XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2867
buoyancy effect may significantly impact the relationship
between frother dosage and flotation recovery, as illustrated
in Figure 2, and therefore requires further study.
SUMMARY AND CONCLUSIONS
Fluidised bed flotation, a leading technology for recovering
coarse particles, is characterised by a radical departure from
the hydrodynamic environment of conventional flotation.
The available literature exploring chemical variables’ impact
on performance in this new flotation regime is highly lim-
ited. Controlling bubble size is crucial for fluidised bed
flotation optimisation. This study focuses on the influence
of frother concentration on coalescence and bubble size,
exploring the interplay between process chemistry and
hydrodynamics.
The study examined the effect of superficial gas velocity
on the bubble size, critical coalescence concentration, and
bubble surface area flux in a fluidised bed flotation system.
From the presented results, the following conclusions can
be drawn:
• The critical coalescence concentration, the mini-
mum bubble size and the bubble surface area flux
were significantly affected by system hydrodynamics.
The overall trends are similar to those observed in
conventional flotation systems, where both the CCC
and the minimum bubble size increased with an
increase in superficial gas velocity.
• In a fluidised flotation system, the dosage of MIBC
required to reach the CCC varied between 100–
200 ppm in the superficial gas velocity range between
0.02 and 0.17 s–1. This is an order of magnitude
increase from a conventional flotation system where
MIBC CCC values vary between 10 and 30 ppm.
• The minimum bubble size attained at CCC was
found to vary between 0.37 and 0.45 mm, signifi-
cantly smaller than that achieved in a conventional
flotation system (0.50–1.0 cm).
• Both the increased CCC values and the higher water
demand in fluidised bed flotation mean that the
frother consumption required to achieve minimum
bubble size is two orders of magnitude higher than
in conventional flotation (approximately 100-fold
increase).
• Fluidised bed flotation needs to consider buoyancy
as an additional factor, and it is not yet known if a
minimum bubble size is required for optimum flota-
tion performance.
The biggest implication of these results for industrial prac-
tice is that many operations that use the HydroFloat ®
technology likely significantly underdose their frother
reagents, falling well short of minimum achievable bubble
sizes. Many plants continue to monitor and dose their
frother reagents on a g/ton basis. This practice is primarily
rooted in accounting practices and does not address perfor-
mance optimisation. This work demonstrates the impor-
tance of considering both the solution-based frother dosage
to achieve optimum flotation performance as well as under-
standing its overall impact on frother consumption from an
operational cost perspective.
FUTURE WORK
The next step in understanding the coalescence response
to changing chemical and hydrodynamical variables is to
increase the system complexity by adding the solids phase.
The fluidised bed, being a highly intricate system, signifi-
cantly affects the movement of bubbles and their interac-
tions with particles and one another. Thus, it is crucial to
explore how fluidised bed properties like mass, porosity,
and the shape/size of particles impact the coalescence of
bubbles.
Future research will also explore how different frother
properties, such as molecular weight, HLB value, and
frother type, influence the water-air interface and bubble
coalescence under diverse hydrodynamic conditions in flui-
dised bed flotation. This will enhance the understanding of
the interplay of chemistry and hydrodynamics in fluidised
bed flotation systems, as well as their influence on coales-
cence and overall flotation performance.
ACKNOWLEDGMENT
The authors express gratitude for the funding and support
provided by the sponsors of the Collaborative Consortium
for Coarse Particle Processing Research Program: Eriez
Flotation Division, Newmont, Glencore Copper, Rio
Tinto and Anglo American. Additionally, they acknowl-
edge the support of the Australian Research Council under
the ARC Centre of Excellence for Enabling Eco-Efficient
Beneficiation of Minerals (CE200100009).
The authors extend their heartfelt gratitude to Bellson
Awatey for his exceptional technical support and training.
Candice Brill’s invaluable contributions in both technical
and academic realms, through engaging discussions and
collaborative work, have greatly enriched this endeavour.
Special thanks to Michael Kilmartin for his aid in work-
place organisation and equipment set-up. Jan Nesset’s
meticulous review and development guidelines have been
instrumental in shaping this project. We sincerely appreci-
ate Andrea Grey and Barry Mitchell’s administrative and
organisational support.
buoyancy effect may significantly impact the relationship
between frother dosage and flotation recovery, as illustrated
in Figure 2, and therefore requires further study.
SUMMARY AND CONCLUSIONS
Fluidised bed flotation, a leading technology for recovering
coarse particles, is characterised by a radical departure from
the hydrodynamic environment of conventional flotation.
The available literature exploring chemical variables’ impact
on performance in this new flotation regime is highly lim-
ited. Controlling bubble size is crucial for fluidised bed
flotation optimisation. This study focuses on the influence
of frother concentration on coalescence and bubble size,
exploring the interplay between process chemistry and
hydrodynamics.
The study examined the effect of superficial gas velocity
on the bubble size, critical coalescence concentration, and
bubble surface area flux in a fluidised bed flotation system.
From the presented results, the following conclusions can
be drawn:
• The critical coalescence concentration, the mini-
mum bubble size and the bubble surface area flux
were significantly affected by system hydrodynamics.
The overall trends are similar to those observed in
conventional flotation systems, where both the CCC
and the minimum bubble size increased with an
increase in superficial gas velocity.
• In a fluidised flotation system, the dosage of MIBC
required to reach the CCC varied between 100–
200 ppm in the superficial gas velocity range between
0.02 and 0.17 s–1. This is an order of magnitude
increase from a conventional flotation system where
MIBC CCC values vary between 10 and 30 ppm.
• The minimum bubble size attained at CCC was
found to vary between 0.37 and 0.45 mm, signifi-
cantly smaller than that achieved in a conventional
flotation system (0.50–1.0 cm).
• Both the increased CCC values and the higher water
demand in fluidised bed flotation mean that the
frother consumption required to achieve minimum
bubble size is two orders of magnitude higher than
in conventional flotation (approximately 100-fold
increase).
• Fluidised bed flotation needs to consider buoyancy
as an additional factor, and it is not yet known if a
minimum bubble size is required for optimum flota-
tion performance.
The biggest implication of these results for industrial prac-
tice is that many operations that use the HydroFloat ®
technology likely significantly underdose their frother
reagents, falling well short of minimum achievable bubble
sizes. Many plants continue to monitor and dose their
frother reagents on a g/ton basis. This practice is primarily
rooted in accounting practices and does not address perfor-
mance optimisation. This work demonstrates the impor-
tance of considering both the solution-based frother dosage
to achieve optimum flotation performance as well as under-
standing its overall impact on frother consumption from an
operational cost perspective.
FUTURE WORK
The next step in understanding the coalescence response
to changing chemical and hydrodynamical variables is to
increase the system complexity by adding the solids phase.
The fluidised bed, being a highly intricate system, signifi-
cantly affects the movement of bubbles and their interac-
tions with particles and one another. Thus, it is crucial to
explore how fluidised bed properties like mass, porosity,
and the shape/size of particles impact the coalescence of
bubbles.
Future research will also explore how different frother
properties, such as molecular weight, HLB value, and
frother type, influence the water-air interface and bubble
coalescence under diverse hydrodynamic conditions in flui-
dised bed flotation. This will enhance the understanding of
the interplay of chemistry and hydrodynamics in fluidised
bed flotation systems, as well as their influence on coales-
cence and overall flotation performance.
ACKNOWLEDGMENT
The authors express gratitude for the funding and support
provided by the sponsors of the Collaborative Consortium
for Coarse Particle Processing Research Program: Eriez
Flotation Division, Newmont, Glencore Copper, Rio
Tinto and Anglo American. Additionally, they acknowl-
edge the support of the Australian Research Council under
the ARC Centre of Excellence for Enabling Eco-Efficient
Beneficiation of Minerals (CE200100009).
The authors extend their heartfelt gratitude to Bellson
Awatey for his exceptional technical support and training.
Candice Brill’s invaluable contributions in both technical
and academic realms, through engaging discussions and
collaborative work, have greatly enriched this endeavour.
Special thanks to Michael Kilmartin for his aid in work-
place organisation and equipment set-up. Jan Nesset’s
meticulous review and development guidelines have been
instrumental in shaping this project. We sincerely appreci-
ate Andrea Grey and Barry Mitchell’s administrative and
organisational support.