3
Outokumpu Mechanism
The original OK (Outokumpu) rotor/stator configuration
of the 1970s is an outcome of scientific testing and hydro-
dynamic calculations resulting in the characteristic design
known throughout the industry as the OK mechanism. Dr.
Kai Fallenius led a team that developed its original design
after five years of rigorous design and experiment cycles.
Several tests and characterizations were conducted in which
the OK mechanism was found to produce a steady flow of
fine bubbles, thus generating a good bubble surface area
flux and efficient flotation. The final success of the original
OK mechanism was proven in real operations (Grönstrand
et al., 2006).
Throughout the years, the OK mechanism came in two
configurations, differing only about the stator setup, mainly
through the introduction of a new stator stand part. The
MM (Multi-Mix) setup was the general-purpose design for
all-around duties with enhanced fines-flotation properties.
The FF (Free-Flow) setup, particularly designed for coarser
flotation applications, creates less turbulence with increased
pumping capacity (Oravainen and Allenius, 2007). Both
OK mechanism setups are shown in Figure 2.
FloatForce® Mechanism
The next iteration of design resulted in the FloatForce
mechanism. The main innovation was around the rotor and
the criteria for the FloatForce rotor design was to improve
pumping and air dispersion without affecting the multiple
positive features of the traditional OK-rotor. The basic
shape is similar, but the slurry and air flows inside the rotor
differ significantly from its predecessor. Air inlets were
moved to separate slots that lie closer to the stator com-
pared to the OK-rotor. Slurry can thereby fill the rotor
completely and pumping or power draw does not drop sig-
nificantly when air feed is increased. Part of the slurry still
flows through the new air slot and enables complete mixing
of air and slurry (Grönstrand et al., 2006). The design fea-
tures wide pumping channels with separated air dispersion
slots to ensure optimal mixing efficiency. The basic shape of
the FloatForce rotor is shown in Figure 3.
Several reported benefits of the FloatForce ® mecha-
nism have been summarized in Nelson et al. (2009), result-
ing in improvement in both metallurgical performance and
operative costs. These benefits include less sanding, higher
overall and coarse particle recovery, lower energy consump-
tion and reduced maintenance costs.
A proven track record of successful performance of
the FloatForce mechanism has been developed since its
launch in 2005 through industry utilization as well as
multiple technical publications (Cesnik, F., 2009, Gamez
et al., 2011, Valdivia et al., 2011, Outotec, 2011, Leon
and Porras, 2013, Yianatos et al., 2012, Bird et al., 2015,
Morgan et al., 2017, Morgan et al., 2021). A summary of
these published results is shown in Table 2.
FLOATFORCE®+ DEVELOPMENT
To ensure industry relevance and optimized performance,
every flotation technology manufacturer should continu-
ously revisit its product portfolio looking for alternatives
to either replace or enhance existing products, and Metso
is not an exception of that. This can be achieved through
innovation, which may result in entirely new products, or
by providing incremental improvements to well-proven
designs that have consistently delivered good performance
since their initial commercialization. The development of
the FloatForce+ mixing mechanism exemplifies the latter
approach.
When it comes to new flotation mixing mechanism
development, Metso carries out a methodology refined
throughout the years, involving experimental work at
Figure 3. FloatForce rotor shape
Figure 2. OK mechanism setups, Multi-Mix (left) and Free-
Flow (right)
Outokumpu Mechanism
The original OK (Outokumpu) rotor/stator configuration
of the 1970s is an outcome of scientific testing and hydro-
dynamic calculations resulting in the characteristic design
known throughout the industry as the OK mechanism. Dr.
Kai Fallenius led a team that developed its original design
after five years of rigorous design and experiment cycles.
Several tests and characterizations were conducted in which
the OK mechanism was found to produce a steady flow of
fine bubbles, thus generating a good bubble surface area
flux and efficient flotation. The final success of the original
OK mechanism was proven in real operations (Grönstrand
et al., 2006).
Throughout the years, the OK mechanism came in two
configurations, differing only about the stator setup, mainly
through the introduction of a new stator stand part. The
MM (Multi-Mix) setup was the general-purpose design for
all-around duties with enhanced fines-flotation properties.
The FF (Free-Flow) setup, particularly designed for coarser
flotation applications, creates less turbulence with increased
pumping capacity (Oravainen and Allenius, 2007). Both
OK mechanism setups are shown in Figure 2.
FloatForce® Mechanism
The next iteration of design resulted in the FloatForce
mechanism. The main innovation was around the rotor and
the criteria for the FloatForce rotor design was to improve
pumping and air dispersion without affecting the multiple
positive features of the traditional OK-rotor. The basic
shape is similar, but the slurry and air flows inside the rotor
differ significantly from its predecessor. Air inlets were
moved to separate slots that lie closer to the stator com-
pared to the OK-rotor. Slurry can thereby fill the rotor
completely and pumping or power draw does not drop sig-
nificantly when air feed is increased. Part of the slurry still
flows through the new air slot and enables complete mixing
of air and slurry (Grönstrand et al., 2006). The design fea-
tures wide pumping channels with separated air dispersion
slots to ensure optimal mixing efficiency. The basic shape of
the FloatForce rotor is shown in Figure 3.
Several reported benefits of the FloatForce ® mecha-
nism have been summarized in Nelson et al. (2009), result-
ing in improvement in both metallurgical performance and
operative costs. These benefits include less sanding, higher
overall and coarse particle recovery, lower energy consump-
tion and reduced maintenance costs.
A proven track record of successful performance of
the FloatForce mechanism has been developed since its
launch in 2005 through industry utilization as well as
multiple technical publications (Cesnik, F., 2009, Gamez
et al., 2011, Valdivia et al., 2011, Outotec, 2011, Leon
and Porras, 2013, Yianatos et al., 2012, Bird et al., 2015,
Morgan et al., 2017, Morgan et al., 2021). A summary of
these published results is shown in Table 2.
FLOATFORCE®+ DEVELOPMENT
To ensure industry relevance and optimized performance,
every flotation technology manufacturer should continu-
ously revisit its product portfolio looking for alternatives
to either replace or enhance existing products, and Metso
is not an exception of that. This can be achieved through
innovation, which may result in entirely new products, or
by providing incremental improvements to well-proven
designs that have consistently delivered good performance
since their initial commercialization. The development of
the FloatForce+ mixing mechanism exemplifies the latter
approach.
When it comes to new flotation mixing mechanism
development, Metso carries out a methodology refined
throughout the years, involving experimental work at
Figure 3. FloatForce rotor shape
Figure 2. OK mechanism setups, Multi-Mix (left) and Free-
Flow (right)