2908 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Full-Scale Cell Performance
The graphs in Figures 9 A and B show the recoveries achiev-
able in a full-scale HydroFloat ® cell at the operational
parameters shown in Table 2. The full-scale recovery plots
are superimposed on the small-scale recovery plots for com-
parison. As stated, the full-scale surveys were done concur-
rently with the small-scale tests on the same flotation feed.
The data in Figure 9 showed only marginal variations
in copper recovery in the full-scale cell when air and water
flow rates were varied compared to the observations in the
small-scale cell. It is also worth noting that the range of Jg
and SWV combinations used in the small-scale tests was
larger than those used in the full-scale surveys therefore,
relatively higher copper recoveries were observed at the
high Jg and SWV values. The full-scale cell is a continuous
system and could be affected by several factors other than
air and water flow rates. Some of these factors include but
are not limited to throughput, residence time, float feed
density, dilution water addition and fluidised bed height.
The small-scale fluidised bed device produced results of
similar magnitude to the full-scale HydroFloat ® how-
ever, the recoveries obtained in the full-scale HydroFloat ®
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20
SWV, cm/s
Jg 0.03 cm/s
Jg 0.1 cm/s
Jg 0.17 cm/s
Figure 8. Effect of water flow rate on the recovery of copper at varying air flow rate
50
60
70
80
90
100
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18
J
g
,cm/s
SWV 0.33 cm/s
SWV 0.66 cm/s
SWV 0.99 cm/s
Full scale Operation
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20
SWV, cm/s
Jg 0.03 cm/s
Jg 0.1 cm/s
Jg 0.17 cm/s
Full scale Operation
A B
Figure 9. Effect of air (A) and water (B) flow rates on the recovery of copper in a full-scale HydroFloat® compared to results
obtained in the small-scale fluidised bed device
Cu
Recovery,
%
CuRecovery,
%CuRecovery,
%

Previous Page Next Page

Extracted Text (may have errors)

2908 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Full-Scale Cell Performance
The graphs in Figures 9 A and B show the recoveries achiev-
able in a full-scale HydroFloat ® cell at the operational
parameters shown in Table 2. The full-scale recovery plots
are superimposed on the small-scale recovery plots for com-
parison. As stated, the full-scale surveys were done concur-
rently with the small-scale tests on the same flotation feed.
The data in Figure 9 showed only marginal variations
in copper recovery in the full-scale cell when air and water
flow rates were varied compared to the observations in the
small-scale cell. It is also worth noting that the range of Jg
and SWV combinations used in the small-scale tests was
larger than those used in the full-scale surveys therefore,
relatively higher copper recoveries were observed at the
high Jg and SWV values. The full-scale cell is a continuous
system and could be affected by several factors other than
air and water flow rates. Some of these factors include but
are not limited to throughput, residence time, float feed
density, dilution water addition and fluidised bed height.
The small-scale fluidised bed device produced results of
similar magnitude to the full-scale HydroFloat ® how-
ever, the recoveries obtained in the full-scale HydroFloat ®
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20
SWV, cm/s
Jg 0.03 cm/s
Jg 0.1 cm/s
Jg 0.17 cm/s
Figure 8. Effect of water flow rate on the recovery of copper at varying air flow rate
50
60
70
80
90
100
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18
J
g
,cm/s
SWV 0.33 cm/s
SWV 0.66 cm/s
SWV 0.99 cm/s
Full scale Operation
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20
SWV, cm/s
Jg 0.03 cm/s
Jg 0.1 cm/s
Jg 0.17 cm/s
Full scale Operation
A B
Figure 9. Effect of air (A) and water (B) flow rates on the recovery of copper in a full-scale HydroFloat® compared to results
obtained in the small-scale fluidised bed device
Cu
Recovery,
%
CuRecovery,
%CuRecovery,
%

Help

Destination page number Search scope Search Text

loading

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2907
pronounced at higher air flow rates compared to lower air
flow rates.
Dankwah et al. (2022) observed that increasing the air
flow rate in a batch fluidised bed reduced the bed height.
They attributed this behaviour to segregation of the par-
ticles within the bed, with the coarser particles settling and
packing at the bottom. Consequently, they conclude that
the packed bed reduces the effective velocity of the rising
fluidisation water, decreasing the upward forces on the
bubble-particle aggregates, thereby reducing recovery. This
is another possible reason for the drop in recovery at high
air flow rates.
The phenomenon where recovery does not continu-
ally increase with increasing air rates has also been found
in conventional flotation. Previous work by Barbian et al.
(2006) and Hadler et al. (2010) investigated the effect of
air flow rate on flotation in conventional cells. They found
that there was an optimum air flow rate at which flotation
recovery increases towards a maximum, followed by a sub-
sequent decrease. They attributed this finding to the prop-
erties of the flotation froth, corresponding to an optimum
balance between froth stability and froth residence time.
However, this mechanism is not applicable to these
tests, as the small-scale fluidised bed device has no froth
layer. These results, therefore, show that the mechanism by
which high air flow rates poorly affect copper recovery is
related to changes in the pulp (free-settling zone /fluidised
bed zone) or detachment at the pulp air interface. Further
work is required to fully understand the competing mecha-
nisms that cause poor recovery at high air flow rates in flui-
dised bed flotation.
Effect of Water Rate on Copper Recovery
The results of the effect of water flow rate on copper recovery
when the air flow rate was varied are presented in Figure 8.
Unlike the air flow rate, water flow rate has a linear rela-
tionship with copper recovery. The same relationship was
observed by Demir et al. (2022) when they varied the water
flow rate in a pilot-scale HydroFloat ® work. Recovery was
lowest at the lowest air flow rate tested, ranging from 62%
to 72% when the water flow rate was varied from 0.33 cm/s
to 0.99 cm/s. Copper recovery was significantly higher
when the cell was operated at Jg of 0.1 cm/s (71% to 85%).
Above Jg of 0.1 cm/s, no further increase in recovery was
observed with increasing water flow rate. Increasing the
water flow rate increases the upward forces on the bubble-
particle aggregates, thereby promoting recovery. This was
observed at both low and high air flow rates.
Other researchers have reported bed expansion with
increasing water flow rate (Zanin et al., 2021, Dankwah
et al., 2022, Verster et al., 2023). Increasing the water flow
rate expands the fluidised bed, which increases the bed
level, thereby shortening the travel distance (the distance
between the top of the bed and the overflow lip) for bub-
ble–particle aggregate. The longer the travel distance, the
higher the probability of the coarse bubble-particle aggre-
gates falling back and settling in the bottom of the bed,
especially at low water flow rates. However, it is important
to note that excessive water flow rates result in unselec-
tive elutriation of finer particles into the concentrate. In
contrast, an insufficient water flow rate will not allow the
fluidised bed to have sufficient porosity for particle-bubble
aggregates to travel through the bed.
50
60
70
80
90
100
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18
Jg, cm/s
SWV 0.33 cm/s
SWV 0.66 cm/s
SWV 0.99 cm/s
Figure 7. Effect of air flow rate on the recovery of copper at varying fluidisation water flow rate
Cu
Recovery,
%

Previous Page Next Page

Extracted Text (may have errors)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2907
pronounced at higher air flow rates compared to lower air
flow rates.
Dankwah et al. (2022) observed that increasing the air
flow rate in a batch fluidised bed reduced the bed height.
They attributed this behaviour to segregation of the par-
ticles within the bed, with the coarser particles settling and
packing at the bottom. Consequently, they conclude that
the packed bed reduces the effective velocity of the rising
fluidisation water, decreasing the upward forces on the
bubble-particle aggregates, thereby reducing recovery. This
is another possible reason for the drop in recovery at high
air flow rates.
The phenomenon where recovery does not continu-
ally increase with increasing air rates has also been found
in conventional flotation. Previous work by Barbian et al.
(2006) and Hadler et al. (2010) investigated the effect of
air flow rate on flotation in conventional cells. They found
that there was an optimum air flow rate at which flotation
recovery increases towards a maximum, followed by a sub-
sequent decrease. They attributed this finding to the prop-
erties of the flotation froth, corresponding to an optimum
balance between froth stability and froth residence time.
However, this mechanism is not applicable to these
tests, as the small-scale fluidised bed device has no froth
layer. These results, therefore, show that the mechanism by
which high air flow rates poorly affect copper recovery is
related to changes in the pulp (free-settling zone /fluidised
bed zone) or detachment at the pulp air interface. Further
work is required to fully understand the competing mecha-
nisms that cause poor recovery at high air flow rates in flui-
dised bed flotation.
Effect of Water Rate on Copper Recovery
The results of the effect of water flow rate on copper recovery
when the air flow rate was varied are presented in Figure 8.
Unlike the air flow rate, water flow rate has a linear rela-
tionship with copper recovery. The same relationship was
observed by Demir et al. (2022) when they varied the water
flow rate in a pilot-scale HydroFloat ® work. Recovery was
lowest at the lowest air flow rate tested, ranging from 62%
to 72% when the water flow rate was varied from 0.33 cm/s
to 0.99 cm/s. Copper recovery was significantly higher
when the cell was operated at Jg of 0.1 cm/s (71% to 85%).
Above Jg of 0.1 cm/s, no further increase in recovery was
observed with increasing water flow rate. Increasing the
water flow rate increases the upward forces on the bubble-
particle aggregates, thereby promoting recovery. This was
observed at both low and high air flow rates.
Other researchers have reported bed expansion with
increasing water flow rate (Zanin et al., 2021, Dankwah
et al., 2022, Verster et al., 2023). Increasing the water flow
rate expands the fluidised bed, which increases the bed
level, thereby shortening the travel distance (the distance
between the top of the bed and the overflow lip) for bub-
ble–particle aggregate. The longer the travel distance, the
higher the probability of the coarse bubble-particle aggre-
gates falling back and settling in the bottom of the bed,
especially at low water flow rates. However, it is important
to note that excessive water flow rates result in unselec-
tive elutriation of finer particles into the concentrate. In
contrast, an insufficient water flow rate will not allow the
fluidised bed to have sufficient porosity for particle-bubble
aggregates to travel through the bed.
50
60
70
80
90
100
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18
Jg, cm/s
SWV 0.33 cm/s
SWV 0.66 cm/s
SWV 0.99 cm/s
Figure 7. Effect of air flow rate on the recovery of copper at varying fluidisation water flow rate
Cu
Recovery,
%

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2909
were lower, possibly due to the other factors affecting its
performance.
Residence time, for instance, plays a vital role in flo-
tation. Demir et al. (2022) observed in their pilot-scale
HydroFloat ® work that Cu recovery increased with increas-
ing residence time. Although the residence time in the
full-scale unit is unknown at this stage, it is expected to be
lower than in the small-scale tests (16 minutes). Perhaps
Cu recovery in the full-scale unit could be improved with
additional flotation time. Further work is required to elu-
cidate the reasons for the higher recoveries observed in the
small-scale fluidised bed device.
Nevertheless, it is important to note that while the
scale-up between the small-scale and full-scale flota-
tion performance was not perfect, it was still remarkably
close—within the range of variation between experimental
conditions.
CONCLUSIONS
This work presented the outcomes of flotation tests con-
ducted in a small-scale fluidised bed flotation device that
uses 1–2 kg of copper ore sample and compared the results
to those obtained from tests conducted in a full-scale indus-
trial unit. Based on the obtained analysis, the following can
be concluded:
• The overall recovery results obtained from the small-
scale fluidised bed device exhibit remarkable repro-
ducibility. This can be attributed to the absence of a
froth phase and the elimination of the need to inter-
mittently scrape concentrate samples, which has the
potential to introduce errors.
• Regression modelling of the data indicates that cop-
per recovery in the small-scale device is a strong
function of air and fluidisation water flow rates, with
air flow rate showing a non-linear relationship with
copper recovery and water flow rate showing a linear
relationship with copper recovery. The relationships
between copper recovery and air and water flow rate
observed in this work were also observed in previous
pilot-scale work by other researchers.
• Copper recovery increased with increasing air flow
rate at all the water flow rates tested, but there
appears to be an optimum beyond which copper
recovery begins to plateau. The leveling off in recov-
ery at the high air flow region indicates the presence
of a competing mechanism, which requires further
work to understand.
• Increasing the water flow rate increased the overall
copper recovery. This was attributed to the expansion
of the fluidised bed as the water flow rate increased,
resulting in higher bed porosity and lower bed den-
sity. This favours high particle-bubble collisions and
attachments. Increasing the water flow rate also
increases the upward forces on the bubble-particle
aggregates, thereby promoting recovery. This was
observed at both low and high air flow rates.
• The small-scale fluidised bed device produced results
of similar magnitude to the full-scale HydroFloat ®
however, the recoveries obtained in the full-scale
HydroFloat ® were lower, possibly due to factors such
as residence time, throughput, and dilution water
addition rate, affecting its performance.
ACKNOWLEDGMENTS
The authors acknowledge the funding support from the
sponsors of the Collaborative Consortium for Coarse
Particle Processing Research Program. The authors
acknowledge the site support provided by the Cadia Valley
Operations team. The authors also acknowledge the support
from the Australian Research Council for the ARC Centre
of Excellence for Enabling Eco-Efficient Beneficiation of
Minerals, grant number CE200100009.
REFERENCES
Awatey, B., Skinner, W. &Zanin, M. 2015. Incorporating
fluidised-bed flotation into a conventional flotation
flowsheet: A focus on energy implications of coarse
particle recovery. Powder Technology, 275, 85–93.
Awatey, B., Thanasekaran, H., Kohmuench, J. N.,
Skinner, W. &Zanin, M. 2013. Optimization of
operating parameters for coarse sphalerite flotation
in the HydroFloat fluidised-bed separator. Minerals
Engineering, 50–51, 99–105.
Ballantyne, G., Powell, M. &Tiang, M. Proportion of
energy attributable to comminution. Proceedings of the
11th Australasian Institute of Mining and Metallurgy
Mill Operator’s Conference, 2012. 25–30.
Barbian, N., Hadler, K. &Cilliers, J. J. 2006. The froth sta-
bility column: Measuring froth stability at an industrial
scale. Minerals Engineering, 19, 713–718.
Dankwah, J. B., Asamoah, R. K., Zanin, M. &Skinner, W.
2022. Influence of water rate, gas rate, and bed particle
size on bed-level and coarse particle flotation perfor-
mance. Minerals Engineering, 183, 107622.
Demir, H. K., Morrison, A., Runge, K., Evans, C. &
Kohmuench, J. The effects of operational param-
eters on HydroFloat ® performance in a metalliferous
application. IMPC Asia-Pacific, 22–24 August 2022
Melbourne, Australia.

Previous Page Next Page

Extracted Text (may have errors)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2909
were lower, possibly due to the other factors affecting its
performance.
Residence time, for instance, plays a vital role in flo-
tation. Demir et al. (2022) observed in their pilot-scale
HydroFloat ® work that Cu recovery increased with increas-
ing residence time. Although the residence time in the
full-scale unit is unknown at this stage, it is expected to be
lower than in the small-scale tests (16 minutes). Perhaps
Cu recovery in the full-scale unit could be improved with
additional flotation time. Further work is required to elu-
cidate the reasons for the higher recoveries observed in the
small-scale fluidised bed device.
Nevertheless, it is important to note that while the
scale-up between the small-scale and full-scale flota-
tion performance was not perfect, it was still remarkably
close—within the range of variation between experimental
conditions.
CONCLUSIONS
This work presented the outcomes of flotation tests con-
ducted in a small-scale fluidised bed flotation device that
uses 1–2 kg of copper ore sample and compared the results
to those obtained from tests conducted in a full-scale indus-
trial unit. Based on the obtained analysis, the following can
be concluded:
• The overall recovery results obtained from the small-
scale fluidised bed device exhibit remarkable repro-
ducibility. This can be attributed to the absence of a
froth phase and the elimination of the need to inter-
mittently scrape concentrate samples, which has the
potential to introduce errors.
• Regression modelling of the data indicates that cop-
per recovery in the small-scale device is a strong
function of air and fluidisation water flow rates, with
air flow rate showing a non-linear relationship with
copper recovery and water flow rate showing a linear
relationship with copper recovery. The relationships
between copper recovery and air and water flow rate
observed in this work were also observed in previous
pilot-scale work by other researchers.
• Copper recovery increased with increasing air flow
rate at all the water flow rates tested, but there
appears to be an optimum beyond which copper
recovery begins to plateau. The leveling off in recov-
ery at the high air flow region indicates the presence
of a competing mechanism, which requires further
work to understand.
• Increasing the water flow rate increased the overall
copper recovery. This was attributed to the expansion
of the fluidised bed as the water flow rate increased,
resulting in higher bed porosity and lower bed den-
sity. This favours high particle-bubble collisions and
attachments. Increasing the water flow rate also
increases the upward forces on the bubble-particle
aggregates, thereby promoting recovery. This was
observed at both low and high air flow rates.
• The small-scale fluidised bed device produced results
of similar magnitude to the full-scale HydroFloat ®
however, the recoveries obtained in the full-scale
HydroFloat ® were lower, possibly due to factors such
as residence time, throughput, and dilution water
addition rate, affecting its performance.
ACKNOWLEDGMENTS
The authors acknowledge the funding support from the
sponsors of the Collaborative Consortium for Coarse
Particle Processing Research Program. The authors
acknowledge the site support provided by the Cadia Valley
Operations team. The authors also acknowledge the support
from the Australian Research Council for the ARC Centre
of Excellence for Enabling Eco-Efficient Beneficiation of
Minerals, grant number CE200100009.
REFERENCES
Awatey, B., Skinner, W. &Zanin, M. 2015. Incorporating
fluidised-bed flotation into a conventional flotation
flowsheet: A focus on energy implications of coarse
particle recovery. Powder Technology, 275, 85–93.
Awatey, B., Thanasekaran, H., Kohmuench, J. N.,
Skinner, W. &Zanin, M. 2013. Optimization of
operating parameters for coarse sphalerite flotation
in the HydroFloat fluidised-bed separator. Minerals
Engineering, 50–51, 99–105.
Ballantyne, G., Powell, M. &Tiang, M. Proportion of
energy attributable to comminution. Proceedings of the
11th Australasian Institute of Mining and Metallurgy
Mill Operator’s Conference, 2012. 25–30.
Barbian, N., Hadler, K. &Cilliers, J. J. 2006. The froth sta-
bility column: Measuring froth stability at an industrial
scale. Minerals Engineering, 19, 713–718.
Dankwah, J. B., Asamoah, R. K., Zanin, M. &Skinner, W.
2022. Influence of water rate, gas rate, and bed particle
size on bed-level and coarse particle flotation perfor-
mance. Minerals Engineering, 183, 107622.
Demir, H. K., Morrison, A., Runge, K., Evans, C. &
Kohmuench, J. The effects of operational param-
eters on HydroFloat ® performance in a metalliferous
application. IMPC Asia-Pacific, 22–24 August 2022
Melbourne, Australia.