Reduction Process Of Iron Ore Research Articles

CFD-DEM simulation of raceway size and mechanical characteristics of industrial scale blast furnace

Abstract The raceway plays a crucial role in ensuring the stable functioning of the ironmaking blast furnace. It is the key site where the chemical reaction of coke combustion takes place, providing the necessary heat and reducing gas for the upper iron ore reduction process. Consequently, the size of the raceway serves as an essential indicator of the blast furnace’s operational condition. In this study, a mathematical model for the raceway of an industrial-scale blast furnace was established. Extensive innovation investigations were conducted to explore the characteristics pertaining to the raceway’s size. The simulation outcomes demonstrate that both the particle size and the inlet velocity exert significant influences on the raceway dimensions. Specifically, the height of the raceway is predominantly affected by the particle size, whereas the inlet velocity predominantly influences the depth of the raceway.

An Integrated Analytics of PEM Electrolyzer and Steel Making

It is widely accepted that the hydrogen-water couple can elevate the green economy circuit if powered by renewable sources of energy. Proton-exchange membrane water electrolyzer (PEMWE) being a clean electrochemical device is expected to provide an amenable solution to the hydrogen-water nexus and act as an enabler to achieving decarbonization of the steel-making industry. In this work, we throw light on the performance of a PEMWE that feeds target hydrogen volumes to a direct iron ore reduction process. The response of the electrolyzer under the presence of a host of operational stressors and variable electricity input is delineated through a macroscale modeling framework. The techno-economics associated with specific energy consumption of the downstream steel-making pathways will be further discussed based on insights from a process cost model.

Kinetic Mechanism Development for the Direct Reduction of Single Hematite Pellets in H2/CO Atmospheres

Increasing interest in the direct reduction process of iron ore has revived investigations on gaseous and heterogeneous iron oxides’ kinetics. Despite extensive studies on the reduction of iron oxides with pure hydrogen or syngas, the development of a generic reduction mechanism for iron oxides is still lacking. The conventional shrinking core model hardly distinguishes between transport and reaction processes, leading to biases or even errors in the kinetic models. In the present study, a porous solid model, which solves mass balances of the individual gas‐phase species and solid ones assuming spherical symmetry, is used for developing a heterogeneous kinetic mechanism accounting for different iron oxidation stages (Fe2O3, Fe3O4, FeO). It also accounts for carbon accumulation and cementite formation to model the carburization phenomena when using carbon‐containing reducing agents like syngas. The proposed generic mechanism successfully reproduces 49 experimental data sets from the literature for single iron oxide pellets’ isothermal reduction with syngas of varying hydrogen content up to pure hydrogen without any adjustment of its parameters. The model predictions are in excellent agreement with the experimental data. Finally, the carburization kinetics are explained, and the factors (e.g., temperature, hydrogen content) affecting the carbon deposition are analyzed.

Characterization of Bio Oil Derived from Palm Kernel Shell Pyrolysis Catalyzed by Iron Ore Based Catalyst

Using bio oil derived from biomass pyrolysis as an alternative fuel continues to be encouraged in order to decrease the utilization of fossil fuels. On the other hand, application of iron ore as a catalyst in the biomass pyrolysis process provides an advantage where there is a mutual effect on the reduction process of iron ore. The objective of the study is to probe the influence of temperature and catalyst concentration to the pyrolysis yields, the characterization of bio-oil gained, and additionally, phase and composition change of the iron ore. This research utilized palm kernel shells as biomass and raw iron ore as catalyst. The experiment was performed at different temperatures (450, 500, and 550oC) and different catalyst concentrations (0, 10, and 15 % of mass). The biomass was located in the lower part of the reactor and the catalyst was positioned on the upper side of the biomass being separated by using a thick layer of glass wool. The pyrolysis process was implemented by drawing off N2 gas to avert the oxygen existence in the reactor. The results exhibited that the highest bio-oil yield, 43.63%, was obtained from the sample of 550oC with non-catalyst, but the highest tar yield was generated from sample of 550°C with 15% of catalyst concentration. GC-MS results showed that catalyst concentration of 15% mass induced opposite effect to composition of phenolic-aromatic compound and acetic acids content compared to the one of 10% mass. Eventually, pyrolysis conditions are able to encourage the reduction process occurred in the iron ore catalyst.

Effect of Carbon Addition on Direct Reduction Behavior of Low Quality Magnetite Ore by Reducing Gas Atmosphere

Recently, direct reduced iron (DRI) has been highlighted as a promising iron source for electric arc furnace (EAF)-based steelmaking. The two typical production methods for DRI are gas-based reduction and reduction using carbon composite pellets. While the gas-based reduction is strongly dependent on the reliable supply of hydrocarbon fuel, reduction using ore-coal composite pellets has relatively low productivity due to solid–solid reactions. To overcome the limitations of the above two processes, and to achieve a more efficient direct reduction process of iron ore, the possibility of combining these two methods was investigated. The experiments focused on performing an initial direct reduction using ore-coal composite pellets followed by a second stage gas reduction. It was assumed that the initial reduction of the carbon composite pellets would enhance the efficiency of the subsequent reduction by gas and the total reduction efficiency. The porosity, as well as the carbon efficiency for direct reduction, were measured to determine the optimal conditions for the initial reduction, such as the size ratio of ore and coal particles. Thereafter, further reduction by the reducing gas was carried out to verify the effect of the preliminary reduction. The reduction kinetics of the reducing gas was also discussed.

Characterization and Reduction Behavior of Carbonized Ore Prepared by Iron Ore Immersion in Tar Derived from Biomass Pyrolysis

The provision of carbon reducing agents for the direct reduction process of iron ore is carried out by immersing the iron ore in a tar solution and then proceeding with the pyrolysis/ carbonization process to obtain carbon deposits on the surface of the iron ore. The purpose of this study is to investigate the characterization and reduction behavior of Fe compounds resulting from impregnation and carbonization processes. In this study, iron ore is immersed in the pine flower tar with immersion time varying from 0 - 12 hours and a fixed ratio of tar / ore 1: 1. The soaking mixture is then carbonized in a vertical tube reactor covered by furnace with N2 gas flowed during the carbonization/pyrolysis process. The carbonization runs with a temperature variation of 450-550°C, for 1 hour, and a heating rate of 10°C/min. From SEM-EDX-Mapping result shows that the immersion method in tar followed by carbonization caused the carbon content in iron ore to increase by 86.68% in a 1: 1 tar/ore ratio, the impregnating time of 6 hours, and a pyrolysis temperature of 450°C. Effect of impregnation duration evidence that immersion times of 6 and 12 hours are sufficient to produce the magnetite phase after the carbonization process. Furthermore, the 6 hours’ duration provides a more optimal peak intensity. Meanwhile, the effect of temperature on the carbonization process shows that 450°C is the optimal temperature to obtain the magnetite phase in the carbonized ore.

Analyses of multi-size particle mixing behavior in an ore pre-reduction rotary kiln by discrete element method

The particle distribution in pre-reduction rotary kiln directly affects the reduction process of iron ore, and in-depth understanding of the mixing behavior is helpful to improve the product quality and productivity. The present work focused on the mixed dynamics of multi-component and multi-size systems in rotary kiln using discrete element method (DEM). We first confirmed that the final particle distribution and mixing degree are independent of the initial particle distribution, and then further discussed the influence of the key operating parameters such as rotating speed, average size ratio and filling degree on mixing behavior. The size segregation pattern of three components shows that the large particles segregated to the outer region, while the small particles were concentrated in the core region, forming an annular distribution with different particle sizes. Furthermore, the results also indicate that the rotational speed and fill degree show strong influence on the mixing time and have little influence on the mixing quality. Conversely, the average size ratio significantly affects on the mixing quality. The particle segregation is suppressed and the coal and iron ore particles are well mixed together for the whole bed when the average size of coal particles is smaller than that of iron ore particle. The findings of this work provide a reference for controlling and optimizing the particle mixing process in pre-reduction rotary kiln.

Effect of Ternary Basicity of Iron Ore-Fluxed Pellets on Melting and Softening Properties in a Blast Furnace

The cohesive zone is a region of low permeability in a blast furnace. This study shows the impact of the chemical composition of pellets on the metallurgical processes occurring in this region during the iron ore reduction process. Sixteen pellets containing varying contents of MgO, CaO, and SiO2 were investigated. The results indicate that increasing the MgO content of pellets improves their high-temperature properties; e.g., reduction degree and softening temperature. Modern equipment was used to replicate the phenomena that occur in the cohesive zone to measure the softening temperature, pressure drop, and the reduction degree of pellets at elevated temperatures and different pellet basicities. These experimental results were used to develop mathematical correlations between parameters related to high-temperature properties and the ternary basicity of the pellets ((CaO + MgO)/SiO2). Defining such relationships will facilitate evaluating the effects of pellet chemical composition on blast furnace processes.

An Analytical Way to Comparing the Affective Parameters on Iranian Pellet Strength

Iron ore pellets are the raw materials for direct reduction process of iron ore to sponge iron pellets and is an important step in the iron and steel production chain. Many of the defects in direct reduction and steel making processes could be identify in the iron ore processing stage. Therefore, the purpose of this study was to select the correct suppliers of iron ore pellets for direct reduction units based on criteria affecting the strength of cooked pellets, which played a key role in optimizing the production criteria of sponge iron and ultimately increasing production efficiency in the steelmaking stage which can be very effective. For this purpose, using the hierarchical analysis model, the parameters affecting the strength of pellets have been identified and studied by experts of several iron and steel production units, and finally, for example, several iron ore pellet production plants have been compared and ranked. According to AHP decision criteria, particle size is the most important parameter affecting the strength of cooked pellets.

Flame analysis for prediction of thermocouple temperature and quality of sponge iron at TATA steel long products limited

The temperature profiles of the gas and charge in a coal-fired rotary sponge iron kiln affect both the iron ore reduction process and accretion formation. The temperature profile of charge is estimated from the eleven thermocouples (TC1-TC11) placed along the 80 m length of the kiln. The quality prediction models are heavily dependent upon the accuracy of the measurement of TC10. However, slowly, as the kiln’s campaign life increases TC10, and other thermocouples too, get corrupted due to deposition of material (accretions) on the thermocouples. At the beginning of the campaign, however, there is no accretion on TC10. In the present work, an attempt is made to directly correlate flame characteristics with TC10 and with quality of iron produced so that when TC10 is corrupted due to accretion or breakdown, we can still survive by using flame characteristics as a guide to control quality. The flame inside the rotary kiln has been analysed by using image analysis procedures for the first time in a sponge iron plant. The flame’s estimated average temperature and pixel intensity information are correlated with (a) the temperature measured by the thermocouple TC10 (which is installed at a distance of 20 m from the rotary kiln outlet hood) and (b) with quality of iron produced. It is found that use of average flame temperature for quality prediction has several advantages in terms of increased accuracy of prediction and quicker response time of flame to short-time changes in coal quality (particle size, moisture, ash content, etc) whereas TC10 thermocouple takes much longer to reflect these changes due to slow process of heat transfer to charge. In addition, the adverse effect of accretion formation on TC10 for quality prediction has been overcome.

Validation of CFD–DEM model for iron ore reduction at particle level and parametric study

Iron ore reduction is a primary unit operation in current metallurgy processes and dominates the energy consumption and greenhouse gas (GHG) emissions of the iron-making process. Therefore, even a slight improvement of the energy efficiency or GHG emissions of iron ore reduction would yield considerable benefits to the cost of pig iron and, more importantly, to mitigation of the associated carbon footprint. The current study presents a discrete model that describes the iron ore reduction process for a single pellet. The transient reaction progress can be predicted and is validated against experimental measurements under various operating conditions, including different reducing gases and temperatures. The effects of pressure, isothermality, gas composition, and flow rate on reduction are investigated. The reduction rate increases significantly with increasing pressure until 5atm, and the entire reduction process occurs more slowly under non-isothermal conditions than under isothermal conditions. This work provides a solid foundation for the development of a comprehensive particulate system model that considers both heat and mass transfer.

Mechanism of surface morphology evolution in the reduction of fine iron ore in a conical fluidized bed reactor

Surface morphology evolution in the reduction of fine iron ore in a conical fluidized bed reactor under various conditions was investigated. Regime diagrams of morphology on iron ore reduction with H2 were obtained for choosing appropriate operating condition. The result indicates that it is beneficial to inhibit the formation of iron whiskers under high H2 content, high gas velocity and low reduction temperature. Further, the formation mechanism of the whiskers in the iron ore reduction with H2 atmosphere was revealed by the quantitative analysis of the relative rate between the iron diffusion and reduction. The result indicates that iron diffusion rate is the dominant factor that brings about whiskers during the reduction. Based on the regime diagrams of morphology, the formation of whiskers could be inhibited with the guidance of a whisker formation tendency value below 2.51 m4·mol−1. This provide a method of guidance for the application on iron ore reduction process by adjusting the relative rate between diffusion of iron and reduction.

Review and Thermodynamic Calculation of Gas-based Shaft Furnace Direct Reduction Ironmaking

Different techniques have been used to study the reduction process of iron ore. In this paper, the reduction process of iron ore by CO at 200~1200°C is calculated. The effects of reducing agent overdose, reducing temperature and VCO2/(VCO+VCO2) on reducing degree were studied. The results show that the reduction degree increases with the increase of reducing agent and slows down gradually. During the reduction process, the reduction degree decreased significantly with the increase of VCO2/(VCO+VCO2). In this temperature segment, the reduction degree has a peak.

A New Analytical Method for Reduction Process of Iron Ore Based on the Power Spectrum

A series of direct smelting reduction experiment has been implemented with different iron ore bases by thermogravimetric analyzers. The derivative thermogravimetric data have been obtained from these experiments. The data are then decomposed by the technology of empirical mode decomposition to receive its embedded characteristics of the power spectrum. Secondly, based on the obtained power spectrum, the energy transferring behavior for reduction process of iron oxide is analyzed and is compared with other methods (i.e., analytical reagent). Finally, the desired spectral characteristics of the power spectrum for the reduction process of Huimin iron ore can be determined. The result would play a significant role in strengthening the smelting process of Huimin iron ore.

Analysis of Cylindrical Briquette Dimension on Total Iron Content and the Degree of Metallization in Direct Reduction Process of Iron Ore and Iron Sand Mixture

Indonesia has abundant resources or raw materials, especially the iron sand raw materials. But, the iron sand processing in Indonesia is still low. Even though, the steel demand in Indonesia is still high. So, the iron sand processing product as raw materials in steelmaking is the solution of it. In this research, the study was conducted by using the variation of briquette dimension of mixture of iron sand and iron ore in Direct Reduction process. The aim of this research is to study the effect of briquette dimension on Fe content and degree of metallization of the Direct Reduced Iron (DRI). First, the iron sand and iron ore were crushed and shieved until pass the 50 mesh standar size. Then, iron sand and iron ore were mixed and briquetted based on the variation of dimension. There are three variations of briquette dimension. Then, the briquettes was reduced at 1250°C for 12 hours. The reduced briquettes then were analyzed using XRD, XRF and degree metallization calculation. The result showed that the dimension of briquette affect the Fe content and the degree metallization of DRI. The dimension of briquette will affect the reductor gas flow in the crucible, so the rate and direction of reduction process of iron oxide will be affected too. The best briquette is Briquette B (7.9 cm for inside diameter, 15.1 cm for outer diameter and 19.5 cm for the height), with 75.02% for Fe total content and 66.52% for degree of metallization. This was due to The briquette B has the most evenly diffused dimension either vertically and horizontally.

Modelling of trace material flow distribution in a melter gasifier based on thermodynamic multiphase equilibrium calculations

In combination with a complex global market environment, the iron and steel industry is dealing with increasing demands for reduction of environmental and greenhouse emissions. Alternative iron making technologies such as Corex® and Finex® can offer solutions for these challenges. The melter gasifier is the central unit operation of these well-established alternative iron making processes. Both offer considerable advantages with respect to economic characteristics and environmental emissions. Similar to the conventional iron making process of the blast furnace route, a variety of different input materials is required for these processes including coal, coke, lump or fine ore, iron ore pellets as well as limestone and dolomite. Most of these raw materials also carry minor amounts of unwanted compounds such as alkali or zinc-based species. The presence of these materials inside a melter gasifier can lead to instability, problematic process conditions and refractory damages. A better understanding of the distribution of these problematic species is therefore of great importance to plant manufacturers and operators. A variety of different multiphase reactions are responsible for the distribution of trace materials within the melter gasifier. In order to get a better understanding of the complex nature of these reactions, a thermodynamic investigation was carried out using calculation routines of HSC Chemistry and FactSage. Based on the findings of this investigation, a multi-zone model was developed using the simulation platform of the gPROMS ModelBuilder®. The model is separated into distinct reaction zones across the height of the melter gasifier to depict the main iron ore reduction process as well as the governing reactions of trace material components. Validation of the model was carried out using reference data of existing plants. The model described in this work is used to analyse the behaviour of trace materials within a melter gasifier. Due to the highly integrated material flows of the Corex® and Finex® iron making processes, the impact on their operational characteristics can be investigated as well. Through this it is possible to optimise the raw material input of these processes, potentially leading to reduced fuel demand and environmental emissions.

Possibilities for CO2 emission reduction using biomass in European integrated steel plants

Iron and steel plants producing steel via the blast furnace-basic oxygen furnace (BF-BOF) route constitute among the largest single point CO2 emitters within the European Union (EU). As the iron ore reduction process in the blast furnace is fully dependent on carbon mainly supplied by coal and coke, bioenergy is the only renewable that presents a possibility for their partial substitution. Using the BeWhere model, this work optimised the mobilization and use of biomass resources within the EU in order to identify the opportunities that bioenergy can bring to the 30 operating BF-BOF plants.The results demonstrate competition for the available biomass resources within existing industries and economically unappealing prices of the bio-based fuels. A carbon dioxide price of 60 € t−1 is required to substitute 20% of the CO2 emissions from the fossil fuels use, while a price of 140 € t−1 is needed to reach the maximum potential of 42%. The possibility to use organic wastes to produce hydrochar would not enhance the maximum emission reduction potential, but it would broaden the available feedstock during the low levels of substitution.The scope for bioenergy integration is different for each plant and so consideration of its deployment should be treated individually. Therefore, the EU-ETS (Emission Trading System) may not be the best policy tool for bioenergy as an emission reduction strategy for the iron and steel industry, as it does not differentiate between the opportunities across the different steel plants and creates additional costs for the already struggling European steel industry.

Phase change of iron ore reduction process using EFB as reducing agent at 900-1200°C

Treatment of low grade iron ore involved reduction of oxygen in iron oxide by using reductant such as carbon monoxide or hydrogen gas. Presently, carboneous materials such as coke/coal are widely used as a source to provide reducing gas, but some problem arises from this material as the gas can harm the environments. Therefore, empty fruit bunch biomass from oil palm becomes an alternative to replace the usage of coke/coal as their major composition is carbon and hydrogen. The idea of replacing coke with biomass will reduce the amount of carbon dioxide release as biomass is a carbon neutral and renewable source, and at the same time abundance of waste from oil palm industries can be overcome. Therefore, the aim of this research is to upgrade the low grade iron with reducibility more than 50% being used in iron and steel making. In this research, low grade iron ore are mixed together with EFB then is making into composite pellet before being reduced at certain parameter chosen. The variables involved in this research is composition EFB (10%, 30% and 50%), temperature (1000°C, 1100°C and 1200°C) and reduction time is fixed with 30 minutes. From the experiment conducted, the highest reducibility achieved is 76.37% at temperature 1200°C. While XRD analysis shows the existence of metallic iron phase started to form at 1000°C with composition of 30% of EFB. Meanwhile, from magnetization test show that at 1200°C the highest magnetic susceptibility is achieved as the dominance phase at 1200°C is metallic phase. Therefore it is an interesting alternative to replace coke with biomass for reducing agent in upgrading low grade iron into workable ores.

Global assessment of biomass suitability for ironmaking – Opportunities for co-location of sustainable biomass, iron and steel production and supportive policies

Iron and steel production processes are amongst the biggest industrial contributors to the global carbon emissions, and national as well as international obligations are set to drive their significant emission reductions. One of the possible strategies is to partially substitute fossil fuels used during the iron ore reduction process by sustainably-sourced biomass. The extent of the opportunities for such fuel switching, however, varies for each country. Theoretically, biomass into ironmaking should be only supported for countries which present co-location of sustainably domestically sourced biomass in sufficient quantity, a substantial iron and steel industry and supportive national policies.Using a multi-criteria global suitability assessment approach developed in this research, the status of countries’ steel industry, sustainable biomass resources and supportive policies were examined for top 40 steel production countries via the blast furnace ironmaking route. The results highlight those countries with significant potential to use domestically sourced biomass for such application and advance the efficient use of the limited biomass resources from the global perspective. Specifically countries such as Canada, Sweden, China, USA and France were identified as the most suitable, but other countries present opportunities that could be overcome if the corresponding barriers are identified.

Direct reduction of iron ore/biomass composite pellets using simulated biomass-derived syngas: Experimental analysis and kinetic modelling

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 1323K within 20min. The apparent activation energies were 86.05kJ·mol−1, 97.53kJ·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.