2020 Volume 60 Issue 11 Pages 2376-2384
High-grade iron ores became more attractive due to the searching for lower slag rate operation in blast furnaces aiming to reduce CO2 emissions as the environmental regulation became even more restricted. The granulation behavior of high-grade ores individually and together with other iron ores played an important role for sintering process. In this context, this work aims to evaluate the granulation behavior of a pellet feed with different specific surfaces. To carry out this study, 25% of pellet feed was added to an iron ore mix in a bench scale drum. The Granulation Index (GI) was determined and samples were collected after granulation step for quasi-particles investigation. The results showed that a previous mechanical treatment of the pellet feed by roller press is suitable in order to enable a good granulation behavior of this fine material, which was essential to guarantee its use as raw material in sintering process. The fraction below 0.045 mm of the pressed pellet feed helped to improve the granulation of the natural pellet feed. The thickness of the adherent layer and means size of quasi-particles increased with the specific surface. The GI results increase with the pellet feed specific surface, up to 1400–1500 cm2/g stabilizing around 86–90%. The fines below 0.15 mm that remained agglomerated, after drop test, had similar behavior of GI. Finally, it was possible to obtain a minimum specific surface level (1400–1500 cm2/g) to achieve an optimum performance in the granulation step which may promote a good sintering process permeability conditions.
