Specific Coke Consumption Research Articles

Development and implementation of technological measures to extend the campaign of blast furnace No. 5 of PJSC Severstal

The work presents generalized experience in the development and implementation at PJSC Severstal of technological measures to extend the campaign of blast furnace No. 5. The authors carried out an analysis, identified and described the problem areas, generalized the principles for ensuring the safety of the shaft lining, boshes and metal receiver of the blast furnace. The results of a study of the working space of blast furnace No. 5 in 2006 are also presented. The identified technological factors ensure an increase in duration of the unit campaign. Technolo­gical measures are given for: washing the blast furnace hearth, reducing chemical erosion of the carbon blocks of the hearth and flange, forming a protective skull in the blast furnace shaft, special methods for loading solid coke substitutes, and organizing an effective structure of the charge column in the blast furnace. It is necessary to use digital models integrated into the blast furnace expert system for operational control of blast furnace technology. The results of the current blast furnace campaign were compared with previous ones. It was proven that the systematic use of all elements of the developed technology makes it possible to achieve high economic indicators while exceeding the standard duration of the campaign by 1.75 times. Experience in technology development made it possible to increase the furnace campaign duration to 17.46 years, achieve a reduction in specific coke consumption by 15.9 %, and increase the specific consumption of natural gas for cast iron smelting by 46.4 %; reduce the specific carbon consumption for cast iron smelting by 6.3 %.

Development of stabilization measures aimed at removing zinc with smelting products and accumulating titanium in the hearth of a blast furnace

AbstractThis paper presents the results of the development of stabilization measures aimed at the removal of zinc with the products of melting and accumulation of titanium in the hearth of a blast furnace. The relevance of the development and use in practice of such measures is due to the unstable fuel and raw materials conditions for the production of cast iron, when their stabilization is a complex and difficult task, as well as the need to extend the campaign of blast furnaces during the overhaul period. The negative effect of zinc oxides on the condition of the blast furnace shaft lining, accompanied by slab formation, and the overconsumption of specific coke consumption, which occurs when zinc circulates in the volume of the blast furnace, require measures to remove zinc from the smelting products. The article proposes such measures, which consist of flushing according to the proposed schedule during the operation of the blast furnace at planned blowing parameters and with the provision of the necessary thermal reserve. In order to lengthen the campaign of a blast furnace, one of the most common methods for protecting the hearth lining is the periodic introduction of titanium‐containing materials into the charge of blast furnaces. The entry of titanium oxides into the furnace, as a rule, is ensured by the use of concentrate or specially prepared ilmenite briquettes with a high titanium content as part of the sinter charge, which can be introduced directly into the composition of the blast furnace charge. The article analyzes the experience of using titanium‐containing materials as part of a blast furnace charge and formulates measures to intensify skull formation in the hearth.

Experience of co-injection of pulverized coal and natural gas into blast furnace hearth under the conditions of PJSC "KAMET-STEEL"

The article provides an analysis of the practical and analytical results of the methods of co-injection of pulverized coal and natural gas into the hearth of blast furnaces by American researchers and practitioners. The analysis shows the advantage of supplying natural gas, as well as pulverized coal, through the lance into the blow channel of the tuyere device. Practical results obtained for the first time in Ukraine of co-injection of pulverized coal and natural gas into the hearth of a blast furnace in unstable charge and fuel conditions of PJSC "KAMET-STEEL" are presented. Practical experiments have proven the efficiency of such injection when fuel additives are injected onto separate lances into the blow channel of the tuyere device, and the natural gas lance is withdrawn so that its combustion occurs before the injection of pulverized coal into the blow channel. The effectiveness of the practical application of the method of co-injecting pulverized coal and natural gas into the hearth of a blast furnace is expressed in a reduction in the specific coke consumption by 10.3 kg/ton of cast iron (or 2.85 %) at a consumption of pulverized coal — 153.4 kg/ton of cast iron and natural gas — 24.5 m3/ton of cast iron. The results obtained allow us to recommend this method of injecting fuel additives under acceptable price conditions, as well as at other metallurgical plants, especially those operating with better conditions for ensuring high temperatures of hot blast — more than 1050 °C. As a result of the analytical studies performed, it was established that: nozzles with two inlets for natural gas and pulverized coal, ensuring the introduction of natural gas into the blast channel before pulverized coal, contribute to the maximum burnout rate of the latter in the blast flow; with this injection method, more methane natural gas is burned, more heat is released due to the combustion reaction, which leads to an increase in the blast temperature at the outlet of the tuyere.

Reduction of specific coke consumption in blast furnace by impact on thermal reverse zone

At the blast furnace of PJSC “Magnitogorsk Metallurgical Plant” (MMK), the specific consumption of coke was reduced by impact on thermal reverse zone (TRZ) by increasing the consumption of natural gas above 120 m3/t of cast iron under conditions of increased reactivity and reduced hot strength of coke. In the first pair of periods, an increase in CRI from 38.4 to 39.3 % with a decrease in CSR from 36.3 to 34.6 % was accompanied by an increase in the ratio of natural gas consumption and total oxygen entering the furnace from 0.43 to 0.45 by increasing the specific gas consumption from 123.2 to 133.5 m3/t of cast iron. The set of actions increased the TRZ length towards the blast-furnace mouth by 1.9 % with its unchanged location along the lower part. Reducing the heat consumption in the TRZ increased the temperature difference between gas and materials there by an average of 36 °С. In the second pair of periods, the consumption of natural gas was 143.9 m3/t of cast iron with a decrease in the oxygen content in the blast from 27.6 to 27.0. They were accompanied by the following changes in the processes under consideration: an increase in the length of the TRZ towards the blast-furnace mouth by 2.6 % and the distance from the tuyere hearth by 3.4 %, an increase in the degree of carbon reduction from 32.0 to 33.3 %, an insignificant (on average 0.3 °С) increase in the temperature difference of gas and materials in the TRZ. In the first pair of periods, reduction in the coke specific consumption was 4.7 kg/t of cast iron with an increase in furnace productivity by 27 t/day. Conditions and course of the processes of the second pair ensured a decrease in the coke specific consumption by 1.6 kg/t of cast iron and led to a decrease in cast iron production by 41 t/day.

Interrelation of gas blowing parameters of blast furnaces and the main quality indicators of coke in the conditions of JSC “Ural Steel”

The aim of the study was to establish the relationship between the gas blowing parameters of a blast furnace (BF) and the quality indicators of coke CRI, CSR and to develop recommendations on the use of measures to increase CSR and reduce CRI in order to increase BF productivity and reduce coke specific consumption. For an objective study, BF No. 1 was chosen with a useful volume of 1007 m3, which worked during the study period with consistently high technical and economic indicators. The results of the analysis of data on the effect on the gas-blast parameters (flow rate and blast pressure) of blast furnace No. 1 of the values of coke reactivity CRI and coke hot strength CSR over a three-year period are presented. Research has revealed that the CRI and CSR values of the coke used at the enterprise do not correspond to the recommended values. A relationship has been established between the gas blowing parameters of a blast furnace and the indices of coke reactivity CRI and hot strength of coke CSR. Measures are proposed to improve coke CRI (decrease) and CSR (increase) in the conditions of Ural Steel JSC, the implementation of which will increase the productivity of blast furnaces and reduce the specific consumption of coke.

Advantages and risks of using ore-coal briquettes in blast furnaces

Reducing carbon consumption, and, consequently, CO2 emissions during iron smelting in blast furnaces is a priority for improving the technology of blast furnace smelting. In the literature, the question of the influence of the development of direct reduction of iron on the consumption of carbon as a source of reducing gas and a source of heat has been considered. In this case, the development of direct reduction in the lower zone of the furnace at temperatures above 900 °C is considered. However, direct (solid-phase) reduction can be implemented in the upper zone of a blast furnace when using ore-coal briquettes in the charge. It is shown that the solid-phase reduction reactions can proceed at temperatures above 700 °C in the upper zone of a blast furnace during the reduction of Fe3O4 and FeO. At the same time, the apparent heat capacity of the charge increases and the temperature of the top gas decreases, which is confirmed by data on the operation of blast furnaces of NLMK PJSC, which use ore-coal briquettes. The raw materials for the production of briquettes are iron ore concentrate, sludge, blast furnace dust, aspiration dust. A bentonite and a ce-ment are used as a binder. The briquettes contain 40‒42% iron and 10‒15% carbon. The theoretical analysis and statistical processing of data on the operation of blast furnaces led to the conclusion that the solid-phase reduction of iron oxides actively proceeds at temperatures below 900 °C. The results of experimental heats showed the use of briquettes allows to reduce the specific consumption of coke and the total carbon consumption of fuel. The prospects for the use of the briquettes are associated with an increase in their mechanical properties. The use of ore coal briquettes obtained from a concentrate with an iron content of 65‒68% will reduce the rate of fuel carbon and CO2 emissions.

Ability to reduce iron with additional hydrogen introduced into the blast-furnace natural gas stream

Equations are obtained, calculations are made on them, and graphs of the temperature dependence of the extremely high degree of hydrogen utilization are presented, which characterize the reduction of iron under conditions when H2O moves from the zone of transformation of FeO into Fe to the zone of transformation of Fe3O4 into FeO and further from the zones of development of these two reactions to the zone of transformation Fe2O3 to Fe3O4 with decreasing amount of hydrogen. Under the blast furnace conditions, the limit value for the hydrogen use is 55–57 %. In the course of studies at a blast furnace with a useful volume of 1370 m3 at PJSC MMK, an increase in the ratio of the amounts of hydrogen supplied with natural gas and oxygen supplied with enriched air blast was accompanied by an increase in the degree of hydrogen use from 47.0 to 50.6 % and a decrease in specific coke consumption from 404.0 to 397.4 kg/t of pig iron. The ratio of specific consumption of coke and total hydrogen of natural gas in the form of hydrocarbons decreased from 1.41 to 1.29 kg/m3. In another series, a rational mode was revealed, characterized by an increased reactivity of coke and a reduced consumption of natural gas, the transition to which reduced the specific consumption of coke from 426.4 to 423.3 kg/t of pig iron. Under current conditions at PJSC MMK, a reduction in the specific consumption of coke by 50 kg/t of pig iron is possible with the consumption of additional hydrogen in the amount of 156 m3/t of pig iron by it introducing into the existing pipeline of natural gas.The article was prepared with the support of the grant of the President of the Russian Federation No. MD-1064.2022.4.

THE ESTIMATION OF THE EFFECT OF COKE, OBTAINED WITH PARTICIPATION OF VOLUME-MODIFYING ADDITIVES, ON THE TECHNICAL AND ECONOMIC INDICATORS OF BLUST FURNACE SMELTING

The article deals with the effect of the coke resistance index CSR (Coke Strength after Reaction) on the technical and economic indicators of the blast furnace process. It is shown that in the production of metallurgical coke using volume-modifying additives in the amount of 0.25% by weight of the coal load, its strength improves, in particular, index CSR. As a volume-modifying additives, α-Al2O3 electrocorundum and α-SiC carborundum with a particle size of <45 μm and vibromilenum α-SiC carborundum with a particle size <12 μm were used.
 Due to the introduction of fine powders of electrocorundum and carborundum into the coal charge, the maximum increase in the coke post-reaction strength index (CSR) by 7.6% was obtained.
 The influence of changes in individual indicators of coke quality on its consumption and productivity of the blast furnace was assessed in accordance with the guidance document of the metallurgical division of Metinvest Holding LLC. This document contains a detailed methodology for use in analyzing fluctuations in specific coke consumption and throughput of blast furnaces influenced by changes in blast furnace process parameters (by factor analysis). This technique is based on quantitative relationships between changing parameters (factors) and specific coke consumption (blast furnace productivity).
 There has been made an expert technical and economic assessment of the feasibility of introducing 0.25% fine powdered α-Al2O3 and α-SiC powders into the mixture from the point of view of blast-furnace production with pulverized fuel injection technology. The results show that, despite the increase in the cost of coke with the introduction of volume-modifying additives into the mixture, a reduction in the cost of iron can be achieved due to the expected reduction in the specific consumption of coke due to an increase in its post-reaction strength.

Hot repair of blast furnace lining – a way to reduce its carbon footprint

The experience of JSC "Tulachermet" in the restoration of the refractory lining of blast furnaces with unshaped refractory materials by the shotcreting method is presented. Using this method of restoring a refractory lining can significantly reduce the cost and duration of repairs and use it more often when critical, especially with respect to coke consumption and the carbon footprint of the unit, values of lining erosion and thermal loads on the blast furnace cooling system are reached. Practical experience has shown the need to use different refractory materials for different zones of the furnace. The state of the refractory lining before the restoration repair is shown. The technology of restoration repair is described, the grades of refractory concretes and the thickness of the lining by furnace zones are indicated. An assessment of greenhouse gas emissions, specific coke consumption and furnace productivity after the repair was carried out. A model of rational decision-making on the restoration of the furnace lining is proposed, depending on the thermal loads on the blast furnace cooling system.

Development and Implementation of Decision Support Systems for Blast Smelting Control in the Conditions of PrJSC “Kamet-Steel”

This article presents a description of three decision support systems (DSS) in the mode of an adviser to the technological personnel of blast furnaces (BF), which were implemented by the Iron and Steel Institute of Z.I. Nekrasov (Dnipro, Ukraine) or underwent pilot testing as part of the automated control system of the BF shop of PrJSC “Kamet-steel” (Kamianske, Ukraine). The first DSS for managing the thermal state was implemented in 2021; it includes the entire list of information necessary for personnel in a convenient and compact form, generates recommendations in case of technology deviations, and, in the case of incorrect actions by the personnel, signals the need for correct actions. The main recommendations from the DSS are to correct the raceway adiabatic flame temperature, coke consumption when its characteristics are specified in (indicators of strength and abrasion, fractional composition, humidity, ash and sulfur), and ore load change. Using the system allows both reducing the specific coke consumption and preventing unplanned downtime. The second DSS for controlling the distribution of fuel additives over air tuyeres is based on information on thermal loads determined on water-cooled elements of tuyere tools. The main recommendations from the DSS are to adjust the amount of injected pulverized coal fuel on individual tuyeres in order to ensure a uniform distribution of the raceway adiabatic flame temperature around the circumference of the BF and, as a result, the energy efficiency of BF smelting. The third DSS for adjusting the parameters of the charging mode is based on information from the means of controlling the temperatures of the gas flow above the surface of the charge in the BF. The functioning of this DSS is based on determining the reference curves for the distribution of the gas flow along the BF radii, corresponding to the minimum consumption of coke and maximum productivity, and on the search for solutions by direct and iterative optimization methods, which allow one, by adjusting the charging parameters, to ensure a rational distribution of charge materials and gas flow in the BF.

Rational technological solutions in production of pig iron in blast furnaces of Magnitogorsk Iron and Steel Works

The main factors affecting the specific consumption of natural gas have been identified. The most significant of them for the existing conditions are the process oxygen consumption, the reactivity of coke (CRI - coke reactivity index) and the hot strength of the coke (CSR - coke strength after reaction). The increase in the specific consumption of natural gas in the shop on average from 106.7 to 135.2 m3/t of pig iron with a replacement equivalent of at least 0.7 kg/m3 was facilitated by an increase in the oxygen content from 26.95 to 27.4 % and an increase in the reactivity of coke from 33.4 to 35.1 %. The technology of loading high-quality sinter from factory No. 5 into blast furnaces of Magnitogorsk Metallurgical Plant (MMK) has been mastered. An increase in the factory’s agglomerate content in the iron ore part of the charge by every 10 % increased the blast furnace productivity by 21.1 t/day while reducing the specific consumption of coke by 2.8 kg/t of pig iron. A local mode for loading flushing materials, depending on the hot strength of coke according to CSR has been developed and implemented.1. Into the ore ridge zone when coke is supplied with the CSR of more than 40%.2. Into different zones with the CSR less than 40 %:– to the axial zone, if the CSR is less than 90 % of the average value for the previous 5 days;– to the ore ridge zone, if the CSR is more than 110 % of the average value for the previous 5 days;– evenly over the top section, if the CSR is 90–110 % of the average value for the previous 5 days.

Analysis of possible ways to reduce sulfur content in pig iron

One of the ways to increase the energy efficiency and intensity of blast furnace smelting, especially when using pulverized coal fuel, is to increase the hot strength of coke. In the conditions of OJSC NLMK, an oil additive was introduced into the coal charge to improve the coke quality. At the same time, sulfur content in the coke increases, and, consequently, sulfur content in the cast iron increases as well. In this regard, the task of finding ways to improve the desulfurization of cast iron in blast furnace becomes urgent. The main factors determining the desulfurization of cast iron are slag basicity, content of MgO oxide in it, temperature of the smelting products, and the slag viscosity. The purpose of this work was to compare the efficiency of sulfur removal by increasing the slag basicity and MgO content. On the basis of wellknown equations, an algorithm was developed that allows the problem to be solved. It was established that an increase in MgO content in the slag promotes desulfurization of cast iron to a greater extent than a basicity increase. In addition, an increase in MgO content by 1 % is accompanied by an increase in slag yield by 3.0 – 3.5 kg/t of cast iron. At the same time, an increase in basicity by 0.01 leads to an increase in the slag yield by 4 – 5 kg/t of pig iron. Consequently, reducing the sulfur content in pig iron by increasing the slag basicity requires less heat. In terms of the specific consumption of coke, difference in heat demand is 0.4 – 0.5 kg/t of pig iron. It is shown that with an increase in MgO content in the slag, the slag viscosity at a temperature of 1450 °C increases to a lesser extent than with an increase in basicity.

РОЗРОБКА ТЕХНОЛОГІЇ ВИРОБНИЦТВА ЗАЛІЗУРОВОГО МОНОСИРОВИНИ ДЛЯ ДОМЕННОЇ ПЛАВКИ

The aim of the work is to develop and test technological regimes for obtaining new types of shelled iron ore materials and mono-raw materials for blast furnace smelting. It is shown that the traditional ways to improve the technology of blast furnace smelting to increase the productivity of the furnace and reduce the specific consumption of coke have largely exhausted their potential. At the same time, the creation of pelleted iron ore mono-raw material with the necessary indicators of the complex of metallurgical characteristics provides additional opportunities to reduce energy costs during blast furnace smelting. The article presents the results of the developed technology for the production of pelleted iron ore monoprocess for blast furnace smelting, which has at the same time a high content of iron and residual carbon. The authors developed new types of iron ore raw materials - fluxed local spikes from iron ore concentrates of different degrees of enrichment, local spikes with increased compared to agglomerate and pellets, iron content and local spikes with high residual carbon content. To obtain local heat, as a high-temperature part of the charge, metallized rolls, metallized ores or mixtures thereof were used. It is shown that the proposed mono-raw material can be produced in existing shops for the production of fired rolls, and can significantly improve the technical and economic performance of pig iron smelting. The components of the charge were mixed, after which the mixture was subjected to heat treatment with a gaseous coolant with oxidizing or weakly oxidizing potential. The specific productivity of the combustion unit and the specific costs of energy resources (heat and electricity) in the production of scuffed mono-raw materials remained almost identical for the production of other local heat. The results of the calculation of blast furnace smelting indices when using in its charge flaked fluxed mono-raw material with high iron and carbon content are presented. Calculations show that the use of this material in blast furnace production will significantly improve the technical and economic performance of pig iron smelting.

ВПРОВАДЖЕННЯ СИСТЕМ ПІДТРИМКИ ПРИЙНЯТТЯ РІШЕНЬ ЩОДО УПРАВЛІННЯ ДОМЕННОЮ ПЛАВКОЮ В УМОВАХ МЕТАЛУРГІЙНОГО ВИРОБНИЦТВА ПрАТ “ДКХЗ“

The aim of the work is to increase the level of automation of blast furnace production through the development and implementation of new systems to support decision-making on the management of blast furnace smelting in changing technological and fuel conditions. The article presents a description of three decision support systems (DSS) in the mode of an adviser to the technological personnel of blast furnaces, which were implemented by the Iron and Steel Institute or underwent pilot testing as part of the automated control system of the blast furnace shop of the metallurgical production of PrJSC "Dniprovskyi Coke Plant" (Kamianske). The first DSS for managing the thermal state was implemented in 2021, it includes the entire list of information necessary for personnel in a convenient and compact form, generates recommendations in case of technology deviations and, in case of incorrect actions of the personnel, signals the need for correct actions. The main recommendations of the system are to correct the raceway adiabatic flame temperature, coke consumption when its characteristics and ore load change. Using the system allows both reducing the specific coke consumption and preventing unplanned downtime. The second DSS for controlling the distribution of fuel additives over air tuyeres is based on information on thermal loads determined on water-cooled elements of tuyere tools. The main recommendations of the system are to adjust the amount of injected pulverized coal fuel on individual tuyeres in order to ensure a uniform distribution of the raceway adiabatic flame temperature around the circumference of the blast furnace and, as a result, the energy efficiency of blast furnace smelting. The third DSS for adjusting the parameters of the charging mode is based on information from the means of controlling the temperatures of the gas flow above the surface of the charge in the blast furnace. The functioning of this system is based on determining the reference curves for the distribution of the gas flow along the furnace radii, corresponding to the minimum consumption of coke and maximum productivity, and on the search for solutions by direct and iterative optimization methods, which allow, by adjusting the loading parameters, to ensure a rational distribution of charge materials and gas flow in the furnace.

A Model to Control the Formation of Multi-Component Charge Portions on a Blast Furnace Conveyor

Introduction. Bell-less tops used in the charging area give significantly wider opportunities for regulating and distributing the charge material along the furnace top radius. Moreover, it becomes feasible to develop the methods for gas flow control and these methods shall differ from the conventional ones. One of such methods is introduction of multi-component portions of the charge with a technology based component ratio. Problem Statement. The bell-less top charging device is not designed for that type of portioning when the charge material mixing is accompanied with a simultaneous shift of one component with respect to other one for a certain set value, while charging. These portions can be formed with the use of computer-aided stock-conveying system, while discharging the material from weighing hoppers into the blast furnace conveyor. Purpose. This research aims at the development of the structure, the functioning algorithms and the mathematical model for the system to control the formation of multi-component mixed charge batches in order to increase the blast furnace productivity and to reduce the specific coke consumption. Materials and Methods. In this research, the methods of automatic control theory and artificial intellect for the synthesis of weight neuro-fuzzy controllers within the automatic control system of charge dosage have been used. The developed system designed to control multi-component charge portioning via PC has been tested by means of simulation modelling methods. Results. There has been developed an algorithm for operating the system for controlling the multi-component mixed charge preparation on the conveyor, given the arrangement of the specified components, their ratios in portions, total volumetric productivity of the conveyor, the variable geometry of the unloaded material, in the connection with the on-line information on the mixing process. The feasibility of the system has been verified by its simulation with the use of standard application tools. Conclusions. It has been established that the designed control system allows the formation of mixed portions of any composition defined by an operator at a given maximum output of the conveyor and prevents its overload in terms of mass or volume.

A Model to Control the Formation of Multi-Component Charge Portions on a Blast Furnace Conveyor

Introduction. Bell-less tops used in the charging area give significantly wider opportunities for regulating and distributing the charge material along the furnace top radius. Moreover, it becomes feasible to develop the methods for gas flow control and these methods shall differ from the conventional ones. One of such methods is introduction of multi-component portions of the charge with a technology based component ratio. Problem Statement. The bell-less top charging device is not designed for that type of portioning when the charge material mixing is accompanied with a simultaneous shift of one component with respect to other one for a certain set value, while charging. These portions can be formed with the use of computer-aided stock-conveying system, while discharging the material from weighing hoppers into the blast furnace conveyor. Purpose. This research aims at the development of the structure, the functioning algorithms and the mathematical model for the system to control the formation of multi-component mixed charge batches in order to increase the blast furnace productivity and to reduce the specific coke consumption. Materials and Methods. In this research, the methods of automatic control theory and artificial intellect for the synthesis of weight neuro-fuzzy controllers within the automatic control system of charge dosage have been used. The developed system designed to control multi-component charge portioning via PC has been tested by means of simulation modelling methods. Results. There has been developed an algorithm for operating the system for controlling the multi-component mixed charge preparation on the conveyor, given the arrangement of the specified components, their ratios in portions, total volumetric productivity of the conveyor, the variable geometry of the unloaded material, in the connection with the on-line information on the mixing process. The feasibility of the system has been verified by its simulation with the use of standard application tools. Conclusions. It has been established that the designed control system allows the formation of mixed portions of any composition defined by an operator at a given maximum output of the conveyor and prevents its overload in terms of mass or volume.

Improvement of Technical and Economic Performance of Blast-Furnace Smelting by Pellet Composition Optimization

One of the main methods to intensify blast-furnace smelting is to improve the quality of the sintered raw materials. The article presents the study results of the influence of the composition and metallurgical properties of various Mikhailovsky GOK pellets introduced into the blast-furnace charge based on the technical and economic indicators of the blast-furnace treatment. The studies include physical modeling of pellet production of various composition, experimental determination of their metallurgical properties, as well as blast-furnace smelting simulation using the balance logical-and-statistical model of the Institute of Metallurgy, Ural Branch of the Russian Academy of Sciences (IMet). According to the simulation results, the productivity of the blast-furnace process increases when using all the test pellets, and the specific coke consumption decreases. It is revealed that when using iron-rich pellets in the charge, the sulfur concentration in the slag is significantly higher, which creates the risk of producing substandard cast iron. Based on the obtained data analysis, the technology for the use of enriched pellets (SiO2 at the level of 6%) seems to be optimal, as it provides an increase in productivity with a relatively low coke consumption and acceptable slag sulfur content.

Control of Blast Furnace Filling Based on Cluster Analysis of Burden Surface Temperature

The cluster analysis of burden surface temperature and plotting graphs, in which nodes are predicted states and edges are a type and weight of filled materials, is a control tool of the blast furnace operation. The control of material charge aiming for a high efficiency of furnace operation (high yield of cast iron, t/day, low specific energy consumption) is maintained by predicted adjustments of weight or filling frequency on the basis of cycles in graphs with the highest ore charge. The proposed control methods make it possible to maintain efficient operation modes of furnace, to increase ore charges, and to decrease specific coke consumption by 4%.

Mastering technology of blast furnace iron smelting using pulverized-coal fuel in the PAO NLMK BF shop № 2

Application of pulverized-coal fuel (PCF) for coke saving is strategic direction of energy costs decreasing for iron smelting in PAO NLMK blast furnaces, which allows to change the structure of coals supply to the plant and to decrease their summarized consumption. Stages of the technology mastering considered, including period of adjusting the PCF preparation and their supplying to the blast furnaces and at the stage of charging system selection and blast regime adjustment ensuring the maximum degree of CO utilization and the specified performance. Analysis of the dynamics of coke consumption and fuel additives showed that the consumption of total carbon fuel remained almost unchanged, despite the difference in the amount of carbon supplied with natural gas and with the PCF. Calculations made by the mathematical model showed that with an increase in the PCF consumption and a decrease in the consumption of natural gas, the replacement rate of coke with natural gas increased by an average of 0.09 kg of coke per 1 cubic meter of natural gas. As a result of the iron smelting technology mastering, in the PAO NLMK BF № 2 a specific coke consumption decrease reached by more than 80 kg/t of iron and natural gas consumption decrease by more than 60 m3/t of iron. The conditions were revealed for the blast furnaces to operate as with minimum coke consumption and with maximum intensity. The blast furnaces operation in the determined regime parameters allow to decrease the fuel costs for iron production.

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.