The necessity of an integrated approach in assessing and choosing a technology for secondary desulfurization of cast iron has been substantiated. It is shown that one of the main parameters and indicators is the consumption of the reagent, which determines all the main indicators of the process. A comparative analysis of the indicators in Table 1 also indicates that in the KR process, an increase in the mass of pig iron in the ladle reduces the desulfurization efficiency, since the transition from a ladle with a mass of 80 and 100 tons of pig iron to large ladles (260 tons) is accompanied by a decrease in the specific degree of desulfurization, removal increases the consumption of the reagent per unit of sulfur removed. Significant specific consumption of reagents (up to 8-17 kg / t of cast iron) and the duration of mixing (up to 8-20 minutes), as well as the cycle - up to 25-68 minutes, which causes tangible losses in the temperature of the cast iron - on average 40-42 ° С, and in a number of desulfurization modes - up to 92-128 °С. This is due to the fact that with an increase in the mass of cast iron, the mass transfer processes between the slag and the molten iron of the ladle deteriorate. The highest specific consumption of reagents in the KR-process ultimately determined the highest costs in the implementation of this process. The lowest specific costs for monoinjection of magnesium predetermine the lowest costs for the industrial development of this process. Actual indicators of industrial blowdowns indicate ohm. that monoinjection of granular magnesium is characterized by the lowest consumption of reagents - on average 0.42-0.55 kg / t of cast iron, the shortest duration of the desulfurization operation - on average 5.5-7.7 minutes and at the same time providing up to super deep desulfurization of cast iron - up to 0.0003–0.001%, desulfurization degree - up to 99%, high sulfur removal rate - on average 12–14.4% / min, high reagent assimilation rate - on average 75–92%. The actual data on the technology applied KR-processes (CaO + CaF2), co-injection of lime with magnesium (CaO + Mg) and monoinjection of granular magnesium according to the Ukrainian injection technology are presented. The costs of desulfurization by KR processes - koninjection - monoinjection are in the ratio 3: 2: 1. The advantage of injection processes of cast iron desulfurization has been substantiated.

The history of the creation and development of the research unit of the Iron and Steel Institute, the department of after-furnace treatment of cast iron is presented. From 1939 to 1983, this structural unit of the ISI was headed by Doctor of Technical Sciences, Professor Natalya Aleksandrovna Voronova, then for 34 years, until 2017, the student and associate of N.A. Voronova – Doctor of Technical Sciences, Professor Shevchenko A.F., from 2017 to the present, the department is headed by Kislyakov V.G. During this period, a set of scientific research and development has provided an opportunity for the department staff to defend 3 doctoral and 16 master's theses. Two employees of the department were awarded the academic title of professor, and ten – senior research assistant. The evolution of the technological process and equipment for the processing of cast iron by granular magnesium in ladles of various capacities is shown. In particular, it was not possible to inject granular magnesium without additives with lances used to inject mixtures of magnesium with fillers into the melt due to blockage of the channel of the magnesium wire at the outlet of the lance. To solve this problem, a lance of a new design was developed, at the outlet of the channel of which an evaporation chamber was installed, the task of which was to remove the section of the lance channel from direct contact with cast iron. The design of tuyeres with evaporation chambers made it possible to virtually eliminate blockages of the tuyere channel. The studies of the interaction of magnesium with molten iron became the scientific basis for the creation of a modern highly automated process for the secondary refining of cast iron by mono-injection of magnesium without additives. This technology received the most successful application in the creation of modernized complexes at Chinese enterprises. Since 2001, 84 complexes of out-of-furnace desulphurization of pig iron and slag download using ISI technology with a total capacity of over 100 million tons/year of low-sulfur and pig iron-free slag have been built and commissioned at 39 plants in China.