2874 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
diluting and displacing the liquid that contains entrained
particles (Dickinson and Galvin, 2014). It was also
observed that as the wash water flux increased to 10% and
30%, chalcopyrite recovery dropped to 86.8% and 84.8%,
respectively. It is likely that increasing wash water flux cre-
ated a higher counter flow on the uprising bubbles, result-
ing in a higher detachment rate of hydrophobic particles
from bubbles (Jera and Bhondayi, 2022). Nevertheless, the
greater reduction of gangue entrainment than the loss of
chalcopyrite recovery enabled a higher product grade of
21.3% and 20.7%, when the wash water flux was increased
by 10% and 30%, respectively.
Comparing the results from tests 1 and 6, it can be
found that when gas flux was increased by 20% and wash
water flux was increased by 10% at the same time, gangue
recovery increased to 12.1% while chalcopyrite recovery
increased to 91.9%. A similar trend was observed in coal
flotation when only gas flux was increased. Increasing gas
flux in coal flotation provides a greater number of bubbles,
which helps the flotation of hydrophobic particles, but also
entrained more gangue particles (Dickinson et al., 2015).
Obviously in test 6, increasing gas flux by 20% prevailed
over increasing wash water by 10% from the baseline. When
the wash water flux was further increased by 30% in test 7,
the effect of increasing wash water flux started to be observed
as well. In test 7, gangue recovery dropped to a lower level
of 10.6% compared to the baseline test. This result is in line
with the previous observation that the increasing of wash
water reduces gangue entrainment during flotation. At the
meantime, chalcopyrite recovery was still maintained at the
high level of 91.8% in test 7 due to the high gas flux applied.
With the lower gangue recovery and higher chalcopyrite
recovery in test 7, the highest chalcopyrite grade of 22.0%
across all the tests was achieved. Comparing tests 6 and 7
to tests 4 and 5, it is clear that when gas flux was increased,
wash water flux needs to be raised at a higher magnitude to
enable gangue entrainment reduction.
In summary, wash water flux had a similar effect on
chalcopyrite flotation and coal flotation in the RFC. The
increasing of wash water flux reduced gangue entrain-
ment while decreasing the recovery of hydrophobic par-
ticles. When gas flux was increased by 20% and wash water
flux was increased by 10%, the effect of increasing gas
flux played a more dominant role, causing higher gangue
entrainment but a higher chalcopyrite recovery at the same
time. When the gas flux was increased by 20% and wash
water flux was increased by 30%, both increases played a
role, causing lower gangue entrainment and a higher chal-
copyrite recovery. When only increasing the gas flux, the
recovery of hydrophobic particles increased, which is in line
with the observation in coal flotation. However, different to
coal flotation, with increasing gas flux, gangue entrainment
was found to decrease. Hence, gas flux had a different effect
on air fraction and liquid motion in chalcopyrite flotation,
compared to coal flotation in the RFC, which was further
studied through CFD simulation in the following section.
CFD Simulation
In this section, the effect of gas flux on air fraction and liq-
uid motion in the RFC’s reverse fluidized bed was studied
through CFD simulation under the same operating condi-
tions tested, including the baseline condition (test 1), the
condition with gas flux reduced by 50% (test 2) and the
condition with gas flux increased by 20% (test 3).
Firstly, the air fraction at the concentrate outlet for
tests 1, 2 and 3 were studied to understand the impact of
gas flux on the effective gas in the system required to trans-
port the entrained particles. The calculated air fraction at
the concentrate outlet versus simulation time for the three
tests were presented in Figure 3.
From Figure 3, it can be found that, as the gas was
injected into the RFC from the start of simulation, the
air fraction at the concentrate outlet gradually increased.
Compared to the simulation at the baseline gas flux (test
1) and the gas flux increased by 20% (test 3) which both
reached an equilibrium at roughly 20 s, the simulation at
the gas flux reduced by 50% (test 2) reached an equilibrium
more slowly, at around 35 s. It is likely that, at a lower gas
Table 3. Chalcopyrite recovery, gangue recovery and chalcopyrite grade under different operating conditions indicated in Table 1
Test Condition Gangue Recovery (%)Chalcopyrite Recovery (%)Chalcopyrite Grade (%)
1 (Baseline) 11.5 87.0 11.1
2 (Gas –50%) 13.5 89.6 15.2
3 (Gas +20%) 10.5 91.3 21.2
4 (Wash water +10%) 10.4 86.8 21.3
5 (Wash water +30%) 10.3 84.8 20.7
6 (Gas +20% &wash water +10%) 12.1 91.9 21.2
7 (Gas +20% &wash water +30%) 10.6 91.8 22.0
diluting and displacing the liquid that contains entrained
particles (Dickinson and Galvin, 2014). It was also
observed that as the wash water flux increased to 10% and
30%, chalcopyrite recovery dropped to 86.8% and 84.8%,
respectively. It is likely that increasing wash water flux cre-
ated a higher counter flow on the uprising bubbles, result-
ing in a higher detachment rate of hydrophobic particles
from bubbles (Jera and Bhondayi, 2022). Nevertheless, the
greater reduction of gangue entrainment than the loss of
chalcopyrite recovery enabled a higher product grade of
21.3% and 20.7%, when the wash water flux was increased
by 10% and 30%, respectively.
Comparing the results from tests 1 and 6, it can be
found that when gas flux was increased by 20% and wash
water flux was increased by 10% at the same time, gangue
recovery increased to 12.1% while chalcopyrite recovery
increased to 91.9%. A similar trend was observed in coal
flotation when only gas flux was increased. Increasing gas
flux in coal flotation provides a greater number of bubbles,
which helps the flotation of hydrophobic particles, but also
entrained more gangue particles (Dickinson et al., 2015).
Obviously in test 6, increasing gas flux by 20% prevailed
over increasing wash water by 10% from the baseline. When
the wash water flux was further increased by 30% in test 7,
the effect of increasing wash water flux started to be observed
as well. In test 7, gangue recovery dropped to a lower level
of 10.6% compared to the baseline test. This result is in line
with the previous observation that the increasing of wash
water reduces gangue entrainment during flotation. At the
meantime, chalcopyrite recovery was still maintained at the
high level of 91.8% in test 7 due to the high gas flux applied.
With the lower gangue recovery and higher chalcopyrite
recovery in test 7, the highest chalcopyrite grade of 22.0%
across all the tests was achieved. Comparing tests 6 and 7
to tests 4 and 5, it is clear that when gas flux was increased,
wash water flux needs to be raised at a higher magnitude to
enable gangue entrainment reduction.
In summary, wash water flux had a similar effect on
chalcopyrite flotation and coal flotation in the RFC. The
increasing of wash water flux reduced gangue entrain-
ment while decreasing the recovery of hydrophobic par-
ticles. When gas flux was increased by 20% and wash water
flux was increased by 10%, the effect of increasing gas
flux played a more dominant role, causing higher gangue
entrainment but a higher chalcopyrite recovery at the same
time. When the gas flux was increased by 20% and wash
water flux was increased by 30%, both increases played a
role, causing lower gangue entrainment and a higher chal-
copyrite recovery. When only increasing the gas flux, the
recovery of hydrophobic particles increased, which is in line
with the observation in coal flotation. However, different to
coal flotation, with increasing gas flux, gangue entrainment
was found to decrease. Hence, gas flux had a different effect
on air fraction and liquid motion in chalcopyrite flotation,
compared to coal flotation in the RFC, which was further
studied through CFD simulation in the following section.
CFD Simulation
In this section, the effect of gas flux on air fraction and liq-
uid motion in the RFC’s reverse fluidized bed was studied
through CFD simulation under the same operating condi-
tions tested, including the baseline condition (test 1), the
condition with gas flux reduced by 50% (test 2) and the
condition with gas flux increased by 20% (test 3).
Firstly, the air fraction at the concentrate outlet for
tests 1, 2 and 3 were studied to understand the impact of
gas flux on the effective gas in the system required to trans-
port the entrained particles. The calculated air fraction at
the concentrate outlet versus simulation time for the three
tests were presented in Figure 3.
From Figure 3, it can be found that, as the gas was
injected into the RFC from the start of simulation, the
air fraction at the concentrate outlet gradually increased.
Compared to the simulation at the baseline gas flux (test
1) and the gas flux increased by 20% (test 3) which both
reached an equilibrium at roughly 20 s, the simulation at
the gas flux reduced by 50% (test 2) reached an equilibrium
more slowly, at around 35 s. It is likely that, at a lower gas
Table 3. Chalcopyrite recovery, gangue recovery and chalcopyrite grade under different operating conditions indicated in Table 1
Test Condition Gangue Recovery (%)Chalcopyrite Recovery (%)Chalcopyrite Grade (%)
1 (Baseline) 11.5 87.0 11.1
2 (Gas –50%) 13.5 89.6 15.2
3 (Gas +20%) 10.5 91.3 21.2
4 (Wash water +10%) 10.4 86.8 21.3
5 (Wash water +30%) 10.3 84.8 20.7
6 (Gas +20% &wash water +10%) 12.1 91.9 21.2
7 (Gas +20% &wash water +30%) 10.6 91.8 22.0