Browsing by Author "Niziaiev, Kostiantyn H."

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    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.
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    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.
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    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.
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    Phosphorus Partition in an Industrial Basic Oxygen Furnace Process in Ukraine
    (Wiley-VCH GmbH, Weinheim, 2024) Volkova, Olena; Tinkova, Nataliia; Onaa, Rapuruchukwu Ifeyinwa; Neubert, Lukas; Niziaiev, Kostiantyn H.; Zotov, Dmytro
    ENG: Phosphorus partition data from Ukrainian integrated steel plants are analyzed, focusing on the influence of parameters such as the basicity (CaO/SiO2), optical basicity, tapping temperature, and the contents of (FeO), (MgO), and (Al2O3) in the slag. It is found that the phosphorus partition decreases with increase in tapping temperature and increases with the optical basicity. An increase in the phosphorus partition (P)/[P] followed by a decrease with increase of (CaO/SiO2) are observed. It is found that the optimal value, break point at which phosphorus partition changes its dependence to opposite, has a direct dependence on tapping temperature. At (CaO/SiO2) = 1.9–2.1, (P)/[P] increases linearly with increasing (FeO). However with higher value of (CaO/SiO2) the breaking point when (P)/[P] starts to decrease with increase in (FeO) is noticed. Thereby the optimal value of (FeO) decreases with increasing tapping temperature. In case of (Al2O3) there is only decreasing of (P)/[P] with all (CaO/SiO2) and tapping temperatures. Moreover, the effect of (MgO) varies with (CaO/SiO2). These industrial results are supported by thermodynamic simulations using FactSage 8.1 and aligned with existing results from the literature.