Browsing by Author "Molchanov, Lavr"

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    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.
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    Physical Modelling of Additives Dissolution Features in the Bath of an Induction Furnace Crucible
    (Associazione Italiana di Metallurgia, Milano, Italia, 2024) Molchanov, Lavr; Golub, Tetiana; Kononenko, Ganna; Koveria, Andrii; Kimstach, Tetiana V.
    ENG: The technology of melting metals in an induction furnace allows the production of a wide range of alloyed steels to meet the different needs of society and is more environmentally friendly as it produces fewer emissions. A special interest for modern metallurgy are the processes of alloying and deoxidizing, which occur directly in the induction furnace by introducing lump additives. In this work, the investigation of the process of melting of additives during induction melting has been studied in order to determine the optimal modes of introduction of deoxidizing and alloying additives into the melt, providing their maximum assimilation by the liquid metal. The study was carried out on the physical model simulating the crucible of a laboratory induction furnace equipped with a closed system of hydrodynamic circulation of liquid. The results demonstrate that the most rational place for the introduction of ferroalloys into the induction furnace crucible is the area of the melt located at a distance of 1/2 radius from the center of the crucible. There is also a tendency for the dissolution time to decrease as the depth of introduction into the melt increases. Considering that in practical industrial conditions, it is extremely difficult to organize the introduction of deoxidizing and alloying agents into the volume of metal melt, the necessity of holding the melt when introducing ferroalloy is reasonable.
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    Study of the Designs of Bottom Blowing Devices for Oxidative Blowing in Teeming Ladles
    (НМетАУ, Дніпро, 2021) Molchanov, Lavr; Arendach, Natalia; Synehin, Yevhen V.
    ENG: It is discussed in the article the concept proposed for the production of ultra-low carbon steel, which involves the production of crude steel in basic oxygen furnace followed by oxidative blowing with an oxygen-argon mixture in a teeming ladle to decrease a carbon content in steel to less than 0.03%. High efficiency of the proposed technology is possible only under the intensive process of metal decarburization, which consists of the three stages: supply of reagents to the gas bubble, chemical interaction of reagents on theinterfacial surface and removal of reaction products. At low carbon concentrations in the metal, the limiting link of the process is carbon mass transfer to the interfacial surface, which can be intensified by melt stirring. The objective of this article is to study the influence of design of the blowing devices, namely, the position and shape of the pores, on the efficiency of metal homogenization in the teeming ladle. Blowing devices with a circular hole, a slit and undirectional porosity were considered. To perform physical simulation by Buckingham's theorem, similarity numbers were chosen to describe the considered process. In particular, it is proposed to use dimensionless volume flow and a modified homochronicity number. Based on the physical simulation on the “water” model, it was found that the best results of homogenization of the chemical composition of the liquid metal in the teeming ladle show blowing devices with undirected porosity. They are ideal for oxidative purging in a crowded ladle with a mixture of argon and oxygen required for the production of ultra-low carbon steel with an oxygen content of less than 0.03%. The purpose of further research is to develop the design of the mixing chamber of the purge device, in which oxygen and argon are pre-mixed before injection into the liquid metal.