Reduction Behaviors of Hematite
to Metallic Iron by Hydrogen at Low
Temperatures
Kun He, Zhong Zheng, Hongsheng Chen, and Weiping Hao
Abstract Low-temperature reduction of hematite to metallic iron by hydrogen is
an essential process for ironmaking based on the blast furnace and non-blast furnace
technologies. In this work, the reduction behaviors of Brazilian hematite in 20%H 2 –
80%Ar at 400–570 °C were investigated in a micro-fluidized bed. Results indicate
that the effect of the gaseous external diffusion can be eliminated as the gas flow rate
reaches 400 mL/min at 500 °C. According to the conversion X, the reaction from
hematite to metallic iron can be divided into two stages, which include the first stage
that corresponds to the process of Fe 2 O 3 → Fe 3 O 4 with X < 1/9 and the second
stage that corresponds to the reaction of Fe 3 O 4 → Fe. During the reduction process,
magnetite is formed gradually and a large number of pores and fissures are observed
on the surface of the ore and peripheral part of the unreacted core of hematite. The
rate constants of all individual reactions tend to increase with increasing temperature,
and the reaction rate of the entire reduction process is suggested to be determined by
the phase boundary reaction.
Keywords Reduction behaviors · Hematite · Hydrogen · Low temperature
Introduction
Carbon emissions from the blast furnace (BF) are the main force of the iron and steel
manufacturing that can be reduced by replacing the carbon with H 2 as a reducing
agent and energy source. Schenk et al. [1] suggested that the only possibility to reduce
the carbon emissions in the ironmaking process is increasing the use of H 2 . Recently,
H 2 was utilized in the ironmaking process in two ways. The gas-injection BF, which
is a new technology with injecting gas instead of the pulverized coal injection [2],
is the first way. For instance, Germany’s first hydrogen-based steel production plant
that uses the H 2 as a reducing agent in the BF has begun operation in Dillingen on
August 24, 2020 [3]. The other way is non-blast furnace technology such as direct
K. He · Z. Zheng (B) · H. Chen · W. Hao
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
e-mail: zhengzh@cqu.edu.cn
© The Minerals, Metals & Materials Society 2021
A. A. Baba et al. (eds.), Energy Technology 2021, The Minerals, Metals
& Materials Series, https://doi.org/10.1007/978-3-030-65257-9_11
111
to Metallic Iron by Hydrogen at Low
Temperatures
Kun He, Zhong Zheng, Hongsheng Chen, and Weiping Hao
Abstract Low-temperature reduction of hematite to metallic iron by hydrogen is
an essential process for ironmaking based on the blast furnace and non-blast furnace
technologies. In this work, the reduction behaviors of Brazilian hematite in 20%H 2 –
80%Ar at 400–570 °C were investigated in a micro-fluidized bed. Results indicate
that the effect of the gaseous external diffusion can be eliminated as the gas flow rate
reaches 400 mL/min at 500 °C. According to the conversion X, the reaction from
hematite to metallic iron can be divided into two stages, which include the first stage
that corresponds to the process of Fe 2 O 3 → Fe 3 O 4 with X < 1/9 and the second
stage that corresponds to the reaction of Fe 3 O 4 → Fe. During the reduction process,
magnetite is formed gradually and a large number of pores and fissures are observed
on the surface of the ore and peripheral part of the unreacted core of hematite. The
rate constants of all individual reactions tend to increase with increasing temperature,
and the reaction rate of the entire reduction process is suggested to be determined by
the phase boundary reaction.
Keywords Reduction behaviors · Hematite · Hydrogen · Low temperature
Introduction
Carbon emissions from the blast furnace (BF) are the main force of the iron and steel
manufacturing that can be reduced by replacing the carbon with H 2 as a reducing
agent and energy source. Schenk et al. [1] suggested that the only possibility to reduce
the carbon emissions in the ironmaking process is increasing the use of H 2 . Recently,
H 2 was utilized in the ironmaking process in two ways. The gas-injection BF, which
is a new technology with injecting gas instead of the pulverized coal injection [2],
is the first way. For instance, Germany’s first hydrogen-based steel production plant
that uses the H 2 as a reducing agent in the BF has begun operation in Dillingen on
August 24, 2020 [3]. The other way is non-blast furnace technology such as direct
K. He · Z. Zheng (B) · H. Chen · W. Hao
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
e-mail: zhengzh@cqu.edu.cn
© The Minerals, Metals & Materials Society 2021
A. A. Baba et al. (eds.), Energy Technology 2021, The Minerals, Metals
& Materials Series, https://doi.org/10.1007/978-3-030-65257-9_11
111