Achievements and development prospects of sintering and blast furnace division of PJSC Severstal

The paper provides a brief description of the metallurgical process at PJSC Severstal, demonstrates the practical experience of reducing the consumption of dry skip coke from 415 to 350 kg/t of pig iron over the period 2014 – 2024, a decrease of 15.7 abs. %, and identifies the potential for further reduction of solid fuel consumption in blast furnace smelting. Research directions and tasks were formulated to adjust the technology in order to reduce the specific consumption of solid carbon fuel (including by replacing coke and its solid carbon substitutes with injected natural gas), improve the metallurgical properties of iron ore charges, and determine the optimal level of secondary resources use in the charge. The authors presented the results of laboratory studies of the processes of liquid phase formation during the melting of ordinary (SiO 2 content 4.9 – 7.2 %) and low-silica (SiO 2 content 2.8 – 3.0 %) pellets. The temperature level of the softening zone, complete loss of gas permeability of the iron ore layer, and drip flow of primary slag melts in low-silica pellets increases by 45 – 50 °C compared to ordinary pellets. The article considers the production results of using 3 – 5 mm iron ore screening directly in the blast furnace process (200,000 tons, or 22.3 kg/t of pig iron in 2017). Based on the results of the studies of coke samples taken from operating blast furnaces at a depth of 10 – 12 m from the charge level and in the lance holes, it was concluded that it is possible to use solid fuel with increased reactivity in conditions of iron smelting with a low alkali load (reduced from 3.2 kg/t of pig iron to 2.8 kg/t of pig iron). Based on laboratory studies, the effect of various compositions of reducing gases with variable hydrogen content on the reduction process of sinter and pellets was established. The reduction factor ( R f , %) increases by 2.5 – 3.0 % for every 5.0 % increase in hydrogen content in the gas mixture. The indicator “carbon consumption during ironmaking in blast furnaces” was determined, which allows to assess the real efficiency of blast furnace smelting from the point of view of the climate agenda, and the results of reducing this indicator by 12.4 kg/t of iron (3.0 rel. %) for the period of 2014 – 2023 were presented. The authors formulated the directions for the development of PJSC Severstal first processing stage, including the gradual abandonment of the sintering stage with an increase in the share of pellets in the blast furnace charge to 90 %, a reduction in consumption of coke in the blast furnace to 270 kg/t of pig iron, and an increase in the consumption of gas-based coke substitute (natural gas) to 300 m 3 /t of pig iron.