The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Vladimir Strezov - One of the best experts on this subject based on the ideXlab platform.
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Mercury Speciation under Laboratory Scale Direct Iron Ore Reduction Process Conditions
2020Co-Authors: Pushan Shah, Vladimir Strezov, Tim Evans, John Takos, Peter F. NelsonAbstract:Mercury is among the most toxic trace metals, a potential neurotoxin which bioaccumulates in the aquatic biota and subsequently enters the food chain. While mercury emissions from coal fired power stations have been extensively studied, much less effort has been devoted to characterise emissions of mercury from Ironmaking process, where contributions of mercury present in the Ore and in the coal used as a reducing agent may be significant. Understanding of the detailed chemistry of mercury in Ironmaking systems and release of different forms of mercury to the atmosphere is important given that the distribution, mobility and bioavailability of mercury depends on its various chemical forms and oxidation states (or speciation). MOreover, speciation of mercury determines the extent of its capture in existing pollution control technologies. This study describes measurements of speciation of mercury in off gas from laboratory scale direct Iron Ore Reduction process involving the use of circulating fluidised bed (CFB) reactor. Speciation of mercury in off gas was determined using the Ontario Hydro sampling train method. Samples of feed coal, Iron Ore and waste products were also collected during the experiments and were analysed for total mercury content to calculate the mass balance of mercury. The measurements were performed under several different operating conditions. An attempt was made to derive possible mechanistic understanding of the chemical reactions leading to mercury transformation under the reducing conditions of Ironmaking processes.
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Assessment of evolution of loss on ignition matter during heating of Iron Ores
Journal of Thermal Analysis and Calorimetry, 2010Co-Authors: Vladimir Strezov, Artur Ziolkowski, Tim J. Evans, Peter F. NelsonAbstract:Ironmaking involves Reduction of Iron Ores to metallic Iron using coke, coal or gas as reductants. Although different Iron Ore Reduction processes exist, prior to each Reduction type, commonly, the hydroxyl and clay materials present in the Iron Ores undergo decomposition as a first stage. The mass loss during decomposition of these materials is termed as Loss on Ignition (LOI). The aim of this work is to apply a computer aided thermoanalytical technique to evaluate five different Iron Ore types during decomposition of the LOI matter and determine associated decomposition temperature ranges and heats of reactions. Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis (TG) were also incorporated to support the analysis interpretation. Three distinctive temperature ranges of decomposition of Iron Ore LOI matter were detected. The first region was associated with dehydration of the hygroscopic moisture at a temperature range between 100 and 150 °C. The second region occurred at a temperature range between 260 and 425 °C during which strongly bonded water was released and the OH groups associated with primarily Iron oxyhydroxides were fractured. The third range, which occurred at a temperature range of 530 and 605 °C, was related to decomposition of the aluminosilicate clay materials.
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Iron Ore Reduction using sawdust experimental analysis and kinetic modelling
Renewable Energy, 2006Co-Authors: Vladimir StrezovAbstract:Iron and steel making are two of the largest energy intensive industries with the highest growth rate in energy consumption of all energy utilisation sectors. In order to meet the growing greenhouse challenges, incorporation of renewable energy sources to the existing and emerging metallurgical operations is desirable. In this respect, biomass can potentially be applied as fuel for minerals processing to stabilise the greenhouse gas emissions as it is renewable and CO2 neutral. The work presented here investigates the fundamental mechanisms of Iron Ore Reduction with biomass wood waste. Several mixtures with different ratios of biomass and Iron Ore were subjected to thermal, gaseous and X-ray Diffraction analysis. The Iron Ore was successfully reduced to predominantly metallic Iron phase when up to 30% by weight of biomass was introduced into the mixture. Reduction commenced at approximately 670°C and was almost completed at 1200°C. Thermal analysis data identified the individual thermal reaction regions associated with developments of individual Iron phases during the heating and were used to calculate the corresponding kinetics of the Reduction process.
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Computational Calorimetric Study of the Iron Ore Reduction Reactions in Mixtures with Coal
Industrial & Engineering Chemistry Research, 2005Co-Authors: Vladimir Strezov, John Lucas, Louis WibberleyAbstract:Thermal analysis on two coals (semi-anthracite and high-volatile coking coal), Iron Ore, and their corresponding mixtures was performed using a computer-aided thermal analysis technique. Samples were heated to 1000 °C at a typical rate of 10 °C/min under an argon atmosphere. It was found that the Iron Ore undergoes several reactions prior to its Reduction, which resulted in an endothermic heat effect. The Iron Ore Reduction commenced at temperatures as low as 580 °C and progressively increased at higher temperatures. Coal devolatilization was found to play an important role in Iron Ore Reduction for the coal−Ore mixtures at temperatures below 920 °C, while the effect of char gasification resulting in CO as a reducing gas was dominant at higher temperatures. No apparent difference in the effect of coal devolatilization on Reduction reactions was observed when low- and high-volatile matter coal was mixed with the Iron Ore. The main difference was detected only in the temperature range where char gasificatio...
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thermal investigations of direct Iron Ore Reduction with coal
Thermochimica Acta, 2004Co-Authors: Vladimir Strezov, John Lucas, Louis James WibberleyAbstract:Abstract In this paper, fundamental mechanisms for Iron Ore Reduction in coal–Ore mixtures have been investigated using several advanced experimental techniques. Firstly, the thermal properties of coal–Ore mixtures were studied and apparent specific heat of coal–Ore mixtures against temperature was obtained at a heating rate of 10 °C/min. Several exothermic and endothermic peaks were observed which were related to the decomposition reactions and Reduction. The flue gases from the mixture were analysed using a mass spectrometer. Secondly, the X-ray diffraction (XRD) and the Iron phase analytical techniques were applied to identify the Iron phase changes with the temperature. It has been found that coal devolatilisation and Iron oxides Reduction occur simultaneously during the heating of the mixture. H2 and CO gases produced from coal devolatilisation and char gasification were responsible for the Reduction of Iron oxides at these temperatures. Iron oxides undergo step-wise Reduction over the whole process. The results in this work provide a fundamental understanding for the direct reduced Ironmaking processes.
Jue Fang - One of the best experts on this subject based on the ideXlab platform.
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Energy Consumption in Smelting Reduction
Steel Research International, 2020Co-Authors: Jue Fang, Xingjuan WangAbstract:The concepts of theOretical gas utilization ratio, smelting heat of Iron Ore and effective calorific value of coal were introduced in this work. The practical gas utilization ratio and the gas consumption in the shaft of a Reduction unit for smelting Reduction were discussed. The COrex process was optimized and the energy consumption was minimized according to the relationship of gas production in the smelting unit and the degree of Iron Ore Reduction in the Reduction unit. It was proven that the most important factor for saving energy in smelting Reduction process is to use coal with suitable effective calorific value for the smelting heat of Iron Ore.
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Metalurgia & Materiais Energy consumption in smelting Reduction (SR) processes
2020Co-Authors: Paulo Santos Assis, Ouro Preto-ufop, Ouro Preto, Jue FangAbstract:In contrast, conventional processes use coke and hematite/sinter in the blast furnace, in SR processes, other alternative fuels and Iron Ore sources, like charcoal and fi ne Iron Ores, can be used to produce sponge Iron. The use of these alternative sources, by SR processes, can reduce envIronmental impacts and lower production costs. At fi rst, the concepts of the theOretical gas utilization ratio, the smelting heat of the Iron Ore and the effective calorifi c value of coal were introduced. Then, the reason for gas utilization ratio and its performance in the shaft as a reducer in the smelting process are discussed and calculated. The relationship between coal consumption and Iron Ore Reduction in the fl uidized bed are also discussed. Finally, the infl uence of post-combustion on coal consumption in an Iron bath furnace are calculated and discussed.
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Experimental Study on Sticking Behavior of Fluidized Bed in Reduction Process
Advanced Materials Research, 2012Co-Authors: Xingjuan Wang, Jue FangAbstract:It is a good way that the fluidized bed is used as a substitute for Reduction shaft in COrex process. Which can reduce energy consumption, envIronmental pollution and construction costs further, and also improve the competitiveness of COrex and blast furnace. At present, the sticking problem is present in Iron Ore Reduction process and interrupts the Reduction process, it has become a major obstacle on the development of fluidized bed. In this paper, a visualization hot model of fluidized bed is introduced. The influence factors on sticking behavior were analyzed from Reduction temperature, gas velocity, atmosphere, degree of metallization or Reduction and property of Iron Ore, the research provided a strong theOretical basis for controlling the sticking.
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Energy consumption in smelting Reduction (SR) processes
Rem-revista Escola De Minas, 2010Co-Authors: Paulo Santos Assis, Jue Fang, T R Mankhand, Carlos Frederico Campos De Assis, Giovanni Felice SaliernoAbstract:In contrast, conventional processes use coke and hematite/sinter in the blast furnace, in SR processes, other alternative fuels and Iron Ore sources, like charcoal and fine Iron Ores, can be used to produce sponge Iron. The use of these alternative sources, by SR processes, can reduce envIronmental impacts and lower production costs. At first, the concepts of the theOretical gas utilization ratio, the smelting heat of the Iron Ore and the effective calorific value of coal were introduced. Then, the reason for gas utilization ratio and its performance in the shaft as a reducer in the smelting process are discussed and calculated. The relationship between coal consumption and Iron Ore Reduction in the fluidized bed are also discussed. Finally, the influence of post-combustion on coal consumption in an Iron bath furnace are calculated and discussed.
Johannes Schenk - One of the best experts on this subject based on the ideXlab platform.
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Iron Ore Reduction by Hydrogen Using a Laboratory Scale Fluidized Bed Reactor: Kinetic Investigation—Experimental Setup and Method for Determination
Metallurgical and Materials Transactions B, 2019Co-Authors: Daniel Spreitzer, Johannes SchenkAbstract:The Reduction kinetics of hematite Iron Ore fines to metallic Iron by hydrogen using a laboratory fluidized bed reactor were investigated in a temperature range between 873 K and 1073 K, by measuring the weight change of the sample portion during Reduction. The fluidization conditions were checked regarding plausibility within the Grace diagram and the measured pressure drop across the material during experiments. The apparent activation energy of the Reduction was determined against the degree of Reduction and varied along an estimated two-peak curve between 11 and 55 kJ mol^−1. Conventional kinetic analysis for the Reduction of FeO to metallic Iron, using typical models to describe gas–solid reactions, does not show results with high accuracy. Multistep kinetic analysis, using the Johnson–Mehl–Avrami model, shows that the initial stage of Reduction from Fe_2O_3 to Fe_3O_4, and partly to FeO, is controlled by diffusion and chemical reaction, depending on the temperature. Further Reduction can be described by a combination of nucleation and chemical reaction, whereby the influence of nucleation increases with an increasing Reduction temperature. The results of the kinetical analysis were linked to the shape of the curve from apparent activation energy against the degree of Reduction.
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Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma
Open Access Journal, 2018Co-Authors: Masab Naseri Seftejani, Johannes SchenkAbstract: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.
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Evaluation of the Limiting Regime in Iron Ore Fines Reduction with H2‐Rich Gases in Fluidized Beds: Fe2O3 to Fe3O4
Chemical Engineering & Technology, 2009Co-Authors: Johannes Sturn, Johannes Schenk, S. Voglsam, Bernd Weiss, Franz WinterAbstract:In metallurgical processes, fluidized-bed technology is gaining mOre importance because of its advantages. Processes with H 2 -rich and CO-rich reducing gases were developed for the Reduction of Iron Ore fines (e.g. FINEX®). For improvement of these new technologies, greater knowledge about the chemical kinetics of Iron Ore Reduction in fluidized beds is necessary. The scope of this work is to evaluate the limiting regime of the Iron Ore fines Reduction. TherefOre, experimental results of Reduction tests were compared with theOretically investigated Reduction rates. These Reduction rates were based on a limitation either of mass transfer through the external gas film to the particle surface, diffusion in a porous product layer (pOre diffusion and Knudsen diffusion), diffusion in a dense product layer (solid diffusion) or the phase boundary reaction. The phase boundary reaction was found to be the most likely limiting reaction regime.
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Iron Ore Reduction in a continuously operated multistage lab scale fluidized bed reactor mathematical modeling and experimental results
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2006Co-Authors: Albin Thurnhofer, Johannes Schenk, Franz Winter, S. Schuster, G. Löffler, A. Habermann, H. Hofbauer, J. ZirngastAbstract:Industrial-scale fluidized bed processes for Iron Ore Reduction (e.g., FIOR and FINMET) are operated by continuous feeding of Ore, while laboratory tests are mostly performed under batchwise operation. The Reduction behavior under continuous operation is influenced by both the residence time of the Iron Ore particles and the Reduction kinetics, which is obtained by batch tests. In a mathematical model for such a process, the effect of both phenomena has to be considered. The residence time distribution of Iron Ore particles in a laboratory fluidized bed reactor was obtained by measuring the response of a step input and described by mathematical models similar to a continuously stirred tank reactor. In the same reactor, Reduction tests with continuous feeding of Iron Ore were performed. Based on batch tests in a fluidized bed reactor, a mathematical model was developed to describe the kinetics of Iron Ore Reduction under fluidized bed conditions. This kinetic model was combined with the fluidized bed reactor model to describe continuous Iron Ore Reduction. In this detailed model, the change of gas composition while rising in the fluidized bed was considered. The degree of Reduction and the gas conversion for reactors in series were calculated. The results obtained by the mathematical model were compared with experimental data from the laboratory-scale reactor.
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Iron Ore Reduction in a laboratory scale fluidized bed reactor effect of pre Reduction on final Reduction degree
Isij International, 2005Co-Authors: Albin Thurnhofer, M Schachinger, Franz Winter, Heinrich Mali, Johannes SchenkAbstract:Fluidized bed processes for Iron Ore Reduction (e.g. FIOR®, FINMET®, FINEX®) operate in a continuous multi-staged countercurrent mode. To optimize Iron Ore Reduction, different operating conditions occur in each stage.Significant influence of the first Reduction stage on the final Reduction degree was observed in industrial plant. The Iron Ore particles seem to “memorize” the precursor autoclave conditions.To optimize Iron Ore Reduction, as well as to develop new Reduction processes, it is necessary to understand this phenomenon. Industrial plants operate on pressures up to 12 bar and temperatures up to 900°C. So a laboratory-scale pressurized fluidized bed reactor was built to perform experiments similar to industrial conditions.Two-stage experiments with Mt. Newman hematite Ore from Western Australia at variable operating conditions show significant influences of temperature and residence time of the pre-Reduction stage on the final Reduction degree. Microscopical analysis showed the influence of mineralogy and texture on the Reduction behavior of original respectively partly reduced Iron Ore. Formed magnetite in the pre-Reduction stage causes a degradation of final Reduction degree. Additionally the amount of newly formed magnetite depends on pre-Reduction temperature, composition of the reducing gas and residence time.
Mian Hu - One of the best experts on this subject based on the ideXlab platform.
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direct Reduction of Iron Ore biomass composite pellets using simulated biomass derived syngas experimental analysis and kinetic modelling
Chemical Engineering Journal, 2017Co-Authors: Yubiao Li, Zhihua Chen, Bo Xiao, Mian HuAbstract:Abstract This paper presents a novel and envIronmentally friendly production of direct reduced Iron (DRI) technology using biomass as an additive agent in Iron Ore pellets and simulated biomass-derived syngas as the reducing agent. The effects of biomass addition on Iron Ore pellets Reduction and consequent Reduction kinetics in simulated biomass-derived syngas atmosphere were investigated. The results demonstrated that the biomass addition improved the pellet porosity and specific surface area, thus increasing both the reducibility and Reduction rate and decreasing the apparent activation energy for pellet Reduction. Mathematical modelling of experimental data indicated an interfacial chemical reaction mechanism with FeO → Fe as the rate controlling step. The simulated biomass syngas is an alternative gas-based reductant to natural gas, coal gas, mOre than 99.5% Reduction degree of the oxidized pellets was reduced at 1323 K within 20 min. The apparent activation energies were 86.05 kJ·mol −1 , 97.53 kJ·mol −1 for the pellets with and without biomass addition. The proposed Iron Ore Reduction process therefOre would be a potential to reduce Iron directly using biomass with high efficiency and real envIronmental benefits.
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Direct Reduction of Iron Ore/biomass composite pellets using simulated biomass-derived syngas: Experimental analysis and kinetic modelling
Chemical Engineering Journal, 2017Co-Authors: Yubiao Li, Zhihua Chen, Bo Xiao, Mian HuAbstract:Abstract This paper presents a novel and envIronmentally friendly production of direct reduced Iron (DRI) technology using biomass as an additive agent in Iron Ore pellets and simulated biomass-derived syngas as the reducing agent. The effects of biomass addition on Iron Ore pellets Reduction and consequent Reduction kinetics in simulated biomass-derived syngas atmosphere were investigated. The results demonstrated that the biomass addition improved the pellet porosity and specific surface area, thus increasing both the reducibility and Reduction rate and decreasing the apparent activation energy for pellet Reduction. Mathematical modelling of experimental data indicated an interfacial chemical reaction mechanism with FeO → Fe as the rate controlling step. The simulated biomass syngas is an alternative gas-based reductant to natural gas, coal gas, mOre than 99.5% Reduction degree of the oxidized pellets was reduced at 1323 K within 20 min. The apparent activation energies were 86.05 kJ·mol −1 , 97.53 kJ·mol −1 for the pellets with and without biomass addition. The proposed Iron Ore Reduction process therefOre would be a potential to reduce Iron directly using biomass with high efficiency and real envIronmental benefits.
Franz Winter - One of the best experts on this subject based on the ideXlab platform.
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Particle fluidization and reaction engineering activities at the Institute of Chemical Engineering, TU Wien
South African Journal of Chemical Engineering, 2020Co-Authors: Franz Winter, Christoph Pfeifer, Tobias Pröll, Reinhard Rauch, Alexander Reichhold, H. HofbauerAbstract:This paper gives an overview of the research activities and highlights on particle fluidization and reaction engineering at the Institute of Chemical Engineering at Vienna University of Technology. It is structured into steam gasification in dual fluidized bed, CO2 capture including oxy-fuel combustion, chemical looping combustion and reforming, synthetic biofuels including synthetic natural gas, Fischer-Tropsch synthesis, mixed alcohols and the production of hydrogen. The chapter is followed by the studies of agglomeration under fluidized bed combustion conditions and catalytic cracking of feeds from biological sources. The paper concludes with Iron Ore Reduction kinetics.
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Evaluation of the Limiting Regime in Iron Ore Fines Reduction with H2‐Rich Gases in Fluidized Beds: Fe2O3 to Fe3O4
Chemical Engineering & Technology, 2009Co-Authors: Johannes Sturn, Johannes Schenk, S. Voglsam, Bernd Weiss, Franz WinterAbstract:In metallurgical processes, fluidized-bed technology is gaining mOre importance because of its advantages. Processes with H 2 -rich and CO-rich reducing gases were developed for the Reduction of Iron Ore fines (e.g. FINEX®). For improvement of these new technologies, greater knowledge about the chemical kinetics of Iron Ore Reduction in fluidized beds is necessary. The scope of this work is to evaluate the limiting regime of the Iron Ore fines Reduction. TherefOre, experimental results of Reduction tests were compared with theOretically investigated Reduction rates. These Reduction rates were based on a limitation either of mass transfer through the external gas film to the particle surface, diffusion in a porous product layer (pOre diffusion and Knudsen diffusion), diffusion in a dense product layer (solid diffusion) or the phase boundary reaction. The phase boundary reaction was found to be the most likely limiting reaction regime.
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Iron Ore Reduction in a continuously operated multistage lab scale fluidized bed reactor mathematical modeling and experimental results
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2006Co-Authors: Albin Thurnhofer, Johannes Schenk, Franz Winter, S. Schuster, G. Löffler, A. Habermann, H. Hofbauer, J. ZirngastAbstract:Industrial-scale fluidized bed processes for Iron Ore Reduction (e.g., FIOR and FINMET) are operated by continuous feeding of Ore, while laboratory tests are mostly performed under batchwise operation. The Reduction behavior under continuous operation is influenced by both the residence time of the Iron Ore particles and the Reduction kinetics, which is obtained by batch tests. In a mathematical model for such a process, the effect of both phenomena has to be considered. The residence time distribution of Iron Ore particles in a laboratory fluidized bed reactor was obtained by measuring the response of a step input and described by mathematical models similar to a continuously stirred tank reactor. In the same reactor, Reduction tests with continuous feeding of Iron Ore were performed. Based on batch tests in a fluidized bed reactor, a mathematical model was developed to describe the kinetics of Iron Ore Reduction under fluidized bed conditions. This kinetic model was combined with the fluidized bed reactor model to describe continuous Iron Ore Reduction. In this detailed model, the change of gas composition while rising in the fluidized bed was considered. The degree of Reduction and the gas conversion for reactors in series were calculated. The results obtained by the mathematical model were compared with experimental data from the laboratory-scale reactor.
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Iron Ore Reduction in a laboratory scale fluidized bed reactor effect of pre Reduction on final Reduction degree
Isij International, 2005Co-Authors: Albin Thurnhofer, M Schachinger, Franz Winter, Heinrich Mali, Johannes SchenkAbstract:Fluidized bed processes for Iron Ore Reduction (e.g. FIOR®, FINMET®, FINEX®) operate in a continuous multi-staged countercurrent mode. To optimize Iron Ore Reduction, different operating conditions occur in each stage.Significant influence of the first Reduction stage on the final Reduction degree was observed in industrial plant. The Iron Ore particles seem to “memorize” the precursor autoclave conditions.To optimize Iron Ore Reduction, as well as to develop new Reduction processes, it is necessary to understand this phenomenon. Industrial plants operate on pressures up to 12 bar and temperatures up to 900°C. So a laboratory-scale pressurized fluidized bed reactor was built to perform experiments similar to industrial conditions.Two-stage experiments with Mt. Newman hematite Ore from Western Australia at variable operating conditions show significant influences of temperature and residence time of the pre-Reduction stage on the final Reduction degree. Microscopical analysis showed the influence of mineralogy and texture on the Reduction behavior of original respectively partly reduced Iron Ore. Formed magnetite in the pre-Reduction stage causes a degradation of final Reduction degree. Additionally the amount of newly formed magnetite depends on pre-Reduction temperature, composition of the reducing gas and residence time.
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an experimental study on the kinetics of fluidized bed Iron Ore Reduction
Isij International, 2000Co-Authors: A. Habermann, Franz Winter, H. Hofbauer, J. Zirngast, Johannes SchenkAbstract:To optimize existing Iron Ore Reduction processes or to develop new ones, it is necessary to know the Reduction kinetics of the Iron Ore of interest under the relevant operating conditions. In this work the Reduction kinetics of hematite fine Iron Ore was studied for industrial-scale processes using the fluidized bed technology. Especially designed batch tests were performed in a laboratory-scale fluidized bed reactor fluidized with H 2 , H 2 O CO, CO 2 , N 2 at atmospheric and elevated pressures to simulate the relevant process conditions. To obtain the Reduction rates and the degree of Reduction, the concentrations of H 2 O, CO, and CO 2 in the outlet gas were analyzed by FT-IR spectroscopy. Preliminary Reduction tests showed a strong effect of the sample weight on the Reduction rates, especially in the early stages of Reduction. The optimum sample weight was determined by partly replacing the hematite with silica sand. Additionally, the silica sand provided a constant and stable flow pattern throughout the Reduction tests. The effects of temperature, gas composition, particle size and pressure on the rates of Reduction were tested and discussed. Rate analysis showed the existence of two phases with different rates during the Reduction tests. Additional investigations (microscope analysis, SEM) demonstrated that in the first phase the rates were controlled by mass transport in the gas phase and in the second phase by the Reduction process within the small grains of the Iron Ore particles.
