571
Dry Beneficiation Studies of Low-Grade Chromite Ore Using
Magnetic Separation
Sharath Kumar Bhoja, Madhurupa Sahoo, Raghu Kumar C, Srinivasa Reddy A
Raw Material Technology, Process Technology Group, Tata Steel Ltd, Jamshedpur, India
Ranjita Sahoo
Ferro Alloy Research group, Process Research Group, R&D, Tata Steel Ltd Jamshedpur, India
Sunil Kumar Tripathy
Natural Resources Research Institute (NRRI), University of Minnesota Duluth, Coleraine, MN, USA
ABSTRACT: In general, chromite ore is beneficiated using gravity separation in multi-stage by using different
unit operations along with classifiers. Traditional beneficiation flowsheets comprise key unit operations such
as wet gravity separation, magnetic separation, and flotation to enrich low-grade chromite ore. However, the
process is wet based, requiring substantial water, making it less environmentally sustainable than processing
low-grade chromite ore. So, exploring an alternative flowsheet with the dry option to treat such low-grade ores
is possible. Dry beneficiation techniques offer a promising alternative by eliminating the need for water and
reducing energy consumption hence, dry beneficiation has gained significant attention in recent years. The
effectiveness of dry beneficiation is influenced by a range of factors like mineralogical composition, particle size
distribution and liberation characteristics.
In the present investigation, detailed characterization studies of low-grade ore were conducted to understand
the mineral assemblage and liberation properties. The low-grade chromite ore was analysed for 26.11% Cr2O3
with 20.5% SiO2, and mineralogical studies indicated the presence of lizardite and chrysotile in association
with chromite. Dry beneficiation was employed to upgrade the low-grade chromite ore and dry high-intensity
magnetic separators using rare earth-roll magnetic separators. It was possible to upgrade the low-grade ore to
34% Cr2O3 and SiO2 16%, which was acceptable to the ferrochrome production but otherwise deemed
unusable. The results obtained are discussed along with the challenges observed and the scope of further research
in enhancing chromite recovery.
Keywords: Chromite ore, Dry beneficiation, Magnetic separation, Mineral characterization, Siliceous low-
grade ore

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Extracted Text (may have errors)

571
Dry Beneficiation Studies of Low-Grade Chromite Ore Using
Magnetic Separation
Sharath Kumar Bhoja, Madhurupa Sahoo, Raghu Kumar C, Srinivasa Reddy A
Raw Material Technology, Process Technology Group, Tata Steel Ltd, Jamshedpur, India
Ranjita Sahoo
Ferro Alloy Research group, Process Research Group, R&D, Tata Steel Ltd Jamshedpur, India
Sunil Kumar Tripathy
Natural Resources Research Institute (NRRI), University of Minnesota Duluth, Coleraine, MN, USA
ABSTRACT: In general, chromite ore is beneficiated using gravity separation in multi-stage by using different
unit operations along with classifiers. Traditional beneficiation flowsheets comprise key unit operations such
as wet gravity separation, magnetic separation, and flotation to enrich low-grade chromite ore. However, the
process is wet based, requiring substantial water, making it less environmentally sustainable than processing
low-grade chromite ore. So, exploring an alternative flowsheet with the dry option to treat such low-grade ores
is possible. Dry beneficiation techniques offer a promising alternative by eliminating the need for water and
reducing energy consumption hence, dry beneficiation has gained significant attention in recent years. The
effectiveness of dry beneficiation is influenced by a range of factors like mineralogical composition, particle size
distribution and liberation characteristics.
In the present investigation, detailed characterization studies of low-grade ore were conducted to understand
the mineral assemblage and liberation properties. The low-grade chromite ore was analysed for 26.11% Cr2O3
with 20.5% SiO2, and mineralogical studies indicated the presence of lizardite and chrysotile in association
with chromite. Dry beneficiation was employed to upgrade the low-grade chromite ore and dry high-intensity
magnetic separators using rare earth-roll magnetic separators. It was possible to upgrade the low-grade ore to
34% Cr2O3 and SiO2 16%, which was acceptable to the ferrochrome production but otherwise deemed
unusable. The results obtained are discussed along with the challenges observed and the scope of further research
in enhancing chromite recovery.
Keywords: Chromite ore, Dry beneficiation, Magnetic separation, Mineral characterization, Siliceous low-
grade ore

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572 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
INTRODUCTION
The green transition, aimed at reducing carbon emissions
and environmental impact, has led to significant changes
in beneficiation strategies, particularly towards dry benefi-
ciation due to its potential to reduce water consumption
and minimize environmental impact by avoiding a tailing
storage pond. Dry beneficiation processes typically require
less water compared to traditional wet methods, making
them more sustainable and aligned with green initiatives.
Furthermore, dry beneficiation can lead to lower energy
consumption and reduced emissions, contributing to the
overall environmental objectives of the green transition
(Tripathy et al., 2017).
Chromite ore, an essential raw material to produce fer-
rochrome and chrome metal, is often found in low-grade
deposits and is conventionally beneficiated using the wet
process, which mainly involves wet gravity concentration
methods. Dry beneficiation techniques, particularly mag-
netic separation, have gained significant attention due to
their potential to upgrade low-grade chromite ores while
minimizing water usage and environmental impact.
This study aims to investigate the effectiveness of dry
beneficiation through magnetic separation in upgrad-
ing low-grade chromite ore, with a focus on assessing the
feasibility of dry beneficiation methods vis-à-vis wet ben-
eficiation. By exploring the potential benefits of magnetic
separation, this research contributes to the ongoing efforts
to develop sustainable and efficient processes for chromite
ore beneficiation.
Literature Review
The process of upgrading low-grade Chromite ore to
achieve Ferrochrome grade is a prevalent procedure in the
Chrome industry. Depending on the geographical loca-
tion, Chromite ore beneficiation aims to eliminate siliceous
gangues such as quartz/serpentine minerals or ferruginous
gangues like hematite/goethite, as well as minor impuri-
ties like magnesium and alumina-bearing mineral phases.
The level of enrichment of chrome ores mainly relies on
the types of minerals present, their chemical composition,
and the texture of the ore. It is commonly believed that all
the Cr2O3 is found in the chromite mineral. However, in
numerous ores, the Cr2O3 content, along with the silicate
gangue, can be quite high, as has been observed in the cur-
rent study.
Conventionally, the beneficiation of Chromite ore is
carried out through gravity concentration owing to the den-
sity difference between the gangue-bearing Silicate minerals
and the chromite minerals, and the most used beneficiation
Figure 1. Literature review of the articles published on the chromite ore beneficiation through magnetic separation.
Visualisation generated though the VOS viewer (using references 1–43)

Previous Page Next Page

Extracted Text (may have errors)

572 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
INTRODUCTION
The green transition, aimed at reducing carbon emissions
and environmental impact, has led to significant changes
in beneficiation strategies, particularly towards dry benefi-
ciation due to its potential to reduce water consumption
and minimize environmental impact by avoiding a tailing
storage pond. Dry beneficiation processes typically require
less water compared to traditional wet methods, making
them more sustainable and aligned with green initiatives.
Furthermore, dry beneficiation can lead to lower energy
consumption and reduced emissions, contributing to the
overall environmental objectives of the green transition
(Tripathy et al., 2017).
Chromite ore, an essential raw material to produce fer-
rochrome and chrome metal, is often found in low-grade
deposits and is conventionally beneficiated using the wet
process, which mainly involves wet gravity concentration
methods. Dry beneficiation techniques, particularly mag-
netic separation, have gained significant attention due to
their potential to upgrade low-grade chromite ores while
minimizing water usage and environmental impact.
This study aims to investigate the effectiveness of dry
beneficiation through magnetic separation in upgrad-
ing low-grade chromite ore, with a focus on assessing the
feasibility of dry beneficiation methods vis-à-vis wet ben-
eficiation. By exploring the potential benefits of magnetic
separation, this research contributes to the ongoing efforts
to develop sustainable and efficient processes for chromite
ore beneficiation.
Literature Review
The process of upgrading low-grade Chromite ore to
achieve Ferrochrome grade is a prevalent procedure in the
Chrome industry. Depending on the geographical loca-
tion, Chromite ore beneficiation aims to eliminate siliceous
gangues such as quartz/serpentine minerals or ferruginous
gangues like hematite/goethite, as well as minor impuri-
ties like magnesium and alumina-bearing mineral phases.
The level of enrichment of chrome ores mainly relies on
the types of minerals present, their chemical composition,
and the texture of the ore. It is commonly believed that all
the Cr2O3 is found in the chromite mineral. However, in
numerous ores, the Cr2O3 content, along with the silicate
gangue, can be quite high, as has been observed in the cur-
rent study.
Conventionally, the beneficiation of Chromite ore is
carried out through gravity concentration owing to the den-
sity difference between the gangue-bearing Silicate minerals
and the chromite minerals, and the most used beneficiation
Figure 1. Literature review of the articles published on the chromite ore beneficiation through magnetic separation.
Visualisation generated though the VOS viewer (using references 1–43)

570 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
• A novel dry belt drum magnetic separator with radial
pole arrangement, high magnetic field intensity of
around 3800 gauss and high gradient was designed
and developed for efficient magnetic separation of
coarse particles 40–400 mm in size. Both experimen-
tal and numerical methods were used in this inves-
tigation. The FEMM software was used to simulate
magnetic field distribution through the surface of the
drum separator.
• The study was conducted in order to produce a pre-
concentrate and final iron ore concentrate from iron
ore waste rock of a magnetite mine with a particle
size of 1200 mm and 15% iron grade on average. The
results of industrial testworks showed that through
magnetic separation and primary crushing prior to
that a final pre concentrate whose yield, iron grade
and iron content recovery are 27.4%, iron 35.08%
and 60.35%, respectively is achievable
• In order to produce a suitable final concentrate, the
pre-concentrate was ground to k80=100 micron and
following that treated by two stages of wet MIMS
separation and also two stages of WHIMS. The
results indicated that a final mixed concentrate with
65.53% iron grade, 44.81% yield and also 83.73%
iron content recovery could be attained. With respect
to the original iron ore waste, the iron recovery was
50.53 wt %.
• Iron was recovered from iron ore waste rock of the
mine through primary crushing and pre-concentra-
tion followed by stages of wet magnetic separation.
Combining these recycling processes can ensure
complete utilization of iron ore waste rock dumps.
ACKNOWLEDGMENTS
The authors would like to thank Fakoor Industrial and
Mining Research Centre (FIMRC) of Iran and Fakoor
Meghnantis Spadana Co. of Iran who supplied the facilities
necessary for this study.
REFERENCES
Augusto, P.A., Martins, J.P., 1999. Min. Eng. 12 (7),
799–807.
Augusto, P.A., Augusto, P., Castelo-Grande, T., 2002.
Miner. Eng. 15 (1–2), 35–43.
Birss, R., Parker, M., Wong, M., 1979. Modeling of fields
in magnetic drum separators. Magn.IEEE Trans. 15,
1305–1309.
Hoffmann, C., Franzreb, M., et al., 2002. A novel high-
gradient magnetic separator (HGMS) design for
biotech applications. IEEE Transactions on Applied
Superconductivity 12 (1), 963–966.
Li, C. Sun, H. Bai, J. Li, L. Innovative methodology for
comprehensive utilization of iron ore tailings: Part 1.
The recovery of iron from iron ore tailings using mag-
netic separation after magnetizing roasting. J. Hazard.
Mater. 2010, 174, 71–77.
Pokrajcic, Z, Lewis-Gray, E, 2010. Advanced comminu-
tion circuit design—essential for industry, AusIMM
Bulletin, August 2010, pp 38 – 42.
Svoboda, J., 1987. Magnetic Methods for the Treatment of
Minerals, Elsevier Science Publishers, Amsterdam.
Wasmuth, H.D., and Unkelbach, K.H., 1991. Recent
developments in magnetic separation of feebly mag-
netic minerals, KHD Humboldt Wedag AG, K61n,
Germany Minerals Engineering, Vol. 4, Nos 7–11,
pp. 825–837.
Xiong, D., Lu, L., Holmes, R.J., 2015. Developments in
the physical separation of iron ore: magnetic separation
Iron Ore.

Previous Page Next Page

Extracted Text (may have errors)

570 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
• A novel dry belt drum magnetic separator with radial
pole arrangement, high magnetic field intensity of
around 3800 gauss and high gradient was designed
and developed for efficient magnetic separation of
coarse particles 40–400 mm in size. Both experimen-
tal and numerical methods were used in this inves-
tigation. The FEMM software was used to simulate
magnetic field distribution through the surface of the
drum separator.
• The study was conducted in order to produce a pre-
concentrate and final iron ore concentrate from iron
ore waste rock of a magnetite mine with a particle
size of 1200 mm and 15% iron grade on average. The
results of industrial testworks showed that through
magnetic separation and primary crushing prior to
that a final pre concentrate whose yield, iron grade
and iron content recovery are 27.4%, iron 35.08%
and 60.35%, respectively is achievable
• In order to produce a suitable final concentrate, the
pre-concentrate was ground to k80=100 micron and
following that treated by two stages of wet MIMS
separation and also two stages of WHIMS. The
results indicated that a final mixed concentrate with
65.53% iron grade, 44.81% yield and also 83.73%
iron content recovery could be attained. With respect
to the original iron ore waste, the iron recovery was
50.53 wt %.
• Iron was recovered from iron ore waste rock of the
mine through primary crushing and pre-concentra-
tion followed by stages of wet magnetic separation.
Combining these recycling processes can ensure
complete utilization of iron ore waste rock dumps.
ACKNOWLEDGMENTS
The authors would like to thank Fakoor Industrial and
Mining Research Centre (FIMRC) of Iran and Fakoor
Meghnantis Spadana Co. of Iran who supplied the facilities
necessary for this study.
REFERENCES
Augusto, P.A., Martins, J.P., 1999. Min. Eng. 12 (7),
799–807.
Augusto, P.A., Augusto, P., Castelo-Grande, T., 2002.
Miner. Eng. 15 (1–2), 35–43.
Birss, R., Parker, M., Wong, M., 1979. Modeling of fields
in magnetic drum separators. Magn.IEEE Trans. 15,
1305–1309.
Hoffmann, C., Franzreb, M., et al., 2002. A novel high-
gradient magnetic separator (HGMS) design for
biotech applications. IEEE Transactions on Applied
Superconductivity 12 (1), 963–966.
Li, C. Sun, H. Bai, J. Li, L. Innovative methodology for
comprehensive utilization of iron ore tailings: Part 1.
The recovery of iron from iron ore tailings using mag-
netic separation after magnetizing roasting. J. Hazard.
Mater. 2010, 174, 71–77.
Pokrajcic, Z, Lewis-Gray, E, 2010. Advanced comminu-
tion circuit design—essential for industry, AusIMM
Bulletin, August 2010, pp 38 – 42.
Svoboda, J., 1987. Magnetic Methods for the Treatment of
Minerals, Elsevier Science Publishers, Amsterdam.
Wasmuth, H.D., and Unkelbach, K.H., 1991. Recent
developments in magnetic separation of feebly mag-
netic minerals, KHD Humboldt Wedag AG, K61n,
Germany Minerals Engineering, Vol. 4, Nos 7–11,
pp. 825–837.
Xiong, D., Lu, L., Holmes, R.J., 2015. Developments in
the physical separation of iron ore: magnetic separation
Iron Ore.