XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1945
low-intensity magnetic separation. The remaining tailings
from the low-intensity magnetic separation were then
subjected to a sequence of high-intensity wet magnetic
separations.
Grinding
In order to determine the impact of grinding time on parti-
cle size and to evaluate the grinding efficiency, a laboratory
scale ball mill with a capacity of 2 kg was used. Samples of
–1 mm BFD were ground for varying time intervals. The
ball mill grinding process involved 1 kg samples, 600 ml
water and 7.911 kg steel balls. The particle size distribution
of the ground material was analyzed using standard ASTM
sieves.
Flotation
A study was conducted on flotation using different size
fractions in both a conventional flotation cell (Denver
D-12 sub-aeration cell with a capacity of 1 litre) and a
laboratory column flotation (100 mm diameter and 2.8 m
length). Diesel oil was used as a collector and MIBC was
used as a frother. Sodium silicate was used as a silica and
iron depressant as well as a dispersant. The pulp density
was maintained at 20% throughout the experiment, and
the pH of the cell bath was kept in the range of 7–8. The
impeller rpm was maintained at a constant 1500 rpm dur-
ing conditioning and scrapping. Each set of froth floatation
was repeated twice, and the average data was taken to mini-
mize errors and ensure reproducibility.
Magnetic Separation
The magnetic separation study was carried out to extract iron
reach particles. The floatation tailing sample was subjected
to a low-intensity wet magnetic separator (approximately
1500 Gauss magnetic intensity) to separate preferably the
magnetite concentrate. The nonmagnetic fractions thus
obtained were subjected to wet high-intensity magnetic
separation (WHIMS). The magnetic intensity in WHIMS
ranges from 2500 gauss to 13000 gauss.
RESULTS AND DISCUSSIONS
Effect of Grinding
Size distribution of ground sample after ball mill grinding is
shown in the Table 4. With increase in grinding time, fine-
ness of ground sample increase. With 5 minutes of grind-
ing time, there is not much change in the size distribution
but beyond 5 minutes, coarser fractions starts decreasing.
Grinding Time of 20 minutes may be considered for gen-
eration of –25 micron size. Similarly, 15 minutes is for –45
micron and 10 minutes for –75 micron size samples.
Iron and Carbon Recovery
Representative ground samples are subjected to floatation
and magnetic separation process with the aim of separation
of different constituents as per their characteristics.
Effect of Collector Dosage in floatation
Flotation results as froth concentrate characteristics has
been depicted in Figures 6–11.
Floatation of –75 micron BFD. The graph in
Figure 6–7 displays the froth flotation results as the col-
lector dosage varies for –75 micron. The yield of the froth
keeps on increasing, but the fixed carbon content only
increases up to 350–400 CC/Ton of collector. Beyond this
point, the froth concentrates start to enrich with iron while
the fixed carbon decreases.
Floatation of –45-micron BFD. The results of the
flotation experiment with varying collector dosage for –45
micron feed size are displayed in Figure 8–9. The yield of the
froth increases as the collector dosage increases. However,
as the collector dosage goes beyond 350 CC/Ton, the froth
concentrates start to become enriched with iron and the
fixed carbon content decreases. These findings suggest that
Table 4. Effect of grinding time on size distribution of ground BFD
As Received 5 Minutes 10 Minutes 15 Minutes 20 Minutes
Weight. %
+75µm 11.26 8.34 6.57 3.21 0.34
–75+45 µm 22.99 16.2 11.56 7.04 4.26
–45+25 µm 0.92 1.84 2.27 4.28 3.53
–25µm 64.83 73.62 79.6 85.47 91.87
low-intensity magnetic separation. The remaining tailings
from the low-intensity magnetic separation were then
subjected to a sequence of high-intensity wet magnetic
separations.
Grinding
In order to determine the impact of grinding time on parti-
cle size and to evaluate the grinding efficiency, a laboratory
scale ball mill with a capacity of 2 kg was used. Samples of
–1 mm BFD were ground for varying time intervals. The
ball mill grinding process involved 1 kg samples, 600 ml
water and 7.911 kg steel balls. The particle size distribution
of the ground material was analyzed using standard ASTM
sieves.
Flotation
A study was conducted on flotation using different size
fractions in both a conventional flotation cell (Denver
D-12 sub-aeration cell with a capacity of 1 litre) and a
laboratory column flotation (100 mm diameter and 2.8 m
length). Diesel oil was used as a collector and MIBC was
used as a frother. Sodium silicate was used as a silica and
iron depressant as well as a dispersant. The pulp density
was maintained at 20% throughout the experiment, and
the pH of the cell bath was kept in the range of 7–8. The
impeller rpm was maintained at a constant 1500 rpm dur-
ing conditioning and scrapping. Each set of froth floatation
was repeated twice, and the average data was taken to mini-
mize errors and ensure reproducibility.
Magnetic Separation
The magnetic separation study was carried out to extract iron
reach particles. The floatation tailing sample was subjected
to a low-intensity wet magnetic separator (approximately
1500 Gauss magnetic intensity) to separate preferably the
magnetite concentrate. The nonmagnetic fractions thus
obtained were subjected to wet high-intensity magnetic
separation (WHIMS). The magnetic intensity in WHIMS
ranges from 2500 gauss to 13000 gauss.
RESULTS AND DISCUSSIONS
Effect of Grinding
Size distribution of ground sample after ball mill grinding is
shown in the Table 4. With increase in grinding time, fine-
ness of ground sample increase. With 5 minutes of grind-
ing time, there is not much change in the size distribution
but beyond 5 minutes, coarser fractions starts decreasing.
Grinding Time of 20 minutes may be considered for gen-
eration of –25 micron size. Similarly, 15 minutes is for –45
micron and 10 minutes for –75 micron size samples.
Iron and Carbon Recovery
Representative ground samples are subjected to floatation
and magnetic separation process with the aim of separation
of different constituents as per their characteristics.
Effect of Collector Dosage in floatation
Flotation results as froth concentrate characteristics has
been depicted in Figures 6–11.
Floatation of –75 micron BFD. The graph in
Figure 6–7 displays the froth flotation results as the col-
lector dosage varies for –75 micron. The yield of the froth
keeps on increasing, but the fixed carbon content only
increases up to 350–400 CC/Ton of collector. Beyond this
point, the froth concentrates start to enrich with iron while
the fixed carbon decreases.
Floatation of –45-micron BFD. The results of the
flotation experiment with varying collector dosage for –45
micron feed size are displayed in Figure 8–9. The yield of the
froth increases as the collector dosage increases. However,
as the collector dosage goes beyond 350 CC/Ton, the froth
concentrates start to become enriched with iron and the
fixed carbon content decreases. These findings suggest that
Table 4. Effect of grinding time on size distribution of ground BFD
As Received 5 Minutes 10 Minutes 15 Minutes 20 Minutes
Weight. %
+75µm 11.26 8.34 6.57 3.21 0.34
–75+45 µm 22.99 16.2 11.56 7.04 4.26
–45+25 µm 0.92 1.84 2.27 4.28 3.53
–25µm 64.83 73.62 79.6 85.47 91.87