578 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Discussion
The test results indicate (refer Figure 9) that by limiting
the roll speed to 150 rpm not more than 30% Cr2O3 is
achieved along with ~19% SiO2. This might be due to mis-
placement happening because of higher retention time pro-
vided to the particles by keeping lower roll speed and this
might have resulted the unwanted particles such as lizard-
ite (weekly magnetic) to report into the magnetic fraction.
Also, not many changes in the Cr2O3 grade were observed
by varying the feed rate and splitter position.
Further by increasing the roll speed to 180 Rpm and
changing the splitter position to 1 (towards mag), some
encouraging results received in terms of Cr2O3%. By
keeping the splitter position towards mag fraction, it was
ensured to have the minimum misplacement and hence
a higher grade as well as a lower yield was achieved. The
best result achieved was 31.27% Cr2O3 with 19.5% SiO2
with a yield of 65.67% by maintaining the feed rate at
50 thereby allowing most of the particles to fall into the
magnetic field intensity. Even at higher roll speed at 200
Rpm no further increase in chromite grade was observed.
However, by keeping the splitter position at 1 and feed rate
at 60, Cr2O3of 31.06% and SiO2 of 19.22% was achieved
with comparatively higher yield of ~86% was noticed.
With the varying combinations of operating parameters
not more than ~31% Cr2O3 and not less than ~19% SiO2
was achieved with a first roll configuration. Hence it was
decided to opt for recleaning configurations in second roll
and third roll by using the product of first roll.
Optimization Test Through Multi-Stage Separation
While conducting the experiments on second roll and
third roll the product of first roll was retreated to achieve a
much cleaner product with a high Cr/Fe. In case of third
roll cleaning configuration the roll speed was further varied
from the fixed range (150–200 Rpm) kept during DOE. A
total of 16 no. of experiments were conducted in this man-
ner and the highest enrichment achieved was ~34% Cr2O3
with ~17% SiO2 and Cr to Fe ratio of ~3. The best results
obtained are depicted Figure 10 .
Similarly, another configuration was tested where the
(Exp 7) non-magnetic fraction of first roll was treated in
Figure 9. Results obtained from the dry magnetic separation studies as per the DOE
Discussion
The test results indicate (refer Figure 9) that by limiting
the roll speed to 150 rpm not more than 30% Cr2O3 is
achieved along with ~19% SiO2. This might be due to mis-
placement happening because of higher retention time pro-
vided to the particles by keeping lower roll speed and this
might have resulted the unwanted particles such as lizard-
ite (weekly magnetic) to report into the magnetic fraction.
Also, not many changes in the Cr2O3 grade were observed
by varying the feed rate and splitter position.
Further by increasing the roll speed to 180 Rpm and
changing the splitter position to 1 (towards mag), some
encouraging results received in terms of Cr2O3%. By
keeping the splitter position towards mag fraction, it was
ensured to have the minimum misplacement and hence
a higher grade as well as a lower yield was achieved. The
best result achieved was 31.27% Cr2O3 with 19.5% SiO2
with a yield of 65.67% by maintaining the feed rate at
50 thereby allowing most of the particles to fall into the
magnetic field intensity. Even at higher roll speed at 200
Rpm no further increase in chromite grade was observed.
However, by keeping the splitter position at 1 and feed rate
at 60, Cr2O3of 31.06% and SiO2 of 19.22% was achieved
with comparatively higher yield of ~86% was noticed.
With the varying combinations of operating parameters
not more than ~31% Cr2O3 and not less than ~19% SiO2
was achieved with a first roll configuration. Hence it was
decided to opt for recleaning configurations in second roll
and third roll by using the product of first roll.
Optimization Test Through Multi-Stage Separation
While conducting the experiments on second roll and
third roll the product of first roll was retreated to achieve a
much cleaner product with a high Cr/Fe. In case of third
roll cleaning configuration the roll speed was further varied
from the fixed range (150–200 Rpm) kept during DOE. A
total of 16 no. of experiments were conducted in this man-
ner and the highest enrichment achieved was ~34% Cr2O3
with ~17% SiO2 and Cr to Fe ratio of ~3. The best results
obtained are depicted Figure 10 .
Similarly, another configuration was tested where the
(Exp 7) non-magnetic fraction of first roll was treated in
Figure 9. Results obtained from the dry magnetic separation studies as per the DOE