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.
Assessment of Soft Skills and Development of Human Resource Management in the Labour Market Competitiveness
(Institute of Market Problems and Economic-and-Ecological Research of the National Academy of Sciences of Ukraine, Odesa, 2025) Furxhiu, Nevila Koçollari; Mulita, Reis; Luchaninova, Olha P.; Harbar, Zhanna
ENG: Introduction. Soft skills are critical and directly affect job performance, adaptability, and the ability to innovate. Soft skills such as creativity, emotional intelligence, critical thinking, and interpersonal interaction increase adaptability to innovation. Readiness for continuous learning and retraining through soft skills is crucial for professional success and competitiveness in the labour market. Aim and tasks. This study comprehensively examines the impact of soft skills on professional competitiveness in the labour market. It develops a multi-level system for assessing these skills, with recommendations for their development in human resource management. Results. The study highlighted the most in-demand skills based on feedback from academics and employers: responsibility (18.2%), creativity (18.9%), communication skills (17.3%), self-organisation (17.2%), emotional intelligence (15.9%), and leadership (12.5%). The content analysis confirms a certain degree of research into job seekers’ demand for soft skills in the labour market. This emphasises its relevance in higher or professional education settings. The employee competitiveness index (ECI) is a composite indicator that integrates the key characteristics of soft skills and amounts to 0.75%. The structural model of the study allowed us to estimate the impact of soft skills on labour productivity both directly and through employment and market demand. In the model, soft skills accounted for 18% of the variance in employment and 30% in market demand, with both indicators exerting significant effects on productivity (β = 0.32 and β = 0.29, respectively). Conclusions. The soft skills of modern specialists indicate their competitiveness in the labour market. The criteria and indicators of soft skills (communication, emotional intelligence, creativity and analytical thinking, flexibility and adaptability, self-organisation and productivity, leadership and management skills) are highlighted, emphasising the vectors for developing these skills. The presence of soft skills increases a specialist’s competitiveness and serves as an indicator of this competitiveness. The development of soft skills increases the competitiveness of employees and contributes to efficiency growth. However, a limitation was identified: some organisations were reluctant to disclose training results, which requires further study.
Characterization of Thermophysical Properties and Crystallization Behavior of Industrial Mold Fluxes
(MDPI, Basel, Switzerland, 2025) Bellé, Matheus Roberto; Yehorov, Anton; Chebykin, Dmitry; Zotov, Dmytro; Volkova, Olena
ENG: This study explores the thermophysical properties and crystallization behavior of two industrial Mold Fluxes (MF1 and MF2) used in continuous steel casting. Viscosity, density, and surface tension were measured using the Rotating Bob Viscometry (RBV) and the Maximum Bubble Pressure (MBP) method, while crystallization dynamics were assessed via the Single Hot Thermocouple Technique (SHTT). Both fluxes showed temperature-dependent viscosity with distinct break temperatures influenced by chemical composition. MF1 had higher viscosity and activation energy (127.72 kJ mol−1) than MF2 (112.11 kJ mol−1) due to its higher Al2O3 content. Density and surface tension decreased linearly from 1523 to 1623 K, with values of 2642–2618 kg m−3 and 299–291 mN m−1 for MF1, and 2708–2656 kg m−3 and 348–305 mN m−1 for MF2. Crystallization analysis showed that MF1 required higher cooling rates (critical cooling rates: 21 K s−1 vs. 18 K s−1 for MF2) for glass formation, highlighting its greater glass-former content.
Complex Solid-Phase Reduction in a Blast Furnace of Self-Healing Pellets of Cold Agglomeration Containing By-Product Carbon Materials of Metallurgical Production
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Vaniukov, Anton A.; Ivashchenko, Valerii P.; Ivanova, Liudmyla Kh.; Kovalov, M.; Tsybulia, Ye.
ENG: The reactions of direct and indirect reduction occurring during the heat treatment of self reducing pellets (SRP) have been studied. In this investigation Blast furnace (BF) sludge which contains particles of coke, has been included in the SRP blend as a source of solid reductant. In the SRP as a part ot the blast furnace burden occur the reactions simultaneously: inside of SRP-direct reduction by Csolid; gasification of carbon and indirect reduction by CO; and outside of SRP-indirect reduction of iron bearing oxides by reducing gas coming from the hearth of blast furnace through the column of charged materials. The experiments was performed continuously from the start temperature (~200 ˚C) to the experimental temperature (500 ˚C; 700 ˚C; 900 ˚C; 1100 ˚C) in argon free environment. Upon reaching the desired temperature argon was replaced by hydrogen during 30 minutes. After that the reduced probe of SRP was cooled in argon. The objective of the present work is to research a quantitate ratio of degree direct reduction inside of SRP and degree of indirect reduction outside of SRP on the top of the blast furnace.
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.
Determination of Bronze БрА7К2О1,5Мц0,3 Crystallization Interval Limit Values and Phase Transformations
(Dnipro University of Technology, Dnipro, 2025) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Solonenko, Lyudmila I.; Repyakh, Serhii I.
ENG: Phase transformations temperatures, crystallization intervals, etc. are any alloy’s fundamental parameters. Alloys’ casting, technological and operational properties are related to them. Nevertheless, unlike two-component bronzes, such requirements for multi-component structural, non-magnetic, corrosion-resistant bronze БрА7К2О1,5Мц0,3 are absent. Purpose. For Cu-Al-Si-Sn-Mn system bronzes, crystallization intervals quantitative values (liquidus and solidus temperatures, crystallization interval size and solid phase relative share in it) have been established. БрА7К2О1,5Мц0,3 bronze’s alloying components’ synergistic and selective influence on its crystallization interval and relative fluidity indicators changing has been determined. Methodology. Well-known methods and research techniques, including thermography, differential thermal analysis, spectral chemical analysis, images analysis digital method have been used in this work. Bronzes fluidity has been assessed using spiral test. Bronze’s alloying elements’ synergistic and selective influences on its characteristics have been determined using chemical elements ratio in it (KR criterion) and experimental data results processing by Excel computer program. Findings. In bronze БрА7К2О1,5Мц0,3 with KR criterion value rising from 0.35 to 0.84, there increase liquidus, solidus temperatures and crystallization interval from 32 to 49 °C. Bronze’s alloying elements’ (Al, Si, Sn, Mn) synergistic and selective influences on its crystallization interval limit values have been determined. It has been established that conditionally-veritable fluidities of БрА7К3О1,5Мц0,3 and БрА9Ж3Л bronzes are practically the same. For Cu-Al-Si-Sn-Mn system bronzes with KR = 0.35‒2.07, solid phase relative volume fraction (φSP) in crystallization temperature range is 60‒63 %. Originality. For the first time, limiting values and phase transformations for БрА7К2О1,5Мц0,3 bronze’s crystallization interval and alloying elements synergistic and selective influence on these indicators have been determined. Practical value. Based on БрА7К2О1,5Мц0,3 bronze’s chemical composition selected, mathematical models have been proposed for its liquidus and solidus temperatures calculating and for transition from dependences of solid phase t(φSP) volume fraction in crystallization temperature range to temperatures’ absolute values t(φSP). Their use will allow increasing the indicators of foundry and technological parameters accuracy forecasting.
Determination of Conditions for Preventing Chemical Wear of Induction Furnace Lining in the "Cupola Furnace – Induction Furnace" Duplex Process
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Nikolaev, Denis A.; Selivorstov, Vadim Yu.; Dotsenko, Yuriy V.; Osypenko, Iryna O.; Kuznetsow, Eugene V.
ENG: The object of research is the melting of cast iron in the “cupola furnace – induction furnace” duplex process. The need to study such a duplex process is dictated by the condition of ensuring the required quality of cast iron in the event that a low-quality or uncontrolled charge is used. This condition cannot be met if the induction furnace is used as the only melting unit. But the problem is that in the process of induction melting of cast iron, in particular at the stage of overheating and holding the melt, a crucible reaction may begin, which leads to chemical wear of the lining. The need to reduce the carbon content in the melt discharged from the cupola furnace requires an increase in temperatures, which creates risks for the onset of a crucible reaction. Based on statistical calculations of cupola melting parameters, it was found that in the melt discharged from the cupola furnace into the induction furnace, the average carbon content is C = 3.47% with a standard deviation SC = 0.14%, and the average silicon content is Si = 2.05% with a standard deviation SSi = 0.21%. At the same time, with a probability of 96%, the carbon content is C = (3.33–3.75)%, and the silicon content corresponds to the range Si = (1.84–2.46)% with a probability of 98%. It was found that the equilibrium constant is in the range (0.15–0.21) with a probability of 97.8% at an average temperature T = 1355°C with a standard deviation of temperature ST = 6°C. With such melt parameters, which are supplied to the induction furnace, the risks of the onset of a crucible reaction do not arise. It was determined that even at temperature regimes sufficient to remove FeO, the risk of the onset of a crucible reaction is minimal. In order to ensure conditions that prevent the onset of a crucible reaction, the following recommendations should be followed for the content of carbon and silicon in high-temperature melting when the temperature is in the range T > 1480°C: C > 0.3% and Si < 0.3%. The results of the study can be used in the melting sections of foundries equipped with cupola furnaces and induction furnaces.
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 O.; 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 Physical-Chemical Patterns during the Formation of Brazed Joints between Tungsten and Carbon-Carbon Composite Material
(TECHNOLOGY CENTER PC, Kharkiv, 2026) Huba, Roman M.; Kamkina, Liudmyla V.; Bushtruk, Serhii I.; Troian, Andrii O.; Asmolovskyi, Serhii Yu.; Oslavskyi, Serhii Yu.
ENG: This study investigates experimentally produced brazed joints between carbon-carbon composite material (CCCM) and tungsten in a vacuum. The task addressed is to obtain high-temperature brazed joints capable of operating at temperatures of 1400–1600°C in a vacuum under conditions of high thermal cycling loads. Existing methods for joining CCCM with tungsten testify for a virtual lack of experience in brazing such materials, especially for structures of thermal emission equipment. In this work, a method was used to produce a metallized layer zone with partial melting using a mixture of Ti-Nb-Zr powders on the inner surface of an CCCM sample. Subsequently, the CCCM and tungsten samples were brazed with a Ti-Nb filler metal at a temperature of 1840°C in a vacuum. The results of microstructural analysis revealed that the brazed joint exhibits a zonal structure. Zone I – a reaction carbide layer (width 10–12 μm), zone II – diffusion layer (width up to 70 μm), zone III – reaction layer adjacent to tungsten (width up to 30 μm). The results of phase formation modeling conducted at a temperature of 1840°C indicate the predominant formation of TiC, NbC, Nb6C5, and Nb2C. Additionally, the distribution of C, Ti, Nb, and W in the brazed joint was determined. The results of the microhardness study confirmed the accuracy of the simulation and showed that microhardness values decrease from Zone I (2300 HV) to Zone III (500–600 HV). The proposed solutions demonstrate that the metallized layer helps retain solder in the joint gap; reduces thermomechanical stresses; and promotes the formation of a gradual hardness gradient. Together, these characteristics improve the ductile properties of the brazed joint. The results of this study could be applied in the field of instrument engineering, specifically in the manufacture of cathode components whose emitters are made from ultrafine powders of rare-earth borides or their alloys.
Determining the Heat and Mass Transfer Patterns in the Tundish of a Continuous Casting Machine
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Terekhov, Dmytro A.; Ruban, Volodymyr O.; Stoianov, Oleksandr M.
ENG: This study’s object is the thermal state of the tundish ladle in a continuous billet casting machine, aimed at prolonging the duration of the series of melts. This paper reports the numerical modeling of the heat and mass transfer processes in the tundish ladle of a continuous billet casting machine (CCM). The model takes into account the hydrodynamics of liquid steel, as well as the temperature distribution in the multilayer lining and the ladle casing; it also makes it possible to predict local wear of the lining based on the analysis of the technological parameters of the process and the chemical composition of steel. Special attention is paid to the study of the temperature and turbulent characteristics of the flow, the residence time of the steel in the ladle, and the influence of its composition on the intensity of destruction of the lining layers. The results make it possible to localize critical areas of thermal and mechanical overload of the ladle lining, in particular the contact zones of the liquid steel jet and the wall areas near the turbos tops, where the following are recorded: shear stress up to 275 Pa; turbulent kinetic energy over 0.14 m2/s2; and metal temperature up to 1830 K. The local wear map built shows the distribution of the lining erosion rate within 2.4–4.3 mm/h depending on the hydrodynamic and chemical conditions. The predictive model combines CFD parameters, the chemical composition of steel, and the pouring speed, which showed high accuracy confirmed by the coefficient of determination R2 = 0.99937. A feature of the result is the comprehensive combination of local flow conditions and steel composition with the erosion model, which has made it possible to give engineering-based recommendations for optimizing the ladle operating modes. The developed predictive model of liner wear rate could be used to monitor its condition, improve ladle operating modes, and increase the reliability of the continuous casting process.
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.
Improvement of Pig Iron Production Technology by Using the Useful Properties of the Potential of Secondary Resources of Raw Materials and Fuels
(Ukrainian State University of Science and Technologies, Dnipro, 2026) Mishalkin, A. P.; Ivashchenko, Valerii P.; Yaroshenko, O. V.; Petrenko, Vitalii O.; Chumak, D. D.
ENG: The scientific and technical relevance of the study lies in determining the directions for improving the ways of using the useful properties of secondary resources in order to intensify the blast furnace process, increase its energy efficiency and reduce pollutant emissions. At the same time, economic efficiency is achieved by reducing the cost of purchasing primary raw materials and reducing waste generation, which corresponds to modern concepts of sustainable development on the way to "green" metallurgy. Purpose of the study. Scientific and practical substantiation of directions for improving the technology of pig iron production through the use of useful properties of secondary resources of raw materials and fuels that have a man-made origin. It is aimed at increasing the level of energy efficiency and improving the slag regime of the blast furnace process, reducing the man-made load on the environment of industrially developed regions of Ukraine. To achieve this goal, the following theoretical and practical tasks will be solved in the study: 1. The analysis of the current state of use of secondary resources of mineral raw materials and fuel in blast furnace production in the conditions of world and domestic metallurgical enterprises has been carried out. 2. The physicochemical properties of the most common types of secondary resources (man-made wastes of metallurgical origin: dust, sludge, scale, production of metallurgical lime: fractions from gas cleaning devices and heat treatment products of waste of plant origin, which are sources of pyrocarbon) have been investigated. Further - determination of the spectrum of their probable purpose, impact on the features and indicators of the blast furnace process, as well as justification of rational ways of their preparation and use. 3. Rational shares of substitution of traditional raw materials and fuels with secondary materials in the blast furnace process are substantiated, the use of which will not reduce the quality of pig iron and will not increase the specific consumption of coke. Their influence on physicochemical and heat-gas-dynamic processes, which is reflected in the characteristic zones of the blast furnace, has been studied. 4. The optimal technological schemes and recommendations for the methods of introduction and rational specific consumption of innovative materials based on man-made wastes have been determined, which will ensure the maximum level of use of their useful properties in the material and thermal balances of the blast furnace process. 5. The technological and environmental advantages of introducing into the blast furnace process a monomaterial, the composition, physicochemical features and spectrum of purpose of which are formed by heat treatment of a mixture of man-made industrial waste, are evaluated and their prospects as a substitute for the corresponding part of pulverized coal fuel (PCF) and fluxes are determined. Research methods. When conducting a comprehensive study, the following methods will be used: - analysis and generalization of materials of scientific and technical literature and patent sources, coordination of their results in accordance with modern trends and the best results of the practice of using secondary resources in blast furnace production; - physicochemical methods of analysis chemical, thermogravimetric, to determine the composition, structure, metallurgical value, probable spectrum of purpose and reactivity of secondary resources of materials - substitutes for iron ore raw materials, coke and pulverized coal fuel (PCF); - thermodynamic forecasting and kinetic modeling of the behavior of experimental materials of secondary origin under the conditions of their heat treatment to assess the influence of their properties on the course of physical and chemical processes and transformations to the thermal and gas-dynamic regime of the blast furnace. The expected results of the study should also include: - development of scientifically grounded recommendations for the effective use of useful properties of the initial potentials of secondary resources of raw materials and fuel in blast furnace production; - establishment of quantitative ratios regarding rational levels of substitution of traditional fuel and raw materials with secondary ones, without reducing the productivity of the furnace and the quality of pig iron while reducing the specific consumption of lime and PCF; - development of a method for the implementation of a complex technological scheme for the preparation, heat treatment of experimental mixtures based on components of mineral raw materials and fuel, followed by the use of an innovative product in the conditions of blast furnace production of pig iron; Scientific novelty of the work. For the first time, systematically, on the basis of the results of an analytical and practical study, the energy efficiency of production and use in the blast furnace process of a two-component monomaterial based on dispersed waste from the production of lime and materials – waste of plant origin, obtained by implementing the effect of their pyrolysis under conditions of joint heat treatment of the initial mixture layer, was substantiated, tested on high-temperature models, poured thermal, in an inclined rotary drum-type furnace. For the first time, a resource-efficient and results-efficient approach has been used to assess the efficiency of the use of materials based on secondary resources of metallurgical and plant origin, based on an integrated combination of the results of thermodynamic forecasting, physical modeling and taking into account the provisions of the exergical methodology for assessing the energy efficiency of the objects of study. Methodological bases have been developed for the selection of rational schemes for the introduction of complex materials based on secondary materials into the blast furnace charge and in the air blast flow to stabilize gas-dynamic conditions in the charge layer, intensify recovery processes with a decrease in the specific consumption of coke per ton of liquid pig iron. The regularities of the influence of the composition and dispersion of secondary resources on the gas-dynamic and thermal parameters of blast furnace smelting have been revealed, which makes it possible to increase the accuracy of predicting the furnace course. It has been proved that the use of materials based on secondary resources of mineral raw materials and fuels can provide the effects of increasing the energy efficiency of pig iron production and reducing the environmental burden, which meets the requirements of sustainable development and the concept of "green metallurgy".
Improving the Cleanness of Low-Carbon Tube Steel Under Steel Plant Conditions
(John Wiley & Sons Ltd., 2026) Zotov, Dmytro; Niziaiev, Kostiantyn H.; Uzlov, Oleg; Puchykov, Oleksandr
ENG: Reducing the number of nonmetallic inclusions in high-quality steel rolled products is of great importance for all steel plants. One of the ways to decrease the size and quantity of alumina and silicate nonmetallic inclusions could be suppressing their formation during steel tapping from the BOF converter to the ladle. This could be achieved by changing part of the aluminum for alternative deoxidizers which do not remain in crude steel. Steel deoxidation with the help of calcium and carbon compounds may allow for a drastic decrease in the quantity of alumina nonmetallic inclusions because of the positive effect on their solubility in liquid steel as well as redundant oxygen removal as a gas in CO and CO2 compounds. Another way to eliminate endogenous Al and Si inclusions is to create favorable thermodynamic conditions to maximize the transfer of nonmetallic inclusions into slag during subsequent ladle furnace treatment. Establishing an optimum range of slag basicity may allow to suppress the harmful spinel inclusions. The effect of calcium carbide preliminary deoxidation during pouring of the semifinished product from BOF converter on the content of nonmetallic inclusions in flat-rolled product has been analyzed. It has been shown that partial replacement of aluminum with calcium carbide during deoxidation of crude steel by BOF tapping together with liquid slag basicity control during ladle furnace treatment allows to reduce content of nonmetallic inclusions in low-carbon steel.
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.
Improving the Performance Properties of Drill Rods for Drilling and Blasting Operations
(M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine, Dnipro, 2025) Minieiev, Serhii; Pazynich, Artem; Hankevich, Valentin; Kiba, Viacheslav; Livak, Oksana; Akulinin, Danil; Pronina, Hanna M.
ENG: The article examines the operating conditions of drilling equipment, particularly drill pipes. The purpose of this study is to develop drill pipes based on the load they experience and the material they are made of. Factors influencing the wear of drill pipes are identified, including friction at pipe joints, thermal wear, abrasive wear, oxidative wear, and others. The working conditions and loads on drill pipes under various drilling scenarios are analyzed, including the maximum loads encountered during the drilling of hard rock using roller bits. The functions of drill pipes are considered, such as transmitting axial force and torque, transporting drilling fluid to the drilling site, removing rock debris from the wellbore. The study justifies and selects materials for drill pipes that balance strength and cost while meeting the requirements of drilling equipment. To achieve this goal, the stress-strain state of drill rods during rotary drilling under operational loads was studied, considering the displacement of working loads or the misalignment of the drill rod and bit axes. Mathematical calculations and data processing are performed using the engineering software package MATHCAD for drill pipes with an outer diameter of DD and an inner diameter of dd, depending on the physical and mechanical properties of the pipe material, axial load on the drill string, and the torque transmitted by the drill pipes. The article provides calculations for drill pipes used in roller drilling of 200 mm diameter wells in hard rock. Connections between drill pipes are analyzed, particularly a specialized locking threaded connection with an increased thread profile height. The study reviews designs used in international practice and domestic drilling equipment manufacturing. A design and calculation of the threaded connection for drill pipes made of 40X steel are presented, along with drawings of the calculated thread profile. The operating conditions of drilling equipment and factors affecting the wear of drill pipes are examined, and recommendations for extending their service life are provided, which can be utilized in the design of new drilling equipment. Suggestions and structural solutions to enhance the performance characteristics of drill pipes are proposed, allowing the selection of optimal material parameters and structural elements of drill pipes based on the operating conditions of the drill string.
Influence of an Electromagnetic Field on Direct Reduction of Iron Oxide Using Hydrogen as a Reducing Agent
(Wiley-Blackwell, USA, 2026) Levchenko, Mykyta; Gryshyn, Oleksandr M.; Velychko, Oleksandr H.; Grek, Oleksandr S.; Nadtochiy, Anzhela A.; Volkova, Olena
ENG: This work investigates the effect of electromagnetic fields (EMF) of varying frequencies on the reduction process of iron oxides and industrial iron ore in a hydrogen atmosphere using thermogravimetric analysis. Both extremely low-frequency (50 Hz) and middle-frequency (25 kHz) EMFs were found to increase the reduction degree and accelerate the reduction reaction compared with experiments without EMF. The application of extremely low-frequency EMF did not cause additional thermal heating of investigated samples. However, with middle-frequency EMF, heating of charged material was observed, which was effectively compensated for by the furnace's automatic power regulation. Experiments with industrial iron ore confirmed that EMF application had a positive effect on reduction process even above the Curie temperature, indicating that the effect is not governed by magnetic properties of iron. These findings demonstrate that EMF-assisted hydrogen reduction can enhance reaction kinetics and reduce hydrogen consumption, offering a promising pathway toward more energy-efficient and sustainable steelmaking.
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.
Metallurgical Processing of Converter Slag
(Satbayev University, Institute of Metallurgy and Ore Benefication, Kazakhstan, 2021) Tleugabulov, S. M.; Aitkenov, N. B.; Zhabalova, G. G.; Velichko, Aleksandr; Uleva, G. A.
ENG: Converter slurries at modern metallurgical plants represent a significant part of metal-containing industrial waste with a high concentration of iron. Currently, there is a problem of their utilization and use as raw materials for metallurgy. The purpose of this work is to study the processes of briquetting and recovery of briquetted products, based on a mixture of converter slurries of gas purification and converter slags. When performing experimental studies on the preparation of sludge briquettes from a mixture of converter sludge of gas purification and converter slag, their metallization and reduction melting in laboratory conditions, the optimal composition of the components of the mixture of converter slag and gas purification sludge was determined by the percentage of iron, which is appropriate for use as a raw material for steel smelting. Experimental studies on the preparation of sludge-coal mixtures from dispersed metal-containing and carbon-containing industrial waste with stoichiometric coal consumption for the recovery of extracted metals have proved the possibility of obtaining sludge-coal briquettes, which are further subjected to metallization and reduction melting. Sequential processing of dispersed production waste, namely drying, metallization and reduction melting, allowed us to obtain at the final stage a metal sample that corresponds to high-quality steel in its composition. Based on the analysis of the results of experimental studies, the technology of reducing melting of metal-containing waste has been developed. As a result of the implementation of the technology, high-quality steels and alloys can be obtained without carburizing the metal, bypassing the production stages of cast iron and high-carbon alloys. The content of harmful impurities of sulfur and phosphorus meets the technical requirements of high-quality steel. The proposed technology for processing slag and sludge from oxygen-converter production will reduce the volume of accumulated production waste.
Method of Sequential Approximation in Modelling the Processes of Heat Transfer and Gas Dynamics in Combustion Equipment
(MDPI, Switzerland, 2022) Rimar, Miroslav; Yeromin, Oleksandr O.; Larionov, Grigoriy; Kulikov, Andrii; Fedak, Marcel; Krenicky, Tibor; Gupalo, Olena V.; Myanovskaya, Yana V.
ENG: The behavior of the processes taking place in furnaces determines the efficiency of fuel chemical energy utilization, the quality of the final products and the environmental safety of the production. Mathematical models of the processes of gas dynamics and heat transfer in the working space of heating equipment are quite complex, and do not allow the establishment of a direct analytical relationship between the quality indicator of the process (F) and the influencing parameters (xi). To simplify the procedure for obtaining the values of the function F depending on the change of parameters xi, a method of successive approximation is presented in the article. The main idea of the method is that the representation of the function around a point from the domain of the function can be extended to the entire domain for many problems of mechanics. The relative error in the definition of the function acquires its maximum value at the border of the area, and a reasonable narrowing of it allows control of the size of the error. Thus, the advantages of using the method are obvious; it is able to provide approximation of the function in a multiplicative form with a controlled error. The distribution of the method to the field of heat transfer problems is presented in this paper. The successful implementation of this method for solving problems of this kind shows that the solution of practical problems may be generalized for the entire domain of the function, despite the fact that the errors of such a representation increase to 5–7% when approaching its limit, which, however, may be considered acceptable for engineering calculations.
A Model to Control the Formation of Multi-Component Charge Portions on a Blast Furnace Conveyor
(National Academy of Sciences of Ukraine, Kyiv, Ukraine, 2020) Rybalchenko, Maria O.; Selegej, Andriy M.; Golovko, Vjacheslav I.; Selegej, S. M.; Mirgorodskaya, O. S.
ENG: 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.
Modification of the Electrode Pitch Operational Properties
(Lviv Polytechnic National University, Lviv, Ukraine, 2021) Starovoyt, Anatoly; Malyi, Evgeniy; Chemerinskii, Michael; Timoshenko, Anatoly
ENG: In this work, the influence of the carbon modifier type and its amount on the processes of carbonization of the electrode pitch and carbon masses for carbon production was investigated experimentally. The paper presents the processes that occur during the carbonization of the electrode pitch and the change in its properties during the modification process. It is shown that the most promising additive is a medium-boiling polymer mixture, which contributes to the carbonization of pitch and improves the physico-chemical properties.
Nanostructured Mesoporous ℽ-Fe2O3: a Novel Photocatalyst for Degradation of Organic Pollutants
(Vasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine, 2021) Hrubiak, A. B.; Khyzhun, O. Yu.; Ostafiychuk, B. K.; Moklyak, V, V.; Yavorskyi, Yu. V.; Lisovsky, R. P.; Keush, Lina G.; Onyskiv, B. B.
ENG: The modified sol-gel synthesis technique was used to created of nanostructured maghemite (γ-Fe2O3). It has been shown that the molar concentration of the original precursors during synthesis affects on the average particle sizes, specific surface area, pore size distributions, optical and conductivity properties. The XPS metod allowed to establish features of electronic structure of the synthesized materials. Optimal conditions for the synthesis of nanostructured maghemite with mesoporous structure were selected. The mechanism of electrical conductivity formation for synthesized mesoporous materials was established. The width of the band gap is determined and its dependence on the molar concentration of precursors is established. The positive correlation between the specific surface area of γ-Fe2O3 samples and photocatalytic activity was installed - the photocatalytic activity of synthesized γ-Fe2O3 increase with growth of specific surface area of γ-Fe2O3 samples.
Online English Speaking Clubs as a Way of Promoting International Student Collaboration
(Başkent University Distance Education Application & Research Center, Ankara, Turkey, 2022) Sharkova, Svitlana; Ageicheva, Anna; Sharkova, Nataliia F.
ENG: Computer-mediated communication despite its traps and pitfalls can become a valuable asset for both foreign language teachers and learners. Nowadays, while using Skype, WhatsApp or Zoom different educational institutions can arrange online sessions of English Speaking Clubs, Round Table discussions to stimulate students to get out of their cocoons and promote international partnerships through technology. Such online meetings of American and Ukrainian students have taken place during the COVID-19 pandemic and Russia’s invasion of Ukraine. However, the process of empowering students with new social skills in digital environment should be critically reflected. The possible ways to facilitate student international collaboration transcending distance and overcoming psychological barriers are described. The chain of activities, including creative tasks and resources that can help educators to equip students with effective social skills, promoting cross-cultural communication are introduced in the article.
The Organization of Iron Ore Agglomerate and Pellets Production with Reduced Environmental Impact
(Baltija Publishing, Riga, Latvia, 2023) Boiko, Maksym M.; Petrenko, Vitalii O.
ENG: Purpose. The steady rise in the cost of traditional energy resources and their negative impact on the environment is leading to an increase in the share of renewable energy sources worldwide. The use of biomass for energy generation based on modern technologies is environmentally safer compared to the energy use of traditional organic resources such as coal. A significant reserve for increasing the use of energy from biomass is concentrated in the metallurgical industry, including the production of pelletised iron ore. Research has been carried out to study the impact of different types of biomaterials on the sintering process of iron ore and the quality of the resulting sinter. The study found that, provided that the process performance and sinter quality are maintained at the appropriate level, it is possible to replace up to 25% of coke fines with charcoal and up to 50% with walnut shells. An analysis of the use of sunflower husks as an alternative fuel was carried out by adding them to the already installed pellet firing system for the grate-tubular kiln-ring cooler installation. It was found that when replacing up to 50 % of natural gas with sunflower husks, the quantitative and qualitative indicators of pellet production remained at the baseline level.
Oxygen Distribution between Phases during Ladle Processing of Aluminum Killed Bof Steels
(НМетАУ, Дніпро, 2021) Boychenko, Serhii; Kirilenko, Yana; Stoianov, Oleksander M.; Niziaiev, Kostiantyn H.; Synehin, Yevgen V.; Sukhovetskyi, Serhii V.
ENG: The modern state of secondary metallurgy is characterized by the sustainable development of technologies that ensure high metal quality by reducing the number of non-metallic inclusions, the which is closely related to the oxygen content in steel after smelting. Therefore, the issues of regularities of oxygen distribution between phases at the stage, BOF - CCM. Purpose. The aim of the research was to determine the conditions of redistribution of oxygen dissolved in the metal depending on the stages of steel processing, to determine the degree of approach of deoxidation processes to thermodynamic equilibrium. Methodology. Research was carried out in industrial scale. Steel grades 34Cr and 36CrB were smelted in BOF of 170–t capacity. Processing of crude steel was carried out in a LF unit with further vacuum degassing and without it and transfer of steel to CCM. At each stage of steel treatment, metal and slag samples were taken using an automatic sampler to determine the chemical composition, and the temperature. Oxygen content were monitored using a "Celox" analyzer. Findings. The carried-out studies showed that before the end of metal processing in the ladle, it is possible to detect individual reoxidation processes caused by unwanted ingress of oxygen from the air and from ladle slag oxides. According to calculations, in the second half of processing in the ladle and during casting, there is a slight deoxidation of steel with aluminum due to a decrease in temperature. Even if during this time due to the exchange reaction between steel and slag, a small amount of Mn and Si is recovered from the ladle slag, while its composition is practically constant throughout the period of steel processing in the ladle, while the metallurgical reactions proceed in the region of thermodynamic equilibrium. Originality. It has been determined that oxygen activity in steel varies unevenly over time and decreases to 3 ppm by the end of treatment in the ladle. While in each case it is in the Fe – a[O] – Al system near the calculated values of thermodynamic equilibrium. Practical value. The use of the obtained regularities makes it possible to obtain the specified content of aluminum in steel for the studied assortment and to predict the burning of deoxidizers and alloying elements, ensuring the reliability of obtaining the required chemical composition of steel with a high degree of purity.
The Phenomenon of Thermodynamic Action during Plastic Deformation of Metals and Their Alloys
(Український державний університет науки і технологій, ННІ ≪Інститут промислових та бізнес технологій≫, ІВК ≪Системні технології≫, Дніпро, 2024) Kuznetsow, Eugene V.
ENG: The most important problem of modern technology for mechanical processing of structural materials is to increase the efficiency of shaping operations. Its full value solution requires the establishment of a functional relationship between the parameters of the force influence on the workpiece and the characteristics of the natural adaptive behavior of the processed material. In this regard, using metals and their alloys as an example, the mechanism and general laws of thermodynamic excitation of solid crystalline bodies during plastic deformation are considered. The relationship between the change in the thermodynamic potentials of the substance of the deformed volume and its behavior during the process of shape forming, as well as in the postoperative period, is described. It is shown based on the synergetic method of analyzing highly nonequilibrium systems that from a technological point of view the most favorable adaptive functional response arises in the case when the deforming influence is exerted taking into account the natural ability of the workpiece substance to relaxation. The got results create the basis for improving the operations of mechanical processing of metals and their alloys by taking into consideration the properties and features of the natural deformation behavior of each concrete material under concrete conditions. They are applicable not only for metal forming operations, but also in cutting technology.