Факультет металургійних процесів та хімічних технологій (ДМетІ) <br> Дніпровський металургійний інститут (ДМетІ)

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ENG: Faculty of Metallurgical Processes and Chemical Technologies (Dnipro Metallurgical Institute)

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Adjusting Properties of Electrode Pitch with Fractions of Coal Tar
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Starovoyt, Anatoly; Malyi, E.; Sorokin, E.; Starovoyt, Maria; Popova, O.
ENG: The paper presents the investigation results of the organic mass modification of the impregnating pitch of coal tar with low pyrolysis degree. The processes that form the pitch operational properties in the impregnation technology of graphitized electrodes were studied. Specific features of the modifying additive effect on the quality characteristics of the pitch and its group composition were established. Such technological approach makes it possible to intensify the impregnation process of blanks for graphitized electrodes.
Analysis of the Mechanism for the Occurrence of a Functional Response during Plastic Deformation of Metals and Their Alloys
(National Metallurgical Academy of Ukraine, Dnipro, 2023) Kuznetsow, E. V.
ENG: Purpose. Perfection the method for designing technological operations of metal pressure processing by establishing a functional connection between the parameters of force action and the characteristics of the natural deformation behavior of workpieces during their shape forming process. Methodology. A combined analytical approach, which is based on a synthesis of the results of fundamental and applied research in the field of physics of deformable solids, metal forming technology, as well as in related fields of natural science, is used. Findings. It is shown that the nature of the adaptive functional response of metals and their alloys to deforming influence is determined by the magnitude of possible changes in the thermodynamic potentials of the disturbed volume of the substance. From a technological point of view the most favorable response occurs when the deforming influence on the workpiece is carried out taking into account the natural ability of its substance to relaxation. Originality. The functional relationship between changes in the thermodynamic potentials of the volume of a metal or alloy and its adaptive behavior during the deformation process, as well as in the postoperative period, is described. Practical value. The findings make it possible to optimize the technological processes of machining of metals and their alloys by pressure, taking into account the natural properties and behavioral characteristics of each concrete material under concrete production conditions.
Application of Biomass Pellets for Iron Ore Sintering
(Trans Tech Publications Ltd, Switzerland, 2021) Kieush, Lina; Koveria, Andrii; Qiao Zhu, Zuo; Boyko, Maksym M.; Sova, Artem; Yefimenko, Vadym
ENG: Purpose. The use of biomass as fuel might solve several technological and environmental issues and overcome certain challenges of sinter production. In particular, as revealed by comprehensive analyses, biomass can be used as fuel for iron ore sintering. In this study, we investigate the use of some raw and pyrolysis-processed biomass pellet types, namely wood, sunflower husks (SFH), and straw, for iron ore sintering. In the experiments, the pyrolysis temperature was set to 673, 873, 1073, and 1273 K, and the proportion of biomass in the fuel composition was set to 25%. It was established that the addition of biofuels to the sintering blend leads to an increase in the gas permeability of the sintered layer. The analysis of the complex characteristics of the sintering process and the sinter strength showed the high potential of wood and sunflower husk pellets pyrolyzed at 1073 and 873 K, respectively, for iron ore sintering. The analysis of the macrostructure of the sinter samples obtained using biomaterials revealed that with higher pyrolysis temperatures; the materials tend to have greater sizes and higher amounts of pores and cracks. The composition analyses of the resultant sinters revealed that with higher temperature, the FeO content of the sinters tends to increase.
Coordinated Control of the Composition of 01yut Steel and Deformation Processing Modes to Achieve Specified Mechanical Properties
(National Metallurgical Academy of Ukraine, Ukrainian State University of Science and Technologies, Dnipro, 2024) Velychko, A. G.; Kamkin, V. Yu.; Proidak, Yurii S.
ENG: Purpose: to investigate the influence of the chemical composition of steel on the output from the chipboard and to establish rational parameters of deoxidation and deformation to ensure the specified values of mechanical properties. Methods: physicochemical modeling, thermodynamic calculations, experimental studies. Results: the carbon content and the degree of oxidation of the semi-finished product from the electric furnace for further vacuum treatment to obtain low-carbon steel were determined. With an increase in the oxygen flow rate supplied to the chipboard and exceeding the value required for the stoichiometry of fuel combustion reactions, the oxidation of the semi-finished product increases. To avoid the formation of calcium silicates, it is necessary to have an active oxygen content below 2.5 ppm, which is ensured by the residual content of dissolved aluminum in steel of 0.025-0.027%. Scientific novelty: The use of complex deoxidizers in steel production allows using the synergistic effect of the joint deoxidizing action of deoxidizing elements. The use of the methodology of physicochemical modeling made it possible to effectively solve the problem of predicting the properties of steel. To study the influence of modifier elements, as well as the main alloying components, a number of parameters characterizing the state of the alloy as a whole (Zу, d) were calculated. Based on information on the significant influence of the chemical composition of the steel on its properties, a database of 150 compositions was prepared to determine the optimal composition of ultra-low-carbon steels of the 01ЮТ, 01ЮТА type by the method of physicochemical modeling. Based on the calculations, the concentrations of elements for steels of the 01ЮТ and 01ЮТА grades were selected.
Criterion Assessment of the Efficiency of Injection Equipment during the Injection of Powdered Ferroalloys
(Ternopil Ivan Puluj National Technical University, 2022) Niziaiev, Kostiantyn H.; Khotiun, Vadym I.
ENG: The purpose of the work is determining the efficiency of injection equipment with the injection of ferroalloys of different fractional composition, density and flow deep into the iron-carbon melt, taking into account the parameters of injection equipment (length and diameter of the pipeline and pressure in the powder-feeder). The analytical review of the literature is performed, which confirmed the advantage of powder injection in a teeming ladle compared to traditional technologies of deoxidation and alloying. Based on known mathematical models adapted to specific technological conditions, mathematical modeling is carried out, which takes into account a number of important parameters for technology, including fractional composition, density and consumption of powder ferroalloy, taking into account the parameters of injection equipment. The optimal diameter of the pipeline is determined. Nomograms of the lowest level of carrier gas consumption are designed. With the help of nomograms, it is possible to control the operation mode of injection equipment in obtaining pulsationless transportation of gas-powder mixture depending on the ferroalloy fraction, its flow rate and density, taking into account the diameter of the pipeline. Based on the results of mathematical modeling, the criterion for assessment the efficiency of injection equipment has been deduced, that makes it possible to determine quickly the pulsationless transport of gas-powder mixture depending on the fraction of powder reagent and pipeline diameter. The consumption of carrier gas depending on the fraction of powder reagent and the diameter of the pipeline, which can be used to control the operation mode of injection equipment in order to obtain pulsationless transport of gas-powder mixture has been determined.
Determining Changes in the Temperature Field of a Graphitized Hollow Electrode During Metal Processing Periods in Ladle-Furnace
(РС Тесhnology Сеntеr, Kharkiv, Ukraine, 2021) Ruban, Volodymyr; Stoianov, Oleksandr M.; Niziaiev, Kostiantyn; Synehin, Yevhen V.
ENG: This paper reports an analysis of the process of heating a graphitized hollow electrode (GHE) during steel processing in ladle-furnace. The results of the numerical modeling of electrode operation are given. The data on the temperature field of the electrode were obtained when electricity was supplied and during periods without electrical loading. Values of the Joule heat released at electrode operation during the periods of metal heating in ladle-furnace were calculated; they amounted to 1.11–1.15 MW/m3. Coefficients of the heat transfer by convection have been calculated for the inner and outer GHE surface: 1.60 and 1.80, and 5–17 W/(m2∙°C), respectively. Values of the electrode temperature gradient in the high-temperature zone were obtained, which, for the first heating period, reached 8,286 °C/m, for the third ‒ to 6,571 °C/m. It was established that during the cooling periods of the electrode, the temperature gradient is significantly reduced and amounts to the inner surface of 379 °C/m; to the outer surface ‒ 3,613 °C/m; the vertical plane to the end of the electrode ‒ 1,469 °C/m. The directions to improve the installation’s thermal work and reduce its resource intensity during out-of-furnace processing of steel have been defined. It has been determined that during the periods of electrode operation with current supply, significant values of the temperature gradient are observed, which are concentrated in the end part. During the periods of operation without current supply, a locally overheated zone forms, taking the shape of a torus flattened along the axis, which is created as a result of the accumulation of heat from the preceding period. The data have been acquired on the effect exerted by the gas supply through a hollow electrode on the parameters of formation of the high-temperature GHE regions. It has been shown that the supply of neutral gas through a graphitized hollow electrode at a flow rate of 0.05 m3/min shifts the high-temperature zone to the periphery by 3.5–4.2 mm, as well as reduces its height by 1.0–1.2 mm. The study reported here could make it possible to calculate expedient gas and material consumption for controlling the oxidation of metal and slag, to reduce the consumption of graphitized electrodes, to bring down energy- and resource costs for metal production.
Determining the Impact of Different Types of Biofuels on the Quality of Iron Ore Pellets
(РС ТЕСHNOLOGY СЕNTЕR, Kharkiv, 2024) Yefimenko, Vadym; Boyko, Maxim M.; Zhuravlova, Svitlana V.; Marko, Anatolii; Tanchev, Oleksandr; Dutniy, Ruslan
ENG: The object of this study is the process of roasting iron ore pellets. The study solves the task of replacing fossil fuel with plant-based fuel in order to reduce environmental load and ensure the stable quality of pellets, which is necessary for use in blast furnaces. The influence of biofuel content at a given temperature and air speed on the strength of pellets after roasting was studied. As a result of the research, it was established that the fuel content has a decisive effect on the strength of pellets. Among all types of fuel that were investigated, pellets with the addition of sunflower husks and wood had the highest strength that meets the requirements for blast furnace melting of 200 kilograms. The use of wheat straw and charcoal does not make it possible to completely replace solid fuel in the layer of pellets. The results show that the use of up to 0.36 % of sunflower husk makes it possible to increase the strength of burned pellets compared to samples without biofuel content. Adding all other considered types of fuel reduced the strength of the pellets. These results are explained by the different content of lignin, cellulose, and hemicellulose, which determines the characteristics of the biomass. The high content of cellulose and hemicellulose allows for high hydrophilicity due to the high number of OH groups and positively affects the formation of raw pellets. Volatile substances released during the combustion of biofuel contribute to the formation of spherical pores, as well as their uniform distribution, which prevents the propagation of cracks under load. Research results make it possible to establish the optimal roasting mode, decrease harmful emissions, and bring down costs by reducing fossil fuel consumption.
Didactic Aspects of Distance Learning in the Conditions of Pandemic and Martial Law
(Dnipropetrovsk State University of Internal Affairs, Dnipro, Ukraine, 2022) Galushko, Olena; Kovalenko-Marchenkova, Yevheniia; Chistyakov, Volodymyr G.
ENG: The article deals with the topical issues of improving the effectiveness of the educational process in higher educational institutions in the conditions of a pandemic and martial law. The evolution of distance learning is considered. Peculiarities of the remote form of education, which functions on the basis of modern psychological and pedagogical and information and communication technologies, have been studied. The peculiarities of the organization of the educational process in higher educational institutions in the context of the pandemic and martial law were analyzed, in particular didactic aspects of the educational process in conditions of danger and increased stress. Special attention is paid to the psychological state of students and ways of reducing stress and activating their attention on the educational process, taking into account the types of information perception (audio, visual, kinesthetic, digital). Ways to improve the distance learning process in the conditions of a pandemic and martial law are proposed.
Effect of the Quality Indices of Coal on Its Grindability
(Dnipro University of Technology, Dnipro, Ukraine, 2022) Miroshnichenko, Denis; Koval, Valentine; Bogoyavlenska, Olena; Pyshyev, Serhiy; Malyi, Evgen I.; Chemerinskiy, Michael S.
ENG: Purpose is to determine the effect of quality indices of coal characterized by different degrees of metamorphism as well as petrographic and ultimate composition on the values of its grindability defined by the Protodyakonov and Hardgrove methods. Methods. 14 coal samples being a part of the raw material base of coking and chemical enterprises of Ukraine were studied. In terms of the samples, the parameters of technical, petrographic, and ultimate analysis were identified. GOST 21153.1-75 Rocks. Method of determining the Protodyakonov strength coefficient and ISO 5074:2015 Bituminous coal. Determination of Hardgrove grindability index were used to identify coal grindability. Graphical and mathematical dependencies between the indices of coal quality (R0, Vdaf, Cdaf, Oddaf) and values of its grindability (f and HGI) were developed. Findings. The obtained mathematical and graphic dependencies of the effect of different indices of coal quality (R0, Vdaf, Cdaf, Oddaf) on the values of its grindability (f and HGI) were obtained. It is shown that dependence of coal quality indices with its strength coefficient (f) is much lower (R2 = 0.550-0.716) than with the Hardgrove grindability index (HGI): R2 = 0.807-0.937. Originality. For the first time, comparative measurements of coal grindability according to the Protodyakonov and Hardgrove methods have been performed. It has been identified that the value of these indices are inversely proportional and described by a second-order polynom. Practical implications. The obtained graphical and mathematic dependencies can be used to predict the operation of crushing equipment for both individual coal and the one of different grade and ultimate composition at coking-chemical and heat-producing enterprises.
Electrical Properties of Tin Oxide Based Varistors with PbO Addition in Humid Air
(Lithuanian Academy of Sciences, 2023) Gaponov, A. V.; Abramova, Olena V.
ENG: The purpose of this paper is to study the electrical properties of the obtained ceramic varistors with PbO addition in the environments with different air relative humidity. Methodology. The studied ceramics (99.4–x) SnO2–0.5Co3O4–0.05Nb2O5–0.05Cr2O3–xPbO (mol.%) with the PbO concentration of х = 0, 0.1, 0.5, 0.7, 1 and 2 mol.% was produced by the traditional ceramic technology. The sample baking was taking place at 1250°С during 1 h. In the process of electrode production, the In-Ga eutectic was applied. The CVC of the samples were measured in the contained chambers with relative humidity of 10–86% above the surface of the water solution of a proper salt (the details are given in Ref. [8]). The values of nonlinearity coefficient α = (E/j) (dj/dE) were measured at the current density of j = 1 mА/cm2. The breakdown electric field E1 was estimated at the same value of j. The electrical conductivity σ = j/E was obtained in the area of low currents. The humidity sensitivity coefficient S was calculated for the j(E) characteristic at the low field by S = (σw2 – σw1)/σw1, where σw1 and σw2 are the electricalconductivity of the sample in the area of low currents at the air relative humidity w1 = 10% and w2 = 86%, respectively. The value of the activation energy of electrical conduction Eσ was calculated with the help of temperature dependences of electrical conductivity in the low electric field by σ = σ0 exp (–Eσ/kT), where σ0 = const, k is the Boltzmann constant, and T is the absolute temperature. Findings. In order to lower the breakdown electric field and simultaneously decrease the humidity sensitivity coefficient of tin oxide ceramics, one can use a small quantity of lead oxide addition. The lowest values of these parameters (E1 = 4390 V/cm and S = 172) were obtained at the concentration of PbO 0.5–0.7 mol.% in SnO2–Co3O4–Nb2O5–Cr2O3–PbO ceramics. The values of the nonlinearity coefficient of such samples are 41–45. The enhancement of PbO concentration increases the low-field electrical conductivity while passing from high voltage varistors to low voltage ones. The obtained new results help to produce SnO2 based varistors that are designed for lower voltage and are less sensitive to the environment influence. Originality. SnO2–Co3O4–Nb2O5–Cr2O3 ceramics is one of the most investigated systems for varistor production [11–13]. It has great non-ohmic current–voltage characteristics (CVC) with quite a large nonlinearity coefficient α ≈ 40–50 and at the same time great gas sensitive properties. Nowadays, the actual task is to decrease the sensitivity of this system to the air humidity. Earlier, this effect was achieved with adding Bi2O3, V2O2 and CuO to the SnO2–Co3O4–Nb2O5–Cr2O3 system [3, 5, 7–9]. Bi2O3, V2O2 and CuO oxides have low melting temperatures, which are less than burning temperatures of ceramics. The samples with such additions have liquid phases in the process of sintering, that is why the sensitivity of these ceramics to the environment decreases. But the humidity sensitivity coefficient of these samples remains quite large [3]. In order to solve the problem of varistor humidity sensitivity, we decided to add lead oxide to the SnO2–Co3O4–Nb2O5–Cr2O3 system. PbO has the melting point Тm ≈ 886°C, therefore the synthesis of such ceramics is the liquid-phase one. There are no published papers about the lead oxide addition to such system. Practical value. The findings may be used in the production of tin oxide SnO2 ceramics with PbO additions in order to use it in optically transparent conducting materials, gas sensitive sensors and varistors.
Energy and Technological Modelling of Metallurgical Processes from Out-of-Furnace Iron Processing to Continuous Casting
(Baltija Publishing, Riga, Latvia, 2023) Stoianov, Oleksandr M.; Petrenko, Vitalii O.; Niziaiev, Kostiantyn G.
ENG: Purpose. Conducted energy-technological modeling of steelmaking processes. It is shown that at different stages of steel production, the increase in energy intensity of steel differs significantly and depends on the chosen technology, equipment and materials used. It has been established that for modern methods of off-blast refining of cast iron, the least energy-consuming technology is the use of mixtures based on lime and magnesium. For the oxygen-converter process, liquid cast iron contributes the largest increase in energy consumption, and for conditions of non-furnace processing of steel, the consumption of electricity for heating the metal. An assessment of the impact of the speed of steel pouring on the MBLZ and the carbon content in the metal on the energy costs of the process is also given.
Improving the Corrosion Resistance of Hot-Rolled Steel Pipes
(Sergeieva&Co, Karlsruhe, Germany, 2023) Bohdan, D. A.; Balakin, Valerii F.; Balakhanova, T. V.; Kuznetsov, Yevhen V.; Nykolayenko, Yuliia М.
ENG: Purpose. Substantiation of the use of surface plastic and dynamic surface deformation (SPD, DSD) combined with anticorrosion inhibitory treatment of general-purpose carbon steel pipes to increase wear resistance of pipelines. Methodology. Samples of hot-formed steel taken from test pipe fragments were subjected to various modes of surface plastic and dynamic surface deformation using corrosion inhibitors. Plastic deformation was carried out with a brush tool with different values of brush pressing against the pipe and processing time. Studies of the protective ability of inhibitors were carried out by an accelerated method with periodic moisture condensation according to DSTU ISO 6270-2:2015. A comparative metallographic study of the metal structure of pipes subjected to PPD and DPD with inhibitors was carried out. Results. The results of experimental studies of the surface corrosion resistance and metallographic structure of 139x5 mm pipes made of steel grade 20 using three types of inhibitors and various modes of dynamic plastic deformation are presented. Scientific novelty. The dynamic surface deformation of metal, which refines its grain structure, creates conditions for formation of "penetration channels" for the inhibitor into the metal structure. The use of DPD makes it possible to reduce the grain size in the surface layer, which suggests possibility of controlling the depth of the inhibitor penetration and, as a result, the corrosion resistance of pipes, depending on the operational requirements. Practical value. It has been established that the use of dynamic surface deformation in combination with a certain inhibitor makes it possible to increase the corrosion resistance by 11–19 times.
Influence of Biocoke on Iron Ore Sintering Performance and Strength Properties of Sinter
(Dnipro University of Technology, Dnipro, Ukraine, 2022) Kieush, Lina; Koveria, Andrii; Boyko, Maksym M.; Yaholnyk, Maksym V.; Hrubiak, Andrii; Molchanov, Lavr; Moklyak, Volodymyr
ENG: Purpose. The research purpose is to substantiate the use of biocoke as a fuel in the iron ore sintering, as well as its influence on the performance and properties of the resulting sinter. To completely replace conventional coke breeze, biocoke is produced using 5 wt.% biomass wood pellets at different carbonization temperatures of 950 or 1100°C. Further, the influence of biocoke on the sintering process and the sinter quality is studied at a high proportion of biomass pellets of 10, 15, 30, 45 wt.% and a carbonization temperature of 950°C. Methods. Carbonization is performed in shaft-type electric furnaces to produce laboratory coke or biocoke. Afterward, the sintering of iron ores is conducted on a sinter plant. To assess the sintering process and the quality of the resulting sinter, the filtration rate is determined on a laboratory sinter plant using a vane anemometer designed to measure the directional flow average velocity under industrial conditions. The sinter reducibility is studied using a vertical heating furnace to assess the effect of coke and biocoke on the sinter’s physical-chemical properties. Findings. It has been determined that biocoke, carbonized at a temperature of 950°C, has good prospects and potential for a shift to a sustainable process of iron ore sintering. Originality. It has been proven that biocoke with a biomass pellet ratio of up to 15 wt.%, obtained at a temperature of 950°C, does not affect the parameters characterizing the sintering process. The sinter strength indicators correspond to the use of 100 wt.% conventional coke breeze. Biocoke used with a high proportion of biomass pellets of 30 and 45 wt.% causes a deterioration in the sinter quality. Practical implications. The results of using biocoke with the addition of 5-15 wt.% biomass pellets and at a temperature of 950°C are within the standard deviation, which makes it possible to use biocoke with 15 wt.% biomass pellets instead of industrial coke breeze.
Influence of Ice Structure on Vitability of Frozen Sand-Water and Sand-Clay Mixtures
(Dnipro University of Technology, Dnipro, Ukraine, 2024) Solonenko, L. I.; Uzlov, Kostiantyn I.; Kimstach, Tetiana V.; Mianovska, Ya. V.; Yakymenko, D. Yu.
ENG: Purpose. To establish influence regularity of sand, water and clay preparation conditions on vitability of frozen mixtures made from combinations of these components and to increase the castings quality in foundries, as well as to improve technologies for artificial freezing of soils for underground constructions. Methodology. In this research, sand, clay, and water are used. Ice quality is estimated visually after water freezing at -15 °C in glass tubes. Frozen mixtures’ vitability at -15 °C is studied on beam-type samples. As indicators of survivability, the time to 1 mm bending of samples on supports and the time to their destruction are accepted. The time is recorded with a stopwatch, the temperature with an alcohol thermometer, the mass with electronic scales and the deflection arrow with a clock-type indicator. Findings. The presence and amount of water-soluble impurities in rare water significantly influence the nature, size and distribution of gas bubbles in ice, as well as frozen sand-water mixtures vitability. Frozen mixtures’ survivability increases with water content in them increasing, and, for sand  water mixtures, survivability is maximum if ice has a homogeneous structure. Among mixtures with clays, the mixture with non-swollen kaolin clay has the greatest vitability. Regarding survivability, recommendations for manufacturing products from frozen foundry mixtures have been developed. Originality. For the first time, deformation change kinetics (bending arrows) under the influence of beam-type samples’ self-mass from mixtures of quartz sand and water and quartz sand, clay and water frozen at -15 °C, which have been previously prepared in different ways, have been investigated. Insights into the influence of various factors and ice quality on the vitability of frozen mixtures have been further developed. Practical value. The obtained results can be useful for expanding ideas about natural frozen soils’ behavior during their cyclic temperature changes, soils artificially frozen during mine shafts elaboration, escalators’ and junctions’ tunnels, etc. when constructing subways. In foundries, the developed recommendations will reduce technological losses and will improve casting quality made using frozen casting molds and cores from sand-water or sand-clay-water mixtures, castings’ patterns and their pouring systems from sand-water mixtures.
International Comparison of Impuritiesmixing and Accumulation in Steel Scrap
(International Society for Industrial Ecology, Blackwell, 2022) Panasiuk, Daryna; Daigo, Ichiro; Hoshino, Takeo; Hayashi, Hideo; Yamasue, Eiji; Tran, Duc Huy; Sprecher, Benjamin; Shi, Feng; Shatokha, Volodymyr
ENG: The accumulation of impurities in the recycling of steel impacts the quality of secondary steel. Understanding impurity levels is crucial in the context of the proliferation of circular economy policies, expected high recycling rates, and growth of scrap consumption. By assuming the accumulation of impurities to be equal worldwide, the understanding of the extent and variation of the mixing and accumulation was limited in previous studies, and the factors influencing those variations were not considered. This is a first cross-national comparison of impurity accumulation in recycled steel. In this study, the copper, tin, nickel, chromium, and molybdenum content was analyzed in over 500 samples of electric arc furnace rebars from China, Japan, Vietnam, Ukraine, and the Netherlands (representing northwestern Europe) with an optical emission spectrometer. The impurity content in rebars represents the content of impurities accumulated in steel scrap in the countries studied. The measured content of impurities was then used to determine the factors influencing the accumulation of those impurities. It was revealed that the recycling technology, the presence of a market for recovered metals, the quality of the material input, steelmaking practices, and the management of byproducts derived from a legislative or economic context played a role in the impurities content. By communicating on scrap chemical content, the collaboration between the recycling and steel industries could be enhanced in terms of matching the demand and supply and facilitating an increase in the scrap share in steelmaking.
Investigating Cavity Formation in an Electric Arc Zone During Out-of-Furnace Processing of Steel
(PC TECHNOLOGY CENTER, Ukraine, 2023) Ruban, Volodymyr O.; Stoianov, Oleksandr M.; Niziaiev, Kostiantyn H.; Synehin, Yevhen V.; Zhuravlova, Svitlana V.; Malii, Khrystyna V.
ENG: The object of this study is the interaction zone between a graphitized hollow electrode (GHE) and a metal bath on the «ladle-furnace» installation. The regularities of the formation of the geometric parameters of the hole were established for the purpose of further evaluation of the heat exchange under the electrode in the arc combustion zone under different operating conditions of the «ladle-furnace» installation. An experimental methodology was devised, and a laboratory setup was built for physical simulation on a cold model. The values of the geometric parameters of the cavity formed by the electric arc discharge in the sub-electrode zone were calculated. In particular, the area of the curved surface of the cavity is about 0.2 m2 at a depth of 40 mm. The regularities of formation of the geometry of the cavity during gas injection through the GHE channel have been established, in particular with regard to the area and depth of the cavity. Thus, with a gas consumption of 3–20 m3/h and a slag cover height of 100 mm, the area reaches 0.28–0.5 m2, while the depth of the cavity ranged from 5 cm to 19 cm, respectively. Rational flow rates of gas supplied through the channel of the graphitized hollow electrode were established, which for a slag cover of 100 mm are 3–6 m3/h and for a slag cover of 200 mm – 6–10 m3/h. The peculiarities of the formation of a metal cavity in the sub-electrode zone under the conditions of gas supply through the channel of a graphitized hollow electrode during out-of-furnace processing of steel at the «ladle-furnace» installation were investigated. The patterns of the formation of the geometry of the cavity in the arc combustion zone, which were obtained using cold modeling, could subsequently make it possible to perform calculations of heat transfer from the electric arc discharge to the metal bath. That will also make it possible to determine the share of heat absorbed by slag and metal under the conditions of using a conventional electrode, and a hollow one with gas supply through its channel during out-of-furnace processing of steel at the «ladle-furnace» installation.
Investigation into the Effect of Multi-Component Coal Blends on Properties of Metallurgical Coke via Petrographic Analysis under Industrial Conditions
(MDPI, 2022) Kieush, Lina; Koveria, Andrii; Schenk, Johannes; Rysbekov, Kanay; Lozynskyi, Vasyl; Zheng, Heng; Matayev, Azamat
ENG: The coalification rank of the coal blend components and their caking properties initially impact the coke’s quality. In part, the quality of coke depends on the technological parameters of the coke production technology, such as the method of blend preparation, the coking condition, the design features of the coke ovens, and the technique used for post-oven treatment. Therefore, to improve the coke quality, the main attention is paid to the quality of the coal blend. The petrographic analysis is the simplest and most reliable way to control coal quality indicators under industrial conditions. In this paper, the effect of nine industrial blends on coke quality using petrographic analysis has been studied. Additionally, this paper addresses the efficient use of coals and the preparation of coal mixtures under industrial conditions, which contributes to the sustainability of cokemaking. For the preparation of blends, 17 coals were used, for which, in addition to petrographic and proximate analyzes, the maximum thickness of the plastic layer was determined. Industrially produced cokes were analyzed for coke reactivity index (CRI), coke strength after reaction with CO2 (CSR), and Micum indices (M25 and M10). It has been established that the petrographic properties of coal blends are reliable parameters for assessing the quality of coke under conditions of an unstable raw material base, multi-component blends, and changes in coking regimes. Moreover, the research results have shown that to ensure the rational use of coals in the preparation of coal blends to achieve the required coke quality and consequently the sustainability of cokemaking, it is necessary to consider not only the mean reflectance of vitrinite but the proximate and caking properties of coals.
Investigation of Physico-Chemical Characteristics of Iron-Containing Technogenic Raw Materials in the Conditions of JSC “AMT”
(Croatian Metallurgical Society (CMS), Zagreb, Croatia, 2023) Mukhametkhan, M.; Mukhametkhan, M.; Zhabalova, G.; Kamkina, Liudmyla V.
ENG: The results of experiments conducted to determine the efficiency of the use of man-made waste, including largescale in volume among the waste of metallurgical production, melted films and sludge of the oxygen converter shop are presented. During the study of the sludge of the converter shop, the chemical, phase, granulometric composition and density of rolling scale and sludge of the oxygen converter shop were revealed.
The Investigation of the Thermal Performance of the Graphitized Hollow Electrode in the "Ladle-Furnace" with the Supply of Neutral Gas
(Physical-Technological Institute of Metals and Alloys of the National Academy of Sciences of Ukraine, Kyiv, 2023) Ruban, Volodymyr O.; Stoianov, Oleksandr M.
ENG: The article presents an analysis of heat transfer efficiency from an electric arc discharge formed in the sub-electrode zone to a metal bath under different operating conditions of the “ladle-furnace” (LF). A numerical modeling methodology has been developed, and the obtained data have been analyzed to determine the heat transfer efficiency with the supply of neutral gas through a graphitized hollow electrode (GHE). The objective of this study is the numerical modeling of the influence of changing the geometric parameters of the metal bath cavity formed by gas injection through the channel of the graphitized hollow electrode on the heat transfer efficiency from the electric arc to the metal bath at different thickness of the slag cover in the “ladle-furnace”. Research methods. Numerical modeling of the heating of the metal bath was performed on a developed 3D model of a steel ladle with liquid metal and a cavity zone formed under the action of an electric arc and gas supplied through the channel of the graphitized hollow electrode. Heating was conducted under different geometric parameters of the cavity and varying heights of the slag cover. The obtained data were analyzed, indicating the advantage of using the graphitized hollow electrode with gas supply through its channel compared to a conventional electrode. Results obtained. The share of heat absorbed by the slag and metal under the conditions of using a conventional electrode and a hollow electrode with gas supply through its channel was determined. The influence of the parameters of the reaction zone formed under the GHE on the heat transfer from the electric arc to the metal bath was determined, with maximum temperature increase values of the metal amounting to 0.6 ºC/min. Scientific novelty. New data were obtained regarding the influence of neutral gas supply through GHE on the amount of heat transferred to the metal by convection, and indicators of the heat flux density from the electric arc to the metal cavity in the sub-electrode zone were determined. Practical significance. It was determined that increasing the area of the metal cavity by supplying gas through the GHE channel improves the heat transfer from the electric arc to the metal bath. Meanwhile, increasing the thickness of the slag cover reduces heat losses to the furnace atmosphere. The carried out research provided important data regarding the thermal performance of the "ladle-furnace" in the sub-electrode zone, which can be further utilized for process optimization.
Metallurgical Coke Production with Biomass Additives: Study of Biocoke Properties for Blast Furnace and Submerged
(MDPI, Switzerland, 2022) Bazaluk, Oleg; Kieush, Lina; Koveria, Andrii; Schenk, Johannes; Pfeiffer, Andreas; Zheng, Heng; Lozynskyi, Vasyl
ENG: Biocoke has the potential to reduce the fossil-based materials in metallurgical processes, along with mitigating anthropogenic CO2- and greenhouse gas (GHG) emissions. Reducing those emissions is possible by using bio-based carbon, which is CO2-neutral, as a partial replacement of fossil carbon. In this paper, the effect of adding 5, 10, 15, 30, and 45 wt.% biomass pellets on the reactivity, the physicomechanical, and electrical properties of biocoke was established to assess the possibility of using it as a fuel and reducing agent for a blast furnace (BF) or as a carbon source in a submerged arc furnace (SAF). Biocoke was obtained under laboratory conditions at final coking temperatures of 950 or 1100 °C. Research results indicate that for BF purposes, 5 wt.% biomass additives are the maximum as the reactivity increases and the strength after reaction with CO2 decreases. On the other hand, biocoke’s physicomechanical and electrical properties, obtained at a carbonization temperature of 950 °C, can be considered a promising option for the SAF.