Per: gerson evaristo de paula júnior (USIMINAS - IPATINGA), Cleyde Regina Campos Silva Netto (USIMINAS), Darlan Silva Siqueira (USIMINAS)
Abstract:
The RDI (reduction degradation index) of sinter is one of the main controlled indicators in the blast furnace, having a considerable impact on the burden permeability and, consequently, on the reactor fuel consumption. Thus, several mechanisms for this phenomenon elucidation have been studied, focusing on ores mix alumina content, which promotes secondary hematites formation with fragile structure. However, even for sintering mixtures with controlled alumina content, the RDI can be high due to the iron ore original hematites, a mechanism little explored in the literature. Therefore, in the present work, sinters produced with iron ore binary mixtures, with hematites of different morphologies and crystal sizes, were evaluated on a pilot scale, for mineralogical evaluations and metallurgical tests. It was found that hematites with larger crystal sizes maintained their primary form in the sinter matrices, with low assimilation. In addition, the sinters produced with high crystal size hematitic ore presented a higher RDI, propitiated by the primary hematites volumetric expansion when reduced to magnetites, promoting cracks propagation in the sinter matrix.