Effects and mechanism of MgO on carbothermal reduction of Fe2TiO4

2021 ◽  
Vol 118 (4) ◽  
pp. 416
Author(s):  
Yunfei Chen ◽  
Xiangdong Xing
Keyword(s):  
Carbothermal Reduction ◽  
Thermodynamic Calculation ◽  
Direct Reduction ◽  
Reduction Temperature ◽  
Iron Particles ◽  
Promoting Effect ◽  
Effect Mechanism ◽  
Metallization Rate ◽  
High Reduction

The effects of MgO on carbothermal reduction of Fe2TiO4 had been researched including the thermodynamic calculation in this paper. And, based on XRD and SEM-EDS, the effect mechanism of MgO on the direct reduction of Fe2TiO4 had been deeply dissected, systematically. The results showed that magnesium titanium phases including MgTi2O5, MgTiO3 and Mg2TiO4 were formatted after MgO added into Fe2TiO4, which was main reason to affect the reduction of Fe2TiO4. When the MgO content in Fe2TiO4 did not exceed 2%, there was the promoting effect on the reduction of Fe2TiO4. With the increase of MgO content from 2% to 8%, the magnesium titanium phases transformed from MgTi2O5, and through MgTiO3 to Mg2TiO4. The inhibition function appeared, and can be weaken in the high reduction temperature. When reduction temperature reaches to 1300 °C, the metallization rate of F-M-8 (the reduction sample of 8% MgO) can reach 80.62% from 56.43% at 1200 °C. However, the aggregation degree of iron particles became worse when MgO was added to the sample.

Research on Direct Reduction Dynamic Model of Carbon-Bearing Pellet Containing Zinc

2011 ◽  
Vol 214 ◽  
pp. 369-373
Author(s):  
Jing Song Wang ◽  
Xiu Wei An ◽  
Wan Hua Yu ◽  
Xue Feng She ◽  
Yin Gui Ding ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Direct Reduction ◽  
Reduction Process ◽  
Reduction Temperature ◽  
Coupled Heat Transfer ◽  
Reducing Gas ◽  
Metallization Rate ◽  
Process Factors

Base on reduction experimental data, considering the reduction process factors like carbon content, reductive removal of ZnO, changing size of pellet, and partial pressure of reducing gas, also coupled heat transfer, mass transfer and chemical reactions, a direct reduction mathematical model on carbon-bearing pellet containing zinc has been established. The reliability of the model was testified by programming and experiments. Experiments showed that, under the reduction conditions that carbon and oxygen mole ratio at 1.0 and reduction temperature 1603K, metallization rate 87% and dezincification rate 99% were observed after 15 minutes of heating.

BF Charge Reduction with Gases of Different H2 Ratio in High Temperature Zone

2011 ◽  
Vol 284-286 ◽  
pp. 1152-1157
Author(s):  
Guo Zhang Tang ◽  
Zhen Gao ◽  
Yan Chang Kong ◽  
Kun Ouyang ◽  
Fu Min Li
Keyword(s):  
Loss Rate ◽  
Direct Reduction ◽  
Mass Loss Rate ◽  
Reduction Rate ◽  
Reduction Kinetics ◽  
Reduction Degree ◽  
Charge Reduction ◽  
Temperature Zone ◽  
Metallization Rate ◽  
Direct Reduction Degree

The reduction of different basicity BF charge with gases of different H2 ratio has been determined to simulate different BF technology. The results reveal: reduction rate (R & r) and metallization rate of charge increase with the H2 ratio increasing, and the temperature increasing while the reducing time becomes longer simultaneously. The direct reduction degree of charge in Hydrogen-enrichment BF is very low, thus the energy consumption of Ironmaking could be reduced. There is certain difference between metallization rate and reduction degree due to reduction kinetics. The mass loss rate of coke increases sharply with the H2 ratio increasing, the H2 ratio of gas should be selected an appropriate value.

scholarly journals Kinetics of the Volume Shrinkage of a Magnetite/Carbon Composite Pellet during Solid-State Carbothermic Reduction

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1050 ◽  
Author(s):  
Guang Wang ◽  
Jingsong Wang ◽  
Qingguo Xue
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Apparent Activation Energy ◽  
Carbothermic Reduction ◽  
Iron Ore ◽  
Carbon Composite ◽  
Volume Shrinkage ◽  
Reduction Temperature ◽  
Iron Particles ◽  
Composite Pellet

The volume shrinkage evolution of a magnetite iron ore/carbon composite pellet during solid-state isothermal reduction was investigated. For the shrinkage, the apparent activation energy and mechanism were obtained based on the experimental results. It was found that the volume shrinkage highly depended on the reduction temperature and on dwell time. The volume shrinkage of the pellet increased with the increasing reduction temperature, and the rate of increment was fast during the first 20 min of reduction. The shrinkage of the composite pellet was mainly due to the weight loss of carbon and oxygen, the sintering growth of gangue oxides and metallic iron particles, and the partial melting of the gangue phase at high temperature. The shrinkage apparent activation energy was different depending on the time range. During the first 20 min, the shrinkage apparent activation energy was 51,313 J/mol. After the first 20 min, the apparent activation energy for the volume shrinkage was only 19,697 J/mol. The change of the reduction rate-controlling step and the automatic sintering and reconstruction of the metallic iron particles and gangue oxides in the later reduction stage were the main reasons for the aforementioned time-dependent phenomena. The present work could provide a unique scientific index for the illustration of iron ore/carbon composite pellet behavior during solid-state carbothermic reduction.

scholarly journals Effect of Different Additives on Reaction Characteristics of Fluorapatite During Coal-Based Reduction of Iron Ore

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 923 ◽  
Author(s):  
Yongsheng Sun ◽  
Wentao Zhou ◽  
Yuexin Han ◽  
Yanjun Li
Keyword(s):  
Iron Ore ◽  
Contact Point ◽  
Energy Dispersive Spectrometer ◽  
Structural Evolution ◽  
Reduction Process ◽  
Reduction Degree ◽  
Reduction Temperature ◽  
Exponential Factor ◽  
Reduction Time ◽  
Effect Mechanism

In the coal-based reduction of high phosphorus oolitic hematite, it is particularly important to study the mechanism of phosphorus regulation during the formation of iron metals for the efficient development and utilization of iron ore. In this study, the thermodynamics of the coal-based reduction process of fluorapatite in different mineral systems, effect mechanism of the reduction degree, kinetics, mineral composition, and morphology of structural evolution samples were systematically investigated using FactSage software, single factor analysis, the isothermal method, X-ray diffraction (XRD), scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS). Thermodynamic analysis indicates that the effect of the SiO2–Fe2O3–C system on reducing the initial reduction temperature of fluorapatite was stronger than that of the Al2O3–Fe2O3–C system. The effect mechanism of the reduction degree demonstrates that increasing the dosage of silica, iron oxide, carbon, reduction time, and reduction temperature could promote the reduction reaction of fluorapatite under certain conditions. Dynamics analysis shows that the best kinetic mechanism functions of the SiO2–Fe2O3–C system and the Al2O3–Fe2O3–C system were A1/3 = 1/3(1 − α)[−ln(1 − α)]−2 and A1/2 = 1/2(1 − α)[−ln(1 − α)]−1, respectively. The activation energy and pre-exponential factor of the reduction kinetics equation in the system containing silica were significantly lower than that in the system containing alumina, which explained that the catalytic effect of silica on the reduction of calcium fluorophosphate was far greater than that of alumina. XRD and SEM/EDS analysis indicate that the solid–solid reaction of alumina, silica, iron, and fluorapatite occurred during the reduction process, while calcium aluminate, calcium silicate, and calcium oxide were formed at the contact point. Among them, iron could absorb P2 gas so that it played a greater role in promoting the reduction of fluorapatite. Increasing the reduction temperature and prolonging the reduction time were beneficial to the reduction of fluorapatite.

scholarly journals Carbothermal Reduction of Iron Ore in Its Concentrate-Agricultural Waste Pellets

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Zhulin Liu ◽  
Xuegong Bi ◽  
Zeping Gao ◽  
Wei Liu
Keyword(s):  
Carbothermal Reduction ◽  
Iron Ore ◽  
Loss Rate ◽  
Direct Reduction ◽  
Agricultural Waste ◽  
Weight Loss Rate ◽  
Iron Concentrate ◽  
High Speeds ◽  
Reduction Of Iron ◽  
Biomass Char

Carbon-containing pellets were prepared with the carbonized product of agricultural wastes and iron concentrate, and an experimental study on the direct reduction was carried out. The experimental results demonstrated that carbon-containing pellets could be rapidly reduced at 1200 to 1300°C in 15 minutes, and the proper holding time at high temperature was 15 to 20 min. The degree of reduction gradually increased with temperature rising, and the appropriate temperature of reducing pellets was 1200°C. The weight loss rate and reduction degree of pellets increased with the rise of carbon proportion, and the relatively reasonable mole ratio of carbon to oxygen was 0.9. A higher content of carbon and an appropriate content of volatile matters in biomass char were beneficial to the reduction of pellets. The carbon-containing pellets could be reduced at high speeds in the air, but there was some reoxidization phenomenon.

Solar Production of Aluminum by Direct Reduction: Preliminary Results for Two Processes

2000 ◽  
Vol 123 (2) ◽  
pp. 125-132 ◽  
Author(s):  
Jean P. Murray
Keyword(s):  
Carbothermal Reduction ◽  
Direct Reduction ◽  
Critical Factor ◽  
Black Body ◽  
Weight Percent ◽  
Primary Aluminum ◽  
Solar Furnace ◽  
Combustion Source ◽  
Concentrated Solar Energy ◽  
Process Heat

The production of aluminum or silicon by reduction of their oxides with carbon is a technical challenge. The temperature required, in the range 2100–2300°C, is too high for practical process heat addition from a combustion source alone. When an electrothermal process is used, only about a third of the energy contained in the fuel used to generate electricity enters the process. Thus, for materials produced electrolytically or in an electric furnace, the energy cost dominates the cost of the final product. By contrast, highly-concentrated solar energy is capable of supplying large amounts of process heat at very high temperatures, and may have real advantages for metals reduction processes. An arc introduces too much energy to the reaction zone. In the case of aluminum, the metal floats and it short circuits the arc. Ideally, the heat would enter at the bottom or side of a reactor, which could be achieved with solar process heat. Among industries, the primary aluminum industry is a major consumer of electricity. It uses about 10 percent of the electricity generated globally for industrial purposes, and about half comes from coal-fired generation stations. This represents about 5 percent of the electricity generated for all sectors. A solar-thermal process would drastically reduce the emission of climate-altering gases, reduce the reliance on electricity, and might be a critical factor in making a direct thermal route from the ore to metal possible. Two industrially-developed processes appear to be attractive candidates for a solar process. Preliminary tests have been performed using a black-body cavity receiver placed at the focus of the Paul Scherrer Institute’s 70 kW tracking parabolic concentrator, and though the experiment had to be ended earlier than planned, a small amount of 61/37 weight percent Al/Si alloy was formed, and the partially reacted pellets showed conversion to Al4C3 and SiC. Further qualitative tests have been performed using the facilities at Odeillo in a 2 kW solar furnace, where the onset of production of both aluminum by direct carbothermal reduction, and Al-Si alloy via carbothermal reduction of a mixture of alumina, silica and carbon could be directly observed.

Growth Characteristics of Metallic Iron Particles in the Direct Reduction of Nickel Slag

2020 ◽  
Vol 51 (3) ◽  
pp. 925-936 ◽  
Author(s):  
Xiaoming Li ◽  
Yi Li ◽  
Xinyi Zhang ◽  
Zhenyu Wen ◽  
Xiangdong Xing
Keyword(s):  
Metallic Iron ◽  
Direct Reduction ◽  
Growth Characteristics ◽  
Iron Particles

scholarly journals Effect of Co2O3 on Oxidation Induration and Reduction Swelling of Chromium-Bearing Vanadium Titanomagnetite Pellets with Simulated Coke Oven Gas

Metals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 16 ◽  
Author(s):  
Weidong Tang ◽  
Songtao Yang ◽  
He Yang ◽  
Xiangxin Xue
Keyword(s):  
Compressive Strength ◽  
Metallic Iron ◽  
Thermodynamic Calculation ◽  
Coke Oven ◽  
Iron Particles ◽  
Coke Oven Gas ◽  
Reduction Swelling ◽  
Lamellar Crystals ◽  
Technical Basis ◽  
And Diffusion

This study discusses the oxidation induration and swelling behavior of chromium-bearing vanadium titanomagnetite pellets (CVTP) with Co2O3 additions. The reduction swelling index (RSI) and compressive strength of reduced CVTP (CSRC) were investigated with simulated coke oven gas (COG). The results show that the compressive strength (CS) of CVTP decreases from 2448 to 1983 N and the porosity of CVTP increases from 14.86 to 22.49% with increasing Co2O3 additions. The Co2O3 mainly exists in the form of CoFe2O4 in both of CVTP and reduced CVTP, and the CoFe2O4 is hard to be reduced by thermodynamic calculation. The Co-bearing phase mainly distributes on gap edges and among adjacent hematite grains. Many cracks and pores distribute along the grain boundaries and damage the connection of hematite grains. The CSRC decreases from 901 to 376 N, and RSI of reduced CVTP increases from 5.87 to 9.05% with increasing Co2O3 additions. The Co2O3 addition facilitates the aggregation and diffusion of metallic iron particles, and the aggregations of metallic iron thicken the lamellar crystals. The pores and interval of grains enlarge with increasing Co2O3 additions. This study can supply the theoretical and technical basis for the utilization of CVTP and waste residue-bearing cobalt with COG recyclable technology.

Influence of Temperature and Holding Time on Number and Size of Metal Particles during Solid-Phase Reduction of Iron by Carbon

2021 ◽  
Vol 316 ◽  
pp. 496-501
Author(s):  
A. Bil'genov ◽  
A.R. Tabylbaeva ◽  
P.A. Gamov
Keyword(s):  
Crystal Lattice ◽  
Solid Phase ◽  
Direct Reduction ◽  
Complex Oxide ◽  
Holding Time ◽  
Iron Particles ◽  
Experimental Conditions ◽  
Influence Of Temperature ◽  
Reduction Of Iron ◽  
Average Size

There is a lack of complete understanding of the mechanism and kinetics of reduction of metals from oxides. This paper presents results and methods of a series of experiments on direct reduction of metals by solid carbon in the form of graphite from a complex oxide with a low iron content in a laboratory muffle furnace at temperatures of 1300, 1400, 1500, 1600 °C and holding time of 1, 3, 5, 7 hours. The statistical analysis of amount and average size of reduced iron particles inside the oxide was studied. Dependence of amount and average size of the reduced iron particles on temperature and time of reduction is presented. The phenomena of iron crystals’ growth, occurring as a result of changes in the crystal lattice of oxide, was studied under experimental conditions. The influence of temperature and holding time on iron particles’ nucleation and their growth in the crystal lattice of a complex oxide were compared. Investigation of mechanism of metals’ reduction from complex oxides and influence of experimental conditions on the nucleation and growth enables to identify new patterns in the process of reduction of metals from their oxides, in general.

Recovery of zinc from electric arc furnace dust by vacuum carbothermal reduction

2021 ◽  
Vol 118 (4) ◽  
pp. 415
Author(s):  
Shaobo Ma ◽  
Zhaohui Zhang ◽  
Shuxiang Xu ◽  
Xintao Li ◽  
Lu Feng
Keyword(s):  
Carbothermal Reduction ◽  
Economic Value ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Optimum Process ◽  
Reduction Temperature ◽  
Arc Furnace ◽  
Electric Arc Furnace Dust ◽  
Thermodynamic Conditions ◽  
Comprehensive Recovery

Recently, the proportion of electric furnace steelmaking has increased rapidly, and the content of electric arc furnace dust has increased. Through comprehensive recovery of electric arc furnace dust, the harm of metallurgical solid waste can be reduced and economic value can be created. In this paper, it gives a common outline about the known recycling techniques from electric arc furnace dusts and presents the carbothermal reduction under vacuum. The evolution in reduction products in the process of vacuum carbothermal reduction of zinc-containing electric arc furnace dust is studied using the X-ray diffraction (XRD) phase and micro-morphology analysis. The thermodynamic conditions for reduction are computed using Factsage 7.1 program. Through thermodynamic study, it is found that the initial temperature of reducing zinc oxide decreases as the pressure of the system drops. In the process of the vacuum carbothermal reduction experiment, the type of reducing agent, reduction temperature, carbon content, and reaction time are studied. According to the test results, the optimum process parameters are determined as follows: reduction time 30 min, reduction temperature 1273 K. The dezincification effect of electric arc furnace dust can reach over 99%.

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