104 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
fluidized bed is a zone of low turbulence and results in a
high degree of interaction between the bubbles and the sol-
ids. Bubble clusters attach to the solid particles rise upwards
and overflow into the concentrate lauder. There is no froth
which also prevents problems associated with detachment
and drop back of coarse particles from the froth phase.
The HydroFloat ® cell requires fines to be removed from
the feed prior to processing to enable a stable fluidised bed
to be formed. The coarseAIR ™ and NovaCell ™ which are
being commercialized by FLSmidth and Jord, respectively,
involve a fluidized bed but reportedly have modifications to
the design that enable processing of a feed containing both
fine and coarse particles (Crompton et al, 2022 Jameson
and Emer, 2019). These new units are being piloted and
evaluated but are yet to be installed and tested at full scale.
These coarse particle flotation technologies can be
installed either to scavenge coarser valuable mineral par-
ticles in the tailing of a conventional flotation circuit or
upfront in the primary grind as a method of preconcentrat-
ing and removing barren/low grade particles prior to sec-
ondary grinding. As a scavenger, they are proving capable of
increasing overall flotation recoveries and are enabling the
flotation feed to be coarsened. By coarsening the feed, sig-
nificant energy reductions can be realized. Coarser flotation
feeds have benefits in tailing processing as a coarser tail-
ing, is easier to dewater. Installing a fluidized bed flotation
cell upfront in the grinding circuit for preconcentration
will be more challenging and is likely to require changes
in the comminution circuit to produce the appropriate
feed. Technologies such as the Vertical Roller Mill are being
investigated because of its ability to produce a stream with
the appropriate feed characteristics.
Fine Particle Flotation
The advent of coarse particle technologies, however, does
not negate the need for advancement in fine particle flota-
tion. Regrinding followed by fine particle flotation is still
required to achieve liberation and an acceptable concen-
trate grade.
Fine particles float very slowly in conventional flotation
tanks because insufficient energy is imparted to the par-
ticles to achieve high probabilities of bubble particle colli-
sion. Many cells are required to provide sufficient residence
time for recovery, resulting in very large plant footprints.
Excessive amounts of flotation residence time also provide
time for the slow floating gangue to be recovered and large
amounts of unselective entrainment recovery. Under these
conditions, flotation selectivity is poor, and multiple stages
of flotation are required to achieve adequate concentrate
grades.
A range of high-intensity pneumatic flotation machines
have been developed, resulting in more rapid flotation
and, in particular, an increase in the recovery of fine par-
ticles. These include the Jameson Cell, Concorde Cell ™,
Imhofloat G-cell, Woodgrove Staged Flotation Reactor,
StackCell ® and the Reflux Flotation Cell (Harbort et al.,
2003 Jameson, 2010 Battersby et al, 2011 Dohm et al.,
2022 Jiang et al, 2019). Of these, the Jameson Cell, com-
mercialized by Glencore Technology, is the most mature
and uptake of this technology is also accelerating. It has
long been used in the coal industry and increasingly so in
base metal sulfide flotation, particularly for cleaning. A
concentrator consisting entirely of Jameson cells was also
recently commissioned at Hudbay’s New Brittania Mill
(Taylor et al, 2022). A schematic diagram of the Jameson
cell depicting its main features is shown in Figure 6.
Most of the pneumatic flotation technologies consist of
a downcomer where high-intensity contacting is achieved
through the impingement of a slurry jet onto a pulp sur-
face. The attachment of particles to bubbles occurs in sec-
onds rather than minutes, enabling a significant reduction
in the plant footprint required to achieve high recoveries.
In many of these cells, the highly turbulent region where
attachment occurs is isolated from the rest of the reactor,
where more quiescent conditions prevail. These quiescent
conditions enable the development of a deep stable froth
phase (or, in the case of the Reflux flotation cell, a bubbly
mixture), which facilitates the use of counter-current froth
washing for high rejection of entrained gangue. The high
kinetic rates and low entrainment recovery enable these
devices to achieve high selectivity in a single flotation stage.
These new designs of flotation machines, therefore, can
simplify and significantly reduce the size of the flotation
concentrator. They improve selectivity and thus enable the
circuit to be “pulled harder,” resulting in higher flotation
recoveries at a target concentrate grade. However, the jury
is still out on whether they can recover fine particles that
cannot be recovered in a conventional cell if given suffi-
cient residence time. It is also unclear which of the new
fine particle flotation technologies will prove superior. This
latter question will not only be a function of the grades
and recoveries able to be produced by the unit but also its
maintenance requirements, ease of control and stability of
operation.
CONTROLLING SURFACE PROPERTIES
Mineral flotation is a surface driven phenomenon.
Successful attachment of particle to a bubble is contingent
on the presence of a net attractive force between the two
objects. This force is a balance between a series of attractive
fluidized bed is a zone of low turbulence and results in a
high degree of interaction between the bubbles and the sol-
ids. Bubble clusters attach to the solid particles rise upwards
and overflow into the concentrate lauder. There is no froth
which also prevents problems associated with detachment
and drop back of coarse particles from the froth phase.
The HydroFloat ® cell requires fines to be removed from
the feed prior to processing to enable a stable fluidised bed
to be formed. The coarseAIR ™ and NovaCell ™ which are
being commercialized by FLSmidth and Jord, respectively,
involve a fluidized bed but reportedly have modifications to
the design that enable processing of a feed containing both
fine and coarse particles (Crompton et al, 2022 Jameson
and Emer, 2019). These new units are being piloted and
evaluated but are yet to be installed and tested at full scale.
These coarse particle flotation technologies can be
installed either to scavenge coarser valuable mineral par-
ticles in the tailing of a conventional flotation circuit or
upfront in the primary grind as a method of preconcentrat-
ing and removing barren/low grade particles prior to sec-
ondary grinding. As a scavenger, they are proving capable of
increasing overall flotation recoveries and are enabling the
flotation feed to be coarsened. By coarsening the feed, sig-
nificant energy reductions can be realized. Coarser flotation
feeds have benefits in tailing processing as a coarser tail-
ing, is easier to dewater. Installing a fluidized bed flotation
cell upfront in the grinding circuit for preconcentration
will be more challenging and is likely to require changes
in the comminution circuit to produce the appropriate
feed. Technologies such as the Vertical Roller Mill are being
investigated because of its ability to produce a stream with
the appropriate feed characteristics.
Fine Particle Flotation
The advent of coarse particle technologies, however, does
not negate the need for advancement in fine particle flota-
tion. Regrinding followed by fine particle flotation is still
required to achieve liberation and an acceptable concen-
trate grade.
Fine particles float very slowly in conventional flotation
tanks because insufficient energy is imparted to the par-
ticles to achieve high probabilities of bubble particle colli-
sion. Many cells are required to provide sufficient residence
time for recovery, resulting in very large plant footprints.
Excessive amounts of flotation residence time also provide
time for the slow floating gangue to be recovered and large
amounts of unselective entrainment recovery. Under these
conditions, flotation selectivity is poor, and multiple stages
of flotation are required to achieve adequate concentrate
grades.
A range of high-intensity pneumatic flotation machines
have been developed, resulting in more rapid flotation
and, in particular, an increase in the recovery of fine par-
ticles. These include the Jameson Cell, Concorde Cell ™,
Imhofloat G-cell, Woodgrove Staged Flotation Reactor,
StackCell ® and the Reflux Flotation Cell (Harbort et al.,
2003 Jameson, 2010 Battersby et al, 2011 Dohm et al.,
2022 Jiang et al, 2019). Of these, the Jameson Cell, com-
mercialized by Glencore Technology, is the most mature
and uptake of this technology is also accelerating. It has
long been used in the coal industry and increasingly so in
base metal sulfide flotation, particularly for cleaning. A
concentrator consisting entirely of Jameson cells was also
recently commissioned at Hudbay’s New Brittania Mill
(Taylor et al, 2022). A schematic diagram of the Jameson
cell depicting its main features is shown in Figure 6.
Most of the pneumatic flotation technologies consist of
a downcomer where high-intensity contacting is achieved
through the impingement of a slurry jet onto a pulp sur-
face. The attachment of particles to bubbles occurs in sec-
onds rather than minutes, enabling a significant reduction
in the plant footprint required to achieve high recoveries.
In many of these cells, the highly turbulent region where
attachment occurs is isolated from the rest of the reactor,
where more quiescent conditions prevail. These quiescent
conditions enable the development of a deep stable froth
phase (or, in the case of the Reflux flotation cell, a bubbly
mixture), which facilitates the use of counter-current froth
washing for high rejection of entrained gangue. The high
kinetic rates and low entrainment recovery enable these
devices to achieve high selectivity in a single flotation stage.
These new designs of flotation machines, therefore, can
simplify and significantly reduce the size of the flotation
concentrator. They improve selectivity and thus enable the
circuit to be “pulled harder,” resulting in higher flotation
recoveries at a target concentrate grade. However, the jury
is still out on whether they can recover fine particles that
cannot be recovered in a conventional cell if given suffi-
cient residence time. It is also unclear which of the new
fine particle flotation technologies will prove superior. This
latter question will not only be a function of the grades
and recoveries able to be produced by the unit but also its
maintenance requirements, ease of control and stability of
operation.
CONTROLLING SURFACE PROPERTIES
Mineral flotation is a surface driven phenomenon.
Successful attachment of particle to a bubble is contingent
on the presence of a net attractive force between the two
objects. This force is a balance between a series of attractive