XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1851
metallic iron. As the reduction reaction progressed, most of
the wüstite transformed into metallic iron. Additionally, a
small portion of the remaining wüstite reacted with quartz
in the ore, producing fayalite. This, along with the iron
oxides wrapped by metallic iron, posed difficulty for fur-
ther reaction with hydrogen. Consequently, these factors
hindered the reduction reaction, leading to a challenging
and sustained increase in the metallization rate.
CONCLUSION
This study marked the inaugural utilization of a hydrogen-
based suspension roasting process to achieve direct reduc-
tion of high-phosphorus acicular hematite at comparatively
lower reduction temperatures (≤900°C). The effects of
reduction conditions on the degree of metallization and
mineral phase composition of the reduction products were
investigated. Under the specified conditions of 800°C tem-
perature, 60% H2 concentration, and a 20-minute dura-
tion, reduction products exhibiting a metalization rate of
approximately 77% were obtained, and that the decrease in
the size of the mineral particles would increase the metal-
lization rate of the reduced product. When the tempera-
ture was increased to above 750°C, the wüstite reacted with
quartz to generate fayalite, and the higher the temperature,
the more fayalite was generated. The generated fayalite can-
not be further reduced by hydrogen gas, which led to an
increase in ferrous content with increasing temperature.
Therefore, it was necessary to control the reduction tem-
perature within a reasonable range. For the hydrogen based
direct reduction of oolitic hematite, the reaction path was
magnetite→wüstite→ metallic iron. During the reduction
process, three states of iron minerals coexist, and metallic
iron would aggregate and fuse. Low valent iron oxides were
wrapped in metallic iron, making it difficult to contact
hydrogen gas. This, together with the generated fayalite,
formed the reason why the metallization rate cannot be
improved.
REFERENCES
Chen, C., Zhang, Y., Zou, K., et al., Flotation
Dephosphorization of High-Phosphorus Oolitic Ore.
Materials, 2023, 13(12), 1485.
Ding, H.-y., Yuan, S., Gao, P., et al., Research on efficient
utilization of high-phosphorus oolitic hematite for
iron enrichment and dephosphorization by hydrogen
mineral phase transformation. Journal of Central South
University, 2023, 30(12), 4021–4035.
Hosford, W.F., Iron and steel. 2012, Cambridge University
Press.
Li, G., Zhang, S., Rao, M., et al., Effects of sodium salts
on reduction roasting and Fe–P separation of high-
phosphorus oolitic hematite ore. International Journal
of Mineral Processing, 2013, 124, 26–34.
Li, W., Liu, D., Han, Y., et al., An innovative study for
pretreatment of high-phosphorus oolitic hematite via
high-temperature heating: phase, microstructure, and
phosphorus distribution analyses. Advanced Powder
Technology, 2023, 34(5), 103996.
Li, W., Wang, S., Han, Y., et al., Recovery of iron from
pyrite cinder by suspension magnetization roasting-
magnetic separation method: Process optimization
and mechanism study. Separation and Purification
Technology, 2024, 332, 125652.
Figure 11. Schematic diagram of the reduction process of oolitic hematite
metallic iron. As the reduction reaction progressed, most of
the wüstite transformed into metallic iron. Additionally, a
small portion of the remaining wüstite reacted with quartz
in the ore, producing fayalite. This, along with the iron
oxides wrapped by metallic iron, posed difficulty for fur-
ther reaction with hydrogen. Consequently, these factors
hindered the reduction reaction, leading to a challenging
and sustained increase in the metallization rate.
CONCLUSION
This study marked the inaugural utilization of a hydrogen-
based suspension roasting process to achieve direct reduc-
tion of high-phosphorus acicular hematite at comparatively
lower reduction temperatures (≤900°C). The effects of
reduction conditions on the degree of metallization and
mineral phase composition of the reduction products were
investigated. Under the specified conditions of 800°C tem-
perature, 60% H2 concentration, and a 20-minute dura-
tion, reduction products exhibiting a metalization rate of
approximately 77% were obtained, and that the decrease in
the size of the mineral particles would increase the metal-
lization rate of the reduced product. When the tempera-
ture was increased to above 750°C, the wüstite reacted with
quartz to generate fayalite, and the higher the temperature,
the more fayalite was generated. The generated fayalite can-
not be further reduced by hydrogen gas, which led to an
increase in ferrous content with increasing temperature.
Therefore, it was necessary to control the reduction tem-
perature within a reasonable range. For the hydrogen based
direct reduction of oolitic hematite, the reaction path was
magnetite→wüstite→ metallic iron. During the reduction
process, three states of iron minerals coexist, and metallic
iron would aggregate and fuse. Low valent iron oxides were
wrapped in metallic iron, making it difficult to contact
hydrogen gas. This, together with the generated fayalite,
formed the reason why the metallization rate cannot be
improved.
REFERENCES
Chen, C., Zhang, Y., Zou, K., et al., Flotation
Dephosphorization of High-Phosphorus Oolitic Ore.
Materials, 2023, 13(12), 1485.
Ding, H.-y., Yuan, S., Gao, P., et al., Research on efficient
utilization of high-phosphorus oolitic hematite for
iron enrichment and dephosphorization by hydrogen
mineral phase transformation. Journal of Central South
University, 2023, 30(12), 4021–4035.
Hosford, W.F., Iron and steel. 2012, Cambridge University
Press.
Li, G., Zhang, S., Rao, M., et al., Effects of sodium salts
on reduction roasting and Fe–P separation of high-
phosphorus oolitic hematite ore. International Journal
of Mineral Processing, 2013, 124, 26–34.
Li, W., Liu, D., Han, Y., et al., An innovative study for
pretreatment of high-phosphorus oolitic hematite via
high-temperature heating: phase, microstructure, and
phosphorus distribution analyses. Advanced Powder
Technology, 2023, 34(5), 103996.
Li, W., Wang, S., Han, Y., et al., Recovery of iron from
pyrite cinder by suspension magnetization roasting-
magnetic separation method: Process optimization
and mechanism study. Separation and Purification
Technology, 2024, 332, 125652.
Figure 11. Schematic diagram of the reduction process of oolitic hematite