Study of the Oxidation Process of Magnetite Fluxed Pellets by Various Methods of Physical and Chemical Analysis

AbstractIn order to obtain the most complete information about the processes occurring during the oxidative roasting of magnetite iron ore pellets, comprehensive studies are carried out using various methods of physicochemical analysis. To approximate the assessment of the most probable reactions occurring in pellets during oxidative heating, a thermodynamic analysis is performed. Based on the sign of the isobaric potential, determined from the equation of the isotherm of a chemical reaction, we judge the possibility of a particular chemical reaction occurring in the direction under consideration. The influence on the dissociation reaction of calcium carbonate is established by the formation of calcium silicates and ferrites, which facilitate its occurrence, as well as the reaction of the interaction of iron oxide with calcium carbonate, which, on the contrary, inhibits its occurrence. A technique is developed for thermographic analysis of solid-gas systems filtered through a layer of granular material, which is implemented on an installation that allows experiments with pellets in a gas flow with different oxygen contents, temperatures, and heat treatment durations. It is experimentally established that pellets are decarbonized most completely and quickly in an atmosphere of inert monatomic gas, as well as in a mixture of gases that do not contain carbon dioxide. Mineralogical studies are carried out on samples of magnetite fluxed pellets in a wide temperature range. The pellets are heated in accordance with a differential heating curve to certain temperatures, and then cooled in order to fix the structure formed by the time the specified temperature is reached. The results obtained in this study are of particular interest to specialists involved in the development of technologies that ensure the production of pellets with strong metallurgical properties.