XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2861
Influence of Hydrodynamics on Frother Efficiency
The CCC value was initially considered an inherent prop-
erty of a particular frother chemistry (Karakashev, Grozev,
Ozdemir et al., 2021). However, it was later established
that the hydrodynamic environment also directly impacts
the CCC value. Cappuccitti and Nesset (2010) showed
that bubble size and coalescence are controlled by the cell’s
hydrodynamic properties as well as the chemistry of the
process. They found that in conventional flotation cells,
CCC increases as the airflow rate increases. The airflow rate
is expressed as a superficial gas velocity (Jg) in the flotation
systems. Superficial gas velocity represents the rate at which
gas flows through a given cross-sectional area of a fluid per
unit of time (Rao, 2023) (Figure 1).
Within the context of fluidised bed flotation, an addi-
tional hydrodynamic parameter must be considered –
buoyancy of a bubble/particle aggregates (Tao, 2005). In
conventional flotation, the typical particle size does not
exceed 150–200 microns (Trahar &Warren, 1976), while a
typical bubble size is in the region of 1.2–2.7 mm (Deglon,
Egya-mensah, &Franzidis, 2000). This means the bubble/
particle aggregate density would typically not exceed buoy-
ancy limitations.
However, in coarse particle flotation, particle sizes can
exceed 800 microns (Janishar Anzoom, Bournival, &Ata,
2024), significantly increasing the density of bubble/parti-
cle aggregates and bringing them closer to buoyancy limits.
For this reason, hydrodynamic considerations must be care-
fully considered in the context of coarse particle flotation,
more so than in conventional flotation.
Bringing Chemical and Hydrodynamic Parameters
Together
Both chemical and hydrodynamic parameters control bub-
ble coalescence. While each effect is relatively understood
on its own, the challenge is understanding their interaction
and the impact of that interaction on coalescence dynamics.
From the hydrodynamic perspective, gas hold-up and
bubble surface area flux (Sb) are the most important, as they
determine the available surface area for particle transpor-
tation and recovery. Sb depends on two variables: bubble
size, usually represented by the Sauter mean diameter (D32)
(Kowalczuk &Drzymala, 2015), and superficial gas veloc-
ity (Jg) (Gorain, Franzidis, &Manlapig, 1997). The math-
ematical expressions of Sb and D32 are shown in Equations
1 and 2, respectively.
S D
J 6
b
g
32
=(1)
D
n d
n d
i
n
i i
i
n
i i
32
1
2
1
3
=
=/
/
(2)
The interaction between chemical and hydrodynamic
parameters can be observed by investigating the change in
bubble size as a response to changes in such parameters as
frother concentration and gas flow rate. Figure 2 schemati-
cally outlines the relationships between parameters repre-
senting the hydrodynamic and chemical variables in the
flotation process, focusing on the fluidised bed flotation
environment. Observing how the bubble size changes with
varying process conditions provides a means to track and
estimate coalescence in the system.
AIMS AND OBJECTIVES
The current work aims to promote a deeper understand-
ing of the interplay between process chemistry and novel
hydrodynamics of fluidised bed flotation. This would aid
the wider implementation of coarse particle flotation using
the HydroFloat ® technology. Specifically, our objective is
Figure 1. a) Bubble size (D32) reduction with increasing
frother dosage showing how CCC increases with Jg b) Effect
of frother dosage on bubble surface area flux (Sb) showing
optimum dosage increasing with Jg (Cappuccitti &Nesset,
2010)
Influence of Hydrodynamics on Frother Efficiency
The CCC value was initially considered an inherent prop-
erty of a particular frother chemistry (Karakashev, Grozev,
Ozdemir et al., 2021). However, it was later established
that the hydrodynamic environment also directly impacts
the CCC value. Cappuccitti and Nesset (2010) showed
that bubble size and coalescence are controlled by the cell’s
hydrodynamic properties as well as the chemistry of the
process. They found that in conventional flotation cells,
CCC increases as the airflow rate increases. The airflow rate
is expressed as a superficial gas velocity (Jg) in the flotation
systems. Superficial gas velocity represents the rate at which
gas flows through a given cross-sectional area of a fluid per
unit of time (Rao, 2023) (Figure 1).
Within the context of fluidised bed flotation, an addi-
tional hydrodynamic parameter must be considered –
buoyancy of a bubble/particle aggregates (Tao, 2005). In
conventional flotation, the typical particle size does not
exceed 150–200 microns (Trahar &Warren, 1976), while a
typical bubble size is in the region of 1.2–2.7 mm (Deglon,
Egya-mensah, &Franzidis, 2000). This means the bubble/
particle aggregate density would typically not exceed buoy-
ancy limitations.
However, in coarse particle flotation, particle sizes can
exceed 800 microns (Janishar Anzoom, Bournival, &Ata,
2024), significantly increasing the density of bubble/parti-
cle aggregates and bringing them closer to buoyancy limits.
For this reason, hydrodynamic considerations must be care-
fully considered in the context of coarse particle flotation,
more so than in conventional flotation.
Bringing Chemical and Hydrodynamic Parameters
Together
Both chemical and hydrodynamic parameters control bub-
ble coalescence. While each effect is relatively understood
on its own, the challenge is understanding their interaction
and the impact of that interaction on coalescence dynamics.
From the hydrodynamic perspective, gas hold-up and
bubble surface area flux (Sb) are the most important, as they
determine the available surface area for particle transpor-
tation and recovery. Sb depends on two variables: bubble
size, usually represented by the Sauter mean diameter (D32)
(Kowalczuk &Drzymala, 2015), and superficial gas veloc-
ity (Jg) (Gorain, Franzidis, &Manlapig, 1997). The math-
ematical expressions of Sb and D32 are shown in Equations
1 and 2, respectively.
S D
J 6
b
g
32
=(1)
D
n d
n d
i
n
i i
i
n
i i
32
1
2
1
3
=
=/
/
(2)
The interaction between chemical and hydrodynamic
parameters can be observed by investigating the change in
bubble size as a response to changes in such parameters as
frother concentration and gas flow rate. Figure 2 schemati-
cally outlines the relationships between parameters repre-
senting the hydrodynamic and chemical variables in the
flotation process, focusing on the fluidised bed flotation
environment. Observing how the bubble size changes with
varying process conditions provides a means to track and
estimate coalescence in the system.
AIMS AND OBJECTIVES
The current work aims to promote a deeper understand-
ing of the interplay between process chemistry and novel
hydrodynamics of fluidised bed flotation. This would aid
the wider implementation of coarse particle flotation using
the HydroFloat ® technology. Specifically, our objective is
Figure 1. a) Bubble size (D32) reduction with increasing
frother dosage showing how CCC increases with Jg b) Effect
of frother dosage on bubble surface area flux (Sb) showing
optimum dosage increasing with Jg (Cappuccitti &Nesset,
2010)