5
Resonant Vibratory Mixing Experiments
For the RVM experiments, an experimental design (DOE)
was used, which had 52 runs based on the factors of time
(minutes), intensity (%),and a combination of DESs using
response surface methodology and a face-centered central
composite design. Stat-Ease Design Expert 13 was used for
the generation of the DOE and analysis. The low and high
levels for the factor of time were 1–30 minutes, intensity
(%),10–70%, and combinations in Table 4 were used.
For each run of RVM experiments, the remaining
unfiltered aliquot of 8mL was taken. The filtered 3mL ali-
quot was stored in the oven for the quantitative analysis
using ICP–OES.
RESULTS AND DISCUSSION
This chapter will discuss the results of all the experiments
undertaken for this research. This will include the SmCo
leaching in different DESs (Ethaline, Reline, Oxaline, and
EG-TBAC), the effect of time, and RAM intensification.
Oxaline
Samarium (Sm) and Cobalt (Co) Conversion (%)from
SmCo Magnet Leaching in Oxaline
Figure 1 shows the conversion of Samarium and Cobalt in
Oxaline. The result shows the high selectivity of Oxaline
to Co (II) over Sm (III) ions. The Sm dissolution is rela-
tively low with less than 10% conversion as compared to
the high Co conversion of 82% after 2hrs. It can also be
seen that time significantly affects the Sm and Co dissolu-
tion process.
It is observed that, as the time continued to increase,
the leaching efficiency did not plateau. This indicates that
a further increase in time for the leaching process will
increase the Co conversion rate. Oxaline is an acidic DES
[36] and the low conversion of the Sm in Oxaline leaching
can be attributed to the slower reaction rates of REE with
organic acids [15]. The low conversion of Sm could be due
to the presence of a protective layer on the surface which
prevented the contact of the Oxaline with the metal as was
reported by [37].
Samarium (Sm) and Cobalt (Co) Conversion (%)from
SmCo Magnet Leaching in Oxaline Without RAM
(WR) and After RAM (AR) Intensification
From Figure 2 both Sm and Co conversions increased with
the RAM intensification after 30 minutes. The rate of dis-
solution of both Sm and Co did not plateau indicating that
higher conversions can be attained by increasing the inten-
sification time. The increase in conversion after the intensi-
fication can be attributed to the RVM, which speeds up the
motion of the liquid and intensifies interfacial mass transfer
[38]. This increases the area around the interface [39], [40]
thereby accelerating the diffusion process [35].
Samarium (Sm) and Cobalt (Co) Conversion (%)from
SmCo Magnet Leaching in Reline
Figure 3 compares the conversion of Sm and Co during the
leaching of the SmCo magnet in Reline. The results show
that the Sm conversion is not proportional to the Co con-
version. As can be seen, the conversion of Sm is very low
Table 3. presents the selected factors and ranges of values
selected for chemical leaching of Samarium-Cobalt magnets
with four different combinations of Deep Eutectic Solvents
Factors Range
Time/hours 1–3.41
Temperature/°C 60–100
Combination
of DESs
Oxaline, Ethaline, Reline,
EG–TBAC
Table 4. presents the selected factors. Each factor has a
low and high value for the process intensification using
a Resodyn Vibratory Mixer after chemical leaching of
Samarium-Cobalt magnets with four different combinations
of Deep Eutectic Solvents was performed
Factors Range and Combinations
Time/minutes 1–30
Intensity/ %1–70
Combination of DESs Reline, Oxaline, Ethaline,
EG-TBAC
Figure 1. Sm and Co conversion (%)from SmCo magnet
leaching in Oxaline
Resonant Vibratory Mixing Experiments
For the RVM experiments, an experimental design (DOE)
was used, which had 52 runs based on the factors of time
(minutes), intensity (%),and a combination of DESs using
response surface methodology and a face-centered central
composite design. Stat-Ease Design Expert 13 was used for
the generation of the DOE and analysis. The low and high
levels for the factor of time were 1–30 minutes, intensity
(%),10–70%, and combinations in Table 4 were used.
For each run of RVM experiments, the remaining
unfiltered aliquot of 8mL was taken. The filtered 3mL ali-
quot was stored in the oven for the quantitative analysis
using ICP–OES.
RESULTS AND DISCUSSION
This chapter will discuss the results of all the experiments
undertaken for this research. This will include the SmCo
leaching in different DESs (Ethaline, Reline, Oxaline, and
EG-TBAC), the effect of time, and RAM intensification.
Oxaline
Samarium (Sm) and Cobalt (Co) Conversion (%)from
SmCo Magnet Leaching in Oxaline
Figure 1 shows the conversion of Samarium and Cobalt in
Oxaline. The result shows the high selectivity of Oxaline
to Co (II) over Sm (III) ions. The Sm dissolution is rela-
tively low with less than 10% conversion as compared to
the high Co conversion of 82% after 2hrs. It can also be
seen that time significantly affects the Sm and Co dissolu-
tion process.
It is observed that, as the time continued to increase,
the leaching efficiency did not plateau. This indicates that
a further increase in time for the leaching process will
increase the Co conversion rate. Oxaline is an acidic DES
[36] and the low conversion of the Sm in Oxaline leaching
can be attributed to the slower reaction rates of REE with
organic acids [15]. The low conversion of Sm could be due
to the presence of a protective layer on the surface which
prevented the contact of the Oxaline with the metal as was
reported by [37].
Samarium (Sm) and Cobalt (Co) Conversion (%)from
SmCo Magnet Leaching in Oxaline Without RAM
(WR) and After RAM (AR) Intensification
From Figure 2 both Sm and Co conversions increased with
the RAM intensification after 30 minutes. The rate of dis-
solution of both Sm and Co did not plateau indicating that
higher conversions can be attained by increasing the inten-
sification time. The increase in conversion after the intensi-
fication can be attributed to the RVM, which speeds up the
motion of the liquid and intensifies interfacial mass transfer
[38]. This increases the area around the interface [39], [40]
thereby accelerating the diffusion process [35].
Samarium (Sm) and Cobalt (Co) Conversion (%)from
SmCo Magnet Leaching in Reline
Figure 3 compares the conversion of Sm and Co during the
leaching of the SmCo magnet in Reline. The results show
that the Sm conversion is not proportional to the Co con-
version. As can be seen, the conversion of Sm is very low
Table 3. presents the selected factors and ranges of values
selected for chemical leaching of Samarium-Cobalt magnets
with four different combinations of Deep Eutectic Solvents
Factors Range
Time/hours 1–3.41
Temperature/°C 60–100
Combination
of DESs
Oxaline, Ethaline, Reline,
EG–TBAC
Table 4. presents the selected factors. Each factor has a
low and high value for the process intensification using
a Resodyn Vibratory Mixer after chemical leaching of
Samarium-Cobalt magnets with four different combinations
of Deep Eutectic Solvents was performed
Factors Range and Combinations
Time/minutes 1–30
Intensity/ %1–70
Combination of DESs Reline, Oxaline, Ethaline,
EG-TBAC
Figure 1. Sm and Co conversion (%)from SmCo magnet
leaching in Oxaline