scholarly journals Reduction of Haematite Using Hydrogen Thermal Plasma

2019 ◽  
Author(s):  
Masab Naseri Seftejani ◽  
Johannes Schenk ◽  
Michael Andreas Zarl
Keyword(s):  
Thermal Plasma ◽  
Hydrogen Plasma ◽  
Reduction Rate ◽  
Reduction Process ◽  
Pilot Scale ◽  
Phosphorus Concentration ◽  
Smelting Reduction ◽  
Reduction Behavior ◽  
Degree Of Reduction ◽  
Hydrogen Utilization

The development of hydrogen plasma smelting reduction as a CO2 emission-free steel-making process is a promising approach. This study presents a concept of the reduction of hematite using hydrogen thermal plasma. A laboratory scale and pilot scale hydrogen plasma smelting reduction (HPSR) process are introduced. To assess the reduction behavior of hematite, a series of experiments has been conducted and the main parameters of the reduction behavior, namely the degree of hydrogen utilization, degree of reduction and the reduction rate are discussed. The thermodynamic aspect of the hematite reduction is considered and the pertinent calculations have been carried out using FactSageTM 7.2. The degree of hydrogen utilization and the degree of reduction were calculated using the off-gas chemical composition. The contribution of carbon, introduced from the graphite electrode, ignition pin and steel crucible, to the reduction reactions was studied. The degree of reduction of hematite, regarding H2O, CO and CO2 as the gaseous reduction products, is determined. It is shown that the degree of hydrogen utilization and the reduction rate were high at the beginning of the experiments, then decreased during the reduction process owing to the diminishing of iron oxide. Conducting experiments with the high basicity of slag B2=2 led to a decrease of the phosphorus concentration in the produced iron.

scholarly journals Reduction of Haematite Using Hydrogen Thermal Plasma

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1608 ◽  
Author(s):  
Masab Naseri Seftejani ◽  
Johannes Schenk ◽  
Michael Andreas Zarl
Keyword(s):  
Thermal Plasma ◽  
Hydrogen Plasma ◽  
Reduction Rate ◽  
Reduction Process ◽  
Pilot Scale ◽  
Phosphorus Concentration ◽  
Smelting Reduction ◽  
Degree Of Reduction ◽  
Reduction Behaviour ◽  
Hydrogen Utilization

The development of hydrogen plasma smelting reduction as a CO2 emission-free steel-making process is a promising approach. This study presents a concept of the reduction of haematite using hydrogen thermal plasma. A laboratory scale and pilot scale hydrogen plasma smelting reduction (HPSR) process are introduced. To assess the reduction behaviour of haematite, a series of experiments have been conducted and the main parameters of the reduction behaviour, namely the degree of hydrogen utilization, degree of reduction and the reduction rate are discussed. The thermodynamic aspect of the hematite reduction is considered, and the pertinent calculations were carried out using FactSageTM 7.2. The degree of hydrogen utilization and the degree of reduction were calculated using the off-gas chemical composition. The contribution of carbon, introduced from the graphite electrode, ignition pin and steel crucible, to the reduction reactions was studied. The degree of reduction of haematite, regarding H2O, CO and CO2 as the gaseous reduction products, was determined. It is shown that the degree of hydrogen utilization and the reduction rate were high at the beginning of the experiments, then decreased during the reduction process owing to the diminishing of iron oxide. Conducting experiments with the high basicity of slag B2 = 2 led to a decrease of the phosphorus concentration in the produced iron.

scholarly journals Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1051 ◽  
Author(s):  
Masab Naseri Seftejani ◽  
Johannes Schenk
Keyword(s):  
Iron Oxide ◽  
Liquid Iron ◽  
Thermal Plasma ◽  
Iron Ore ◽  
Hydrogen Plasma ◽  
Reduction Rate ◽  
Plasma Arc ◽  
Ionization Degree ◽  
Reduction Reactions ◽  
Plasma State

The production of iron using hydrogen as a reducing agent is an alternative to conventional iron- and steel-making processes, with an associated decrease in CO2 emissions. Hydrogen plasma smelting reduction (HPSR) of iron ore is the process of using hydrogen in a plasma state to reduce iron oxides. A hydrogen plasma arc is generated between a hollow graphite electrode and liquid iron oxide. In the present study, the thermodynamics of hydrogen thermal plasma and the reduction of iron oxide using hydrogen at plasma temperatures were studied. Thermodynamics calculations show that hydrogen at high temperatures is atomized, ionized, or excited. The Gibbs free energy changes of iron oxide reductions indicate that activated hydrogen particles are stronger reducing agents than molecular hydrogen. Temperature is the main influencing parameter on the atomization and ionization degree of hydrogen particles. Therefore, to increase the hydrogen ionization degree and, consequently, increase of the reduction rate of iron ore particles, the reduction reactions should take place in the plasma arc zone due to the high temperature of the plasma arc in HPSR. Moreover, the solubility of hydrogen in slag and molten metal are studied and the sequence of hematite reduction reactions is presented.

scholarly journals Slag Formation during Reduction of Iron Oxide Using Hydrogen Plasma Smelting Reduction

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 935 ◽  
Author(s):  
Masab Naseri Seftejani ◽  
Johannes Schenk ◽  
Daniel Spreitzer ◽  
Michael Andreas Zarl
Keyword(s):  
Iron Oxides ◽  
Iron Ore ◽  
Hydrogen Plasma ◽  
Reduction Process ◽  
Slag Formation ◽  
Smelting Reduction ◽  
Steel Making ◽  
Reduction Of Iron ◽  
Reduction Behaviour ◽  
Continuous Feeding

Replacing carbon by hydrogen is a huge step towards reducing CO2 emissions in the iron- and steel-making industry. The reduction of iron oxides using hydrogen plasma smelting reduction as an alternative to conventional steel-making routes has been studied at Montanuniversitaet Leoben, Austria. The aim of this work was to study the slag formation during the reduction process and the reduction behaviour of iron oxides. Furthermore the reduction behaviour of iron ore during continuous feeding was assessed. Mixtures of iron ore and calcined lime with a basicity of 0, 0.8, 1.6, 2.3, and 2.9 were melted and reduced by hydrogen. The off-gas composition was measured during the operations to calculate the process parameters. The reduction parameters, namely the degree of reduction, degree of hydrogen utilisation, produced iron, and slag, are presented. The results of the batch-charged experiments showed that at the beginning of the reduction process, the degree of hydrogen utilisation was high, and then, it decreased over the operation time. In contrast, during the continuous-feeding experiment, the degree of hydrogen utilisation could be kept approximately constant. The highest degrees of reduction and hydrogen utilisation were obtained upon the application of a slag with a basicity of 2.3. The experiment showed that upon the continuous feeding of iron ore, the best conditions for the reduction process using hydrogen could be applied.

Simulation and experimental research on top blown burner lance used for chrome ore smelting reduction process

2018 ◽  
Vol 115 (5) ◽  
pp. 511
Author(s):  
Shaoyan Hu ◽  
Rong Zhu ◽  
Kai Dong ◽  
Runzao Liu ◽  
Nan Jiang
Keyword(s):  
Reduction Rate ◽  
Steel Production ◽  
Reduction Process ◽  
Flame Length ◽  
Raw Material ◽  
Smelting Reduction ◽  
Propane Combustion ◽  
Combustion Flame ◽  
Submerged Arc Furnace ◽  
Stainless Steel Production

Chrome ore smelting reduction process in converter for crude stainless steel production has won increasing attention because of utilizing cheap chrome ore as raw material instead of ferrochromium alloy, which can reduce the production cost significantly. Thermodynamic and kinetic mechanisms of chrome ore smelting reduction have been well investigated by previous studies. How to improve the dissolution rate and reduction rate of chrome ore in actual production is the key problem of industrial application. In this paper, a method of using combustion flame to convey chrome ore powder was studied. Numerical simulation works were carried out to study the structure of top blown burner lance blowing propane combustion flame and chrome ore powder simultaneously. Optimal design of burner lance was confirmed and made for experiment. Flame measurement experiment was carried out to study the flame characteristics before and after powder addition, indicating that the addition of powder helps to prolong the flame length. Then a pilot experiment of chrome ore smelting reduction was carried out in a 0.5 ton submerged arc furnace, metallurgical effects under conditions with and without combustion flame were compared and analyzed. The results showed that the combustion flame can not only preheat the chrome ore powder, but also heat the molten slag of impact zone, obtaining better reaction rate and higher chrome ore yield.

scholarly journals Influence of MgO on Low Temperature Reduction and Mineralogical Changes of Sinter in Simulated COREX Shaft Furnace Reducing Conditions

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 272 ◽  
Author(s):  
Deqing Zhu ◽  
Jianlei Chou ◽  
Benjing Shi ◽  
Jian Pan
Keyword(s):  
Low Temperature ◽  
Shaft Furnace ◽  
Reduction Rate ◽  
Reduction Process ◽  
Smelting Reduction ◽  
Temperature Reduction ◽  
Corex Shaft Furnace ◽  
Reducing Conditions ◽  
Before And After ◽  
Low Temperature Reduction

COREX (Coal-Reduction-Extreme) smelting reduction process provides a sustainable developing way for ironmaking industry, but the sources of iron ore materials restrict its development in China. Meanwhile, the application of sinter, which is marked by low manufacture cost and overcapacity in China, to COREX furnace faced proportion limitation due to its worse low temperature reduction degradation performance. This work explored the influence of MgO content on the low-temperature (550 °C) reduction of sinter in reducing conditions simulating COREX shaft furnace. The mineralogical change of sinter containing different content of MgO before and after reduction was analyzed by X-ray diffraction (XRD), optical microscopy, and scanning electron microscopy for revealing the action mechanism of MgO on the low-temperature-reduction of sinter. The results show that increasing MgO (1.36–3.10%) improved the low temperature reduction degradation performance of sinter, and decreased its reduction degree and reduction rate at low temperature. More MgO the sinter contained, less Fe2O3 and SFCA was observed in sinter. Meantime, less Fe2O3 was reduced and the generation of innerstress was restrained during reduction process. The improved RDI (reduction degradation index) in COREX process of sinter by increasing MgO content is a comprehensive result of lowering strength and inhibiting probable reduction of sinter.

scholarly journals Isothermal and Non-Isothermal Reduction Behaviors of Iron Ore Compacts in Pure Hydrogen Atmosphere and Kinetic Analysis

2020 ◽  
Author(s):  
Abourehab Hammam ◽  
Ying Li ◽  
Hao Nie ◽  
Lei Zan ◽  
Weitian Ding ◽  
...  
Keyword(s):  
Heating Rate ◽  
Iron Ore ◽  
Reduction Rate ◽  
Reduction Process ◽  
Gas Diffusion ◽  
Hydrogen Atmosphere ◽  
Pure Hydrogen ◽  
Degree Of Reduction ◽  
Isothermal Reduction ◽  
Co Gas

Abstract This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient than with CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

scholarly journals Slag Formation During Reduction of Iron Oxide Using Hydrogen Plasma Smelting Reduction

2020 ◽  
Author(s):  
Masab Naseri Seftejani ◽  
Johannes Schenk ◽  
Daniel Spreitzer ◽  
Michael Andreas Zarl
Keyword(s):  
Iron Oxides ◽  
Iron Ore ◽  
Hydrogen Plasma ◽  
Reduction Process ◽  
Slag Formation ◽  
Smelting Reduction ◽  
Steel Making ◽  
Reduction Of Iron ◽  
Reduction Behaviour ◽  
Continuous Feeding

Replacing carbon by hydrogen is a huge step towards reducing CO2 emissions in the iron- and steel-making industry. The reduction of iron oxides using hydrogen plasma smelting reduction as an alternative to conventional steel-making routes has been studied at Montanuniversitaet Leoben, Austria. The aim of this work was to study the slag formation during the reduction process and the reduction behaviour of iron oxides. Furthermore, the reduction behaviour of iron ore during continuous feeding was assessed. Mixtures of iron ore and calcined lime with a basicity of 0, 0.8, 1.6, 2.3, and 2.9 were melted and reduced by hydrogen. The off-gas composition was measured during the operations to calculate the process parameters. The reduction parameters, namely the degree of reduction, degree of hydrogen utilisation, produced iron, and slag, are presented. The results of the batch-charged experiments showed that at the beginning of the reduction process, the degree of hydrogen utilisation was high, and then, it decreased over the operation time. In contrast, during the continuous-feeding experiment, the degree of hydrogen utilisation could be kept approximately constant. The highest degrees of reduction and hydrogen utilisation were obtained upon the application of a slag with a basicity of 2.3. The experiment showed that upon the continuous feeding of iron ore, the best conditions for the reduction process using hydrogen could be applied.

Material Structure of Microcrystalline Silicon Deposited with an Expanding Thermal Plasma

2003 ◽  
Vol 762 ◽  
Author(s):  
C. Smit ◽  
D.L. Williamson ◽  
M.C.M. van de Sanden ◽  
R.A.C.M.M. van Swaaij
Keyword(s):  
Thermal Plasma ◽  
Hydrogen Plasma ◽  
Plasma Chemistry ◽  
Plasma Source ◽  
Growth Direction ◽  
Interaction Time ◽  
Material Structure ◽  
Average Particle ◽  
Microcrystalline Silicon ◽  
X Ray

AbstractExpanding thermal plasma CVD (ETP CVD) has been used to deposit thin microcrystalline silicon films. In this study we varied the position at which the silane is injected in the expanding hydrogen plasma: relatively far from the substrate and close to the plasma source, giving a long interaction time of the plasma with the silane, and close to the substrate, resulting in a short interaction time. The material structure is studied extensively. The crystalline fractions as obtained from Raman spectroscopy as well as from X-ray diffraction (XRD) vary from 0 to 67%. The average particle sizes vary from 6 to 17 nm as estimated from the (111) XRD peak using the Scherrer formula. Small angle X-ray scattering (SAXS) and flotation density measurements indicate void volume fractions of about 4 to 6%. When the samples are tilted the SAXS signal is lower than for the untilted case, indicating elongated objects parallel to the growth direction in the films. We show that the material properties are influenced by the position of silane injection in the reactor, indicating a change in the plasma chemistry.

scholarly journals Reduction Mechanism of Fine Hematite Ore Particles in Suspension

2021 ◽  
Author(s):  
Zhiyuan Chen ◽  
Christiaan Zeilstra ◽  
Jan van der Stel ◽  
Jilt Sietsma ◽  
Yongxiang Yang
Keyword(s):  
Particle Size ◽  
Temperature Drop ◽  
Reduction Rate ◽  
Reduction Process ◽  
Reciprocal Relationship ◽  
Drop Tube ◽  
Surface Nucleation ◽  
Order Of Magnitude ◽  
Relationship Of ◽  
Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

scholarly journals A Study on the Effect of Alumina on the Morphology and Reduction Behavior of Sinter by In Situ Observation

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 740
Author(s):  
Sang Gyun Shin ◽  
Wan Ho Kim ◽  
Dong Joon Min
Keyword(s):  
Reduction Rate ◽  
Al2o3 Content ◽  
Confocal Laser ◽  
In Situ Observation ◽  
Sintering Process ◽  
Reduction Behavior ◽  
Reducing Gas ◽  
Interfacial Chemical Reaction ◽  
Reaction Routes

The effects of Al2O3 content on the morphology and reducibility of sinter were respectively investigated using confocal laser microscopy and thermogravimetric analysis at 1273 K under CO gas. To understand the effects of the sintering process, separate samples were prepared via the equilibrium and metastable reaction routes. In the equilibrium samples, the addition of Al2O3 led to the formation of the silico-ferrite of calcium and alumino phase and a decrease in the reduction rate due to the lowered reactivity of iron oxide. In contrast, in the metastable samples, the reduction rate increased after the addition of 2.5 mass% Al2O3. The addition of Al2O3 decreased the fraction of the liquid phase and increased the fraction of pores in the sample. As a result, the reduction rate is proportional to the Al2O3 content owing to the changes in the sinter morphology. In determining the reduction rate of the sinter, the influence of the microstructure on the diffusion of the reducing gas is more significant than that of the interfacial chemical reaction due to the formation of the SFCA phase. The microstructure changes of the sinter with the addition of Al2O3 and the corresponding reduction behaviors are further discussed.

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