2
and transport, such as launders and crowder are rare.
Therefore, a fundamental understanding of the effect of
froth crowders and launders on flotation performance is
essential to a scale up process from flotation lab tests. This
difficulty of not being able to scale up is due to the froth
being scraped off during a flotation test in the laboratory
and, therefore, does not exhibit a natural behavior, and it is
not possible to increase the transport distance of the froth
(Coleman, 2009).
These days there are several industrial launder and
crowder designs that are used particularly in large vol-
ume cells to improve froth management (Figure 6). Their
characteristics will be defined during the design and engi-
neering phase of a green field project. When it comes to
brownfields, the correct froth management gear needs to be
carefully selected not only in terms of metallurgical perfor-
mance but also in terms of flexibility to be installed through
retrofits. Table 1 summarizes three different projects where
metallurgical improvement was achieved through launder
retrofits in Cu-Mo rougher-scavenger circuits:
Concisely, Center launder upgrades have been a suc-
cessful way to improve metallurgical performance in large
flotation cells with low froth collection, the retrofit effect
can be maximized if process optimization is undertaken
following the upgrade. Nonetheless, crowding via center
launder has its own limitation, and currently there are not
many options for a given large flotation cell with low froth
recovery that was originally equipped or recently retrofit-
ted with center launders. Process optimization might be a
way, but it can only handle as far as the limitations of the
existing assets. (Bermudez et al, 2021). A potential solution
for flotation cells with too low froth carrying rate was intro-
duced by Outotec SEAP (now Metso Australia) named
“Radial froth crowders” or “drop-in crowders.” These were
proposed to be installed on top of peripheral and center
launders to increase crowding. Figure 3 details the solution
(Morgan, 2018). However, these crowders were not prop-
erly scaled-up for flotation cells larger than 200 m3. Some
challenges to use this solution for cells with the volume of
300 m3 or larger include: Adding more crowding closer to
the tank perimeter where comprise larger section of FSA in
Figure 1. Froth transport parameters relative to flotation cell
volume
Table 1. Summary of launder retrofit projects, in descending
order: Bermudez et al (2021), Bermudez et al (2022),
Weiping Liu et al (2022) and D. R. Seaman et al (2022)
Plant Country
Flotation
Machines
Launder
Retrofit
Hudbay
Constancia
Peru 3 × 300 m3 cells Center
Launder
Rio Tinto
KUCC
USA 3 × 300 m3 cells Center
Launder
FMI Bagdad USA 3 × 300 m3 cells Center
Launder
NewCrest Red
Chris
Canada 6 × 200 m3 cells Center
Launder
Figure 2. Photo comparison between both launder
configurations, radial launders (left) and center launder
(right) in Kennecott (2022
and transport, such as launders and crowder are rare.
Therefore, a fundamental understanding of the effect of
froth crowders and launders on flotation performance is
essential to a scale up process from flotation lab tests. This
difficulty of not being able to scale up is due to the froth
being scraped off during a flotation test in the laboratory
and, therefore, does not exhibit a natural behavior, and it is
not possible to increase the transport distance of the froth
(Coleman, 2009).
These days there are several industrial launder and
crowder designs that are used particularly in large vol-
ume cells to improve froth management (Figure 6). Their
characteristics will be defined during the design and engi-
neering phase of a green field project. When it comes to
brownfields, the correct froth management gear needs to be
carefully selected not only in terms of metallurgical perfor-
mance but also in terms of flexibility to be installed through
retrofits. Table 1 summarizes three different projects where
metallurgical improvement was achieved through launder
retrofits in Cu-Mo rougher-scavenger circuits:
Concisely, Center launder upgrades have been a suc-
cessful way to improve metallurgical performance in large
flotation cells with low froth collection, the retrofit effect
can be maximized if process optimization is undertaken
following the upgrade. Nonetheless, crowding via center
launder has its own limitation, and currently there are not
many options for a given large flotation cell with low froth
recovery that was originally equipped or recently retrofit-
ted with center launders. Process optimization might be a
way, but it can only handle as far as the limitations of the
existing assets. (Bermudez et al, 2021). A potential solution
for flotation cells with too low froth carrying rate was intro-
duced by Outotec SEAP (now Metso Australia) named
“Radial froth crowders” or “drop-in crowders.” These were
proposed to be installed on top of peripheral and center
launders to increase crowding. Figure 3 details the solution
(Morgan, 2018). However, these crowders were not prop-
erly scaled-up for flotation cells larger than 200 m3. Some
challenges to use this solution for cells with the volume of
300 m3 or larger include: Adding more crowding closer to
the tank perimeter where comprise larger section of FSA in
Figure 1. Froth transport parameters relative to flotation cell
volume
Table 1. Summary of launder retrofit projects, in descending
order: Bermudez et al (2021), Bermudez et al (2022),
Weiping Liu et al (2022) and D. R. Seaman et al (2022)
Plant Country
Flotation
Machines
Launder
Retrofit
Hudbay
Constancia
Peru 3 × 300 m3 cells Center
Launder
Rio Tinto
KUCC
USA 3 × 300 m3 cells Center
Launder
FMI Bagdad USA 3 × 300 m3 cells Center
Launder
NewCrest Red
Chris
Canada 6 × 200 m3 cells Center
Launder
Figure 2. Photo comparison between both launder
configurations, radial launders (left) and center launder
(right) in Kennecott (2022