No abstract

Nowadays, one of the pressing issues is the problem of reducing material and energy costs in the production of certain types of products. Of particular importance are issues of slag formation due to the development of a ladle furnace (LF) plant for smelting special and alloyed steel grades with stringent requirements for the content of harmful impurities. Therefore, the question of choosing the rational composition of the slag-forming mixture (SFM) requires special attention. The aim of this work is to carry out research to solve the problems of improving the quality and competitiveness of manufactured metal products. The paper presents analytical and experimental studies of the phase composition and melting temperature of the CaF2-CaO system, which is the basis of the slag-forming mixture for refining steel in a ladle at domestic metallurgical enterprises. Previous studies on the replacement of fluorspar in the SFM with mineral raw materials of the domestic field showed that the alternative is the use of pegmatite from the Eliseevskoye field (Zaporizhzhya region). This contains alkali metal oxides Na2O and K2O, which affect both the decrease in slag viscosity of metallurgical production and the effect of desulfurization of the metal melt. Experimental studies of the melting points of fluorspar, pegmatite, and mixtures thereof with lime have been performed. Also, corundum and periclase-carbon refractory, which is usually used for lining the slag belt of LF buckets, were used as a substrate on which the process of melting of the studied materials and their mixtures took place. It is shown that pegmatite favorably affects the process of lime rarefaction and the formation of slag melt and can be used as a component of the SFM. The use of pegmatite can completely or partially replace fluorspar in the composition of the slag mixture with lime.

The aim of the work is to establish patterns of influence of the chemical composition of blast-furnace slags on the thermophysical properties of their melts, which is relevant to ensure high technical and economic indicators of the blast furnace. Experimental studies of the temperature of molten iron and slag at their release from a blast furnace with a volume of 1500 m3 have been carried out. It is shown that the temperatures of iron and slag have almost identical values and vary in the range of 1451÷14870С. On a Anton Paar rotary rheometer, viscosity measurements were made in the temperature range of 1320 ÷ 15000С and it was shown that the viscosity of slags from the blast furnace output exceeds its optimal value of 0.3 Pa.second. Based on the correlation-regression analysis of the literature data and the performed experimental studies, the enthalpy of the melts was determined as a function of the chemical composition of blast-furnace slags, which are represented through stoichiometry (ρ) and temperature. It is shown that when temperature fluctuations of slag melts in the range of 1453 ÷ 14870С their enthalpy changes in the range of 1933÷2031 kJ/kg. A predictive model for calculating the enthalpy of blast-furnace slags is proposed. On the basis of the proposed predictive model, the enthalpy of blast furnace slags for a blast furnace with a volume of 1500 m3 was calculated taking into account their actual temperatures at the outlet.

The aim of the work is to solve the problem of choosing the optimal composition of iron ore materials for blast furnace loading. An analytical review of the existing approaches to assessing the quality and methods for selecting a rational composition of iron ore materials implemented as part of the control system of domestic and foreign blast furnaces in modern conditions has been carried out. A method of modeling the processes of directional formation of melts, developed at the Iron and Steel Institute, is proposed. The description of the processes of transformation of iron ore materials in a blast furnace and the properties of liquid smelting products was carried out using the parameters of interatomic interaction in melts. The technique uses a set of integral criteria and physicochemical models that allow estimating charge, gas-dynamic and temperature melting conditions. The influence of the quality of iron ore on the properties of primary melts and final products of blast-smelting is analyzed. An integral indicator of the quality of the charge and an integral indicator of the temperature blast mode have been developed. The main difference of the proposed approach to the selection of the composition of the charge from similar developments focused on the traditional criterion «basicity of the final slag» is the use of a set of physico-chemical criteria that characterize the quality and properties of iron ore, primary and final blast furnace slag. The use of the developed prognostic models and criteria as part of automated blast furnace control systems allows us to predict the chemical composition of iron and slag. Stabilization of slag properties within the specified limits ensures the smelting of cast iron of the required composition and a reduction in coke consumption in the current unstable conditions of smelting iron.