Blast Furnace Production Research Articles

Improved multi-layer online sequential extreme learning machine and its application for hot metal silicon content

Hot metal silicon content is an important indicator for measuring the smooth operation of the blast furnace. However, the hot metal silicon content cannot be directly detected online. Hence, this paper proposes a prediction model of the hot metal silicon content based on the improved multi-layer online extreme learning machine (ML-OSELM). The improved ML-OSLEM algorithm is based on ML-OSELM, the variable forgetting factor (VFF) and the ensemble model. VFF is introduced to make the new coming data get more emphasis. The ensemble model can overcome the overfitting problem of ML-OSELM. This improved algorithm is named as EVFF-ML-OSELM. The real blast furnace production data are used to testify the established prediction model based on EVFF-ML-OSELM. Compared with the prediction models of the hot metal silicon content based on other algorithms, the simulation results demonstrate that the prediction model based on EVFF-ML-OSELM has better prediction accuracy and generalization performance.

A Study on High-Grade Iron ore Beneficiation to Reduce Alumina for Enhanced Blast Furnace Productivity

Iron ore pellets are largely characterized by inherent physical and chemical properties of the ore. Alumina and silica play important roles in determining the productivity of a Blast Furnace. On average, one percent increase in iron content improves productivity by 2% and reduces coke consumption by 1%. Therefore higher iron ore feed content to blast furnace is always preferred. Indian hematite, though rich in iron content has a higher content of alumina and lower silica content. Alumina to silica ratio is as high as 1.5–3%. Adverse alumina to silica ratio is detrimental for the blast furnace. This should be less than 1.5 and preferably below 1. High alumina content in the blast furnace burden irrespective of its composition (Lumps, Sinter and Pellet) generates slag with higher viscosity. This needs a higher amount of fluxes and coke, thereby producing large slag volumes and thus decreasing productivity of blast furnace. In general, 1% increase in alumina content in a blast furnace burden increases coke rate by 2.2%, decrease in the productivity by 4% and an increase in flux consumption by 30Kg /t of hot metal production. A typically high-grade iron ore assaying Fe 64%, SiO2 2.70%, Al2O3 2.50% is received at ArcelorMittal Nippon Steel India (Formerly known as Essar Steel India Ltd), Dabuna. The study with various beneficiation circuits was carried out to reduce alumina with least possible rejects. Subsequently, we were able to bring Al2O3 down by 0.15–0.30% in final concentrate. This resulted in productivity enhancement of Blast furnace by up to 3.69 T/cum/day. The 1905 cum working volume blast furnace has produced 7012 tons which was 140% of nameplate capacity. The study here highlights the optimization of beneficiation circuit for high-grade iron ore to attain higher productivity of both Pellet Plant and Blast Furnace with the least amount of rejections.

Algorithms and software for optimal management of raw materials, fuel and energy resources in blast furnace production

The structure of optimization model of optimal management of raw materials, fuel and energy resources in the blast-furnace shop of iron and steel works is represented. The following blocks are taken as system basis: 1) calculation of the set of parameters that characterize the thermal, gas-dynamic, slag and blasting modes for every blast furnaces of the shop during the base period; 2) calculation of linearized model coefficients (constants of transferring via different exposure pathways) individually for every blast furnace as well as properties of iron ore raw materials, fluxing additions, blasting parameters, parameters of fuel-enriched blast influencing the technical-and-economic indices of separate furnaces performance, their thermal, gas-dynamic and slag operation modes in the course of blast-furnace melting according to UrFU-MMK blast-furnace production model within the base period; 3) solution of tasks that consider the optimal allocation of raw materials, fuel and energy resources for the project period of blast furnaces operation; 4) analysis of obtained results and providing of recommendations on the optimization of blast furnaces parameters. The developed functional model of optimal distribution of raw materials, fuel and energy resources for the engineering and technology personnel of blast-furnace shop is illustrated; the main functions and interconnections between the separate functional blocks are defined. The functions of created “Optimal management of raw materials, fuel and energy resources in the blast-furnace production” software that is realized in the Microsoft Visual Studio 2017 (C# programming language) programming environment in the form of web application are pointed out. The program product provides the engineering and technology personnel of blast furnace shop of iron and steel works with the opportunity to solve the tasks of optimal distribution of fuel and energy resources (natural gas and oxygen consumption) within the group of blast furnaces in the different technological situations.

Numerical investigation of mixed layer effect on permeability in a dynamic blast furnace

AbstractGas flow distribution in a blast furnace (BF) plays a significant role in BF smooth operation, productivity, and thermal efficiency. It is affected by the distribution of burden materials composed of alternating coke and ferrous ore layers. While moving downward coke and ferrous layers of different sizes can mix and form the so‐called mixed layers. Generally, the porosity is lower and hence the pressure drop is higher in the mixed layers. These variations can change the gas flow distribution and BF performance. Previous work tried to quantify the effect of material properties and process conditions on the formation of mixed layers and the resulting local porosity variation. However, these studies were often conducted under simplified conditions. Few were dedicated to the formation of mixed layers in a BF and its effect on BF performance. This work studies the formation of mixed layers in an experimental BF by using a combined computational fluid dynamics and discrete element method approach. The effect on BF performance was evaluated under different operational conditions including different size ratios of coke to iron ore particles, burden distribution, batch weight, and discharge rate. The results obtained were helpful to optimize burden charge for improving BF performance.

Influence of multiple factors on the alkali metal enrichment in blast furnaces by a thermodynamic model

ABSTRACTAlkali metal circulation enrichment occurs in blast furnaces, which is harmful to the blast furnace. The amount of enrichment helps to quantify the effect of alkali metals on blast furnace production, but it is not possible to directly measure the actual alkali metal enrichment in blast furnaces for technical reasons. On the basis of a thermodynamic model, FactSage was used to calculate the effects of alkali loading, slag basicity, MgO content in the slag and Al2O3 content in the slag on the alkali metal enrichment in the blast furnace. Quantitative relationships among various factors and the enrichment were obtained, and the degree of influence of various factors on the amount of enrichment was determined. The basicity B2 of the slag was the key factor for enrichment. With an increase in the slag basicity of 0.1, the enrichment of K and Na increased by 5.3 and 1.6 kg/tHM, respectively.

Mathematical Model for Estimating the Optimal Distribution of Ore Charge Along the Blast Furnace Radius Based on Zonal Balances

Equipping blast furnaces with bell-less top (BLT) chargers is intended for reducing the consumption of costly and scarce coke, as well as increasing the productivity of blast furnaces. However, equipping a furnace with BLT charger does not always lead to achieving these goals. In a number of cases, the result is opposite. This made a number of researchers doubt the feasibility of further installation of bellless top charging equipment on blast furnaces. The experience of operating the bell-less top charger showed that a simple replacement of a double-bell charger with bell-less top one does not produce an improvement in blast-furnace process parameters, such as a decrease of coke consumption and increase in productivity. A bell-less top charger is just a management tool that can be used to achieve this goal. But like with all other tools, it is important to learn how to use it. For this purpose, it is important to provide a blast furnace with the evaluation and control means to manage the distribution of the charge materials along the furnace throat radius and utilization of thermal and chemical energy of the gas flow. The distribution of the charge materials along the furnace throat radius is associated with the variation in ore charge (ore-to-coke (O/C) ratio). Different values of the O/C ratios along the furnace throat radius play an important role in the formation of a gas flow inside the blast furnace. A mathematical model is proposed to be used as a tool for estimating the optimal distribution of the ore charge along the furnace radius based on the zonal balances of the blast-furnace process. Such model was used to analyze the study results related to the effect of the O/C ratio variation along the furnace throat radius on a decrease in coke consumption and increase in productivity of the blast furnaces operating in Japan and Russia. A satisfactory agreement between the calculated and actual results allows recommending such mathematical model for preliminary calculation of the optimal distribution of ore charge along the radius of the blast furnace. This makes it possible to calculate the bell-less top charging systems, as well as identify the furnace zones with unsatisfactory utilization of thermal and reduction energy of the gas flow.

Theoretical and practical research on relationship between blast air condition and hearth activity in large blast furnace

From the results calculated by theoretical derivations, it was found that the characteristics of tuyere raceway determined by the operation condition for blast air played a critical effect on the heart activity. The speed and kinetic energy of blast air should be proportional to the volume of blast furnace (BF), and the comprehensive optimization of air volume and tuyere which should vary with the quality of raw materials was essential. The calculation methods of air volume ratio and coefficient for different BFs were put forward. Moreover, the details on hearth activity recovery of a 4747 m3 blast furnace in China were elaborated. Based on the extensive experience in blast furnace production, the various phenomena used to judge air speed and kinetic energy whether reasonable were discussed. In summary, hearth activity was closely related to the characteristics of BF raceway and reasonable air speed and kinetic energy could effectively improve the activity.

Study of binders for ecologically safe anhydrous tap-hole clays

Detailed analytical review of the existing tap-hole clays used in the blast furnace production at various metallurgical enterprises is made. It is established that it is necessary to ensure environmental safety when using tap-hole clay. It is clarifi ed that synthetic resins (phenol-formaldehyde and novolac resins) are used instead of harmful coal-tar resin for the production of tap-hole clays. The oxidation of coal-tar resin and pitch occurs up to temperature of 600 °С, which is especially important for large blast furnaces equipped with 2...4 tap-holes.

Development and production of large blast furnaces from 2015 to 2016 in China

This article has reviewed the production status, total reductant consumption, raw materials and operation principle indexes of large blast furnaces in China from 2015 to 2016. The developing actuality of Chinese large BFs has been quantitatively analyzed and the existing problems have been proposed clearly. Based on that, maintaining production stable, enhancing the quality of raw materials and improving the operation principles are suggested. Large BFs take advantages of high-quality hot metal, energy saving, cost-cutting, high mechanization and automation levels and are sufficient to meet the challenges of economic crisis, environmental pressure and security risk form the future. Thus, the number of large BFs in China will continue to increase in the future.

Development and production of Chinese large blast furnaces in 2019 compared with 2015–2016

By comparing the production indexes of large blast furnaces (BF) in China between the first half of 2019 and 2015–2016, the production status, reductant consumption, raw materials and operation conditions have been reviewed. In the first half of 2019, Chinese large BFs still had made a lot of achievements, but it is also discovered by comparison that not only the raw materials quality but also the large BFs stability have the trend of getting worse, so some work should be done to stop and recover the unfavorable situation. Based on that, the expectations of enhancing the raw materials quality and improving the operation conditions are suggested. Large BFs make great contributions to energy saving, low-carbon, high automatic, environmental protection and economic development, so there will be more large BFs constructed and put into production in China in the future.

Formation of an optimal cement matrix for vibropress products

Modern approaches to the formation of new generation concretes make it possible to replace part of the fine aggregate with finely ground mineral powders, which are by-products of metallurgical and chemical industries, the construction industry, as well as various substandard quartz sands. In the studies carried out, metallurgical slags (MS), broken glass (BG), dust from gas cleaning of metallurgical production (DGCMP), and ground quartz sand (GQS) were used. The aim of the study is to obtain an optimal flow rate of a hydraulic binder by forming an optimal cement matrix. The dosage of finely ground powders varied in the range of 20-49 % of the portland cement consumption. It has been established that the most acceptable finely ground mineral powders in compositions for the production of vibropress products are: quartz ground sand, metallurgical granulated slag of blast furnace production, gas cleaning dust and ground glass. Powders obtained on the basis of glass scrap can be considered as an additional raw material base in the production of materials for road-building purposes. Operational properties such as water absorption and the rate of concrete curing indicate their prospects. However, the economic costs of collecting, sorting glass, obtaining a powder with a specific surface area of 3000 cm2/g are not reasonable at this point in time.

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.

Developing the Technology of Regenerative Siderite Ore Roasting in Shaft Furnaces

This paper shows that the existing siderite ore preparation techniques do not allow achieving high blast-furnace smelting levels as compared with using black iron ore concentrates with a high iron content. To make blast-furnace smelting more efficient, it is necessary to use the metallized product made by regenerative siderite ore roasting. The technology developed for this roasting allows producing metallized concentrate with a Fe content of 65–68%. The main provisions of regenerative siderite ore roasting in shaft furnaces are formulated, and the three-zone shaft furnace design proposed for implementing this process. The thermal and consumption parameters of the process are provided as well as the lean gas circuit of regenerative ore roasting. This circuit allows significant cutting the expenses. The metallized siderite ore product with a high iron content allows gaining major economic benefits in blast-furnace production.

Heat Exchange in the Granulation Chamber of an Installation for Slag Dry Granulation

In the blast-furnace production, fiery-liquid slags have temperatures of about 1400–1500 °C at the exit from the furnace. For the utilization of their sensible heat, the world leading countries develop special installations for slag dry granulation aimed at getting dry granulated slags and using the heat of liquid slags for the purposes of heating of air or another gas. In addition, the introduction of the process of slag dry granulation instead of the wet granulation of slag applied at present excludes the possibility of ejection of harmful sulfur compounds and does not require additional heat consumption spent for drying wet granulated slags. In the available methods aimed at the dry granulation of slags, it is proposed to use the air heated to a temperature of 500–600 °C in a boiler (utilizer) intended for the generation of steam, which is then either delivered to a turbine generating electric energy or directly used for the industrial purposes. We propose a method for the numerical analysis of heat exchange in the process of cooling of blast-furnace slag in the granulation chamber of the installation for dry granulation. By using this method, one can determine the optimal main size of the granulation chamber, i.e., its radius.

Sintered Iron-Ore Manufacturing Capabilities when Using Combined Fuel

In order to create thermal conditions that form the same time-temperature conditions throughout the height of the sinter-feed mixture after (1) blending, (2) source material pelletizing, (3) laying on the fire grate, (4) initial layer heating under the ignition hood, and (5) ignition of the solid charge fuel, a natural gas-air mixture with an air flow coefficient > 3.5 is supplied to the sinter-feed layer through a gas-air distribution device (GAD), and is then heated while passing through a hot upper sinter layer to the ignition temperature (450–600°C) with the gaseous fuel formation at 1100–1150°C in the 40–60 mm active burning-zone layer. The heat released in this process provides additional heating of the upper layer horizons to the required sintering charge material temperature. GAD design tests using an AK–50 sintering machine showed equalization of the redox conditions and a decrease in the yield of small sinter fractions in the drum sample, which improves the sintering machine productivity by 30–35% with an efficient fine coke consumption of 2.5–2.9%. When switching to sinter by using combined fuel, the blast furnace productivity increases by 10–14%, and the specific fuel consumption in coke per unit of iron made decreases by 8%.

Improvements to Mixing of Natural Gas and Hot-Air Blast in the Air Tuyeres of Blast Furnaces with Thermal Insulation of the Blast Duct

Using natural gas as an additional fuel in a blast furnace is known to reduce coke consumption during blast-furnace production. In a standard tuyere, the hot blast pushes the natural gas up against the surface of the blast duct, resulting in poor mixing between the natural gas and the hot blast, which in turn leads to incomplete combustion and pyrolysis of the natural gas. One approach for improving mixing between the natural gas and the hot blast is to modify the blast-channel geometry. An engineering design solution was proposed, and the gas dynamics, thermal conditions, and stress/strain state of the air tuyere for this solution were analyzed via ANSYS modeling. Toroidal protrusions on an insert near the outlet of the air tuyere (swirlers) or on the gas inlet nozzle flange (rim) were considered; these protrusions also protect the insert against premature damage in areas subject to the most severe mechanical damage. The following assumptions were made: The model scope includes both the fluid medium within the blast duct and the thermal insulation insert, i.e., this can be thought of as a conjugate heat exchange problem, and heat transfer to the cooling system water was taken into account using the generalized boundary conditions. We show that modifying the insert geometry so that there is a protrusion on the working surface or installing a rim in the area where the insert starts to show damage, will increase mixing of the natural gas into the blast air and during combustion. This then increases the blast temperature at the tuyere outlet, which in turn increases the natural-gas flow rate and reduces coke usage. A similar result was achieved for wear on the insert.

IA: The Journal of the Society for Industrial Archaeology, Theme Issue: The Archaeology, by Frederic L. Quivik, ed.

IA: The Journal of the Society for Industrial Archaeology, Theme Issue: The Archaeology, by Frederic L. Quivik, ed.

PRODUCTION OF NON-ROASTING PELLETS FROM THE WASTE OF SHABROVSKY TALCUM COMBINE

Technogenic wastes are by-products of any production. At the same time, they can be a raw material for obtaining useful products. In particular, the waste from the Shabrovsky talcum combine, can be used to produce magnesian fluxes. They are dispersed, so must be agglomerated. Therefore, a method has been proposed for the preparation of non-roasting pellets. As a binder, a mixture of water and peat, treated in a hydropercussion cavitation device, was used. The resulting material is a colloidal system with particle size of less than 10–4 m. To measure the particle size, dynamic light scattering method was used. For comparison, a similar mixture of water and peat treated in a planetary mill was studied. An analysis of the data obtained has shown that particles of micron size occupy up to 90 % of volume in the sample after treatment of the mixture in hydropercussion cavitation device. In a sample that was ground in a planetary mill, most of the particles are characterized by tens or even hundreds of microns. Determination of crushing strength of non-roasting pellets is performed by compressing in a tensile machine of model P-0.5. For this purpose, the granules were used both immediately after granulation and after drying at 105 °C to a moisture content of less than 1.5 %. With an optimum proportion of binders of 15 – 20 %, the strength of raw pellets was 15 N, and the strength of dry pellets was 90 N. With a binder percentage of less than 15 %, both raw and dried pellets had low strength. With a binder content of more than 20 %, the mixture had excessive plasticity and tackiness, which led to the formation of conglomerates of several granules. Despite the fact that the strength parameters of the non-roasting pellet are lower than those of pellets used in blast-furnace production, they are sufficient for use in steelmaking processes.

Modeling of the Production Capacity of the Enterprise in the Conditions of Combined Production Flows of Metallurgical Production

Today there is no complex solution to the problem of calculation and optimization of production capacity, taking into account the performance of the main aggregates and the throughput of equipment of auxiliary sections in the combined production streams of metallurgical production. There is no method for finding bottlenecks in combined production streams. There is no classification of bottlenecks. The purpose of the article is to develop scientific and methodological recommendations for optimizing the enterprise (subdivision) in terms of combined production streams. Achieving the goal requires solving the following tasks: analysis of theoretical foundations and methods of calculation of production capacity; development of a formal representation of the structure of combined production streams; choice of mathematical model for optimization of production capacity. Analysis of studies and publications shows the impossibility of solving the problem of optimizing the production capacity of an enterprise without combining the formal representation of the structure of production streams with the corresponding mathematical model. It is proposed to submit the structure of combined production streams in the form of a graph-mathematical model. A network graph of combined production streams of blast furnace production was constructed. To calculate and optimize the production capacity, the problem of the maximum flow in the network, which is the task of linear programming, is used. The problem of finding the maximum flow in the grid, that is, the maximum production output of the unit to take into account the performance of the main aggregates and the capacity of the service stations, is solved. The maximum flow in the grid means the optimal value of the production capacity. Solving the dual problem of maximum flow gives the possibility of finding a minimum cut in a network, which is analogous to the bottleneck in the combined production flows. The following classification of bottlenecks in combined production streams is proposed: local, nodular, cross-sectional. The proposed methods of research and solving the formulated problems generalize and develop the well-known theoretical principles of the economy and the organization of production.

Effect of Nut Coke Addition on Physicochemical Behaviour of Pellet Bed in Ironmaking Blast Furnace

One of the primary causes that limit the blast furnace productivity is the resistance exerted to the gas flow in the cohesive zone by the ferrous burden. Use of nut coke (10–40 mm) together with ferrous burden proves beneficial for decreasing this resistance. In present study, effect of nut coke addition on the olivine fluxed iron ore pellet bed is investigated under simulated blast furnace conditions. Nut coke mixing degree (replacement ratio of regular coke) was varied from 0 to 40 wt% to investigate the physicochemical characteristics of the pellet bed. Three distinct stages of bed contraction are observed and the principal phenomena governing these stages are indirect reduction, softening and melting. It is observed that nut coke mixing enhances the reduction kinetics, lowers softening, limits sintering and promotes iron carburisation to affects all three stages. In the second stage, the temperature and displacement range is reduced by 60°C and 24%, respectively upon 40 wt% nut coke mixing. Addition of nut coke exponentially increases the gas permeability (represented by pressure drop and S-value). A higher degree of carburisation achieved on the pellet shell (iron) is suggested to be the principal reason for decrease in the pellet melting temperature. The pellets softening temperature increases by approximately 4°C, melting and dripping temperature drops by 11°C and 12°C, respectively, for every 10 wt% nut coke addition. Consequently, the nut coke addition shortens the softening, melting and dripping temperature ranges, which shows improved properties of the cohesive zone.