2
field to recover the minerals of interest without interference
from other minerals (Morkun, 2021 Patra, 2015 Gururaj,
1983). Agglomerating agents bridge many particles of the
minerals of interest together, to form larger flakes, therefore
preventing the drop in recovery (Choi, 2023 Roy, 2012).
Rheology modifiers change pulp viscosity to make it settle
more slowly so the particles stay in suspension for enough
time to be recovered (Boger, 2010 Klein, 2005).
This study aims to evaluate the performance of addi-
tives to enhance slime mass yield in high-gradient mag-
netic separation. For this purpose, tests on tailings were
performed with and without the presence of additives. The
best results are shown in this paper.
METHODOLOGY
The sample used in this study was collected from the slimes
thickener of an iron ore producer in Brazil. It was char-
acterized in terms of particle size distribution and chemi-
cal and mineralogical composition. The underflow of the
slimes thickener would go through a VPHGMS (Vertical
Pulsating High Gradient Magnetic Separator), shown in
Figure 2, to investigate the most effective additives for
magnetic separation. The non-magnetic would then com-
pose the tailings and the magnetic, the concentrate, which
would subsequently go through flotation. Table 1 describes
the parameters and reagents’ dosage for the tests.
RESULTS AND DISCUSSION
Characterization of slimes
Figure 3 shows that this was a fine sample. 95% of the
particles were smaller than 45 µm and 30% were under
10 µm. The main mineral components found (Table 2)
were iron, silica, and alumina, common to iron ore tailings.
As observed in Table 3, the iron content of this sample was
spread in the forms of hematite and goethite, the latter con-
taining impurities and being difficult to concentrate. There
was also quartz, a small amount of gibbsite, and a consider-
ably high content of kaolinite, which is a complex mineral
to be floated in reverse iron ore flotation. Therefore, this
sequence of processes (flotation after magnetic separation)
makes it easier to achieve a cleaner concentrate, as kaolinite
is not attracted to the magnetic field. However, as mag-
netic separators usually present low mass yields, in terms of
fines concentration, the main objective was to increase mass
yield at this stage.
Figure 2. Outotec SLon, the VPHGMS used in the tests
Table 1. Tests parameters and reagents dosage
Parameters Products Dosage
pH 8 CADM
23-226
50 g/t
100 g/t
Matrix 1.5 mm CADM
23-236
50 g/t
100 g/t
Magnetic field 10,000 Gauss FLOTICOR
MS 19510
50 g/t
100 g/t
Pulsation 20 Hz FLOTICOR
MS 19124
50 g/t
100 g/t
Solid content 30%–35% CADM
23-237
50 g/t
100 g/t
CADM
23-238
50 g/t
100 g/t
Table 2. X-ray fluorescence of the slimes sample
XRF (%)
Al
2 O
3 9.00
CaO 0.1
Fe 42.5
K2O 0.05
MgO 0.16
Mn 0.98
P 0.155
SiO
2 19.4
TiO
2 0.35
LOI 7.56
Table 3. X-ray diffraction of the slimes sample
XRD (%)
Quartz 14.4
Hematite 28.6
Goethite 29.3
Kaolinite 25.8
Gibbsite 2.0
field to recover the minerals of interest without interference
from other minerals (Morkun, 2021 Patra, 2015 Gururaj,
1983). Agglomerating agents bridge many particles of the
minerals of interest together, to form larger flakes, therefore
preventing the drop in recovery (Choi, 2023 Roy, 2012).
Rheology modifiers change pulp viscosity to make it settle
more slowly so the particles stay in suspension for enough
time to be recovered (Boger, 2010 Klein, 2005).
This study aims to evaluate the performance of addi-
tives to enhance slime mass yield in high-gradient mag-
netic separation. For this purpose, tests on tailings were
performed with and without the presence of additives. The
best results are shown in this paper.
METHODOLOGY
The sample used in this study was collected from the slimes
thickener of an iron ore producer in Brazil. It was char-
acterized in terms of particle size distribution and chemi-
cal and mineralogical composition. The underflow of the
slimes thickener would go through a VPHGMS (Vertical
Pulsating High Gradient Magnetic Separator), shown in
Figure 2, to investigate the most effective additives for
magnetic separation. The non-magnetic would then com-
pose the tailings and the magnetic, the concentrate, which
would subsequently go through flotation. Table 1 describes
the parameters and reagents’ dosage for the tests.
RESULTS AND DISCUSSION
Characterization of slimes
Figure 3 shows that this was a fine sample. 95% of the
particles were smaller than 45 µm and 30% were under
10 µm. The main mineral components found (Table 2)
were iron, silica, and alumina, common to iron ore tailings.
As observed in Table 3, the iron content of this sample was
spread in the forms of hematite and goethite, the latter con-
taining impurities and being difficult to concentrate. There
was also quartz, a small amount of gibbsite, and a consider-
ably high content of kaolinite, which is a complex mineral
to be floated in reverse iron ore flotation. Therefore, this
sequence of processes (flotation after magnetic separation)
makes it easier to achieve a cleaner concentrate, as kaolinite
is not attracted to the magnetic field. However, as mag-
netic separators usually present low mass yields, in terms of
fines concentration, the main objective was to increase mass
yield at this stage.
Figure 2. Outotec SLon, the VPHGMS used in the tests
Table 1. Tests parameters and reagents dosage
Parameters Products Dosage
pH 8 CADM
23-226
50 g/t
100 g/t
Matrix 1.5 mm CADM
23-236
50 g/t
100 g/t
Magnetic field 10,000 Gauss FLOTICOR
MS 19510
50 g/t
100 g/t
Pulsation 20 Hz FLOTICOR
MS 19124
50 g/t
100 g/t
Solid content 30%–35% CADM
23-237
50 g/t
100 g/t
CADM
23-238
50 g/t
100 g/t
Table 2. X-ray fluorescence of the slimes sample
XRF (%)
Al
2 O
3 9.00
CaO 0.1
Fe 42.5
K2O 0.05
MgO 0.16
Mn 0.98
P 0.155
SiO
2 19.4
TiO
2 0.35
LOI 7.56
Table 3. X-ray diffraction of the slimes sample
XRD (%)
Quartz 14.4
Hematite 28.6
Goethite 29.3
Kaolinite 25.8
Gibbsite 2.0