XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 497
contaminants (Flippov et al., 2014). Magnetic separation
is used to enrich iron ore samples that demonstrate either
para- or ferromagnetic behavior (Flippov et al., 2014).
Magnetic separation can be performed on wet or dry mate-
rial, with wet being a slurry (Flippov et al., 2014). Magnetic
separators are broken down into two categories: high and
low intensity (Flippov et al., 2014). Low intensity magnetic
separation (LIMS) is used for ores that demonstrate strong
magnetic behavior, typically these ores have a high propor-
tion of ferromagnetic minerals like magnetite (Flippov et
al., 2014). High intensity magnetic separation is reserved
for weakly magnetic iron bearing minerals, such as hema-
tite, goethite, and limonite (Flippov et al., 2014).
METHOD
Two iron ore samples were tested in this research project:
1. “Ultrafines” iron ore sample, with particle size (d90)
10 µm, was collected from an iron ore processing
plant in Brazil. Its fine granulometry makes it a
poor candidate for flotation. In general, fines suffer
from low collision efficiencies in flotation which
adversely impacts separation efficiency (Miettinen
et al., 2010). According to Lima et al., a concen-
tration of 20% hematite under 20 µm reduces
the quartz recovery of particles over 74 µm from
97% to 62% (Lima et al., 2020). This reduction
of quartz recovery often necessitates the separation
of the ultrafine portion of iron by hydrocyclones
(Lima et al., 2020). However, because this portion
is excluded from the flotation processing, it is not
sufficiently enriched. Therefore, an alternative pro-
cessing method that serves to enrich the iron ore
would be attractive.
2. An air-classified iron ore sample, with particle
size (d90) 150 µm, from Brazil. This sample was
the fine product of an air classification separation
whereby the coarse fraction was removed.
The mineralogy of the samples was provided by supplier of
the material and is summarized in Table 1.
The majority of both samples are composed of hema-
tite and no significant proportion of magnetite is present in
the sample. The gangue minerals are primarily quartz and
kaolinite.
The particle size analysis below was performed on a dry
basis using a laser diffraction-based Malvern Mastersizer
3000E.
Further chemical analysis was performed by STET. The
‘loss on ignition’ was measured by burning 4 grams of sam-
ple at 1000 °C for one hour. A Malvern-Panalytical Zetium
wavelength dispersive X-ray fluorescence instrument was
used to determine the chemical composition of the iron ore
sample. The results of this analysis are reported as an aver-
age with standard deviations of 102 measurements of the
feed material in Table 3.
Figure 1. Model of STET separator
Table 1. Mineralogy of “ultrafines” iron ore and “air-classified” iron ore samples
Sample Hematite Goethite Quartz Kaolinite
Ultrafines Iron Ore 50.8% 17.9% 12.5% 18.5%
Air-classified Iron Ore 50.6% 3.4% 40.9% 3.5%
contaminants (Flippov et al., 2014). Magnetic separation
is used to enrich iron ore samples that demonstrate either
para- or ferromagnetic behavior (Flippov et al., 2014).
Magnetic separation can be performed on wet or dry mate-
rial, with wet being a slurry (Flippov et al., 2014). Magnetic
separators are broken down into two categories: high and
low intensity (Flippov et al., 2014). Low intensity magnetic
separation (LIMS) is used for ores that demonstrate strong
magnetic behavior, typically these ores have a high propor-
tion of ferromagnetic minerals like magnetite (Flippov et
al., 2014). High intensity magnetic separation is reserved
for weakly magnetic iron bearing minerals, such as hema-
tite, goethite, and limonite (Flippov et al., 2014).
METHOD
Two iron ore samples were tested in this research project:
1. “Ultrafines” iron ore sample, with particle size (d90)
10 µm, was collected from an iron ore processing
plant in Brazil. Its fine granulometry makes it a
poor candidate for flotation. In general, fines suffer
from low collision efficiencies in flotation which
adversely impacts separation efficiency (Miettinen
et al., 2010). According to Lima et al., a concen-
tration of 20% hematite under 20 µm reduces
the quartz recovery of particles over 74 µm from
97% to 62% (Lima et al., 2020). This reduction
of quartz recovery often necessitates the separation
of the ultrafine portion of iron by hydrocyclones
(Lima et al., 2020). However, because this portion
is excluded from the flotation processing, it is not
sufficiently enriched. Therefore, an alternative pro-
cessing method that serves to enrich the iron ore
would be attractive.
2. An air-classified iron ore sample, with particle
size (d90) 150 µm, from Brazil. This sample was
the fine product of an air classification separation
whereby the coarse fraction was removed.
The mineralogy of the samples was provided by supplier of
the material and is summarized in Table 1.
The majority of both samples are composed of hema-
tite and no significant proportion of magnetite is present in
the sample. The gangue minerals are primarily quartz and
kaolinite.
The particle size analysis below was performed on a dry
basis using a laser diffraction-based Malvern Mastersizer
3000E.
Further chemical analysis was performed by STET. The
‘loss on ignition’ was measured by burning 4 grams of sam-
ple at 1000 °C for one hour. A Malvern-Panalytical Zetium
wavelength dispersive X-ray fluorescence instrument was
used to determine the chemical composition of the iron ore
sample. The results of this analysis are reported as an aver-
age with standard deviations of 102 measurements of the
feed material in Table 3.
Figure 1. Model of STET separator
Table 1. Mineralogy of “ultrafines” iron ore and “air-classified” iron ore samples
Sample Hematite Goethite Quartz Kaolinite
Ultrafines Iron Ore 50.8% 17.9% 12.5% 18.5%
Air-classified Iron Ore 50.6% 3.4% 40.9% 3.5%