Blast Furnace Process Research Articles

Evaluation of Some Uncertainties in the Modeling of Blast Furnace Hydrogen Injection

While blast furnaces remain the dominant ironmaking technology, there is growing interest in using hydrogen to partially replace coke and pulverized coal to reduce CO2 emissions in this hard‐to‐decarbonize process. However, significant discrepancies in modeling the tuyere injection of hydrogen are noted in the literature, which can challenge the scale‐up from modeling predictions and pilot trials to actual blast furnace operations. To address this, the impact of uncertainties in the assumptions of the temperature in the thermal reserve zone and the ratio of H2 and CO utilization on the results of blast furnace process modeling are evaluated using a 1D steady‐state zonal model. The study indicates that variations in the assumed value of thermal reserve zone temperature significantly impact the estimation of optimal hydrogen injection rate, coke replacement ratio, and direct CO2 emissions reductions. In contrast, the same parameters are much less affected by the variations in the assumed value of the proportion between H2 and CO utilization ratios, which, however, affect the top gas composition. A need for further research to determine the range of the difference in temperatures of gas and solid in the thermal reserve zone tolerable for smooth blast furnace operation is highlighted.

Studies to determine the influence of the basicity modulus on the qualitative and quantitative indicators of production technology and the material composition of the sintere

In recent years, the increase in the efficiency of the blast furnace process is largely associated with the use of sinter with improved metallurgical properties. In the blast furnace charge of PJSC NLMK, the share of sinter is 60–75% with a change in basicity from 1.3 to 1.8. Studying the material composition of agglomerates of different basicity and their characteristics allows us to adjust the technological process and determine the optimal modulus of basicity depending on specific conditions. Agglomerates with a basicity index of: 1.3; 1.4; 1.5; 1.6; 1.7 and 1.8. As a result of the research, it was established that the maximum vertical sintering speed and specific productivity of the sintering process correspond to the basicity of the sinter of 1.7. The influence of the basicity of the agglomerate on its strength is extreme, with a basicity of 1.4 the minimum strength of the agglomerate was obtained. Increasing the basicity of the agglomerate by more than 1.4 monotonically increases its strength. The nature of the change in the strength of the ag-glomerate with a change in basicity is determined by the mineral composition of the binder and is associated with a decrease in the proportion of glass in the structure of the agglomerate and an increase in the proportion of the crystalline silicate-ferrite binder. When studying the material composition, it was established that the samples of agglomerates have an identical phase composition, but differ in the phase ratio. Crystallization of calcium ferrites in contact with iron oxides contributes to the strengthening of the agglomerate, and the presence of impurities (Al, Si, Mg) in them increases the melting point. As a result of mineralogical and analytical studies, it was established that the highest metallurgical properties are found in agglomerates with a basicity modulus of 1.6–1.8.

CFD-DEM study on the raceway transport phenomena and thermo-chemical behaviors in a three-dimensional blast furnace: Effects of process parameters

An in-depth exploration of the kinetic behaviors of the raceway can provide practical insights for optimizing blast furnace (BF) operations. In this study, the transport phenomena and thermo-chemical behaviors in the raceway of a three-dimensional BF were simulated from particulate scale by using the discrete element method-computational fluid dynamics (DEM-CFD) approach. The effects of process parameters (blast velocity, oxygen concentration, blast temperature, coke size and distribution, tuyere insertion depth, and tuyere inclination) on coke combustion characteristics (mass fraction distributions of gas species and reaction kinetics rate) and thermo-chemical behaviors (particle volume fraction, raceway size, mass loss, and coke temperature) were investigated. Meanwhile, microstructures of coke bed were analyzed, and correlations were established for raceway size prediction. The results indicate that the mass fraction distributions of O2 and CO are similar, both showing balloon-like shapes. The distributions of both the CO2 mass fraction and the kinetic rates of reactions exhibit annular shapes. The raceway size increases or even overlaps with increasing blast velocity/oxygen concentration/PSD standard deviation of coke and decreasing blast temperature/coke size. Too large or too small tuyere insertion depth or tuyere inclination is not conducive to the formation of the raceway. Besides, the mass loss, temperature, and microstructures also vary with the process parameters. RSM model can well predict the raceway depth, width, and height. This study extends the particle-scale model by considering transport phenomena towards the global perspective of a real BF, and the obtained new findings on the complex reacting behaviors in the raceway will provide better insights into the optimization of the BF process.

A Self-Adaption Growth Model for the Burden Packing Process in a Bell-Less Blast Furnace

The burden structure directly decides the distribution of gas flow inside a blast furnace (BF). Falling, stacking, and descending bulk materials are the three main processes for burden formation, among which the stacking process plays a decisive role. The Discrete Element Method (DEM) and theoretical modelling were combined to predict stacking behavior in this study. Falling and stacking behaviors were first simulated based on DEM. The repose angle during the stacking process and mass fraction distribution in the radial direction were analyzed. Then, the upper, centroid, and lower trajectory falling lines were determined, and a polynomial relation was found between the angle and the packing height. The influences of three parameters on the repose angle were investigated. Compared with the natural repose angle and chute inclination angle, the effects of the trajectory line depth appeared trivial. The polynomial relation between the repose angle and the packing height was specified to be a function of the natural angle of repose and the chute inclination angle. A three-trajectory falling model and quadratic expression were embedded in the theoretical model, yielding a self-adaption packing model. The model was proved reliable with a low relative error, below 15%.

Development and study of a method for controlling anomalous behavior in the blast furnace process

Development and study of a method for controlling anomalous behavior in the blast furnace process

Investigation on desulfurization and ground granulated blast furnace slags reutilization for carbon dioxide sorption in a fluidized bed reactor

BackgroundThe atmospheric CO2 concentration is significantly increasing due to the utilization of fossil fuel in various activities. Implementation of steel slag is considered as a promising strategy for carbon capture MethodsIn this study, the slags from desulfurization (De-S) and ground granulated blast furnace (GGBS) processes in the steel company waste were applied as the sorbent in CO2 removal using a fluidized bed system. Various operating conditions were applied to determine the influence of operating parameters on sorbent performance. Moreover, examination on sorbent characteristic change and kinetics calculation were also carried out in this study. Significant findingOptimum operating temperature was reached by the application of 600 and 500 °C for De-S and GGBS slag, respectively. The higher CO2 concentration and 5 % water vapor improved the sorbent utilization. However, excessive water vapor and low fluidized velocity decreased the performance of sorbent. De-S slag performed better on overall CO2 capture process compared to GGBS slag. Therefore, upscaled study with 10 times greater size was further conducted with the 150–300 µm De-S slag for the CO2 capture from oxy-fuel and air combustion. The higher CO2 partial pressure in the flue gas of oxy-fuel combustion increased the capture process efficiency.

Blast Furnace Slag Formation Prediction Model Using Classical Thermodynamics

Blast furnace (BF) ironmaking is the most widely used technology for hot metal production. In steelmaking industry, 80% of the steel in the world is produced in the BF‐basic oxygen furnace route. It is well known that poor quality of the raw material i.e., high gangue content in the iron ore affects the BF process performance and the cohesive zone formation, which is the most critical zone in the BF operations. Increased gangue content in the iron ore causes variation in the slag formation and slag volume thus affecting the fuel rate and BF performance. Therefore, in this study, the slag formation is studied to understand the slag properties at different locations inside the BF. The model is based on classical thermodynamics and is implemented using ChemApp linked with FactSage databases. The model aids in understanding the slag formation in the BF for various burden chemistry, fuel, and flux inputs. The final hot metal and slag composition along with the exit gas volume and composition predicted from this model are compared with industrial BF plant data operating across different conditions.

Influence of reduction parameters on, weight loss, crack propagation, iron whisker growth, and morphological characteristics of directly reduced iron produced by non-contact direct reduction process

Non-contact direct reduction (NDR) is an alternative technique in iron and steelmaking. Direct reduced iron production (DRI) uses it. To further harness the metallurgical and operational capabilities of the process for its suitability as an alternative feed in the blast furnace process, there is a need to study the effect of the reduction parameters on the weight loss, crack propagation level, gas porosity, iron whisker growth, and morphological characteristics of the DRI. Thus, this paper attempts to utilize the NDR process using commercially acquired goethite-hematite ore in a carbon-monoxide atmosphere from wood charcoal under specified isothermal conditions, with a reduction temperature range from 570, 800, and 1000 °C. The effect of reduction parameters on weight loss, crack propagation, iron whisker growth, and morphological properties of the DRI was investigated using standardized reduction reaction practices under a nitrogen gas atmosphere with a flow rate of 120 mL. Mineralogical and morphological analyses of the direct reduced iron (DRI) and charcoal were performed using XRF and SEM/ED analysis. Proximate and ultimate analyses of the reductant were performed to ascertain their physical and chemical properties. The results show that reduction parameters tremendously influence the weight loss, crack propagation, gas porosity level, and metallurgical quality of the DRI. The reduction degree and swelling extent of the DRI also increase with crack propagation and iron whisker growth. Thus, the overall reduction mechanism still follows the usual stepwise chronological reduction order (Fe2O3 → Fe3O4 → FeO → Fe) regardless of temperature, with ash layer control being the reaction rate control. The NDR technique shows no carbon deposition in the DRI metal matrix. It indicates that this approach can serve as a viable alternative for DRI production in the ironmaking process.

Effect of Basicity and MgO/Al2O3 Ratio on Viscosity and Crystallization Behavior of HIsmelt Titanium‐Containing Slag

Numerous challenges persist in the smelting of vanadium–titanium magnetite using the blast furnace process. These challenges can be overcome by adopting the HIsmelt process, without the need for additional ore or enhanced slag operations. In this study, the effects of basicity and the MgO/Al2O3 ratio on slag viscosity and crystallization behavior are investigated through thermodynamic calculations and experiments. In the results, a decrease in slag viscosity with an increase in basicity and MgO/Al2O3 ratio is demonstrated. Notably, MgO/Al2O3 ratios have a minor impact on the viscosity and break temperature of the slag. With a TiO2 content of 40 wt% in the slag, perovskite phases are identified as the main equilibrium solid precipitates during the crystallization process under various basicity and MgO/Al2O3 ratios. As the slag temperature decreases further, the liquid phase content in the slag progressively decreases, reaching complete crystallization at 1159.0 °C. For industrial production, it is advisable to maintain the binary basicity of the slag within the range of 1.0–1.1, with the MgO/Al2O3 ratio around 0.6. Herein, the research findings contribute to a deeper understanding of the viscosity and crystallization behavior of HIsmelt titanium‐containing slag.

Alternative Reductants for the Blast Furnace Process and Catalytic Treatments of Exhaust Gases: a Review

Blast Furnace (BF) process is dominant in the iromaking industry in the World. Growing demand for steelmaking raw materials results in fast consumption of fossil fuels, which are required for the BF operation and also serve as reducing agents. To lower the carbon footprint and achieve sustainable development, as well as circular economy, there is an increased need for using alternative reducing agents for BFs, such as waste plastics, bio-based materials etc. Those materials can be recycled or upcycled by utilization in BF process. Catalytic recycling/upcycling of exhaust gases was proposed, as it could be highly profitable, and, as well lower the carbon footprint of the BF process.

Development of Mass–Energy Balance Model Based on a New Process of RSF with Hy-O-CR

At present, blast furnace (BF) ironmaking is still the main process for producing hot metal in China and around the world. Under the constraint of the global goal of “double carbon”, it is urgent to carry out hydrogen metallurgical innovation for the existing BF ironmaking process with higher carbon emissions. In recent years, BF technology with hydrogen enrichment and pure oxygen has made some progress, effectively reducing carbon emissions of hot metal per tons, but it is still unable to break through the technical bottleneck of emission reduction of more than 30%. In view of this, the authors put forward an ironmaking technology of a reduction smelting furnace (RSF) that is hydrogen-rich and utilizes pure oxygen and carbon recycle (Hy-O-CR), which breaks through the technical defect of traditional BF emission reduction of less than 30% by reshaping the furnace. Firstly, the construction process of the mass and energy balance model for two main unit modules in the new process (RSF with Hy-O-CR and top gas cycle) is introduced, and then the parameter optimization under specific scenario conditions is analyzed, and the influence mechanism of several key variables on the parameters in the furnace is obtained. Finally, the emission of CO2 in the whole process is explored in the case of two typical operating parameters. The results show that after using CCUS technology, the minimum value of direct CO2 emission is 215.93 kg/tHM, which is as high as 84.58% compared with the traditional BF process. Even if the removed CO2 is counted in carbon emissions, the minimum value of direct or indirect carbon emissions is 729.85 kg/tHM, and the proportion of emission reduction can reach 47.87%. The research results show that the reconstruction of Hy-O-CR technology can change the ratio of direct reduction and indirect reduction, which greatly breaks through the emission limit of the traditional BF and provides a new reference for hydrogen metallurgy technology and a basis for further study of the optimization of RSF size.

CO2 emission evaluation and cost analysis of oxygen blast furnace process with sintering flue gas injection

CO2 emission evaluation and cost analysis of oxygen blast furnace process with sintering flue gas injection

Solid Flow in an Experimental Oxygen Blast Furnace Model: Effects of Recycled Gas and Raceway

The oxygen blast furnace (OBF) process with top gas recycling is recognized as a promising ironmaking process, due to its high productivity and low CO2 emissions. The solid flow plays a crucial role in this process. Therefore, the solid flow in OBF was investigated using a cold experimental OBF model in this paper. The results indicate that the plug flow is the primary solid flow pattern in the upper and middle zones of the OBF. A slight convergence flow and a smaller deadman zone were observed at the bosh. The influence of recycled gas on solid flow was found to be quite limited. Additionally, the raceway size affects the burden structure and deadman zone, but the production rate had little impact. Both the raceway size and production rate have different effects on the repose angle of the deadman zone, and it varies by 14–18°. The findings of this study may have important implications for understanding the structure of solid flow in OBF. The results can be used to optimize the process parameters and equipment design to improve the efficiency of iron production while reducing environmental impact.

Dynamic analysis of liquid permeability in the dripping zone of blast furnace and reaction behavior at the slag-coke interface

The dripping zone connects the cohesive zone and the hearth, it is one of the key areas of the blast furnace (BF). This study aims to explore the mechanism of the dripping process in BF. The dripping experiments under different conditions were carried out. Dynamics of liquid permeability in the dripping zone was analyzed, the reaction behavior at the slag-coke interface was investigated, and the consumption of coke in the dripping zone was clarified. The results show that: The retention ratio increases with the increase of Al2O3 content. The increase in retention ratio is related to the viscosity of slag. Once the Al2O3 content in slag increases, Si4+ coordination polymer ions in tetrahedra will be replaced by Al3+ cations, forming a tetrahedral structure of [AlO4]5– tetrahedron. The retention ratio decreases with the increase of FeO content. The dissociation of free oxygen ions (O)2– from FeO increases the concentration of free oxygen ions (O)2– in slag, this reduces the viscosity of slag. The presence of FeO can compensate for the increase in retention ratio caused by Al2O3. The quantitative relationship between retention ratio and Al2O3 content and FeO content in slag is obtained. The reduction reaction of FeO occurs at the slag-coke interface, the molten iron takes on the shape of small iron beads, which is the result of multiple small droplets gathering. The reduction of TiO2 is carried out by a series of reactions, the Ti exhibits a granular embedding state in molten iron, its color is darker than that of molten iron and its particles have distinct edges and corners. In the slag-coke area of retained sample, the reduction reaction occurs between coke and oxides in slag. The carbon will be consumed, resulting in a decrease in particle size. In the iron-coke area of retained sample, the carburization reaction occurs in large quantities due to the carbon content of molten iron in hearth is undersaturated, coke is further consumed.

Поєднання енерго-ресурсозберігаючих та екологічно безпечних технологій в проєктах ДП «ГИПРОКОКС»

DOI: 10.31081/1681-309X-2024-0-1-21-26 Specialty 161. U.D.C. 621.311 COMBINATION OF ENERGY-SAVING, RESOURCE-SAVING AND ENVIRONMENTALLY FRIENDLY TECHNOLOGIES IN THE PROJECTS OF THE SE "GIPROKOKS" © T.F. Trembach, M.V. Mezentseva, I.O. Radychuk (STATE ENTERPRISE "STATE INSTITUTE FOR DESIGNING ENTERPRISES OF COKE OVEN AND BY-PRODUCT PLANTS'' (SE "GIPROKOKS''), 61002, 60 Sumska str., Kharkiv, Ukraine) The article deals with the issues of energy efficiency and implementation of environmental technologies in coke production, which is one of the most energy-intensive and environmentally hazardous, but at the same time has a great potential of fuel and energy resources. The experience and achievements of SE GIPROKOKS in the use of modern technologies aimed at reducing energy and resource consumption, as well as ensuring environmental safety, are reflected. Particular attention is paid to innovative approaches to the development, design and implementation of environmentally friendly technologies in production, which help reduce emissions and negative impact on the environment. The article analyses the application of organisational, technical, design, technological and other energy saving measures in the projects of SE “GIPROKOKS” for metallurgical and coke-chemical enterprises. The most effective of these are technological: improving the quality of coke, what, when used in the blast furnace process, leads to a reduction in energy consumption; using less energy-intensive technologies and secondary energy resources. These technologies primarily include the coal charge stumping technology. Flue gas heat from the coke oven battery heating system has a significant energy potential that is released into the atmosphere, leading to irreversible heat losses and causing a negative impact on the environment. The use of a heat recovery unit with thermal flue gas treatment will significantly reduce emissions of harmful components in flue gases into the atmosphere. In its projects, SE “GIPROKOKS” pays considerable attention to the use of secondary resources generated in coke production processes, which is a vivid example of combining energy-saving, resource-saving and environmentally friendly technologies. Keywords: coke production, secondary products, utilisation, energy saving, resource saving, environmental safety, technological measures. Corresponding author: T.F. Trembach, e-mail: ozos@giprokoks.com

Evaluation, Prediction, and Feedback of Blast Furnace Hearth Activity Based on Data‐Driven Analysis and Process Metallurgy

For complex, difficult‐to‐control, and hour‐delay blast furnace (BF) systems, the quantitative characterization, prediction, and adjustment of the BF hearth activity are significant in improving the furnace status. In this study, data including raw fuel, process operation, smelting state, and slag and iron discharge during the entire BF process are analyzed, with a total of 171 variables and 5033 groups of data. Based on the knowledge of BF technology, a comprehensive index of hearth activity is then proposed to quantitatively characterize and grade the activity level of the BF hearth; the rationality of this method is verified from the two aspects of furnace heat level and furnace status coincidence. Compared with the traditional single‐machine learning algorithm, the performance of the proposed method that combines genetic algorithm and stacking exhibits significant improvement. The hit rates for 10% and 5% errors in the prediction and estimation of hearth activity are 94.64% and 80.36%, respectively. To enhance the BF hearth activity, quantized and dynamic actions and suggestions are also simultaneously pushed. The model of BF hearth activity is successfully applied in practical online production. During the application period, the average furnace hearth activity increases by 10% compared to the historical value.

Influence of the material composition of the original ore on the quality of the iron ore concentrate.

In recent years, improvement of blast-furnace process efficiency is largely associated with an increase in the iron content in iron ore concentrates – the feedstock for agglomeration. The study of the material composition of ores, their features makes it possible to adjust the scheme of preparation of raw materials and determine the optimal content of iron in the concentrate for further processing. When studying the material composition, it was found that the sample of iron ore is represented by ferruginous quartzites of the silicate-magnetite type in combination with magnetite. In the original ore sample, magnetite dominates among ore minerals, and quartz and amphiboles dominate among rock-forming minerals. The coarseness and shape of the isolation of magnetite in all varieties of rocks are generally favorable for enrichment; the mineral is characterized by clear rectilinear and slightly sinuous contours, which contributes to its selective isolation. It should be noted that the magnetite content remains constant as the coarseness of the sample material decreases. Automated mineralogical analysis established that 87.36% of iron is associated with magnetite (with fluctuations in size classes from 86.23 to 91.37%); the rest of the iron is associated with rock-forming minerals. The theoretical content of magnetite in iron ore concentrate, achievable by enriching the original ore of the studied sample, according to automated mineralogical analysis, will be 95.83%, which, in turn, will provide the maximum possible iron content in magnetite concentrate of 68.57%. The existing technology of mining and enrich-ment using 4 types of ores from the Stoilenskoye deposit, with a planned increase in iron to 70%, will result to fluctua-tions of this component in the concentrate from 68.0 to 70.0%.

Numerical Investigation of the Inner Profiles in Ironmaking Blast Furnace: Effect of the Ratio of Belly Diameter to Effective Height

The elaborate and appropriate design of blast furnace (BF) inner profile is indispensable. In practice, in this work, dumpiness, quantified by the ratio of belly diameter to effective height (RD–H), primarily determines the inner profile and significantly affects the BF performance. However, the effects of RD–H on BF operation are not investigated thoroughly, and an optimal range of RD–H is not yet proposed. In this work, a numerical study on this topic is presented to recommend an RD–H range for BF designers. This is achieved by using a recently developed 3D multi‐fluid BF process model based on a 380 m3 industrial BF. In the results, it is shown that both too slender and too dumpy BFs do not favor BF production. Excessively slender BF leads to a dramatic increase in gas pressure drop; however, the saving of coke or the improvement of productivity is insignificant. In contrast, excessively dumpy BF leads to a dramatic increase in coke rate and a significant decrease in productivity. Under the current conditions, the recommended dumpiness exists in the value of RD–H at around 0.35, where a low coke rate, low gas pressure drop, high productivity, and high thermal energy utilization are all ensured.

Analysis of the possibility of replacing carbon with hydrogen in the conditions of smelting cast iron from vanadium-containing titanomagnetites

75 % of the total carbon dioxide emissions by ferrous metallurgy enterprises is generated in the blast furnace process. One of the directions of CO2 emission reduction in pig iron production is partial replacement of carbon monoxide with hydrogen as a reducing agent. It is shown that such a replacement can lead to a decrease in the total carbon consumption due to reduction of heat consumption for the direct reduction of iron oxides. Using a mathematical model of the blast furnace process, the efficiency of partial replacement of process fuel (coke, natural gas, pulverized coal) with a hydrogen additive was evaluated. Calculations were performed for the operating conditions of blast furnaces of EVRAZ NTMK JSC, which melt vanadium-containing titanomagnetites. The coefficients of process fuel replacement with hydrogen and the coefficients of the influence of the replacement of process fuel with hydrogen on the change in CO2 emissions are calculated. The dependence of the change in the productivity of the furnace on the consumption of hydrogen at a constant minute flow rate of the blast and its adjustment to maintain the pressure drop has been established. It is shown that in the absence of gas dynamics reserves, the replacement of process fuel with hydrogen will be accompanied by a decrease in furnace productivity. The smelting of pig iron from titanomagnetites with the replacement of technological fuel with hydrogen will complicate the refining of melting products due to an increase in the formation of titanium carbides and carbonitrides. The reduction in CO2 formation at hydrogen entering the blast furnace with natural gas is 0.35 kg/m3 compared to pure hydrogen replacement of 0.73 kg/m3, not taking into account CO2 emission during hydrogen production

Improved operation of a large-scale blast furnace using a hybrid dynamic model based optimizing control scheme

In the steel industry, the blast furnace (BF) is a core piece of equipment along the route from iron ore to steel, with the largest energy consumption and CO2 emissions. The stable, efficient, and economically viable thermal control of blast furnaces is still a challenging task, and fully automatic solutions are not applied industrially. The process exhibits multi-phase and multi-scale physio-chemical phenomena, in the presence of fast and very slow dynamics with latency periods of 6-8 h. Direct online measurements of key inner variables are missing, and unknown disturbances are strongly influencing the process; in particular, the quality of solid raw materials that are fed at the top of the furnace. Partial automation is the state-of-the-art strategy in the operation and control of industrial blast furnaces, and the experience and the dedication of the operators have a direct impact on the stability and efficiency of the operation. Model-based optimizing control schemes, which can be deployed either in closed-loop or as a guidance system to achieve a smooth, efficient, and reliable operation of blast furnaces, are promising. In this work, we propose a hybrid dynamic model based optimizing control scheme for the stable, energetically efficient, and economically optimal thermal control of blast furnaces. The underlying optimization problem is formulated as a combined tracking and performance optimizing control problem, where the goal is the tight control of the hot metal silicon content ([Si]) and the slag basicity (SB), while simultaneously maximizing the CO-efficiency of the furnace. These two variables are key product quality indices, and [Si] is an indicator of the internal thermal state of the BF process. Simulation results using real operational data of a large-scale industrial blast furnace are presented to demonstrate the potential of the approach for an improved operation of blast furnaces.