Possibilities of heat-power spraying of wet charge during formation of structural properties of agglomerated iron ore materials

The substantiated problem of improving the structural properties of agglomerated metallurgical raw materials is associated with the formation of a favorable pore structure in iron ore pellets. The author analyzed various methods for the formation of structural properties of molded dispersed materials in various industries. The paper presents the technological capabilities of promising technologies for production of iron ore pellets based on the heat-power spraying of wet charge on pelletizer’s charge skull and pelletized materials. The physical possibilities of heat-power spraying of wet charge in the forced nucleation and in the process of forming the iron ore pellets’ structural properties are disclosed at the stage of pelletizing. The technical features and production operations of the main technologies for wet charge spraying and the design features of devices for obtaining pellets are shown. The paper describes the experimental unit and technology for the forced nucleation. The macro- and microstructure of the germ mass at forced nucleation were studied. Principles of the formation of regulated structure and improved metallurgical properties in iron ore pellets were substantiated. The article presents the description and characteristics of structural changes on the surface of the sprayed charge layer. A hypo­thesis was put forward about the structural correspondence of geometric dimensions and relief of charge lappings and cavities in the sprayed layer with the nature of porosity and germ structure. The germ mass affects the pellets’ structural properties. The author obtained the dependences of structural changes’ relative values on the sprayed layer surface on pressure of air-charge jet and particle size of the sprayed charge. There is relationship between geometric dimensions of the sprayed charge layer and the structural changes’ size. A probable mechanism of porosity formation in the germ mass during heat-power spraying of a wet charge onto the pelletizer skull was formulated. The aerodynamic characteristics of air-charge jet influence the formation of porosity. New possibilities of heat-power spraying of wet charge can intensify pellets production and improve their quality.