2706 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
(2007). Therefore, fine particles are necessary to help coarse
particles to recover from the froth phase.
The froth phase is generally described as accumulat-
ing bubbles loaded with particles on top of the pulp phase.
The characteristics of the froth phase were observed to be
strongly dependent on the particle size present within it.
Two distinct sections of froth develop, one beneath the
pulp level and one above it. The section of froth submerged
in the pulp is termed the primary froth phase, while the
portion above the pulp is referred to as the secondary froth
phase in this paper. It is possible that the cluster phase dis-
cussed by Jameson et al. (2020), which forms beneath the
froth layer, is the primary froth phase. Note that in this
study, clusters reaching the top of the pulp phase accumu-
late, pack together, and form a dense phase of bubbles and
particles. The clusters do not appear to be loosely held.
Also, Jameson et al. (2020) suggested that the develop-
ment of the cluster layer beneath the froth phase may be
attributed to the clusters’ insufficient buoyancy, preventing
them from rising in the froth phase. Despite limited inves-
tigation in this study, a specific type of cluster struggling to
rise was not observed. However, it was observed that clus-
ters tend to accumulate below the pulp surface, forming a
primary froth phase. The reason clusters develop beneath
the pulp is due to their high density compared to the air
phase above the pulp, preventing their movement above the
pulp surface. The transfer of particles from the primary froth
phase to the secondary phase (above the pulp surface) is pos-
sible if the froth is stable and gradually expands over time.
It’s important to note the limitations of our study. We
only examined particle sizes up to 300 µm, and it’s possible
that the behavior of bubble clusters during froth forma-
tion might vary with larger particles. This suggests a need
for additional research to explore the transfer rate of par-
ticles from the primary phase to the secondary phase and to
determine the maximum particle size capable of rising in the
secondary phase. Such research could be conducted in both
batch and continuous flotation processes, providing a more
comprehensive understanding of the froth phase dynamics.
The bubble surface area is reduced when the bubbles
coalesce and become larger in the froth phase. As a result,
some particles, especially coarse particles, drop off from the
froth. However, this was observed elsewhere. This suggests
selective detachment does not occur for particle sizes up to
300 µm. It is important to note that various other param-
eters may also play crucial roles in this process, including
particle density, hydrophobicity, reagent concentration,
and airflow rate.
Note that the coalescence of the froth is brought through
the drainage mechanism, which is a point of maintaining
the froth to drain out the entrained particles. The water
recovery was not quantified in this study, which could pro-
vide valuable insights into the dynamics of the froth phase.
Additionally, the investigation was conducted using single
mineral particles. Exploring the impact of varying particle
sizes for both valuable minerals and gangue particles would
contribute to a more comprehensive understanding of the
phenomena occurring in the froth phase.
CONCLUSION
The results of this study show that when clusters rise to the
top of the pulp phase, they create the froth phase, which ini-
tially accumulates below the pulp level. The further growth
of the froth phase is influenced by the particle size range
present in the froth. In the presence of discrete coarse par-
ticles (–300 +100 µm), the froth developed below the pulp
level and struggled to grow. However, with the presence of
fine particles, the froth phase expanded, carrying the coarse
particles with it above the pulp phase and overflowing from
the cell lip. This indicates that fine particles help transport
coarse particles through the froth phase above the pulp
phase, facilitating the successful recovery of coarse particles.
The maximum particle size studied in this investigation
was 300 µm, and it was successfully recovered in the pres-
ence of fine particles in the froth. Nevertheless, the forma-
tion of bubble clusters with particles more than 300 µm
and their impact on the development of the froth phase
and recovery is an intriguing aspect that will be explored in
future studies.
ACKNOWLEDGMENTS
The authors express their gratitude for the funding sup-
port from the Australian Research Council (ARC) for
the ARC Centre of Excellence for Enabling Eco-Efficient
Beneficiation of Minerals (grant number: CE200100009).
SJA acknowledges the financial support provided by the
Australian government and the University of New South
Wales, Sydney, through the Australian Government
Research Training Program Scholarship.
REFERENCES
Ata, S. 2012. Phenomena in the froth phase of flotation—
A review. International Journal of Mineral Processing,
102, 1–12.
Bournival, G., De Oliveira E Souza, L., Ata, S. &
Wanless, E. J. 2015. Effect of alcohol frothing agents
on the coalescence of bubbles coated with hydrophobi-
zed silica particles. Chemical Engineering Science, 131,
1–11.
(2007). Therefore, fine particles are necessary to help coarse
particles to recover from the froth phase.
The froth phase is generally described as accumulat-
ing bubbles loaded with particles on top of the pulp phase.
The characteristics of the froth phase were observed to be
strongly dependent on the particle size present within it.
Two distinct sections of froth develop, one beneath the
pulp level and one above it. The section of froth submerged
in the pulp is termed the primary froth phase, while the
portion above the pulp is referred to as the secondary froth
phase in this paper. It is possible that the cluster phase dis-
cussed by Jameson et al. (2020), which forms beneath the
froth layer, is the primary froth phase. Note that in this
study, clusters reaching the top of the pulp phase accumu-
late, pack together, and form a dense phase of bubbles and
particles. The clusters do not appear to be loosely held.
Also, Jameson et al. (2020) suggested that the develop-
ment of the cluster layer beneath the froth phase may be
attributed to the clusters’ insufficient buoyancy, preventing
them from rising in the froth phase. Despite limited inves-
tigation in this study, a specific type of cluster struggling to
rise was not observed. However, it was observed that clus-
ters tend to accumulate below the pulp surface, forming a
primary froth phase. The reason clusters develop beneath
the pulp is due to their high density compared to the air
phase above the pulp, preventing their movement above the
pulp surface. The transfer of particles from the primary froth
phase to the secondary phase (above the pulp surface) is pos-
sible if the froth is stable and gradually expands over time.
It’s important to note the limitations of our study. We
only examined particle sizes up to 300 µm, and it’s possible
that the behavior of bubble clusters during froth forma-
tion might vary with larger particles. This suggests a need
for additional research to explore the transfer rate of par-
ticles from the primary phase to the secondary phase and to
determine the maximum particle size capable of rising in the
secondary phase. Such research could be conducted in both
batch and continuous flotation processes, providing a more
comprehensive understanding of the froth phase dynamics.
The bubble surface area is reduced when the bubbles
coalesce and become larger in the froth phase. As a result,
some particles, especially coarse particles, drop off from the
froth. However, this was observed elsewhere. This suggests
selective detachment does not occur for particle sizes up to
300 µm. It is important to note that various other param-
eters may also play crucial roles in this process, including
particle density, hydrophobicity, reagent concentration,
and airflow rate.
Note that the coalescence of the froth is brought through
the drainage mechanism, which is a point of maintaining
the froth to drain out the entrained particles. The water
recovery was not quantified in this study, which could pro-
vide valuable insights into the dynamics of the froth phase.
Additionally, the investigation was conducted using single
mineral particles. Exploring the impact of varying particle
sizes for both valuable minerals and gangue particles would
contribute to a more comprehensive understanding of the
phenomena occurring in the froth phase.
CONCLUSION
The results of this study show that when clusters rise to the
top of the pulp phase, they create the froth phase, which ini-
tially accumulates below the pulp level. The further growth
of the froth phase is influenced by the particle size range
present in the froth. In the presence of discrete coarse par-
ticles (–300 +100 µm), the froth developed below the pulp
level and struggled to grow. However, with the presence of
fine particles, the froth phase expanded, carrying the coarse
particles with it above the pulp phase and overflowing from
the cell lip. This indicates that fine particles help transport
coarse particles through the froth phase above the pulp
phase, facilitating the successful recovery of coarse particles.
The maximum particle size studied in this investigation
was 300 µm, and it was successfully recovered in the pres-
ence of fine particles in the froth. Nevertheless, the forma-
tion of bubble clusters with particles more than 300 µm
and their impact on the development of the froth phase
and recovery is an intriguing aspect that will be explored in
future studies.
ACKNOWLEDGMENTS
The authors express their gratitude for the funding sup-
port from the Australian Research Council (ARC) for
the ARC Centre of Excellence for Enabling Eco-Efficient
Beneficiation of Minerals (grant number: CE200100009).
SJA acknowledges the financial support provided by the
Australian government and the University of New South
Wales, Sydney, through the Australian Government
Research Training Program Scholarship.
REFERENCES
Ata, S. 2012. Phenomena in the froth phase of flotation—
A review. International Journal of Mineral Processing,
102, 1–12.
Bournival, G., De Oliveira E Souza, L., Ata, S. &
Wanless, E. J. 2015. Effect of alcohol frothing agents
on the coalescence of bubbles coated with hydrophobi-
zed silica particles. Chemical Engineering Science, 131,
1–11.