Blast Furnace Performance Research Articles

Effects of pellet-sinter interaction parameters on component segregation and bed porosity considering flow velocity and mixture composition: A DEM study

Bed permeability is a crucial factor in blast furnace performance which depends on the material distribution achieved through charging. Since a homogeneous bed of pellet and sinter is recommended, it is crucial to understand whether segregation of the pellet-sinter mixture occurs during charging. The Discrete Element Method is useful in this regard; however, simulations of pellet-sinter mixture charging currently lack credibility since pellet-sinter interaction parameters have not yet been calibrated and validated. Determining pellet-sinter interaction parameters will require significant efforts, so it is useful to know whether mixture segregation and the resulting bed permeability are sensitive to these parameters. In this work, we investigate to what extent the restitution coefficient, sliding friction coefficient and rolling friction coefficient between pellet and sinter affect segregation during bed formation and the resulting permeability in terms of porosity using a simplified charging setup. The investigation is done for different mixture compositions and flow velocities, and analysis settings including sample size and sampling directions. We conclude that all parameters affect segregation and porosity, regardless of the composition and velocity. Hence, all mixture parameters including the interaction parameters between the components must be carefully calibrated when developing a model for predicting permeability.

ОСОБЕННОСТИ РАБОТЫ ДОМЕННОЙ ПЕЧИ НА АГЛОМЕРАТЕ РАЗНОЙ ОСНОВНОСТИ

The paper shows the peculiarities of blast furnace performance when different types of iron ore material are used. It is noted that the main types of iron ore raw materials are sinter and pellets, their advantages and disadvantages are given. The influence of increased pellet consumption on blast furnace smelting is indicated. The influence of sinter basicity on its strength and recoverability is noted. The results of calculating the indicators and the operation mode of the blast furnace at increased sinter basicity and an increased ratio between its consumption and pellets are presented.

Impact of chute cross-sectional shape on the ironmaking blast furnace performance: A numerical investigation

Rotating chutes play a critical role in determining burden distribution on the throat of blast furnaces, thereby influencing the overall ironmaking process. This study aims to explore the influence of chute cross-sectional shape at an industrial scale using a numerical approach. The simulation results demonstrate that the semicircular chute results a lower ore/coke ratio in the central area compared to the trapezoidal chute, while exhibiting a higher ratio at the periphery. Correspondingly, this leads to a lower productivity, higher coke rate, and increased pressure drop within the furnace. These effects can be attributed to the more coke is loaded in central region which has an elevated cohesive zone. Furthermore, with the chute angle for ore increasing, the blast furnace performance with the trapezoidal chute exhibits greater stability compared to that with the semicircular chute. This investigation provides valuable insights for selecting appropriate chute designs to enhance performance and efficiency.

Combustion characteristics of charcoal, semicoke, and pulverized coal in blast furnace and their impacts on reactor performance

Injecting new fuels like charcoal and semicoke into ironmaking blast furnaces (BF) helps reduce pulverized coal and coke consumption, leading to significant environmental and economic benefits. This paper comprehensively assesses the performance of blast furnace with the injection of charcoal, semicoke, or pulverized coal. For this purpose, a recently integrated BF model that simulates the whole BF below the burden surface in terms of the gas-solid-liquid-powder multiphase reacting flows is extended to simulate the application of charcoal and semicoke injection. The combustion characteristics of charcoal, semicoke, and pulverized coal in raceways are first revealed. Then, the effects of the combustion on the in-furnace states and overall BF performances are compared in detail. The results show that the overall BF performance in terms of gas flame temperature, coke rate, and hot metal temperature is susceptible to specific components in the injected fuels, including moisture content and fixed carbon ratio. A lower moisture and a higher fixed carbon ratio result in a higher gas flame temperature and fuel-coal replacement ratio and thus a lower coke rate. Overall, the charcoal and semicoke injection is feasible, however, subject to approximate pre-treatment. This integrated BF model can offer a cost-effective way to explore the injection of new fuels of various types to reduce carbon dioxide emissions.

Investigating effect of coke porosity on blast furnace performance based on multi-physical fields

Investigating effect of coke porosity on blast furnace performance based on multi-physical fields

Influence of iron ore concentrate quality on metallurgical properties of pellet

One of the important factors for improving the technical and economic performance of blast furnaces is the iron content in the iron ore part of the charge. At the same time, there is evidence that when using iron ore concentrate with an iron content of more than 66‒67% for the production of pellets, their strength decreases, and adjustments to the heating modes are required. In recent years, Russian mining enterprises have been implementing technological measures to increase the mass fraction of iron in the concentrate to 68‒70%. The results of a study of the influence of concentrate quality indicators (mass fraction of iron, specific surface value) on the pelletizing technology and metallur-gical properties of pellets are presented. Concentrates with a mass fraction of iron of 66.6, 68.0, 69.2% and a specific surface of 1576, 1999, 2015 cm2/g, respectively, were used as an object of study. It was found that increasing the iron content and specific surface area in the concentrate leads to an improvement in the raw pelletizing technology ‒ plasticity and the proportion of pellets with a size of 5‒16 mm increase. Roasting of laboratory pellets in baskets on a roasting machine showed a multidirectional change in the metallurgical properties of the pellets. The compressive strength index decreased, the hot strength changed little, the softening-melting temperature range (SMTR) decreased from 308 to 200‒290 °C. Mineralogical studies have established that the decrease in these indicators (strength and SMTR) was influenced by a decrease in the amount of silicate binder and the uneven distribution.

Development of Alternative Reductant using Biomass for Reducing CO<sub>2</sub> in Ironmaking Process

Technologies to reduce CO<sub>2</sub> emissions in the steel industry have been actively developed since the early 1990s in order to deal with global climate change. In particular, the utilization of various types of biomass including wood, bamboo, grass, food and agricultural by-product are being attempted as carbon neutral fuels in the blast furnace process. In this study, an alternative reducing agent for coke and pulverized coal using biomass was developed and the effect on blast furnace performance and CO<sub>2</sub> reduction was evaluated. The first investigation was whether a burden material made of torrefied biomass mixed with iron ore and coal (Iron-bearing Biomass Coke, IBC) could be used as a substitute for coke in the form of a carbonized briquette. In addition, a method of mixing torrefied biomass with pulverized coal (Bio-PC) to inject through tuyere in a blast furnace was examined. As a result, when coke was replaced with 10% of IBC, the reducibility of the sintered ore was improved in association with an increased CO gas utilization ratio, hence CO<sub>2</sub> emissions decreased by 2.3%. Furthermore, the combustion efficiency of Bio-PC mixed with 10% of torrefied biomass was improved by 13.2%, thus, the amount of CO<sub>2</sub> emissions was calculated to decrease by 4%. These results suggest that the possibility of using IBC and Bio-PC in blast furnaces, as they could effectively reduce CO<sub>2</sub> emissions in the ironmaking process.

Coke dry quenching and implications on coke quality and blast furnace performance

ABSTRACT The advent of coke dry quenching (CDQ) in coke-making benefited coke plants not only in reducing coke moisture but also in extracting a part of the sensible energy within the hot incandescent coke with a reduction in environmental pollution. In addition to these direct benefits, other advantages include (1) improved coke quality, (2) enablement of higher coke production without compromising quality, (3) online coal-cake bulk density measurement, and (4) improved blast furnace performance. The present study at Tata Steel, Jamshedpur, concentrates on the assessment of these additional benefits when CDQ units were operated at full capacity. Besides, the article also focuses on reviewing the major obstacles faced during CDQ operation, such as clinker formation and coke flotation issues.

Effects of shaft angle on the performance of an ironmaking blast furnace: A CFD study

An ironmaking blast furnace (BF) is a key chemical reactor for producing hot metal from iron oxides ore rapidly while the shaft profile significantly affects the flow-thermal-chemical behaviors inside a BF; however, the design is largely based on empirical correlations. In this article, a recent multi-fluid blast furnace model is adopted to quantitatively study the influence of shaft angle on the performance of a BF, in terms of in-furnace phenomena of flow-, thermal-, and chemical-behaviors as well as the overall performance indices. The results show that, the relatively small shaft angle is beneficial for the development of central gas flow while largely increasing the possibility of the formation of mixed region near periphery area. Meanwhile, the gas residence time increases with the increased shaft angle but in a quite limited range. In addition, the overall furnace performance indices including top gas utilization and coke rate can be affected with the changed shaft angle. Finally, the reasons behind the selection/design and evolvement of shaft angle with the increased furnace inner volume are explored, and the corresponding strategies to ensure the smooth operation are discussed. This model provides a useful tool for shaft angle design of ironmaking BFs.

Development of the Model for Estimating Coke Fine Ratio in Blast Furnace

Improving operation performance of blast furnaces is necessary to reduce CO2 emissions and pig iron costs. One of the important factors for the operation is keeping gas permeability well in the blast furnace. Coke fines affect gas permeability and the operation condition become worse, therefore clarification and prediction of the generation behavior of coke fines in blast furnaces are desired.

High Temperature Softening and Melting Interactions Between Newman Blend Lump and Sinter

In this work, the softening and melting (S&M) behaviour and whole blast furnace (BF) performance of Newman Blend Lump (NBLL), plant sinter, and sinter-NBLL mixture were studied using S&M under load test and numerical BF modelling. Both physical and chemical interactions between sinter and lump were confirmed in the S&M process. Significant improvements were found in the S&M behaviour of the sinter-NBLL mixture because of the physical and chemical interaction. The physical interaction was examined using X-ray/Neutron Computed Tomography (CT) scanning on the samples from interrupted S&M under load tests. The void fraction in the ferrous layer of the sinter-NBLL mixture was found to be similar to the sinter and was higher than that for NBLL. The chemical interaction was investigated by analysing the Ca transfer from sinter to NBLL, which indicated that Ca transfer started around 1200°C in the S&M process. FactSage was used to assist in the interpretation of the S&M test results. It was found that the NBLL sample starts to melt at a lower temperature compared to other burdens used in the present study, which also agreed well with the CT scan results. The whole BF performance of different ferrous burdens was studied using the experimental results as inputs. The sinter-NBLL mixture behaved more like the sinter than the NBLL; compared with the sinter only burden with the same total basicity, the sinter-NBLL combination formed a more permeable CZ, had a lower total BF pressure drop, and a higher gas utilization rate.

Understanding of Blast Furnace Performance with Biomass Introduction

The blast furnace still dominates the production and supply of metallic units for steelmaking. Coke and coal used in the blast furnace contribute substantially to CO2 emissions from the steel sector. Therefore, blast furnace operators are making great efforts to lower the fossil CO2 emissions and transition to fossil-free steelmaking. In previous studies the use of pre-treated biomass has been indicated to have great potential to significantly lower fossil CO2 emissions. Even negative CO2 emission can be achieved if biomass is used together with carbon capture and storage. Blast furnace conditions will change at substantial inputs of biomass but can be defined through model calculations when using a model calibrated with actual operational data to define the key blast furnace performance parameters. To understand the effect, the modelling results for different biomass cases are evaluated in detail and the overall performance is visualised in Rist- and carbon direct reduction rate (CDRR) diagrams. In this study injection of torrefied biomass or charcoal, top charging of charcoal as well as the use of a combination of both methods are evaluated in model calculations. It was found that significant impact on the blast furnace conditions by the injection of 142 kg/tHM of torrefied biomass could be counteracted by also top-charging 30 kg/tHM of charcoal. With combined use of the latter methods, CO2-emissions can be potentially reduced by up to 34% with moderate change in blast furnace conditions and limited investments.

Towards a better understanding of the mechanical behavior of a fixed bed of eucalyptus charcoal in a blast furnace using a specific compression test

The properties of wood charcoal layers have an effect on the performance of small-scale blast furnaces. In order to characterize the mechanical behavior of a fixed bed of eucalyptus charcoal, a specific uniaxial compression test was designed and used with charcoal layers of different characteristics. This layer test has the potential to be standardized, and it made it possible to consider the bulk properties of randomly layout charcoal pieces, which was better adapted than single specimen tests in the fiber direction. A total of eight charcoal layers were prepared with two carbonization temperatures (500 °C and 900 °C), two granularities (10 mm and 20 mm), and two different testing temperatures (20 °C and 300 °C). Characteristic parameters of the compression tests were then determined as the particle size distribution, the mechanical energy, and the mean power. The charcoal produced at 900 °C and with a granularity of 20 mm was more resistant to breakage than the others were, and a high quantity of large particles remained after the tests. Significant correlations existed between the carbonization temperature, granularity, and mechanical power of the compression test. The mechanical power was the main parameter that determined the resistance to breakage of a charcoal bed in compression.

Numerical Study of the Influence of Burden Batch Weight on Blast Furnace Performance

Burden batch weight is a critical operating parameter in the blast furnace (BF) system. It directly affects solid distribution such as coke-layer and ore-layer thickness and thus gas permeability and thermal–chemical conditions inside a BF. However, in the open literature, few quantitative studies have been reported on the influence of burden batch weight on BF performance, such as cohesive zone (CZ) shape and location, reducing gas evolution, and iron oxide reduction behaviors. In this study, a multi-fluid BF model is used to investigate the BF performance with different burden batch weights systematically. This model features the layered burden structure with respective chemical reactions in respective coke and ore layers and a burden batch weight sub-model. The results show that, under the given simulation conditions, with the increased burden batch weight from 112 to 140 tons, the average gas velocity in central regions is significantly suppressed by ~ 1 m/s; the average gas and solid temperatures are decreased by ~ 160 K and the position of CZ decreased by ~ 7 m near the BF center; moreover, the gas utilization efficiency is improved by ~ 2.5 pct; the reduction load of the BF becomes heavier, particularly by ~ 0.05 near the BF center; the fuel rate is decreased by ~ 2.5 kg/thm, meaning a higher furnace efficiency. This study provides theoretical support for batch weight selection and optimization in BF ironmaking practice.

Numerical Simulation of a Coke Oven Using Decoupling Techniques

Cokemaking is an important unit operation in an integrated steel plant as coke quality has a strong influence on blast furnace performance. A two-dimensional (2D) model coupling physico-chemical phenomena inside combustion and coking chambers of a coke oven has been presented. It was implemented using the computational fluid dynamics software Ansys Fluent and was solved by a serial decoupling approach to improve convergence and to reduce computational time. The model predictions for gas temperatures inside the combustion chamber and the effect of coal moisture content on evolution of coke bed temperatures are in reasonable agreement with published experimental data. The computational time required for the 2D model is six times lower than that for a corresponding three-dimensional model. This model is useful for model-based optimization of cokemaking and for designing coke ovens with reduced computational burden.

Зарубіжний досвід утворення та використання доменних шлаків

We should regard an issue of efficient use of feedstock and, in particular, a transition to waste-free technology from the perspective of adjusting differences between economic growth (more resources in production required) and “productive capacity” of the environment (depletion of mineral resources, lowering of resources quality, disruption of environment balance). It is possible to adjust these differences not only by using resources rationally and comprehensively but also by processing generated industrial waste. In the Ukrainian metallurgical industry, these issues are very important because of the abundant practice of use of out-of-date resource and energy-intensive technologies and feedstock of poor quality. International experience shows that the metallurgical industry has rich potential in reducing generated waste. On average specific solid waste generation for a unit of product in the metallurgical industry in developed countries is 1.5-3 times lower than in Ukraine. One of the important processes of blast-furnace performance is the generation of slag; slag is one of the most valuable secondary materials. Recently international metallurgical enterprises started implementing a hundred percent recycling of use industrial waste. Moreover, for the past decade there were a lot of efforts made to process slag so to meet strict EU environmental requirements, hence we can regard it not as waste but as an industrial by-product. We use slag mainly in the road sector – for road construction, agriculture ‒ for liming of soils, metal industry – as an iron-containing substance for secondary melting in blast furnaces. The cement industry is the main consumer of blast furnace slag. EU regulations allow up to 35% of granulated blast furnace slag in Portland cement and up to 80% in Portland blast-furnace cement. The addition of blast furnace slag into the mixture increases the performance of blast furnaces and reduces fuel consumption by 15% and prime cost by 25-30 %. Apart from that the slag as an additive considerably improves several construction and technical peculiarities of cement. International experience and expert assessments say that Ukraine has not only huge potential in reducing blast furnace slag generation but also a need for its comprehensive processing with up-to-date technologies and state-of-the-art equipment that can bring an economic and environmental advantage.

Influence of the prime hard coking coal in stamp charge cokemaking: true or false

The production of hot metal through the blast furnace route is stilled the most cost-effective and highly productive process and probably remains the coming decades besides developed many alternative ironmaking technologies. In the recent past, the working volume of the blast furnace has been increased drastically to increase the blast furnace productivity. This means the blast furnace performance is more correlated to specific productivity which measures the efficiency in terms of ton hot metal. These modern blast furnaces favour high quality of coke, i.e. high coke CSR and M40 value, high iron content sinter and pellets. These high quality of input raw materials increased blast furnace efficiency and productivity. Generally, cokemakers increases the ratio of prime hard coking coal in the coal blend to achieve the high quality of coke. This increase in prime hard coking coal is not desirable for coke oven batteries because it creates high oven wall pressure and high coke cost and also not suitable for raw material security. The present investigation highlights few cases which clearly show that the high quality of coke (coke CSR: 69–71) may be easily produced with the optimal proportion of prime hard coking coal in the blend if the selection of coals is proper. Results confirmed that upto 30% primary hard coking coal with 15% non-coking coal in the coal blend produce an excellent quality of coke which naturally requires a careful selection on the blend component. The optimum composite coking potential (CCP) value of 4.6–4.9 is the ideal value for producing coke CSR in the range of 69–71 in recovery stamp charge cokemaking process in the real-time plant operation. Therefore, it is necessary to select the right coals for the coal blend based on the adopted cokemaking technologies to conserve the reserve of prime hard coking coal, oven health and cost-effectiveness.

Model study of central coke charging on ironmaking blast furnace performance: Effects of charing pattern and nut coke

Ironmaking blast furnace (BF) is a slow-moving bed chemical reactor and is facing many challenges such as low-grade raw materials. Central coke charging (CCC) can accommodate low-grade materials including low-grade iron ore, low-grade coal and nut coke (a low-grade coke) and meanwhile helping stabilize BF operations, but it lacks systematic and quantitative studies. In this work, a multi-fluid BF model, which considers flow-thermal-chemical behaviors of gas, solid and liquid phase is further developed, featuring a CCC burden profile sub-model and an ore-nut coke mixture sub-model. It is used to study the influences of CCC patterns including CCC opening radius and nut coke rate (NCR) on BF performance and identify the optimal CCC operational conditions. The results show that, when CCC opening radius increases from 1/64 to 1/4, carbon solution-loss reaction is further suppressed while top gas temperature and coke rate encounter an increase by ~200 K and ~43 kg/ton hot metal (kg/tHM), respectively. On the other hand, when NCR increases, BF performance varies non-linearly; the highest BF performance indices are attained at the NCR of 20 kg/tHM, namely the optimal NCR. This model provides a cost-effective way to systematically study and design CCC operation in BF practice.

Analysis of the Effect of Organizational Factors on Blast Furnace Operating Indices

The effect is analyzed of organizational factors on blast furnace operating indices under contemporary intense smelting conditions: current banking time, fanning time, and compliance with the discharge schedule. The quantitative effect of these factors on blast furnace performance was established more the thirty years ago and needs adjustment. It is demonstrated that production losses associated with banking depend on duration and number, and production losses associated with fanning depend on duration, amount, and degree of blast pressure reduction. Dependences (equations) are determined for production loss connected with banking and fanning. The effect of banking and fanning time on the change in equivalent coke consumption is determined. Values obtained differ from those used previously. The effect of discharge schedule on furnace performance and specific coke consumption for AO EVRAZ NTMK loses its relevance.

Blast furnace performance improved through optimal radial distribution of materials at the top while changing the charging pattern

Blast furnace performance improved through optimal radial distribution of materials at the top while changing the charging pattern