XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2963
coarse particles, detachment forces are higher than forces
of attachment between- particles and bubbles, resulting in
detachment of particles from bubbles and low recoveries
(Wang et al., 2016).
An alternative to increase coarse particle recovery is to
replace the mixing mechanism with liquid fluidization com-
bined with air to achieve flotation (Kromah et al., 2022
Mankosa and Luttrell, 2002 Jameson, 2007). The fluidiza-
tion is promoted by adding water in a tank, targeting for a
velocity that is above the minimum fluidization velocity for
a certain particle diameter. (Kromah et al., 2022). The min-
imum fluidization velocity is directly proportional to the
particle diameter (Dankwah et al 2022), which means that
more water is needed to fluidize bigger particles. Kromah
et al., 2022 listed the water consumption as a limitation
for the fluidized bed flotation cells, as well as mandatory
pre-classification for one of the available technologies and
precise control in the fluidization water, to ensure that all
large particles are kept in the bed and not ejected towards
the OF. Additionally, dewatering is required to adjust the
concentrate solids percentage for final grinding (Jaques et
al., 2021). This dewatering will add complexity and cost to
a flow sheet and can be an expensive solution.
Another alternative to recover coarse particles is to pro-
mote the separation in the froth phase instead of in the
slurry phase. One way to attach the particle directly to the
froth is to feed the cell on or in the froth phase, instead of
feeding it in the slurry phase. This will remove the need
for coarse particle-bubble aggregates to transition from the
slurry phase to the froth phase. This methodology has been
studied since at least the 1960s, with Knaus submitting a
patent titled “Verfahren zur Flotation von Mineralien und
Vorrichtung zur Durchfuhrung des Verfahrens” in 1968.
At least two other technologies with unique features used
the same froth feeding principle such as Separation in Froth
(Nenno et al., 2004) and FUD (Uruzar, 2011).
Metso has designed a new coarse particle flotation
(CPF) device (Figure 1) with a novel feeding arrangement
that feeds the slurry in/on the froth and has the similar pro-
cess variables as any conventional flotation equipment: feed
particle size distribution includes coarse plus traditional
particles sizes (µm), Jg (cm/s), collector dosage (g/t), frother
dosage (ppm) and froth depth (mm). One advantage of this
approach is that no fluidization water is required. The sol-
ids percentage from the products are similar to the ones
achieved with TankCells ®, which can have the concentrate
directed to the regrinding circuit without any dewatering
stage. Any water that may be needed would only be added
to maintain a typical water balance around a standard
mechanical flotation cell. Another advantage is there is no
lower limit for the feed size range. Therefore, classification
is not a requirement for this technology, but it can be used
if that process step makes sense within the flowsheet.
The new flotation device is specifically designed for
coarse particle flotation applications, however it also has
high recoveries of fines. Figure 1 illustrates the new technol-
ogy with the feed on top of the tank. The new equipment
is operated as a pneumatic flotation device, which has the
aeration zone located in the bottom part of the tank. Air is
introduced into the unit in the aeration zone by the use of
a sparger. Above the aeration zone, there is the froth zone,
and the feeding zone is located in the froth zone. The feed-
ing apparatus is designed to introduce the feed stream with
low velocity and energy on the top part of the cell. Water
Figure 1. Sketch from the novel flotation technology with feeding on/in the froth
coarse particles, detachment forces are higher than forces
of attachment between- particles and bubbles, resulting in
detachment of particles from bubbles and low recoveries
(Wang et al., 2016).
An alternative to increase coarse particle recovery is to
replace the mixing mechanism with liquid fluidization com-
bined with air to achieve flotation (Kromah et al., 2022
Mankosa and Luttrell, 2002 Jameson, 2007). The fluidiza-
tion is promoted by adding water in a tank, targeting for a
velocity that is above the minimum fluidization velocity for
a certain particle diameter. (Kromah et al., 2022). The min-
imum fluidization velocity is directly proportional to the
particle diameter (Dankwah et al 2022), which means that
more water is needed to fluidize bigger particles. Kromah
et al., 2022 listed the water consumption as a limitation
for the fluidized bed flotation cells, as well as mandatory
pre-classification for one of the available technologies and
precise control in the fluidization water, to ensure that all
large particles are kept in the bed and not ejected towards
the OF. Additionally, dewatering is required to adjust the
concentrate solids percentage for final grinding (Jaques et
al., 2021). This dewatering will add complexity and cost to
a flow sheet and can be an expensive solution.
Another alternative to recover coarse particles is to pro-
mote the separation in the froth phase instead of in the
slurry phase. One way to attach the particle directly to the
froth is to feed the cell on or in the froth phase, instead of
feeding it in the slurry phase. This will remove the need
for coarse particle-bubble aggregates to transition from the
slurry phase to the froth phase. This methodology has been
studied since at least the 1960s, with Knaus submitting a
patent titled “Verfahren zur Flotation von Mineralien und
Vorrichtung zur Durchfuhrung des Verfahrens” in 1968.
At least two other technologies with unique features used
the same froth feeding principle such as Separation in Froth
(Nenno et al., 2004) and FUD (Uruzar, 2011).
Metso has designed a new coarse particle flotation
(CPF) device (Figure 1) with a novel feeding arrangement
that feeds the slurry in/on the froth and has the similar pro-
cess variables as any conventional flotation equipment: feed
particle size distribution includes coarse plus traditional
particles sizes (µm), Jg (cm/s), collector dosage (g/t), frother
dosage (ppm) and froth depth (mm). One advantage of this
approach is that no fluidization water is required. The sol-
ids percentage from the products are similar to the ones
achieved with TankCells ®, which can have the concentrate
directed to the regrinding circuit without any dewatering
stage. Any water that may be needed would only be added
to maintain a typical water balance around a standard
mechanical flotation cell. Another advantage is there is no
lower limit for the feed size range. Therefore, classification
is not a requirement for this technology, but it can be used
if that process step makes sense within the flowsheet.
The new flotation device is specifically designed for
coarse particle flotation applications, however it also has
high recoveries of fines. Figure 1 illustrates the new technol-
ogy with the feed on top of the tank. The new equipment
is operated as a pneumatic flotation device, which has the
aeration zone located in the bottom part of the tank. Air is
introduced into the unit in the aeration zone by the use of
a sparger. Above the aeration zone, there is the froth zone,
and the feeding zone is located in the froth zone. The feed-
ing apparatus is designed to introduce the feed stream with
low velocity and energy on the top part of the cell. Water
Figure 1. Sketch from the novel flotation technology with feeding on/in the froth