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Preliminary Study on Direct Reduction Technology of
Oolitic Hematite by Hydrogen-Based Suspension Roasting
Xuesong Sun, Yanjun Li, Jianwen Yu, Yuexin Han, Peng Gao
School of Resources and Civil Engineering, Northeastern University, Shenyang, China
National-local Joint Engineering Research Center of High-efficient Exploitation Technology for
Refractory Iron Ore Resources, Shenyang, China
ABSTRACT: Oolitic hematite, a representative refractory iron ore, lacks a precedent for direct reduction
treatment in suspension state. This paper investigated an efficient and environmentally friendly technology
for hydrogen based suspension roasting of oolitic hematite. The study explored the influence of reduction
temperature, H2 concentration, and reduction time on the metallization degree of the reduction products. The
phase composition and microstructure of the samples were analyzed using X-ray diffraction (XRD), scanning
electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The experimental findings revealed that,
under optimal conditions—reduction temperature of 800°C, H2 concentration of 60%, and reduction time of
20 minutes, the reduced product achieved a metallization rate of 76.89%, meeting the requirements for electric
furnace melting. It was worth noting that at temperatures higher than 750°C, fayalite would be generated, and
at the same time, the generated metallic iron aggregates would wrap the incompletely reduced iron oxides. These
two reasons hindered the further progress of the reduction reaction.
Keywords: Suspension Roasting Direct Reduction Oolitic Hematite Hydrogen Based
INTRODUCTION
The surge in demand for iron ore resources in China, neces-
sitating an annual import of 1.1 billion tons at a cost of
nearly $130 billion (Lin et al., 2023 Wang et al., 2023 You
et al., 2023), has prompted a wealth of imports while con-
siderable difficult-to-utilize iron ore resources within China
remain (Tang et al., 2022 Zhu et al., 2020). Among these
resources, oolitic hematite stands out as a significant iron
ore reserve, constituting over 10% of the total reserves (Li
et al., 2023). Oolitic hematite presents a complex oolitic
structure, with gangue and hematite enveloped in rings
layer by layer, exhibiting fine iron mineral distribution.
Predominant gangue minerals include chlorite and apatite,
with generally elevated phosphorus content (Li et al., 2013
Pan et al., 2022 Wu et al., 2023c). Therefore, the effective
utilization of oolitic hematite has been a longstanding focus
for Chinese researchers.
Currently, the treatment of oolitic hematite primar-
ily involves traditional beneficiation methods and a com-
bined beneficiation and smelting approach. Traditional
beneficiation methods typically include grinding, mag-
netic separation-flotation, or gravity separation-magnetic
separation-flotation (Chen et al., 2023 Liu et al., 2014).
However, due to the characteristics of fine dissemina-
tion size, low grade, and complex composition of oolitic
hematite, obtaining superior products through traditional
Preliminary Study on Direct Reduction Technology of
Oolitic Hematite by Hydrogen-Based Suspension Roasting
Xuesong Sun, Yanjun Li, Jianwen Yu, Yuexin Han, Peng Gao
School of Resources and Civil Engineering, Northeastern University, Shenyang, China
National-local Joint Engineering Research Center of High-efficient Exploitation Technology for
Refractory Iron Ore Resources, Shenyang, China
ABSTRACT: Oolitic hematite, a representative refractory iron ore, lacks a precedent for direct reduction
treatment in suspension state. This paper investigated an efficient and environmentally friendly technology
for hydrogen based suspension roasting of oolitic hematite. The study explored the influence of reduction
temperature, H2 concentration, and reduction time on the metallization degree of the reduction products. The
phase composition and microstructure of the samples were analyzed using X-ray diffraction (XRD), scanning
electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The experimental findings revealed that,
under optimal conditions—reduction temperature of 800°C, H2 concentration of 60%, and reduction time of
20 minutes, the reduced product achieved a metallization rate of 76.89%, meeting the requirements for electric
furnace melting. It was worth noting that at temperatures higher than 750°C, fayalite would be generated, and
at the same time, the generated metallic iron aggregates would wrap the incompletely reduced iron oxides. These
two reasons hindered the further progress of the reduction reaction.
Keywords: Suspension Roasting Direct Reduction Oolitic Hematite Hydrogen Based
INTRODUCTION
The surge in demand for iron ore resources in China, neces-
sitating an annual import of 1.1 billion tons at a cost of
nearly $130 billion (Lin et al., 2023 Wang et al., 2023 You
et al., 2023), has prompted a wealth of imports while con-
siderable difficult-to-utilize iron ore resources within China
remain (Tang et al., 2022 Zhu et al., 2020). Among these
resources, oolitic hematite stands out as a significant iron
ore reserve, constituting over 10% of the total reserves (Li
et al., 2023). Oolitic hematite presents a complex oolitic
structure, with gangue and hematite enveloped in rings
layer by layer, exhibiting fine iron mineral distribution.
Predominant gangue minerals include chlorite and apatite,
with generally elevated phosphorus content (Li et al., 2013
Pan et al., 2022 Wu et al., 2023c). Therefore, the effective
utilization of oolitic hematite has been a longstanding focus
for Chinese researchers.
Currently, the treatment of oolitic hematite primar-
ily involves traditional beneficiation methods and a com-
bined beneficiation and smelting approach. Traditional
beneficiation methods typically include grinding, mag-
netic separation-flotation, or gravity separation-magnetic
separation-flotation (Chen et al., 2023 Liu et al., 2014).
However, due to the characteristics of fine dissemina-
tion size, low grade, and complex composition of oolitic
hematite, obtaining superior products through traditional