Effect of flux granulometry on the sintering process using thermodynamic analysis

Abstract

Granulometry of fluxes plays a vital role in melt formation during sintering and ultimately affects sinter quality. This primarily depends on viscosity and chemistry of melt formed in the process which in turn depends on several parameters such as the alumina content of iron ore (and therefore base mix), the amount and type of flux added to the base mix as well as reducing conditions. Limestone and pyroxenite are the two major fluxes used in sintering. Smaller sized materials (typically less than 1 mm) in the base mix form the primary melt during sintering and subsequently dissolve the derivatives of iron along with gangue. Sinter quality is greatly affected by flux granulometery because of alternation in the local melt chemistry. Despite of various efforts in direct correlating the sinter quality with melt chemistry, no insights can be provided in improving the process parameters. Therefore, thermodynamic modelling studies can influence on changes in flux granulometery on sinter phases, which forms the basis of this work. In this study, the effect of the <1mm fraction of limestone and pyroxenite on sinter phases was investigated using thermodynamic analysis. Percentage of -1mm fraction in fluxes, limestone and pyroxenite, was varied in base mixture to get different local chemistries for bulk chemistry of sinter. Thermodynamic heating and cooling cycle’s analysis was performed to predict the final phases in the sinter. Analysed results revealed that with increase of percentage of -1mm in limestone results in increase of calcium ferrite in sinter with availability of CaO and magnetite, spinel and silicate phases gets predominant with higher percentage of pyroxenite. Keywords : Iron ore sintering, Thermodynamic analysis, Granulometry.