In recent years, the increase in the efficiency of the blast furnace process is largely associated with the use of sinter with improved metallurgical properties. In the blast furnace charge of PJSC NLMK, the share of sinter is 60–75% with a change in basicity from 1.3 to 1.8. Studying the material composition of agglomerates of different basicity and their characteristics allows us to adjust the technological process and determine the optimal modulus of basicity depending on specific conditions. Agglomerates with a basicity index of: 1.3; 1.4; 1.5; 1.6; 1.7 and 1.8. As a result of the research, it was established that the maximum vertical sintering speed and specific productivity of the sintering process correspond to the basicity of the sinter of 1.7. The influence of the basicity of the agglomerate on its strength is extreme, with a basicity of 1.4 the minimum strength of the agglomerate was obtained. Increasing the basicity of the agglomerate by more than 1.4 monotonically increases its strength. The nature of the change in the strength of the ag-glomerate with a change in basicity is determined by the mineral composition of the binder and is associated with a decrease in the proportion of glass in the structure of the agglomerate and an increase in the proportion of the crystalline silicate-ferrite binder. When studying the material composition, it was established that the samples of agglomerates have an identical phase composition, but differ in the phase ratio. Crystallization of calcium ferrites in contact with iron oxides contributes to the strengthening of the agglomerate, and the presence of impurities (Al, Si, Mg) in them increases the melting point. As a result of mineralogical and analytical studies, it was established that the highest metallurgical properties are found in agglomerates with a basicity modulus of 1.6–1.8.
