XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3213
and left to dry under 25 cc/min of air purge gas flow. During
that time, approximately 0.75% water moisture was lost.
The samples were then heated at 10°C/min up to 1000°C
and the weight loss curves are displayed in Figure 2. In
TGA-FTIR, the purge gas flow was increased to 50 cc/min
for carrying the evolved gas through the heated transfer line
into the FTIR’s gas cell where they were scanned in real-
time. Four spectra were averaged and Fourier transformed
to display a full spectrum (4000–1000 cm–1) with a resolu-
tion of 2 cm–1 every 6 seconds. In TGA-FTIR, the purge
gas and ramping rate parameters were modified to improve
FTIR detection sensitivity as explained below.
Wavenumbers corresponding to molecular vibrations
of interest were selected and their intensities as a func-
tion of furnace temperature. The resulting gas evolution
profiles are shown in Figure 3 bottom for Sample B, as an
example. Four vibrations of interest were monitored: O-H
from H2O, C-O from CO2, C-O from CO, and C-H from
organic molecules. The four FTIR band wavenumbers used
for real-time monitoring of the four gases are listed on
each profile. The evolved gas profiles could be correlated
to weight losses observed on the TGA curve (Figure 3 top).
The evolved gases of interest were the ones which dis-
played C-H bond vibration, indicative of the release of
organic fragments from binder decomposition. The TGA
experimental parameters were therefore tuned in order to
increase the sensitivity for the FTIR C-H bond detection.
The TGA purge gas was set to nitrogen in order to avoid
combustion hence producing more organic fragments with
C-H bonds. The TGA ramping rate was set to 20°C/min
to favorize detection sensitivity by decreasing evolved gases
dilution form the purge gas. The temperature range during
which the binders decomposed, generating gaseous frag-
ments bearing C-H bonds, was monitored for each of the
black mass samples. As an example, the temperature range
for the Sample B black mass (Figure 3) was 300–550°C.
The TGA weight loss curves as a function of temperature
are displayed in Figure 2 for Samples A, B, and C along
with the temperature ranges during which binder decom-
position was observed by FTIR. The figure clearly shows
that the onset of decomposition and range of decomposi-
tion is different for all three black mass samples which sug-
gest different binder composition for each of them.
METALLURGICAL TESTING
Each flotation test was conducted on approximately 150–
250g as-is or pre-treated black mass in a one litre cell with
a benchscale Denver flotation machine. Pulp density in the
rougher flotation stage ranged from 10–20% and was not
controlled due to sample limitation. Subsequent cleaning
was also conducted in a one litre cell. Flotation was con-
ducted in room temperature, 1250 rpm, and at 2 L/min air.
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000
Temperature (°C)
SAMPLE A: 360-460 °C
SAMPLE B: 300-550 °C
SAMPLE C: 325-500 °C
Figure 2. TGA weight loss curves, in air, for Samples A, B, and C as a function of temperature along with
the temperature ranges (solid lines) during which binder decomposition was observed by FTIR detection
of C-H vibration
Weight
(%)
and left to dry under 25 cc/min of air purge gas flow. During
that time, approximately 0.75% water moisture was lost.
The samples were then heated at 10°C/min up to 1000°C
and the weight loss curves are displayed in Figure 2. In
TGA-FTIR, the purge gas flow was increased to 50 cc/min
for carrying the evolved gas through the heated transfer line
into the FTIR’s gas cell where they were scanned in real-
time. Four spectra were averaged and Fourier transformed
to display a full spectrum (4000–1000 cm–1) with a resolu-
tion of 2 cm–1 every 6 seconds. In TGA-FTIR, the purge
gas and ramping rate parameters were modified to improve
FTIR detection sensitivity as explained below.
Wavenumbers corresponding to molecular vibrations
of interest were selected and their intensities as a func-
tion of furnace temperature. The resulting gas evolution
profiles are shown in Figure 3 bottom for Sample B, as an
example. Four vibrations of interest were monitored: O-H
from H2O, C-O from CO2, C-O from CO, and C-H from
organic molecules. The four FTIR band wavenumbers used
for real-time monitoring of the four gases are listed on
each profile. The evolved gas profiles could be correlated
to weight losses observed on the TGA curve (Figure 3 top).
The evolved gases of interest were the ones which dis-
played C-H bond vibration, indicative of the release of
organic fragments from binder decomposition. The TGA
experimental parameters were therefore tuned in order to
increase the sensitivity for the FTIR C-H bond detection.
The TGA purge gas was set to nitrogen in order to avoid
combustion hence producing more organic fragments with
C-H bonds. The TGA ramping rate was set to 20°C/min
to favorize detection sensitivity by decreasing evolved gases
dilution form the purge gas. The temperature range during
which the binders decomposed, generating gaseous frag-
ments bearing C-H bonds, was monitored for each of the
black mass samples. As an example, the temperature range
for the Sample B black mass (Figure 3) was 300–550°C.
The TGA weight loss curves as a function of temperature
are displayed in Figure 2 for Samples A, B, and C along
with the temperature ranges during which binder decom-
position was observed by FTIR. The figure clearly shows
that the onset of decomposition and range of decomposi-
tion is different for all three black mass samples which sug-
gest different binder composition for each of them.
METALLURGICAL TESTING
Each flotation test was conducted on approximately 150–
250g as-is or pre-treated black mass in a one litre cell with
a benchscale Denver flotation machine. Pulp density in the
rougher flotation stage ranged from 10–20% and was not
controlled due to sample limitation. Subsequent cleaning
was also conducted in a one litre cell. Flotation was con-
ducted in room temperature, 1250 rpm, and at 2 L/min air.
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000
Temperature (°C)
SAMPLE A: 360-460 °C
SAMPLE B: 300-550 °C
SAMPLE C: 325-500 °C
Figure 2. TGA weight loss curves, in air, for Samples A, B, and C as a function of temperature along with
the temperature ranges (solid lines) during which binder decomposition was observed by FTIR detection
of C-H vibration
Weight
(%)