DETERMINATION OF HEAT AND MASS TRANSFER CHARACTERISTICS IN THE PROCESS OF DECARBONIZATION OF THE CONVERTER BATHS. MESSAGE 3

High-temperature experimental studies performed using two-chamber models of oxygen converters are devoted to the analysis and study of processes in a converter bath under various modes of combined purging with the supply of mixing neutral gas through the bottom. During the processing of experimental data, the values of changes in the transient and critical carbon concentrations in the melt were determined depending on the conditions and especially the purge mode, the height of the oxygen tuyere and the layout of the nozzles in the bottom. Bottom purging with neutral gas with a flow rate of 0.05 – 0.20 m³/(t∙min), while improving the mixing of the bath, reduces the transient carbon concentrations in the range from 0.9 ‒ 1.2 % for upper purging conditions to 0.4 – 0.5 % for combined purging, starting from which oxygen unused for the oxidation of impurities in the reaction zone begins to intensively calculate the volume of the melt. Based on the experimental data obtained to determine the mass transfer coefficients in the melt, the effective carbon diffusion coefficients for various melting conditions and periods were estimated depending on the steady-state melt circulation parameters and the characteristic dimensions of the steelmaking bath using accepted assumptions and using analytical models obtained by analyzing the shape of the reaction zone and the interaction of gas jets with the melt. Calculation formulas have been obtained and calculations of the characteristics of mass transfer processes in a conversion bath have been performed after reducing the carbon concentration below the transition values determined experimentally. The values of effective diffusion coefficients for laboratory converters have been obtained, which are 20 ‒ 270 cm²/s, based on the characteristics of industrial converters with a capacity of 160 tons, which are 800 ‒ 2700 cm²/s. The information obtained can be used to optimize the designs of aggregates and the technology of combined purging.