ANALYSIS OF STRUCTURAL CORRELATION BETWEEN THE SURFACE RELIEF OF THE SPRAYED CHARGE LAYER AND THE POROSITY OF IRON ORE PELLETS

The role of the surface relief of the germ centers obtained in the process of jet spraying of wet charge mass in the formation of porosity and structure of iron ore pellets is analyzed. The possibilities of increasing the reactivity of the pelletized metallurgical product due to the formation of open porosity of pellets by the method of jet spraying of iron ore charge onto the surface of the charge garnishing are shown. To analyze the structural properties of the germ mass, a structural correlation factor is proposed that characterizes the relationship between the relative volume of structural depressions on the surface of the deposited charge layer forming the germ mass and the porosity of the embryos. Two areas of structural correlation have been established between volumetric changes on the surface of the embryos and porosity, depending on the structural correlation factor. In the first, most extended region (Ф = 1.0 – 2.4), a linear structural correlation was established between the relief volume changes on the surface of the sprayed charge layer and its porosity. The Pearson correlation coefficient, calculated using the MS Excel program, is 0.99 for this dependence. This area of structural correlation corresponds to a wide range of parameters of the air-charge jet and indicators of charge materials used to produce wet pellets using forced nucleation technology. In the second region (Ф < 1.0), no structural correlation was recorded, characteristic of the first region of the dependence between volumetric changes on the surface of the sprayed charge layer and the porosity of the embryos. This level of structural correlation is due to the predominant effect of the air-charge jet on the deep zones of the deposited layer, which causes a viscous mass flow and an active manifestation of mass-exchange processes in the volume of embryos at elevated pressures of the air-charge current, leading to the formation of open porosity. Examples from the production practice of pelletizing wet iron ore charge are presented, which correlate with the obtained research results. On the basis of the obtained data, the conditions for optimizing the structure of the embryos are formulated, the mechanism for the formation of the structure and porosity of the germ mass in the process of jet spraying of wet charge in the production of iron ore pellets is clarified.

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