КОМПЛЕКСНЕ ДОСЛІДЖЕННЯ ОСОБЛИВОСТЕЙ ПЕРЕБІГУ ОКИСНЕННЯ ВУГЛЕЦЮ В СТАЛЬКОВШІ ПРИ ДОННОМУ БУЛЬБАШКОВОМУ ПРОДУВАННІ СУМІШШЮ ГАЗІВ СИСТЕМИ «КИСЕНЬ — НЕЙТРАЛЬНИЙ ГАЗ»

The out-of-furnace processing unit has long become an important component of the high-quality steel production chain in modern steelmaking conditions. It provides the iron-carbon liquid semi-product that was produced in an oxygen converter acquires the necessary properties and turns into liquid steel. In addition to carrying out deoxidation, alloying or modification in the ladle during out-of-furnace processing, it is possible to continue the oxidation of impurities to the necessary low levels. Such process should shorten the duration of the previous stage of oxygen blowing and reduce losses of liquid steel with slag due to its possible reoxidation during additional blowing time. The paper presents the results of the study of the peculiarities of the oxidation process in a steel ladle under the conditions of the bottom supply of a mixture of gases “oxygen — neutral gas” through a porous block. A thermodynamic study of the predicted oxidation process was carried out according to the Gibbs free energy index that reflects the possibility of free course of reactions. This indicator was calculated taking into account the conditions of bottom blowing in the ladle — the influence of the depth of the bath. It was established that carbon oxidation reactions with the participation of gaseous oxygen receive the highest priority. Research on a low-temperature model of the mixing characteristics of a ladle bath with a bottom bubble purge made it possible to evaluate the rational mode of gas introduction for the evaluated conditions. It was established that for effective carbon oxidation, it is necessary to increase the proportion of the bath covered by bubbles of the purge gas and the time of their stay in the bath, sufficient to achieve homogeneity. Such conditions correspond to the physical model's bottom purge intensity of about 1 m3/t h, that creates a “swirling”, pulsating flow of bubbles capable of involving the largest part of the bath in mixing, even capturing the lower layers. When converted to a real industrial 250-ton ladle, this corresponds to an intensity of 0.34—0.36 m3/t∙h.