Questions about the oxidative roasting of iron ore raw materials (agglomerates and pellets) are studied. Features of the phase structure of the iron ore raw materials containing titan and vanadium are discussed. Reducibility, durability, and the softening and melting temperatures of metallurgical iron ore raw materials are studied in vitro. The objects of the research are titaniferous ores containing different amounts of titan dioxide. The behaviors of agglomerates and pellets in a blast furnace are studied, and the influence of their physical and chemical properties on heat and mass transfer processes are researched by means of a mathematical model. The main indices of blast furnace smelting—productivity, coke consumption, composition of top gas, cast iron, and slag—are shown. It is established that the increase in titanium dioxide content in pellets, as the amount of concentrate with increased TiO2 content increases, does not cause deterioration in the quality of iron ore raw materials being prepared for blast furnace smelting. At the same time, as the hot strength of raw materials increases, the temperature at which softening begins increases and the temperature interval of softening of materials decreases.

The article presents the results of a study of formation mechanism of magnesia-ferrite when heated siderites of the Bakal deposit with different iron oxide content in an inert and oxidizing atmosphere. It was established that in the case of firing in an inert atmosphere, the decomposition of siderite with high iron content begins at a lower temperature and the enthalpy of such decomposition is less. This effect can be explained by the different phase composition of the samples. The main phases formed under conditions of oxidative firing are hematite and magnesia-ferrite. The amount of hematite and magnesia-ferrite produced in the samples with different iron oxide content during firing in an oxidizing atmosphere is different. Siderite with high content of iron oxides contains more hematite in the firing products than magnesia-ferrite, and siderite with a low content of iron oxides contains more magnesia-ferrite in the firing products than hematite. Formed under conditions of oxidative firing magnesia-ferrites are solid solutions and differ in the degree of substitution of iron and magnesium ions. In siderites with high content of iron oxides, the degree of substitution of magnesium ions with iron ions is greater than in samples with a low content of iron oxides. Since the siderites of the Bakal deposit are poor ore formations, the considerable amount of magnesia-ferrite formed in them during firing makes it difficult to separate silicate and iron-oxide firing products by traditional enrichment methods. Wustite in the products of oxidative firing is not detected, because under these conditions it is in a metastable state and in the presence of a weakly oxidizing atmosphere is converted into magnetite. The scientific novelty is the explanation of the mechanism of siderite decomposition and the description of products of such decomposition. Understanding of the mechanism of decomposition of siderite from the Bakal deposit made it possible to develop the technology of reductive firing of siderite to facilitate separation of its products, and which consists in the regulation of the phase composition of silicate products of reductive firing, ensuring the collapse of magnesia-ferrite and output of iron oxide in a separate phase. The developed technology can be used to provide high-quality enrichment of siderite from the Bakal deposit.

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Strength characteristics of iron ore agglomerates of various basicity (mechanical strength and abrasion resistance, thermomechanical strength) have been investigated. The chemical and phase compositions of iron ore agglomerates, their microstructure and local chemical composition were analyzed. Dependences of the strength characteristics of iron ore agglomerates of various basicity on the morphology of silicate bond have been obtained. Dependences of influence of basicity of iron ore agglomerates on their strength characteristics depending on the proportion of phase components are obtained. It has been shown that an increase in the proportion of stabilized silicoferrite (SFCA) in the composition of agglomerates has a positive effect on their thermomechanical strength, which will increase the productivity of the blast furnace and significantly reduce the emission of dust.

Metallurgical characteristics of iron ore agglomerates of various basicity (reducibility, strength after reduction (LTD+6.3), temperatures of the beginning and ending of softening) have been investigated. The phase composition (XRD) of iron ore agglomerates and their microstructure were analyzed by optical microscopy. Various dependences of influence of the basicity of iron ore agglomerates on their metallurgical characteristics with respect to the proportion of phase components that have been obtained. It has been shown that an increase in the proportion of stabilized silicoferrite (SFCA) in the agglomerate has a positive effect on their strength after reaction, which will further increase the productivity of the blast furnace and significantly reduce dust emission.