XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1827
into maghemite in the air-cooling, which has a smaller
remanence and coercivity.
CONCLUSION
The comparison of air cooling, water quenching, and nitro-
gen cooling processes was studied in the magnetization
roasting of limonite ore. It indicated that air cooling is a
feasible cooling process for magnetizing roasting of limo-
nite ore. Compared with the traditional water quenching
and nitrogen cooling process, a very good magnetic separa-
tion index with an iron grade of 55.94% and recovery of
93.39% was achieved. In the air-cooling process, no hema-
tite characteristic peaks were found in the roasted ore. The
synthetic magnetite was oxidized by O2 into maghemite
but not hematite. Due to the ferrimagnetism of magnetite
and maghemite, iron minerals can be easily recovered from
gangue minerals like quartz. The roasted ore in the air-cool-
ing process exhibited strong magnetism and the saturation
magnetization was 30.10 Am2/kg. Unlike water quenching
and nitrogen cooling, the remanence (5.90 Am2/kg) and
coercivity (8.7 kA/m) of roasted ore significantly decreased
in the air-cooling process because of the formation of
maghemite.
ACKNOWLEDGMENTS
Thanks for the financial support of the National Natural
Science Foundation of China (Grant No. 52104249).
INTEREST STATEMENT
On behalf of all authors, the corresponding author states
that there is no conflict of interest.
REFERENCES
Astuti, W., Novita, S., Nurjaman, F., 2017. Reduction
mechanism of indonesian limonite ore by solid reduc-
ing agents. Journal of Physics: Conference Series. 817,
012063. doi: 10.1088/1742-6596/817/1/012063.
Cornell, R. M., Schwertmann, U., 2003. The iron oxides:
structure, properties, reactions, occurrences and uses,
John Wiley &Sons,
Fu, X., Chen, Z., Xu, X., He, L., Song, Y., 2019. Deposits
in Gas-fired Rotary Kiln for Limonite Magnetization-
Reduction Roasting: Characteristics and Formation
Mechanism. Metals. 9, doi: 10.3390/met9070764.
Jang, K. O., Nunna, V. R. M., Hapugoda, S., Nguyen,
A. V., Bruckard, W. J., 2014. Chemical and mineral
transformation of a low grade goethite ore by dehy-
droxylation, reduction roasting and magnetic separa-
tion. Minerals Engineering. 60, 14–22. doi: 10.1016
/j.mineng.2014.01.021.
Maksum, A., Husein, M. K. E., Permana, S., Rustandi,
A., Soedarsono, J. W., 2018. A preliminary study
on the reduction of limonite ore by using rice
husk as a reducing agent. IOP Conference Series:
Materials Science and Engineering. 316, 012050. doi:
10.1088/1757-899x/316/1/012050.
O’connor, F., Cheung, W. H., Valix, M., 2006. Reduction
roasting of limonite ores: effect of dehydroxylation.
International Journal of Mineral Processing. 80,
88–99. doi: 10.1016/j.minpro.2004.05.003.
Ponomar, V. P., 2018. Thermomagnetic properties of the
goethite transformation during high-temperature
treatment. Minerals Engineering. 127, 143–152. doi:
10.1016/j.mineng.2018.08.016.
Roy, S. K., Nayak, D., Rath, S. S., 2020. A review on
the enrichment of iron values of low-grade Iron ore
resources using reduction roasting-magnetic separa-
tion. Powder Technology. 367, 796–808. doi: 10.1016
/j.powtec.2020.04.047.
Rzepa, G., Bajda, T., Gaweł, A., Debiec, K., Drewniak, L.,
2016. Mineral transformations and textural evolution
during roasting of bog iron ores. Journal of Thermal
Analysis and Calorimetry. 123, 615–630. doi: 10.1007
/s10973-015-4925-1.
Song, S., Lu, S., Lopez-Valdivieso, A., 2002. Magnetic sep-
aration of hematite and limonite fines as hydrophobic
flocs from iron ores. Minerals Engineering. 15, 415–
422. doi: 10.1016/S0892-6875(02)00054-7.
Sun, Y., Cao, Y., Han, Y., Li, Y., 2018. Oxidation
Kinetics of Magnetite During the Cooling Process
of Magnetization Roasting. Journal of Northeastern
University (Natural Science). 39, 90–94. http://
xuebao.neu.edu.cn/natural/CN/Y2018/V39/
I12/1759.
Tang, J. A., Valix, M., 2006. Leaching of low grade limo-
nite and nontronite ores by fungi metabolic acids.
Minerals Engineering. 19, 1274–1279. doi: 10.1016
/j.mineng.2006.04.009.
Thompson, R., 2012. Environmental magnetism, Springer
Science &Business Media,
Uwadiale, G. G. O. O., 1992. Magnetizing Reduction of
Iron Ores. Mineral Processing and Extractive Metallurgy
Review. 11, 1–19. doi: 10.1080/08827509208914211.
Valix, M., Cheung, W. H., 2002a. Effect of sulfur on the
mineral phases of laterite ores at high temperature
reduction. Minerals Engineering. 15, 523–530. doi:
10.1016/S0892-6875(02)00069-9.
into maghemite in the air-cooling, which has a smaller
remanence and coercivity.
CONCLUSION
The comparison of air cooling, water quenching, and nitro-
gen cooling processes was studied in the magnetization
roasting of limonite ore. It indicated that air cooling is a
feasible cooling process for magnetizing roasting of limo-
nite ore. Compared with the traditional water quenching
and nitrogen cooling process, a very good magnetic separa-
tion index with an iron grade of 55.94% and recovery of
93.39% was achieved. In the air-cooling process, no hema-
tite characteristic peaks were found in the roasted ore. The
synthetic magnetite was oxidized by O2 into maghemite
but not hematite. Due to the ferrimagnetism of magnetite
and maghemite, iron minerals can be easily recovered from
gangue minerals like quartz. The roasted ore in the air-cool-
ing process exhibited strong magnetism and the saturation
magnetization was 30.10 Am2/kg. Unlike water quenching
and nitrogen cooling, the remanence (5.90 Am2/kg) and
coercivity (8.7 kA/m) of roasted ore significantly decreased
in the air-cooling process because of the formation of
maghemite.
ACKNOWLEDGMENTS
Thanks for the financial support of the National Natural
Science Foundation of China (Grant No. 52104249).
INTEREST STATEMENT
On behalf of all authors, the corresponding author states
that there is no conflict of interest.
REFERENCES
Astuti, W., Novita, S., Nurjaman, F., 2017. Reduction
mechanism of indonesian limonite ore by solid reduc-
ing agents. Journal of Physics: Conference Series. 817,
012063. doi: 10.1088/1742-6596/817/1/012063.
Cornell, R. M., Schwertmann, U., 2003. The iron oxides:
structure, properties, reactions, occurrences and uses,
John Wiley &Sons,
Fu, X., Chen, Z., Xu, X., He, L., Song, Y., 2019. Deposits
in Gas-fired Rotary Kiln for Limonite Magnetization-
Reduction Roasting: Characteristics and Formation
Mechanism. Metals. 9, doi: 10.3390/met9070764.
Jang, K. O., Nunna, V. R. M., Hapugoda, S., Nguyen,
A. V., Bruckard, W. J., 2014. Chemical and mineral
transformation of a low grade goethite ore by dehy-
droxylation, reduction roasting and magnetic separa-
tion. Minerals Engineering. 60, 14–22. doi: 10.1016
/j.mineng.2014.01.021.
Maksum, A., Husein, M. K. E., Permana, S., Rustandi,
A., Soedarsono, J. W., 2018. A preliminary study
on the reduction of limonite ore by using rice
husk as a reducing agent. IOP Conference Series:
Materials Science and Engineering. 316, 012050. doi:
10.1088/1757-899x/316/1/012050.
O’connor, F., Cheung, W. H., Valix, M., 2006. Reduction
roasting of limonite ores: effect of dehydroxylation.
International Journal of Mineral Processing. 80,
88–99. doi: 10.1016/j.minpro.2004.05.003.
Ponomar, V. P., 2018. Thermomagnetic properties of the
goethite transformation during high-temperature
treatment. Minerals Engineering. 127, 143–152. doi:
10.1016/j.mineng.2018.08.016.
Roy, S. K., Nayak, D., Rath, S. S., 2020. A review on
the enrichment of iron values of low-grade Iron ore
resources using reduction roasting-magnetic separa-
tion. Powder Technology. 367, 796–808. doi: 10.1016
/j.powtec.2020.04.047.
Rzepa, G., Bajda, T., Gaweł, A., Debiec, K., Drewniak, L.,
2016. Mineral transformations and textural evolution
during roasting of bog iron ores. Journal of Thermal
Analysis and Calorimetry. 123, 615–630. doi: 10.1007
/s10973-015-4925-1.
Song, S., Lu, S., Lopez-Valdivieso, A., 2002. Magnetic sep-
aration of hematite and limonite fines as hydrophobic
flocs from iron ores. Minerals Engineering. 15, 415–
422. doi: 10.1016/S0892-6875(02)00054-7.
Sun, Y., Cao, Y., Han, Y., Li, Y., 2018. Oxidation
Kinetics of Magnetite During the Cooling Process
of Magnetization Roasting. Journal of Northeastern
University (Natural Science). 39, 90–94. http://
xuebao.neu.edu.cn/natural/CN/Y2018/V39/
I12/1759.
Tang, J. A., Valix, M., 2006. Leaching of low grade limo-
nite and nontronite ores by fungi metabolic acids.
Minerals Engineering. 19, 1274–1279. doi: 10.1016
/j.mineng.2006.04.009.
Thompson, R., 2012. Environmental magnetism, Springer
Science &Business Media,
Uwadiale, G. G. O. O., 1992. Magnetizing Reduction of
Iron Ores. Mineral Processing and Extractive Metallurgy
Review. 11, 1–19. doi: 10.1080/08827509208914211.
Valix, M., Cheung, W. H., 2002a. Effect of sulfur on the
mineral phases of laterite ores at high temperature
reduction. Minerals Engineering. 15, 523–530. doi:
10.1016/S0892-6875(02)00069-9.