ШЛЯХИ ВДОСКОНАЛЕННЯ ТЕХНОЛОГІЇ ПІДГОТОВКИ ЧАВУНУ ДО КИСНЕВО-КОНВЕРТЕРНОЇ ПЛАВКИ

Abstract

The aim of the research is to find ways to improve the technology of the iron preparing for the oxygen-converter smelting. This development will help to increase the competitiveness of Ukrainian plants’ metal products.Methodology. During the research, the analysis of iron refining technologies, which are used at metallurgical plants of Japan, the USA, Western Europe and Ukraine, was provided. The main factors, which largely determine the low competitiveness of metal products in Ukraine, have been established. It is shown that in order to increase the steel production’s efficiency, it is necessary to develop an energy-efficient one-stage technology for preparation of iron for converter smelting. It could be done by the preliminary refining of iron with the removal of silicon and sulfur from it in a casting ladle.Results. The research of one-stage preliminary complex processing of iron made it possible to determine that in this variant of iron processing, desiliconization of the melt is ensured in the reaction zone of the oxygen-fuel stream action. The stream carries powdered dolomitized lime in suspension. The process is accompanied by the emission of heat and intense slagging of CaO particles. It ensures the formation of floating drops of synthetic slag, which is close to the CaO – SiO2 – Al2O3 – MgO system with a reduced oxidation potential. At the same time, the desulfurization of iron is proceeded in the bubbling zone through the interaction of sulfur with floating drops of synthetic slag, which have a high absorption capacity for sulfides. The formation of the main cover slag is also ensured in order to intensify the desulfurization process. The formation of the main cover slag reduces the losses of iron in the form of beads during slag downloading and increases the temperature of iron during its processing.Scientific novelty. The scientific substantiation of research is provided. The subject of the final research is the mechanism and kinetics of the process of simultaneous desiliconization and desulfurization of iron . A new energy-saving technology for iron refining in a casting ladle with simultaneous removal of silicon and sulfur in the combined reaction zone is proposed. This reaction zone is formed by the blowing powdered lime dolomite into the melt through a submersible lance in oxygen-fuel streams. One of the features of such technology is preliminary feeding of pig or rod aluminum into the metal.Practical use. An improved technology of one-stage preliminary complex processing of iron in casting ladles with simultaneous removal of silicon and sulfur is proposed. This technology will significantly reduce the loss of iron and heat with the loaded slag during processing. As a result of this technology’s implementation, the percentage of silicon and sulfur in iron will be reduced to the level of 0.15 – 0.30 % and 0.005 – 0.010 %, respectively, without heat loss. The use of such iron in the production of oxygen-converter steel will reduce the consumption of lime for smelting. It also will reduce the loss of metal with a smaller amount of slag. The use of such iron will aslo reduce the specific consumption of iron.