Furnace Productivity Research Articles

Anomaly detection of the blast furnace smelting process using an improved multivariate statistical process control model

Anomaly detection and early warning of the blast furnace ironmaking process is an important research direction of blast furnace production. In this paper, through the analysis and optimization of the multivariate statistical process control (MSPC) model, MSPC based on TOPSIS and the grey (GT-MSPC) model is established based on the problems of missing alarms, false alarms and untimely prediction in the abnormal detection process of the traditional blast furnace ironmaking production process. First, a composite volatility (CV) that consists of the squared prediction error and T2 is computed to form the MSPC model. The parameters of different training set sizes and different alarm conditions are optimized by using the technique for order preference by similarity to an ideal solution model to optimize the effect of anomaly detection and fault diagnosis. Second, according to the results of the contribution plot, the fault diagnosis of abnormal occurrence is carried out, the main influencing factors of abnormal occurrence are analysed, and the monitoring is strengthened. Finally, the grey model is used to predict CV to realize anomaly early warning and form the GT-MSPC model. By collecting the field data of blast furnace production and performing empirical analysis, the results show that the GT-MSPC model has higher anomaly detectability. The detection rate is 50 % higher than that of the manual observation method, and the GT-MSPC model alarms 16.4861 min earlier than manual detection method. Fault diagnosis can accurately locate the main influencing factors of blast furnace anomalies, such as the furnace body static pressure and differential pressure. In summary, the GT-MSPC model realizes the accurate identification and prediction of anomalies and greatly reduces the occurrence of missing and false alarms and untimely prediction in the blast furnace system, thus reducing the risk of blast furnaces. It can be used to assist field engineers in dealing with abnormal faults and improve the product quality and production safety of blast furnace ironmaking.

Techno-economic case study on Oxyfuel technology implementation in EAF steel mills – Concepts for waste heat recovery and carbon dioxide utilization

Compared to integrated steel production via blast furnace and basic oxygen furnace, the electric arc furnace route saves energy and carbon dioxide emissions. While the major part of the energy is provided in the form of electric power, a substantial fraction of thermal energy is supplied by the combustion of direct fuels. In the present study, we describe available options for increasing the energy efficiency and cut down on carbon dioxide emissions in electric arc furnace steel mills. Based on these technologies, we develop possible process layouts including the transition to Oxyfuel ladle preheating, on-site utilization of the CO 2 -rich product gas and off-gas heat as well as the recovery of waste heat from the hot gas duct of the electric arc furnace for process steam production. With the aid of an energy system model, a case study is carried out to determine the potential for fuel savings as well as carbon dioxide and waste heat utilization. In a technical assessment, we investigate the relationship between the storage capacities, the carbon dioxide and waste heat utilization ratios as well as the fuel and CO 2 emission savings. The subsequent economic analysis yields the optimum system layout under different framework conditions.

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.

Situational optimization of the work of the thermal department, taking into account the ordering instability

The task of optimizing the functioning of the thermal department consists in determining such a plan for the operation of a complex of roller furnaces, which guarantees the fulfillment of the received orders for heat-treated steel wire and corresponds to the maximum profit for a given planning interval. To solve this problem, it is necessary to identify the situational and normative models of the performance of the control object, which is implemented by the authors on the proposed clock approach. In order to build models, preliminary comprehensive studies of the production process in the thermal department of the steel wire shop were carried out. The article considers the tact method for constructing a normative model for the functioning of the thermal department, reflecting the multi-mode operation of roller furnaces, which is used to substantiate the situational standards for the productivity of the department, which includes several units. The features of the organization of material flows are revealed; the structure of the technological process of heat treatment has been determined, a rigid connection has been established in the operation of the zones of the roller furnace. Formula-algorithmic normative situational models of the thermal department functioning have been formed, technically possible and standard values of operation cycles, furnace productivity and the department as a whole have been calculated. A tact method is proposed for calculating the standard productivity of a roller furnace, based on the decomposition of the control object (thermal department) and production operations. Variants of the efficient operation of the department are considered, taking into account changes in demand for hardware products, changes in the range of wire, the number of simultaneously operating furnaces, their technological modes and loading. As an illustration, three options for changing the demand for heat-treated wire are considered, for which the optimal modes of use of heat-treating furnaces have been determined.

Numerical Study on Combustion Behavior of Semi-Coke in Blast Furnace Blowpipe-Tuyere-Combustion Zone

Injecting low-cost semi-coke is critical to reducing blast furnace production costs. The combustion behavior of the co-injection of semi-coke and undersized coke powder is still rarely studied. In this work, a three-dimensional CFD mathematical model was established to simulate the gas velocity, temperature, composition distribution and burnout of semi-coke during the combustion of pulverized semi-coke. The influence of mass fraction of semi-coke on the composition and burnout in the combustion zone of blast furnace was also studied. The results show that the maximum concentrations of CO and H2 in the combustion zone are 36% and 8%, respectively. With the decrease of the semi-coke ratio in the blended coal, the fixed carbon content and the calorific value of the blended coal increase, but the burnout of the blended coal reduces. When bituminous coal is single injected, the burnout reaches 70%, which is higher than that of semi-coke. In actual production, for the semi-coke and coke powder injecting into the blast furnace, a proportion of bituminous coal can be appropriately added to improve the burnout rate of the coal blends and increase the H2 content in reducing gas.

Prediction of Blast Furnace Fuel Ratio Based on Back‐Propagation Neural Network and K‐Nearest Neighbor Algorithm

In recent years, CO2 emissions from the industry have gradually become a major concern, with CO2 from blast furnace production processes being an important source. If the key factors affecting the fuel ratio in the production process can be found and predicted, it can effectively guide the blast furnace production and reduce CO2 emissions. Herein, 55 production parameters that are important in the operation of a blast furnace are analyzed, and high‐correlation filtering and reverse feature elimination to find the four parameters that have the most influence on the fuel ratio of the blast furnace are used. These parameters are oxygen enrichment rate, raceway flame temperature, per ton of iron blast consumption, and coke ratio. Finally, two models, back propagation (BP) neural network and k‐nearest neighbor are used to predict the fuel ratio using these four parameters. Using BP is more effective than using K‐nearest neighbor (KNN); the accuracy of BP is 93.02%, and KNN is 90.48% when the error is within 2%.

A metallurgical coke replacement derived from torrefied wood chips pre-treated by wet oxidation

We investigated the use of thermally treated wet oxidized biomass as feedstock to produce a metallurgical coke substitute and subjected the torrefied woodchip to wet oxidation at 80 °C for 30 min. To obtain a metallurgical coke substitute, the wet oxidized biomass was thermally treated at 900 °C at a heating rate of 10 °C/min under N2 atmosphere. Samples were characterised using different techniques. The proximate analysis revealed that the coke substitute had an ash yield of 4.3 wt%, compared to 16.1 wt% for metallurgical coke. The coke substitute had a lower sulphur content compared to metallurgical coke. The results for CO2 reactivity showed that the final reactivity of the prepared coke substitute was six times higher than that of the metallurgical coke. The lower sulphur content, lower ash yield and higher reactivity of the prepared coke compared to the industrial coke is advantageous in the steelmaking industry; these properties will increase blast furnace production and decrease environmental problems associated with the use of industrial coke.

Intelligent optimization system of burden structure in sintering and blast furnace ironmaking process based on improved genetic algorithm

ABSTRACT Under the premise of ensuring the smooth production of the blast furnace, the quality and output of molten iron, minimizing the cost of hot metal and reducing the impact of harmful elements are the most difficult problems faced by iron and steel enterprises at present. The intelligent optimization system of burden structure in the whole process of sintering and blast furnace ironmaking is developed based on the principle of blast furnace ironmaking and material balance, improved genetic algorithm and penalty function. It includes four parts: raw fuel database, intelligent sintering optimization, blast furnace burden structure intelligent optimization and company cost accounting. The industrial application shows that the system can not only guarantee the output and quality of molten iron, but also effectively reduce the cost of molten iron in the process of optimizing the sintering and blast furnace production of the steel company.

SPECIFIC FEATURES OF VECTOR OPTIMIZATION METHODS FOR SELECTING THE OPTIMAL COMPOSITION OF BLAST FURNACE CHARGE

Technological and mathematical formulation of the problem of optimizing the composition of multicomponent blast furnace charge, which will ensure the melting of cast iron of the required composition and the given technical and economic indicators of the melting is formulated. The features of the developed algorithm for solving the problem of multicriteria conditional nonlinear optimization with the use of modified simplex methods (Box, Nedler - Mead) are outlined. As a result, an optimal compromise solution in a given area of constraints is found, taking into account a special class of technological constraints, which makes it possible to form scientifically valid recommendations for choosing a rational composition of charge materials in modern conditions of blast furnace production.

Automatic Control System for Thermal State of Reverberatory Furnaces in Production of Nickel Alloys

Automatic Control System for Thermal State of Reverberatory Furnaces in Production of Nickel Alloys

Polymeric Structure Evolution Behavior Analysis of Aluminosilicate-Based Smelting Slag

The physical and chemical properties of the CaO–SiO2–Al2O3–MgO slag system depend on structure evolution caused by the synergistic mechanism among the components at high temperature, especially the structural complexity of the anion group. In this study, Si–O, Al–O, and Al–Si–O anion groups were found in the high-temperature slag systems at 1773 K. The [Si2O5]2− (Q3) structural unit of the silicate polymer changed to [Si2O6]4− (Q2), [Si2O7]6− (Q1), and [SiO4]4− (Q0) as the binary basicity (R2) and ω(MgO)/ω(Al2O3) increased, while there was a trend toward a simplified structure. That is, the stability of each structural unit weakened, and the relative content of non-bridging oxygen increased. As a result, the degree of polymerization of slag decreased, and the experimental results of the relative content of non-bridge oxygen can be fitted well with the calculations from the reference documents. At the same time, the number of Si–O–Al structural units gradually decreased. The 27Al-MAS-NMR spectroscopy results showed that the structure of aluminate changed from [AlO4]5− tetrahedral structure to [AlO5]7− pentahedral and [AlO6]9− octahedral structure, and the degree of polymerization of the slag decreased. Comprehensive analysis showed that basicity controlled within 1.2 with the ω(MgO)/ω(Al2O3) ratio; less than 0.55 allows for suitable fluidity and energy-saving ability, which is beneficial for the stable and smooth production of the blast furnace.

ORGANIZATION OF ACCOUNTING BY-METALLURGICAL PRODUCTS

In the work according to the reliable financial statements of PJSC "Dnipro Metallurgical Plant" a study of the peculiarities of the organization of accounting for the production of by-products of metallurgical products and considered the principles of formation of production costs in the system of accounts. The characteristic of organizational and administrative structure of the metallurgical enterprise is given; the type of activity and assortment of production output are estimated. The basic principles, elements of the accounting policy of the enterprise are studied and the order "About the organization of the account of the metallurgical enterprise" in the part of accounting display of finished metallurgical production is characterized. It is noted that the organization of accounting at a large metallurgical enterprise is formed using an obsolete system of registers - journals-orders, which were introduced into the accounting system in the last century. This approach to the organization of accounting is not a violation of applicable law, but too time-consuming, some transactions in different journals are duplicated, and their paperwork requires additional costs. Regulations on the accounting policy of the plant were approved in accordance with the NP (S) BU and taking into account the provisions of international financial reporting standards IFRS. In the course of the research it was concluded that the accounting of by-products of blast furnace production is carried out simultaneously with the production of basic metallurgical products. Having formed the logs of accounting entries,it is established that by-products are accounted for from production as finished, and then sent to bring to a certain condition back into production. This approach to accounting is irrational and can not adequately reflect the production process. Therefore, the accounting algorithm of improvement of correspondence of the account of by-products is offered in work and accounting records of formation of reliable cost of by-products (slag) are developed.

Применение кальций содержащих техногенных материалов глиноземного производства в качестве мелиорантов

For utilization of sintering furnace gas purification facilities dust, in addition to the closed dust-turnover scheme, it is proposed to partially withdraw it from the electrostatic precipitators and direct it for use in agriculture. The fields of electrostatic precipitators of alumina production furnaces contain various chemical compounds, therefore it is advisable to use the dust, selected from 1-3 fields of electrostatic precipitators of sintering furnaces, containing more than 30% calcium oxide, as fine powder as ameliorant for deoxidation of soils. The positive influence of introducing wastes of gas-cleaning facilities of sintering furnaces into acidic soil on the increase of morphometric indicators of plant development, germination energy, germination rate, mass of sprouts of test cultures (garden cress and soft spring wheat) has been shown. Experimental studies have shown that plants that were grown in the soil with the addition of this dust have a more developed root system and stronger shoots. Keywords: ECOLOGY, SPECKING STOVES, ELECTROPHILTER DUST, AGRICULTURE, MELIORANT, ACIDIC SOILS

Efficient utilization of copper slag in an innovative sintering process for Fe–Ni–Cu alloy preparation and valuable elements recovery

In this study, copper slag and low-grade nickel laterite were synergistically utilized via an innovative sintering process with multi-force fields. Their sintering performance and the reduction and softening dripping characteristics of Fe–Ni–Cu product sinter were determined. The strengthening mechanism of the innovative sintering technology was revealed. The obtained Fe–Ni–Cu alloy and smelting slag from the melting dripping process were characterized. Carbon emissions reduction and other valuable elements treatment were also discussed. Due to the formation of the denser sinter microstructure and the reduction of high smelting components, sintering performances in the innovative sintering process are substantially improved. Compared with the base case, tumble index and productivity are improved by 24.87% and 19.59%, respectively. Solid fuel consumption is reduced by 27.14%. The reduction and softening dripping characteristics of Fe–Ni–Cu product sinter are excellent as well. The obtained Fe–Ni–Cu alloy with high purity can be used as the high-quality burden for copper-bearing stainless steel and high-strength alloy steel and its quality can be further improved by optimizing the smelting process parameters in the near future. In addition, the obvious carbon emissions reduction in sintering-blast furnace production can be achieved and other valuable elements such as S, Zn and Pb can be conveniently recycled in form of sulphuric acid and Pb–Zn dust, respectively.

Assessment of the possibility of ferrous metallurgy decarbonization

The analysis of the known methods of decarbonization of the production process ferrous metals is given. It is shown that the most effective ways to reduce CO2 emissions from metallurgical enterprises into the environment are sorption from exhaust gases and replacing carbon fuel with hydrogen. However, sorption methods for capturing CO2 are too expensive due to the high cost of sorbents and are accompanied by the formation of a large amount of waste (4.5–8 t/t of rolled stock), for the placement of which large areas are required. Abandoning sinter-blast furnace production and switching to conversion metallurgy will reduce the carbon footprint by 75 %, however, due to the scarcity of scrap, the possibilities of this method are limited. Switching to directpr duction of iron, provided that all types of fuel are replaced by hydrogen, will reduce the carbon footprint by 90 %. At the same time, it will be necessary to have 181 kg of H2 for the production of 1 ton of rolled metal throughout the cycle. To supply all world steel companies with hydrogen, the existing hydrogen-producing capacities will have to be increased at least sixfold. Obtaining hydrogen for the needs of ferrous metallurgy using the cheapest conversion method will increase the cost of rolled products by at least one third, and obtaining this gas by electrolysis will double the cost of rolled products. It will be necessary to create power plants operating with alternative energy sources such as solar panels and wind generators to cover the needs of the metallurgical plant in electricity taking into account the cost for generating hydrogen. The allocation of such plants will require large areas, that are difficult to withdraw from farmland. Decarbonization of ferrous metals production is a complex and costly task, and therefore can be realized only in the long run.

Разработка технологии комплексной переработки шлаков Златоустовского металлургического завода

Introduction. Currently, many metallurgical companies in Russia are experiencing difficulties with the supply of raw materials. One of the solutions to this problem is the involvement in the reuse of secondary resources that are formed in metallurgical processing. So there are more than 15 million tons of them on the territory of Zlatoust steel Mill. The development of metallurgical slag processing technology will partially solve the problem of the company’s own raw material base. Methodology. To develop an effective technology for complex processing of metallurgical slags of Zlatoust steel Mill four samples were taken from various sections of slag dumps. Research results and discussion. The work studied the chemical and mineralogical composition of samples, conducted studies on the enrichment of slags. To study the enrichment of metallurgical slags by the magnetic enrichment method, studies have been carried out, including separation of material with a size of -100 +40 mm on a drum separator and material with a size of -40+0 mm on a separator in a suspended state. The results show that products made of a material with a size of -100+40 mm meet the requirements for direct use in blast furnace production. and products obtained from a size class of -40+0 mm meet the requirements of agglomeration production. The chemical analysis of the obtained products after magnetic separation in a suspended state indicates significant nickel content in the magnetic separation tails of the sample with a size of -40+0 mm. The study of the microstructure of the sample showed that the size of nickel inclusions is on average 1 mm. In this work studies have been carried out on the grinding of tails to a size of less than 1 mm and enrichment on gravity apparatuses. Studies comparing the results of metallurgical slag enrichment on a concentration table and a centrifugal concentrator have shown significantly higher efficiency of slag separation on a centrifugal concentrator. Conclusions. The obtained results on the enrichment of metallurgical slags ofZlatoust steel Mill allows us to recommend a comprehensive processing technology. As a result of enrichment the following products are obtained: magnetic product 1 with a mass fraction of iron 88.4% when extracting 35.2%. magnetic product 2 with a mass fraction of iron 42.7% when extracting 12.4% and nickel-containing concentrate with a mass fraction of nickel 4.85% when extracting 67.9%.

Study of the effect of the composition of the binder on the mechanical characteristics of dust briquettes of electric arc furnace production

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Sintering of iron ore pellets with an increased content of solid fuel

The paper considers the issue of increasing the productivity of blast furnaces. One of the methods, along with increasing the amount of blowing and reducing coke consumption, is the use of high-quality metallized charge. Therefore, the substantiation of the possibility of wide use of solid fuel as a source of thermal energy and reducer of iron oxides, in the production of iron ore ingots is relevant. Research task at in the production of coils: increasing the strength of fluxed coils containing solid fraction fuel 0.08-0.8 mm, improving their degree of metallization and the possibility of transferring part of the recovery process from blast furnace to the stage of sintering of hybrid agglomerated charge materials. N

Development of a mathematical model to monitoring the velocity of subsidence of charge material column in the blast furnace based on the parameters of gas pressure in the furnace tract

A problem of estimating the velocity of subsidence of a column of charge materials using non-contact methods was considered. This is important because the level of furnace charge materials and the velocity of their subsidence are main indicators of melting intensity determining the furnace productivity. The design of a blast furnace and its blast path were described and existing methods and means of controlling the velocity of charge materials in the blast furnace were analyzed. A mathematical model was presented for estimating the velocity of subsidence of charge materials in a blast furnace based on the magnitude and fluctuations of gas pressure along the furnace shaft height. The model is based on the fact that the furnace gases rise up in the furnace shaft through elementary channels in the column of charge materials consisting of a combination of capacitances and resistances. Volume of capacities and values of resistance of elementary channels are constantly changing. This changes hydraulic resistance to gas movement in the blast furnace. The system of differential equations describes the dependence of the amplitude of pressure fluctuations on the amplitude of change in coefficients of resistance and frequency of pressure fluctuations on the frequency of change in coefficients of resistance. The experimental data on velocity of the column of charge materials and fluctuations in the pressure differential in the furnace were processed and their significant relationship was shown to confirm the previous theoretical study results. To assess the model adequacy, the simulation method was used. The results of the simulation model work were confirmed by experimental data. The developed mathematical model can be introduced into production. This will make it more economical and safer through better and more predictable control and improved flexibility in operation under different production conditions.

Solid solubility and site preference of Ti in 3C- and 6H-SiC

Ti is a background impurity in SiC due to its presence in the graphite parts of the SiC production furnace, and it has large impacts on the electrical and magnetic performance of SiC. Herein, the solid solubilities of Ti in 3C- and 6H-SiC were measured at the SiC–TiSi2 thermodynamic equilibrium, and the values of the enthalpy and entropy of dissolution for Ti in 3C- and 6H-SiC were estimated through thermodynamic analysis, which were also confirmed using the formation energy calculation of defects. The soft X-ray emission (SXE) lines of Ti-Lℓ for Ti-doped 3C- and 6H-SiC were explained by the calculated hole transition energies (HTEs) between the L1 and M3 levels in different possible defects, experimentally indicating that Ti prefers the substitution of the Si-site in both 3C- and 6H-SiC. Additionally, the zero-phonon line (ZPL) calculation provided a possible explanation for the origin of the ZPLs in the photoluminescence (PL) spectra of the Ti in 6H-SiC.