Abstract:To explore the reduction
swelling process of pellets prepared from
the Bayan Obo iron ore concentrate, based on the iron oxide reduction
theory of pellets, the reduction of pellets prepared from the Bayan
Obo iron ore concentrate was analyzed by thermogravimetric experiments
and kinetic calculations in three stages. The reason for the abnormal
swelling of pellets prepared from the Bayan Obo iron ore concentrate
was analyzed from the perspective of kinetics. The research results
showed that carbon deposition oc… Show more
“…[ 11 ] It has been reported that the activation energy range is 4.2–21 KJ mol −1 when the rate limiting step is internal diffusion and over 42 kJ mol −1 is interfacial chemical reaction. [ 45 ] Our value of activation energy for pure hydrogen reduction falls in between internal diffusion and chemical reaction resistance cases ( Table 4 ).…”
Direct reduction of iron ore (DRI) is gaining an increased attention due to the growing need to decarbonize industrial processes. The current industrial DRI processes are performed using reformed natural gas, which results in CO2 emission, although it is less than carbothermic reduction in the blast furnace. Carbon‐free reduction may be realized through the utilization of green H2 as a reducing agent, in place of natural gas. Herein, the effects of various gas mixtures and temperature on the reduction kinetics of the hematite iron‐ore pellets are focused on in this work. Pellets are reduced at 700, 800, 850, and 900 °C in hydrogen and using various gas mixes at 850 °C. Morphology of the pellets is investigated with the help of scanning electron microscopy and mercury intrusion porosimetry. The effects of temperature and gas composition on the reduction kinetics and porosity of the pellets are discussed. A notable effect of reduction rate on the internal structure of the pellets is detected, slower reduction rate yielded bigger pores offsetting the gas composition. Higher temperature results in coarser pores and higher porosity. Increase of CO content in the gas mix also leads to bigger pore size.
“…[ 11 ] It has been reported that the activation energy range is 4.2–21 KJ mol −1 when the rate limiting step is internal diffusion and over 42 kJ mol −1 is interfacial chemical reaction. [ 45 ] Our value of activation energy for pure hydrogen reduction falls in between internal diffusion and chemical reaction resistance cases ( Table 4 ).…”
Direct reduction of iron ore (DRI) is gaining an increased attention due to the growing need to decarbonize industrial processes. The current industrial DRI processes are performed using reformed natural gas, which results in CO2 emission, although it is less than carbothermic reduction in the blast furnace. Carbon‐free reduction may be realized through the utilization of green H2 as a reducing agent, in place of natural gas. Herein, the effects of various gas mixtures and temperature on the reduction kinetics of the hematite iron‐ore pellets are focused on in this work. Pellets are reduced at 700, 800, 850, and 900 °C in hydrogen and using various gas mixes at 850 °C. Morphology of the pellets is investigated with the help of scanning electron microscopy and mercury intrusion porosimetry. The effects of temperature and gas composition on the reduction kinetics and porosity of the pellets are discussed. A notable effect of reduction rate on the internal structure of the pellets is detected, slower reduction rate yielded bigger pores offsetting the gas composition. Higher temperature results in coarser pores and higher porosity. Increase of CO content in the gas mix also leads to bigger pore size.
“…The addition of MgO is considered to reduce the reduction swelling index. In the reduction process of Bayan Obo pellets, MgO stabilizes the crystal structure of magnetite, inhibits the directional crystallization ability of FeO crystals, and finally inhibits the growth of iron whisker, which can reduce the reduction expansion phenomenon at all stages of pellet reduction as shown in Figure 9 [42,89]. Figure 9. Changes in the gradual RSI of pellets prepared from the Bayan Obo iron ore concentrate [89].…”
Section: Metallurgical Properties Of Mgo-bearing Pelletsmentioning
confidence: 99%
“…In the reduction process of Bayan Obo pellets, MgO stabilizes the crystal structure of magnetite, inhibits the directional crystallization ability of FeO crystals, and finally inhibits the growth of iron whisker, which can reduce the reduction expansion phenomenon at all stages of pellet reduction as shown in Figure 9 [42,89]. Figure 9. Changes in the gradual RSI of pellets prepared from the Bayan Obo iron ore concentrate [89]. …”
Section: Metallurgical Properties Of Mgo-bearing Pelletsmentioning
confidence: 99%
“…Figure9. Changes in the gradual RSI of pellets prepared from the Bayan Obo iron ore concentrate[89].…”
It is imperative to reduce the pollution and energy consumption in the blast furnace ironmaking process. High pellets operation is a developing direction in the future. The function of blast furnace slag system cannot be ignored. In order to balance the MgO content in blast furnace slag and improve the metallurgical properties of pellets in the high pellets ratio operation, the research on MgO-bearing pellets is necessary. In this paper, the metallurgical properties of MgO-bearing pellets and the properties of blast furnace slag effect by MgO in different raw material conditions, especially for Vanadium Titanomagnetite, were analysed and summarized. This review provided a reference for the development of MgO-bearing pellets and the performance of blast furnace slag effect by MgO. It is hoped to reduce pollution and promote the technical progress of blast furnace ironmaking.
Several studies have reported about different hydrogen production and storage materials. The use of metal oxides, particularly iron oxides, as hydrogen storage materials offers a promising solution to bridge hydrogen production and utilization. The iron‐steam process, dating back to the 18th century, leverages iron's ability to bind oxygen from steam, producing hydrogen and iron oxides. This study revisits the iron/iron oxide system for its dual application as a hydrogen storage medium and as an energy carrier in systems like fuel cells. When integrated with high‐temperature electrolysis and fuel cells, this system can efficiently operate between 600 and 1000 °C. The key to long‐term performance lies in understanding the formation and stability of oxygen‐binding structures. Stabilizing the iron oxides for cycling procedures with other metal oxides like Al2O3, SiO2, and CaO is inevitable. Ceramic‐stabilized iron oxide pellets offer advantages including high cycling capability, efficient charge/discharge operations, and potential syngas production. They are particularly suitable for heavy goods vehicles, short‐term storage, and large‐scale industrial applications. Critical process parameters for the iron oxide material and process design must be investigated if an accurate assessment of the performance of this hydrogen storage concept is to be transferred into efficient practice.
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