related de-coating efficiency can be
determined vie image analysis. Figure 3 b) shows a partly
de-coated cathode side of the MEA with labeling the areas.
The de-coating efficiency for anode and cathode for
one MEA in relation to the stressing speeds of the commi-
nution test is shown in Figure 4. It is calculated as the ratio
of the de-coated area to the total area, where each point in
the diagram represents a membrane fragment and the line
is related to the mean values of the experiment. It is shown
that the cathode side of the membrane can be completely
de-coated, while the anode layer is more difficult to remove.
This would allow selective recovery of the cathode material.
Figure 2. Particle size distributions of different cells crushed with a 20 mm grid. C2 and C3 are cylindrical
cell types, P2 and P6 prismatic cell types (Wilke et al., 2023a)
Figure 3. a) small scale hammer mill for decoating of MEAs, b) partly decoated and not ruptured MEA
circle with decoating efficiency for cathode of 47,6%
For the feasibility study, circles with a diameter of about
5 mm were punched out of the MEAs and subjected to dif-
ferent stressing speeds in the hammer mill with a discharge
screen diameter of 1 mm. The products of the comminu-
tion process are membrane fragments, which are torn and
de-coated to varying degrees depending on the stressing
rate, and an electrode powder containing precious metals.
Due to the low feed quantities too little electrode pow-
der is produced for reliable quantitative analysis. For this
reason, the decoating success is analyzed based on the de-
coated membrane fragments. Using micro-X-ray fluores-
cence analysis (µ-XRF), which makes the de-coated areas
and the remaining electrode layer visible by elemental
mapping, the area-related de-coating efficiency can be
determined vie image analysis. Figure 3 b) shows a partly
de-coated cathode side of the MEA with labeling the areas.
The de-coating efficiency for anode and cathode for
one MEA in relation to the stressing speeds of the commi-
nution test is shown in Figure 4. It is calculated as the ratio
of the de-coated area to the total area, where each point in
the diagram represents a membrane fragment and the line
is related to the mean values of the experiment. It is shown
that the cathode side of the membrane can be completely
de-coated, while the anode layer is more difficult to remove.
This would allow selective recovery of the cathode material.
Figure 2. Particle size distributions of different cells crushed with a 20 mm grid. C2 and C3 are cylindrical
cell types, P2 and P6 prismatic cell types (Wilke et al., 2023a)
Figure 3. a) small scale hammer mill for decoating of MEAs, b) partly decoated and not ruptured MEA
circle with decoating efficiency for cathode of 47,6%