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Flotation—Is There a Place for a New Flotation Cell?
Michael G. Nelson
Stantec Inc., Salt Lake City, Utah
Robert Dunne
Perth, WA
ABSTRACT: In conventional flotation cells the particle size recovery of the valuable mineral(s) follows an
inverted U shape. The mineral particle size for which recovery is the highest is found across the apex of the
inverted U while mineral recovery decreases on either size of the inverted U, in the coarse and fine particle size
classes. The reasons for the decrease in coarse and fine particle size recovery will be presented, with a review of
methods to increase the coarse and fines recovery in conventional flotation machines.
It is likely that the present unit capacity (600 m3) of the primary rougher-scavenger flotation machines will
increase. For example, large low-grade copper mines are processing 100,000 to 200,000 t of ore daily. Some of
the features of these cells intended to partially increase fine- and coarse-particle size recovery will be presented.
To make a significant improvement in fine- and coarse-particle size recovery the flotation hydrodynamics
(high shear or low turbulence) and reagent chemistry must be different than those in conventional flotation
machines. One critical aspect in the overall process is generating fine and coarse particle streams ahead of flota-
tion machines. All these aspects will be discussed and examples of the available flotation machines and applica-
tions will be given. Finally, the potential for a new flotation cell will be addressed.
INTRODUCTION
In the early application of froth flotation to mineral pro-
cessing, dozens of designs for machines and systems were
conceived, patented, and tested. Eventually the mining
industry settled on a rectangular tank fitted with an agita-
tor to suspend the solids, introduce and disperse the air,
and mix the two. Each cell had a discharge launder along
one side, to carry away the froth concentrate that formed
at the top of the cell. There were variations and improve-
ments, but the basic design changed very little in almost
50 years. A detailed discussion of the development of
flotation cell technology is provided by Lynch et al. (2010)
In the early 1970s, commodity demand and energy
costs increased dramatically, while ore grades continued
to decrease. Bigger processing plants, with bigger equip-
ment, were required. Square tanks continued to get bigger,
but finally reached a point where bigger sizes were struc-
turally infeasible and cylindrical cells were introduced.
Modifications to cell mechanisms were also tested. That
innovation continues, and some recent designs are shown
in Figure 1.
These innovations in design addressed one or more of
the following design challenges:
1. Decrease unit cost by increasing equipment size
2. Improve recovery of fine particles
3. Improve recovery of coarse particles
4. Minimize gangue entrainment and loss of coarse
particles in the froth zone
Flotation—Is There a Place for a New Flotation Cell?
Michael G. Nelson
Stantec Inc., Salt Lake City, Utah
Robert Dunne
Perth, WA
ABSTRACT: In conventional flotation cells the particle size recovery of the valuable mineral(s) follows an
inverted U shape. The mineral particle size for which recovery is the highest is found across the apex of the
inverted U while mineral recovery decreases on either size of the inverted U, in the coarse and fine particle size
classes. The reasons for the decrease in coarse and fine particle size recovery will be presented, with a review of
methods to increase the coarse and fines recovery in conventional flotation machines.
It is likely that the present unit capacity (600 m3) of the primary rougher-scavenger flotation machines will
increase. For example, large low-grade copper mines are processing 100,000 to 200,000 t of ore daily. Some of
the features of these cells intended to partially increase fine- and coarse-particle size recovery will be presented.
To make a significant improvement in fine- and coarse-particle size recovery the flotation hydrodynamics
(high shear or low turbulence) and reagent chemistry must be different than those in conventional flotation
machines. One critical aspect in the overall process is generating fine and coarse particle streams ahead of flota-
tion machines. All these aspects will be discussed and examples of the available flotation machines and applica-
tions will be given. Finally, the potential for a new flotation cell will be addressed.
INTRODUCTION
In the early application of froth flotation to mineral pro-
cessing, dozens of designs for machines and systems were
conceived, patented, and tested. Eventually the mining
industry settled on a rectangular tank fitted with an agita-
tor to suspend the solids, introduce and disperse the air,
and mix the two. Each cell had a discharge launder along
one side, to carry away the froth concentrate that formed
at the top of the cell. There were variations and improve-
ments, but the basic design changed very little in almost
50 years. A detailed discussion of the development of
flotation cell technology is provided by Lynch et al. (2010)
In the early 1970s, commodity demand and energy
costs increased dramatically, while ore grades continued
to decrease. Bigger processing plants, with bigger equip-
ment, were required. Square tanks continued to get bigger,
but finally reached a point where bigger sizes were struc-
turally infeasible and cylindrical cells were introduced.
Modifications to cell mechanisms were also tested. That
innovation continues, and some recent designs are shown
in Figure 1.
These innovations in design addressed one or more of
the following design challenges:
1. Decrease unit cost by increasing equipment size
2. Improve recovery of fine particles
3. Improve recovery of coarse particles
4. Minimize gangue entrainment and loss of coarse
particles in the froth zone