XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2947
combines the superficial gas velocity and bubble size into a
single quantity, according to the following equation:
Sb =bd /(6 · Jg)
where Jg is the superficial gas rise velocity and bd is the
average bubble diameter. Sb is an important parameter as it
links gas dispersion to flotation performance, being directly
proportional to the kinetic flotation rate.
Recently Harbort and Felipe (2022) reported on a flo-
tation machine database that contains over 4,000 entries
and includes gas dispersion measurements (such as bubble
size, gas hold-up and superficial gas velocity), cell dimen-
sions, and impeller tip speeds. Data comes from numer-
ous operating sites and commodity groups, including gold,
copper, molybdenum, nickel, palladium, lead-zinc, plati-
num, silica, phosphate, coal and iron ore. Flotation duties
registered include flash flotation, pre-flotation, roughing,
scavenging, and cleaning circuits.
Measurements have been conducted on a wide range
of flotation machines from different manufacturers. This
includes forced air machines, such as Outotec (Metso) and
Dorr Oliver, and self-aerated machines, such as Denver
and WEMCO. The database also includes several flotation
columns, such as the Microcel, Eriez/CMT Slamjet, and
Jameson cell.
Available data allowed an evaluation of variation in
flotation machine gas characterization for Outotec (now
Metso), WEMCO, Agitair, Dorr-Oliver, and Jameson cells,
for the Eriez columns fitted with Microcel atomizers and
SlamJet aspirators. Miscellaneous columns were grouped
together for evaluation.
The relationship between Jg and bubble size is not lin-
ear. This is evident in Figure 2 where each type of flotation
machine has a maximum limiting Sb, or kinetic rate, based
on gas characteristics. Flotation machines can be catalogued
in two groups, based on the rate at which Jg is converted
into Sb, which characterizes how effectively increased air
addition increases kinetic rate.
The first group includes WEMCO, Outotec, Agitair,
Dorr-Oliver (Metso), and Jameson cells. These machines
are more effective bubble surface area flux generators. The
second group includes the Microcel, SlamJet, and the mis-
cellaneous columns, which are less effective bubble surface
area flux generators.
If the data is treated as a first order rate reaction, then k,
the rate at which Jg is converted into Sb and the maximum
Sb, Sbmax, can be calculated, as shown in Table 1. Table 1
includes machines for which data were available.
Table 1. Values of k and S
bmax for various flotation machines.
(modified from Harbort and Felipe, 2022)
Flotation Machine Type k S
bmax
Wemco 1.47 73
Metso Outotec 1.47 75
Dorr-Oliver 1.31 80
Agitair 1.61 72
Microcel 1.45 60
SlamJet 0.85 72
Jameson 1.64 72
Miscellaneous columns 0.8 74
Figure 2. Aeration Data from Various Flotation Machines (Harbort and Felipe, 2022)
combines the superficial gas velocity and bubble size into a
single quantity, according to the following equation:
Sb =bd /(6 · Jg)
where Jg is the superficial gas rise velocity and bd is the
average bubble diameter. Sb is an important parameter as it
links gas dispersion to flotation performance, being directly
proportional to the kinetic flotation rate.
Recently Harbort and Felipe (2022) reported on a flo-
tation machine database that contains over 4,000 entries
and includes gas dispersion measurements (such as bubble
size, gas hold-up and superficial gas velocity), cell dimen-
sions, and impeller tip speeds. Data comes from numer-
ous operating sites and commodity groups, including gold,
copper, molybdenum, nickel, palladium, lead-zinc, plati-
num, silica, phosphate, coal and iron ore. Flotation duties
registered include flash flotation, pre-flotation, roughing,
scavenging, and cleaning circuits.
Measurements have been conducted on a wide range
of flotation machines from different manufacturers. This
includes forced air machines, such as Outotec (Metso) and
Dorr Oliver, and self-aerated machines, such as Denver
and WEMCO. The database also includes several flotation
columns, such as the Microcel, Eriez/CMT Slamjet, and
Jameson cell.
Available data allowed an evaluation of variation in
flotation machine gas characterization for Outotec (now
Metso), WEMCO, Agitair, Dorr-Oliver, and Jameson cells,
for the Eriez columns fitted with Microcel atomizers and
SlamJet aspirators. Miscellaneous columns were grouped
together for evaluation.
The relationship between Jg and bubble size is not lin-
ear. This is evident in Figure 2 where each type of flotation
machine has a maximum limiting Sb, or kinetic rate, based
on gas characteristics. Flotation machines can be catalogued
in two groups, based on the rate at which Jg is converted
into Sb, which characterizes how effectively increased air
addition increases kinetic rate.
The first group includes WEMCO, Outotec, Agitair,
Dorr-Oliver (Metso), and Jameson cells. These machines
are more effective bubble surface area flux generators. The
second group includes the Microcel, SlamJet, and the mis-
cellaneous columns, which are less effective bubble surface
area flux generators.
If the data is treated as a first order rate reaction, then k,
the rate at which Jg is converted into Sb and the maximum
Sb, Sbmax, can be calculated, as shown in Table 1. Table 1
includes machines for which data were available.
Table 1. Values of k and S
bmax for various flotation machines.
(modified from Harbort and Felipe, 2022)
Flotation Machine Type k S
bmax
Wemco 1.47 73
Metso Outotec 1.47 75
Dorr-Oliver 1.31 80
Agitair 1.61 72
Microcel 1.45 60
SlamJet 0.85 72
Jameson 1.64 72
Miscellaneous columns 0.8 74
Figure 2. Aeration Data from Various Flotation Machines (Harbort and Felipe, 2022)