Thermal analyses of the sintering reactions of iron ores

Sintering phenomena of iron ores have been examined by applying several methods of thermal analyses, i.e., thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Particular focus was given on the assimilation and melting behavior of major raw materials. For the reaction between fine iron ores and limestone, heat of initial melting has a negative relation with SiO₂ content of the ore. Mineral state of Al₂O₃ component influences the melting temperature of the mixture, possibly through the stabilization of calcium ferrite phase formed during heating. However, that of MgO component does not have much effect on the melting behavior. Increase in particle size of ore gives remarkable effect in promoting initial melting when using ores having relatively high gangue minerals at a lower total CaO concentration. In contrast, increase in limestone size tends to suppress initial melting at higher total CaO concentration. Reaction between melt and coarse iron ore particles proceeds from lower temperature when using pisolitic ores while ore having high iron content slowly dissolves at higher temperature. Reactivity of dolomite with melt is larger than serpentine and promotes formation of initial melting.