2428 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
transport zones. For this reason, the relation between the
flotation rate obtained in a more ideal flotation process,
such as the batch flotation, and the flotation rate observed
in an industrial flotation operation, shows a large scale-up
factor.
Recent efforts to characterize the flotation process by
modelling the pulp and froth zones separately have shown
that the main contribution to the scale-up factor relates to
the froth transport, which accounts for around 50% of the
total scale-up factor (Yianatos et al., 2010a Yianatos et al.,
2024). In addition, other problem that remains unsolved is
the identification of the effective collection volume in the
pulp zone, which is different from the pulp volume mea-
sured in plant, e.g., using radioactive tracers. Typically, the
effective pulp volume is around 85–90% of the nominal
cell volume, after subtracting the froth zone and the pulp
gas holdup. In addition, the probability of particles detach-
ment in the collection zone of mechanical cells is higher for
coarser particles due to the lower liberation and higher tur-
bulence induced by the rotor. Further, the mean residence
time of bubbles in a large flotation cell is around 20–50 s,
while in a laboratory cell is 7–12 s. In summary, despite
the accuracy of measurements on effective volume and resi-
dence time of pulp, the actual collection residence time is
unknown.
In recent years, a number of new devices, the inten-
sified flotation cells, have been developed and gradually
incorporated to the industry (Hassanzadeh et al., 2022a
2022b). These devices increase the collection zone efficiency
by contacting the gas (at the bubbles generation point) and
pulp under an intensive energy dissipation condition, in
a reduced control volume. In these devices, it is possible
to better estimate the residence time devoted for the par-
ticles collection process relative to the total residence time
of pulp in the cell.
The following paragraphs describes an example of esti-
mating the particles collection residence time in mechani-
cal cells and in alternative intensified flotation cells.
MECHANICAL CELLS
Measurement of the Effective Pulp Volume in
Industrial Mechanical Cells
The hydrodynamic characterization of industrial flotation
circuits requires a good estimation of the actual residence
time the pulp spend in the cells. The evaluation of the
effective pulp residence time in a flotation plant is difficult
because typically, there is no direct measurements of the
pulp volumetric feed flowrates entering the flotation cir-
cuits, and there is not a direct measurement of the actual
pulp volume in the cell. A good estimate of the overall
volumetric flowrate considers the on-line measurement of
the dry solid flowrate entering the grinding circuit plus the
solid percentage of the flotation pulp feed. However, com-
monly the flotation circuits have more than one flotation
line in parallel, which normally have not an even distribu-
tion of the pulp flowrates. To address this problem, the use
of radioactive tracer tests has proven to be an effective tool
(Yianatos and Diaz, 2011). Using this approach is possible
to estimate the pulp distribution among parallel lines, and
the effective mean residence time per each flotation line.
For example, the effective pulp volume in a copper
flotation plant of Codelco Norte Division, Codelco-Chile,
was measured (Yianatos et al., 2010a). The rougher circuit
consists of three flotation lines in parallel. The total solid
feed flowrate measurement from the feed belts to the SAG
mills allows for the calculation of the solid flowrate per flo-
tation line, considering the corresponding solids percentage
of each line, and the measurement of the actual mean resi-
dence time per line. This study compares Line 1 consisting
of one 300 m3 cell followed by the first six 160 m3 cells and
Line 3 consisting of eight 160 m3 cells. The effective pulp
volume evaluation considers the nominal cells volume plus
the transfer volumes between cells, less the froth volume
and the pulp gas holdup. In addition, a mean pulp flow-
rate entering the concentrate (5.5% of the feed flowrate)
decreased the mean flowrate passing the flotation circuit,
according to the adjusted mass balance, with a feed solids
percent of 38%. In Line 1, the 300 m3 cell and 160 m3 cells,
showed a froth volume of 45 m3 and 24 m3, respectively,
pulp gas holdup of 15%, and the transfer volume between
cells of 4.8 m3 (3%). In Line 3, the 160 m3 cells, showed a
froth volume plus the pulp gas holdup of 19.2 m3 (12%),
and transfer volume between cells of 4.8 m3 (3%), with a
feed solids percent of 39%. Thus, the effective pulp volume
in cells of Line 1 was 85% and in Line 3 was 88%. During
sampling, the volumetric flowrate distribution between the
two testing lines was 33.6±0.4% for Line 1 and 30.4±0.1%
for Line 3. Figure 1 shows a good correspondence between
the residence time estimated in cell 1 (around five minutes)
and the whole line, considering the flowrate distribution
between lines and the effective pulp volume of each line, for
different pulp flowrates during samplings.
Flotation Kinetic Characterization
The actual flotation kinetics characterization requires the
identification of the effective collection residence time,
which can be significantly lower than the effective pulp
residence time in an industrial flotation circuit.
transport zones. For this reason, the relation between the
flotation rate obtained in a more ideal flotation process,
such as the batch flotation, and the flotation rate observed
in an industrial flotation operation, shows a large scale-up
factor.
Recent efforts to characterize the flotation process by
modelling the pulp and froth zones separately have shown
that the main contribution to the scale-up factor relates to
the froth transport, which accounts for around 50% of the
total scale-up factor (Yianatos et al., 2010a Yianatos et al.,
2024). In addition, other problem that remains unsolved is
the identification of the effective collection volume in the
pulp zone, which is different from the pulp volume mea-
sured in plant, e.g., using radioactive tracers. Typically, the
effective pulp volume is around 85–90% of the nominal
cell volume, after subtracting the froth zone and the pulp
gas holdup. In addition, the probability of particles detach-
ment in the collection zone of mechanical cells is higher for
coarser particles due to the lower liberation and higher tur-
bulence induced by the rotor. Further, the mean residence
time of bubbles in a large flotation cell is around 20–50 s,
while in a laboratory cell is 7–12 s. In summary, despite
the accuracy of measurements on effective volume and resi-
dence time of pulp, the actual collection residence time is
unknown.
In recent years, a number of new devices, the inten-
sified flotation cells, have been developed and gradually
incorporated to the industry (Hassanzadeh et al., 2022a
2022b). These devices increase the collection zone efficiency
by contacting the gas (at the bubbles generation point) and
pulp under an intensive energy dissipation condition, in
a reduced control volume. In these devices, it is possible
to better estimate the residence time devoted for the par-
ticles collection process relative to the total residence time
of pulp in the cell.
The following paragraphs describes an example of esti-
mating the particles collection residence time in mechani-
cal cells and in alternative intensified flotation cells.
MECHANICAL CELLS
Measurement of the Effective Pulp Volume in
Industrial Mechanical Cells
The hydrodynamic characterization of industrial flotation
circuits requires a good estimation of the actual residence
time the pulp spend in the cells. The evaluation of the
effective pulp residence time in a flotation plant is difficult
because typically, there is no direct measurements of the
pulp volumetric feed flowrates entering the flotation cir-
cuits, and there is not a direct measurement of the actual
pulp volume in the cell. A good estimate of the overall
volumetric flowrate considers the on-line measurement of
the dry solid flowrate entering the grinding circuit plus the
solid percentage of the flotation pulp feed. However, com-
monly the flotation circuits have more than one flotation
line in parallel, which normally have not an even distribu-
tion of the pulp flowrates. To address this problem, the use
of radioactive tracer tests has proven to be an effective tool
(Yianatos and Diaz, 2011). Using this approach is possible
to estimate the pulp distribution among parallel lines, and
the effective mean residence time per each flotation line.
For example, the effective pulp volume in a copper
flotation plant of Codelco Norte Division, Codelco-Chile,
was measured (Yianatos et al., 2010a). The rougher circuit
consists of three flotation lines in parallel. The total solid
feed flowrate measurement from the feed belts to the SAG
mills allows for the calculation of the solid flowrate per flo-
tation line, considering the corresponding solids percentage
of each line, and the measurement of the actual mean resi-
dence time per line. This study compares Line 1 consisting
of one 300 m3 cell followed by the first six 160 m3 cells and
Line 3 consisting of eight 160 m3 cells. The effective pulp
volume evaluation considers the nominal cells volume plus
the transfer volumes between cells, less the froth volume
and the pulp gas holdup. In addition, a mean pulp flow-
rate entering the concentrate (5.5% of the feed flowrate)
decreased the mean flowrate passing the flotation circuit,
according to the adjusted mass balance, with a feed solids
percent of 38%. In Line 1, the 300 m3 cell and 160 m3 cells,
showed a froth volume of 45 m3 and 24 m3, respectively,
pulp gas holdup of 15%, and the transfer volume between
cells of 4.8 m3 (3%). In Line 3, the 160 m3 cells, showed a
froth volume plus the pulp gas holdup of 19.2 m3 (12%),
and transfer volume between cells of 4.8 m3 (3%), with a
feed solids percent of 39%. Thus, the effective pulp volume
in cells of Line 1 was 85% and in Line 3 was 88%. During
sampling, the volumetric flowrate distribution between the
two testing lines was 33.6±0.4% for Line 1 and 30.4±0.1%
for Line 3. Figure 1 shows a good correspondence between
the residence time estimated in cell 1 (around five minutes)
and the whole line, considering the flowrate distribution
between lines and the effective pulp volume of each line, for
different pulp flowrates during samplings.
Flotation Kinetic Characterization
The actual flotation kinetics characterization requires the
identification of the effective collection residence time,
which can be significantly lower than the effective pulp
residence time in an industrial flotation circuit.