574 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
In conclusion, while literature on the magnetic sepa-
ration of chromite ore is limited, detailed mineralogical
characterization studies are essential for the selection and
optimization of magnetic separators. The present investi-
gation includes thorough characterization of ore to under-
stand the distribution of SiO2 and Cr2O3 in different
mineral phases and to understand the amenability of SiO2
reduction through magnetic separation. A high intensity
dry magnetic separator was used to evaluate the efficiency
of separation of chromite by varying different process
parameters.
MATERIALS AND METHODOLOGY:
Chromite Samples
The samples for the study were obtained from the low-grade
mines in the Kamarda area, Odisha, India and subjected to
systematic sampling methods for head sample reduction.
The size reduction process involved drawing samples and
progressively reducing their sizes from less than 100mm
20mm, and 1mm. Size analyses were then carried out
at each specified size to provide a comprehensive under-
standing of the sample characteristics at different scales.
Furthermore, the samples were subjected to chemical anal-
ysis, size-wise chemical analysis, Megascopic analysis, XRD
(X-ray diffraction) analysis, and SEM (scanning electron
microscopy) analysis to assess their chemical composition
and structural properties.
Particle Characterization
The particle size distribution (PSD) of the sample was mea-
sured in a laboratory sieve shaker. ICP-AES (Integra XL,
I.R. Tech. Pvt. Ltd. (GBC Scientific Equipment, Victoria,
Australia)) was carried out for the chemical assays. The
mineral analysis was carried out by X-ray diffraction (XRD)
supplied by PANanalytical B.V. (Malvern Panalytical,
Almelo, The Netherlands). These analyses were crucial in
understanding the mineralogical and chemical characteris-
tics of the low-grade chromite ore.
Experimental Set Up
The experimental set up used is rare earth roll magnetic
separator (RERMS) supplied by Outokumpu make – L/P
10–30 laboratory model (refer Figure 2) .The magnetic
roll is 200 mm wide and is made with the highest strength
Neodymium magnets with a rated magnetic field intensity
of ~12,500 G when measured on a belt surface. This sep-
arator can operate continuously and has a variable speed
drive system to maintain roll speed at desired setting and a
digital Rpm read-out.
Experimentation Methodology
A Design of Experiments (DOE) was conducted by varying
three operating parameters: roll speed, feed rate, and split-
ter position. Fifteen experiments were finalized for the first
roll configuration to determine the optimal combination
of results.
The range of roll speed and feed rate was determined
based on preliminary scoping experiments. Subsequently,
additional experiments were carried out using the second
and third roll configurations to target the production of a
cleaner product. Throughout the testing, the middling frac-
tion generated during the first roll was combined with the
non-magnetic fraction and considered as non-magnetics
(i.e., for roll 1 non-mag =mid +non-mag). In this process,
the chromite-bearing particles were collected as magnetics.
CHARACTERIZATION STUDIES
The low-grade chromite ore was subjected to comprehen-
sive characterization using various analytical techniques.
Figure 3 shows the megascopic view of the ROM sample.
Figure 2. The experimental set up used for the separation
studies
Table 2. Range of operating variables
Roll Speed (rpm) Feed Rate (tph) Spitter Position
150 0.1 –1 (towards N.mag)
180 0.25 0 (neutral)
200 0.4 1 (towards Mag)
In conclusion, while literature on the magnetic sepa-
ration of chromite ore is limited, detailed mineralogical
characterization studies are essential for the selection and
optimization of magnetic separators. The present investi-
gation includes thorough characterization of ore to under-
stand the distribution of SiO2 and Cr2O3 in different
mineral phases and to understand the amenability of SiO2
reduction through magnetic separation. A high intensity
dry magnetic separator was used to evaluate the efficiency
of separation of chromite by varying different process
parameters.
MATERIALS AND METHODOLOGY:
Chromite Samples
The samples for the study were obtained from the low-grade
mines in the Kamarda area, Odisha, India and subjected to
systematic sampling methods for head sample reduction.
The size reduction process involved drawing samples and
progressively reducing their sizes from less than 100mm
20mm, and 1mm. Size analyses were then carried out
at each specified size to provide a comprehensive under-
standing of the sample characteristics at different scales.
Furthermore, the samples were subjected to chemical anal-
ysis, size-wise chemical analysis, Megascopic analysis, XRD
(X-ray diffraction) analysis, and SEM (scanning electron
microscopy) analysis to assess their chemical composition
and structural properties.
Particle Characterization
The particle size distribution (PSD) of the sample was mea-
sured in a laboratory sieve shaker. ICP-AES (Integra XL,
I.R. Tech. Pvt. Ltd. (GBC Scientific Equipment, Victoria,
Australia)) was carried out for the chemical assays. The
mineral analysis was carried out by X-ray diffraction (XRD)
supplied by PANanalytical B.V. (Malvern Panalytical,
Almelo, The Netherlands). These analyses were crucial in
understanding the mineralogical and chemical characteris-
tics of the low-grade chromite ore.
Experimental Set Up
The experimental set up used is rare earth roll magnetic
separator (RERMS) supplied by Outokumpu make – L/P
10–30 laboratory model (refer Figure 2) .The magnetic
roll is 200 mm wide and is made with the highest strength
Neodymium magnets with a rated magnetic field intensity
of ~12,500 G when measured on a belt surface. This sep-
arator can operate continuously and has a variable speed
drive system to maintain roll speed at desired setting and a
digital Rpm read-out.
Experimentation Methodology
A Design of Experiments (DOE) was conducted by varying
three operating parameters: roll speed, feed rate, and split-
ter position. Fifteen experiments were finalized for the first
roll configuration to determine the optimal combination
of results.
The range of roll speed and feed rate was determined
based on preliminary scoping experiments. Subsequently,
additional experiments were carried out using the second
and third roll configurations to target the production of a
cleaner product. Throughout the testing, the middling frac-
tion generated during the first roll was combined with the
non-magnetic fraction and considered as non-magnetics
(i.e., for roll 1 non-mag =mid +non-mag). In this process,
the chromite-bearing particles were collected as magnetics.
CHARACTERIZATION STUDIES
The low-grade chromite ore was subjected to comprehen-
sive characterization using various analytical techniques.
Figure 3 shows the megascopic view of the ROM sample.
Figure 2. The experimental set up used for the separation
studies
Table 2. Range of operating variables
Roll Speed (rpm) Feed Rate (tph) Spitter Position
150 0.1 –1 (towards N.mag)
180 0.25 0 (neutral)
200 0.4 1 (towards Mag)