Qualitative study of melt composition on reshaping behaviour of suspended model iron ore sinter configurations

Iron ore sintering is a complex agglomeration process that converts iron ore fines into a lumpy form suitable for charging into an ironmaking blast furnace. To achieve agglomeration iron ore fines are mixed with coke (fuel) and fluxes (which promote melt formation). During sintering high temperatures (~1350°C) are reached and melts form amongst ore particles. Major structural transformation occurs in this high temperature region, where the packed bed of granulated material transforms into a bed with large agglomerated regions and voids. There is limited understanding of the forces driving agglomeration and it is not possible to observe the transformation process in-situ. Sintering melts play a fundamental role in driving structural change due to their wetting nature, resulting in strong surface forces. This exploratory study demonstrates how an ash fusion furnace can be utilised to investigate surface forces driving high temperature melt driven agglomeration. Wetting and reshaping of pressed analogue sinter mix tablets, with compositions that reflect melt forming regions in the sinter bed, were observed on alumina tiles as they were heated. Sinter mix tablets were then suspended in different configurations adjacent to pressed hematite substrates. On heating, melt formation activated capillary forces that pulled material together, while in another configuration melt wetting and surface energy reduction behaviour resulted in increased sphericity. The study also demonstrated the importance of melt basicity (CaO/SiO₂), with greater movement and reshaping as basicity increase