2
improve flotation efficiency, reduce energy consumption,
and support sustainable operation. Building on the achieve-
ments of its predecessor, FloatForce, the FloatForce+ aims
to deliver enhanced metallurgical performance, energy sav-
ings, and environmentally responsible design.
In this paper the results of industrial-scale testing of
the FloatForce+ rotor at the Kennecott Copperton con-
centrator is presented. By comparing FloatForce+ with
the original FloatForce model, the goal was to evaluate its
impact on key performance indicators, including metallur-
gical performance, mixing capability and energy efficiency.
Unfortunately, the metallurgical comparison wasn’t possible
due to variation in feed. Additionally, the paper highlights
the design innovations behind FloatForce+ and details its
metallurgical performance in the industrial trial.
HISTORY OF METSO FLOTATION
MIXING MECHANISMS
Metso’s development of flotation mixing mechanisms spans
over five decades, with each successive innovation advanc-
ing performance and energy efficiency. The journey began
in the 1970s with the Outokumpu Multi-Mix design, fol-
lowed by the Outokumpu Free-Flow configuration in the
1990s. These advancements laid the groundwork for the
FloatForce mechanism, which was introduced in 2005
(Rinne, 2023).
The original Outokumpu (OK) rotor-stator mecha-
nism, developed by Dr. Kai Fallenius and his team, rep-
resented a major leap forward in flotation technology.
Through rigorous hydrodynamic calculations and testing,
the OK mechanism delivered a steady distribution of fine
bubbles and offered two configurations: the Multi-Mix for
general and fine flotation, and the Free-Flow for coarser flo-
tation, which reduced turbulence and enhanced pumping
capacity (Oravainen and Allenius, 2007).
The FloatForce mechanism, developed to build on this
foundation, incorporated a refined design that improved
slurry pumping and air dispersion by introducing separate
air slots positioned closer to the stator. This design allowed
for increased air intake without compromising power sta-
bility, resulting in improved metallurgical performance,
greater energy efficiency, and reduced maintenance require-
ments (Grönstrand et al., 2006). The FloatForce+ further
refines these features, continuing Metso’s commitment to
sustainable and high-performance flotation technology.
Rotor Design Process: from Concept to Optimization
The development of Metso’s flotation mixing mechanisms
follows a rigorous methodology, incorporating experi-
mental work across laboratory, pilot, and industrial scales.
Computational Fluid Dynamics (CFD) modeling plays a
crucial role in the design process, particularly in the early
stages, to explore potential designs efficiently, conserve
resources, and accelerate the creation of commercially
viable products. Throughout development, CFD model-
ing continues to validate experimental results and optimize
design features.
The FloatForce+ development began in 2019, with
a team of Metso specialists defining new design criteria,
building upon the successful features of the FloatForce
mechanism. Initial brainstorming sessions led to the devel-
opment of novel rotor and stator concepts, which were
refined using iterative CFD simulations to evaluate key
performance indicators. The design refinements, verified
through lab and pilot testing at Metso’s Research Center in
Pori, Finland, culminated in a final design that retained the
effective separate channels for air and slurry from previous
FloatForce but added new top holes to improve pumping
and re-mixing. Recent, CFD simulations confirmed that
the FloatForce+ rotor exhibited enhanced turbulent kinetic
energy and energy dissipation, supporting its ability to
improve flotation performance (see Figure 1).
Expected Benefits of the FloatForce+ Rotor
The FloatForce+ rotor builds upon the foundational
design of its predecessor, incorporating several enhance-
ments aimed at improving pumping efficiency, reducing
power consumption, and supporting sustainable manu-
facturing practices. These optimizations were designed to
result in improvements in both metallurgical performance
and energy efficiency compared to the original FloatForce
model.
A key design objective for FloatForce ®+ was ensuring
that the rotor could be seamlessly retrofitted into exist-
ing Metso flotation cells as well as third-party machines.
This compatibility allows for a straightforward installa-
tion process without the need for modifications, enabling
operators to upgrade their flotation systems efficiently. The
redesigned rotor shape, which improves efficiency and sus-
tainability features, is shown in Figure 2. By incorporating
resource-efficient materials, reducing energy consumption,
and enhancing metallurgical performance, the FloatForce+
rotor offers a clear path toward more sustainable, high-per-
formance flotation operations.
EXPERIMENTAL
To compare the performance of two rotor designs,
FloatForce and FloatForce+, samples were collected from
an Outotec-branded TC-300 mechanical flotation cell
(300 m3) located at Rio Tinto’s Kennecott mine in Salt
improve flotation efficiency, reduce energy consumption,
and support sustainable operation. Building on the achieve-
ments of its predecessor, FloatForce, the FloatForce+ aims
to deliver enhanced metallurgical performance, energy sav-
ings, and environmentally responsible design.
In this paper the results of industrial-scale testing of
the FloatForce+ rotor at the Kennecott Copperton con-
centrator is presented. By comparing FloatForce+ with
the original FloatForce model, the goal was to evaluate its
impact on key performance indicators, including metallur-
gical performance, mixing capability and energy efficiency.
Unfortunately, the metallurgical comparison wasn’t possible
due to variation in feed. Additionally, the paper highlights
the design innovations behind FloatForce+ and details its
metallurgical performance in the industrial trial.
HISTORY OF METSO FLOTATION
MIXING MECHANISMS
Metso’s development of flotation mixing mechanisms spans
over five decades, with each successive innovation advanc-
ing performance and energy efficiency. The journey began
in the 1970s with the Outokumpu Multi-Mix design, fol-
lowed by the Outokumpu Free-Flow configuration in the
1990s. These advancements laid the groundwork for the
FloatForce mechanism, which was introduced in 2005
(Rinne, 2023).
The original Outokumpu (OK) rotor-stator mecha-
nism, developed by Dr. Kai Fallenius and his team, rep-
resented a major leap forward in flotation technology.
Through rigorous hydrodynamic calculations and testing,
the OK mechanism delivered a steady distribution of fine
bubbles and offered two configurations: the Multi-Mix for
general and fine flotation, and the Free-Flow for coarser flo-
tation, which reduced turbulence and enhanced pumping
capacity (Oravainen and Allenius, 2007).
The FloatForce mechanism, developed to build on this
foundation, incorporated a refined design that improved
slurry pumping and air dispersion by introducing separate
air slots positioned closer to the stator. This design allowed
for increased air intake without compromising power sta-
bility, resulting in improved metallurgical performance,
greater energy efficiency, and reduced maintenance require-
ments (Grönstrand et al., 2006). The FloatForce+ further
refines these features, continuing Metso’s commitment to
sustainable and high-performance flotation technology.
Rotor Design Process: from Concept to Optimization
The development of Metso’s flotation mixing mechanisms
follows a rigorous methodology, incorporating experi-
mental work across laboratory, pilot, and industrial scales.
Computational Fluid Dynamics (CFD) modeling plays a
crucial role in the design process, particularly in the early
stages, to explore potential designs efficiently, conserve
resources, and accelerate the creation of commercially
viable products. Throughout development, CFD model-
ing continues to validate experimental results and optimize
design features.
The FloatForce+ development began in 2019, with
a team of Metso specialists defining new design criteria,
building upon the successful features of the FloatForce
mechanism. Initial brainstorming sessions led to the devel-
opment of novel rotor and stator concepts, which were
refined using iterative CFD simulations to evaluate key
performance indicators. The design refinements, verified
through lab and pilot testing at Metso’s Research Center in
Pori, Finland, culminated in a final design that retained the
effective separate channels for air and slurry from previous
FloatForce but added new top holes to improve pumping
and re-mixing. Recent, CFD simulations confirmed that
the FloatForce+ rotor exhibited enhanced turbulent kinetic
energy and energy dissipation, supporting its ability to
improve flotation performance (see Figure 1).
Expected Benefits of the FloatForce+ Rotor
The FloatForce+ rotor builds upon the foundational
design of its predecessor, incorporating several enhance-
ments aimed at improving pumping efficiency, reducing
power consumption, and supporting sustainable manu-
facturing practices. These optimizations were designed to
result in improvements in both metallurgical performance
and energy efficiency compared to the original FloatForce
model.
A key design objective for FloatForce ®+ was ensuring
that the rotor could be seamlessly retrofitted into exist-
ing Metso flotation cells as well as third-party machines.
This compatibility allows for a straightforward installa-
tion process without the need for modifications, enabling
operators to upgrade their flotation systems efficiently. The
redesigned rotor shape, which improves efficiency and sus-
tainability features, is shown in Figure 2. By incorporating
resource-efficient materials, reducing energy consumption,
and enhancing metallurgical performance, the FloatForce+
rotor offers a clear path toward more sustainable, high-per-
formance flotation operations.
EXPERIMENTAL
To compare the performance of two rotor designs,
FloatForce and FloatForce+, samples were collected from
an Outotec-branded TC-300 mechanical flotation cell
(300 m3) located at Rio Tinto’s Kennecott mine in Salt