XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3677
iron concentrate. However, the inner wrapped magnetite
needs to be finely ground to enhance its dissociation.
High-purity iron concentrate preparation experiment
Conditional tests were used to optimize the production
process and determine appropriate process parameters to
obtain qualified high-purity iron concentrate. The tailings
were discarded in advance through an electromagnetic con-
centrator, as shown in Table 7. According to the analysis
in Section 3.1, grinding was required to achieve efficient
dissociation of minerals during the preparation of high-
purity iron concentrate. Therefore, under the magnetic
field intensity of 1.0×105 A/m, utilizing a drum weak mag-
netic separator for roughing and an electromagnetic separa-
tor for cleaning, the influence of iron ore size was exhibited
as shown in Figure 10. The results (Figure 5) show that
the total Fe grade of weak magnetic concentrate (WMC)
increases with decreasing particle size due to the increased
degree of dissociation of iron minerals. As impurities were
further removed during cleaning, the total Fe grade of elec-
tromagnetic beneficiation concentrates (EBC) has been
further improved. It can be seen from the silica and acid
insoluble content that the impurity removal and particle
size changes have a reasonable correlation. The finer the
particle size, the higher the impurity removal.
Furthermore, electromagnetic selection can further
reduce the impurity content in WMC. Considering the
impact of feed indicators on the product particle size and
quality on subsequent operations, a feed of particle size
with –38 μm content of 90% was chosen to conduct the
next test. Through the roughing of weak magnetic sepa-
ration and cleaning of electromagnetic separation, a con-
centrate with a total Fe grade of 71.63% can be obtained
at a recovery of 95.60%, acid insoluble matter content of
0.78%, and SiO2 content of 0.70%. This is because there
were magnetite-rich concatemers in the concentrate, which
have strong magnetism. Therefore, these impurities will
enter the concentrate and reduce its total Fe grade. To
remove this part of impurities, it is often necessary to fur-
ther liberate the gangue grains and combine comminution
with other separation methods for purification.
To improve the quality of iron concentrate and meet
the standard requirements of high-purity iron concentrate,
the dissociation of minerals was enhanced by grinding and
EBC. Stirring mills often replace traditional ball mills for
fine grinding due to their low energy consumption and
simple operation. The grinding conditions of the stirred
mill were determined through systematic process optimi-
zation experiments. EBC was ground in the second stage
with a concentration of 68.5% Fe, a material-to-ball ratio
of 0.8, a media filling rate of 75%, a median size distribu-
tion of 8 mm steel balls, and a mill speed of 300 rpm. It
can be seen from the results in Figure 6(a) that as the grind-
ing size increases (–30 μm content decreasing), the total
Fe grade of the second-stage electromagnetic concentration
concentrate is close to 72%. Fe recovery also marginally
decreases. With the decrease in particle size, the removal
75 85 90 95
0.0
0.5
20
40
60
80
100
TFe grade TFe recovery SiO
2 content Acid insoluble content
(a)
75 85 90 95
0.0
0.5
20
40
60
80
100
TFe grade TFe recovery SiO
2 content Acid insoluble content
(b)
Figure 5. Test results of (a) one stage of weak magnetic separation (WMC), left, and (b) one stage of electromagnetic
separation (EBC), right
Table 7. Test results of pre-concentration
Product
Yield,
wt%
Total Fe,
wt%
Recovery,
wt%
Pre-concentration
concentrate
93.80 68.19 97.35
Pre- concentration
tailings
6.20 28.11 2.65
Total 100.00 65.70 100.00
71.03 71.35 71.44 71.48
98.1 98.21 98.18 98.37
1.27 0.97 1.12 0.98 1.33 1.16 1.2 1.05
Grade/Recov
er y
(%)71.28 71.47 71.63 71.73
96.93 97.06 97.03 97.39
1.06 0.77 0.7 0.92 1.11 0.82 0.78 1.07
Grade/Recov
er y
(%)
iron concentrate. However, the inner wrapped magnetite
needs to be finely ground to enhance its dissociation.
High-purity iron concentrate preparation experiment
Conditional tests were used to optimize the production
process and determine appropriate process parameters to
obtain qualified high-purity iron concentrate. The tailings
were discarded in advance through an electromagnetic con-
centrator, as shown in Table 7. According to the analysis
in Section 3.1, grinding was required to achieve efficient
dissociation of minerals during the preparation of high-
purity iron concentrate. Therefore, under the magnetic
field intensity of 1.0×105 A/m, utilizing a drum weak mag-
netic separator for roughing and an electromagnetic separa-
tor for cleaning, the influence of iron ore size was exhibited
as shown in Figure 10. The results (Figure 5) show that
the total Fe grade of weak magnetic concentrate (WMC)
increases with decreasing particle size due to the increased
degree of dissociation of iron minerals. As impurities were
further removed during cleaning, the total Fe grade of elec-
tromagnetic beneficiation concentrates (EBC) has been
further improved. It can be seen from the silica and acid
insoluble content that the impurity removal and particle
size changes have a reasonable correlation. The finer the
particle size, the higher the impurity removal.
Furthermore, electromagnetic selection can further
reduce the impurity content in WMC. Considering the
impact of feed indicators on the product particle size and
quality on subsequent operations, a feed of particle size
with –38 μm content of 90% was chosen to conduct the
next test. Through the roughing of weak magnetic sepa-
ration and cleaning of electromagnetic separation, a con-
centrate with a total Fe grade of 71.63% can be obtained
at a recovery of 95.60%, acid insoluble matter content of
0.78%, and SiO2 content of 0.70%. This is because there
were magnetite-rich concatemers in the concentrate, which
have strong magnetism. Therefore, these impurities will
enter the concentrate and reduce its total Fe grade. To
remove this part of impurities, it is often necessary to fur-
ther liberate the gangue grains and combine comminution
with other separation methods for purification.
To improve the quality of iron concentrate and meet
the standard requirements of high-purity iron concentrate,
the dissociation of minerals was enhanced by grinding and
EBC. Stirring mills often replace traditional ball mills for
fine grinding due to their low energy consumption and
simple operation. The grinding conditions of the stirred
mill were determined through systematic process optimi-
zation experiments. EBC was ground in the second stage
with a concentration of 68.5% Fe, a material-to-ball ratio
of 0.8, a media filling rate of 75%, a median size distribu-
tion of 8 mm steel balls, and a mill speed of 300 rpm. It
can be seen from the results in Figure 6(a) that as the grind-
ing size increases (–30 μm content decreasing), the total
Fe grade of the second-stage electromagnetic concentration
concentrate is close to 72%. Fe recovery also marginally
decreases. With the decrease in particle size, the removal
75 85 90 95
0.0
0.5
20
40
60
80
100
TFe grade TFe recovery SiO
2 content Acid insoluble content
(a)
75 85 90 95
0.0
0.5
20
40
60
80
100
TFe grade TFe recovery SiO
2 content Acid insoluble content
(b)
Figure 5. Test results of (a) one stage of weak magnetic separation (WMC), left, and (b) one stage of electromagnetic
separation (EBC), right
Table 7. Test results of pre-concentration
Product
Yield,
wt%
Total Fe,
wt%
Recovery,
wt%
Pre-concentration
concentrate
93.80 68.19 97.35
Pre- concentration
tailings
6.20 28.11 2.65
Total 100.00 65.70 100.00
71.03 71.35 71.44 71.48
98.1 98.21 98.18 98.37
1.27 0.97 1.12 0.98 1.33 1.16 1.2 1.05
Grade/Recov
er y
(%)71.28 71.47 71.63 71.73
96.93 97.06 97.03 97.39
1.06 0.77 0.7 0.92 1.11 0.82 0.78 1.07
Grade/Recov
er y
(%)