Influência da granulometria e da mineralogia na qualidade dos briquetes

Abstract

The growing demand for decarbonization in steelmaking processes has driven the search for alternatives capable of significantly reducing carbon dioxide (CO2) emissions, especially through the substitution of fossil fuels and the optimization of steel production stages. In this context, compact agglomerated briquettes produced from iron ore fines, charcoal, or steelmaking residues stand out as a sustainable alternative, as they promote better utilization of furnace charge, reduce material losses, and enable the use of inputs with lower environmental impact, contributing to cleaner steel production aligned with global carbon reduction targets. Despite their high application potential, the production of briquettes with adequate mechanical strength and metallurgical properties still represents a current technological challenge due to the multiple variables involved in the briquetting process. Among these variables, the particle size distribution and mineralogy of the iron ore play a fundamental role, as they directly influence particle packing and material behavior during the agglomeration process, making experimental studies and systematic analyses indispensable. In this work, two distinct types of iron ore from different geological provinces in Brazilian territory were used, one originating from the southeastern region and the other from the northeastern region. For material characterization, physical and chemical analyses were performed using X-ray Diffraction (XRD), Mössbauer Spectroscopy (MS), X-ray Fluorescence (XRF), and Thermal Analysis (TA), aiming to investigate differences in crystalline structure, chemical composition, and thermal behavior of the ores, as well as their possible impacts on the quality of the produced briquettes. Furthermore, the influence of particle size distribution and its correlation with the mechanical strength of briquettes obtained from both ores were evaluated. Based on granulometric analyses, particle size distribution curves were constructed, which were simulated in the Elkem Materials Mixture Analyzer (EMMA) software and fitted to the modified Andreassen model in order to investigate the optimal particle packing. According to this model, the closer the raw material granulometric curve is to the theoretical curve, the higher the degree of mixture packing, which directly reflects in increased mechanical strength of the briquettes. Finally, the produced briquettes were subjected to cold tests, including drop, tumbling, and compression tests, in order to evaluate their quality in terms of impact resistance, abrasion resistance, and uniaxial compressive strength. The obtained results highlight the importance of controlling and fine-tuning particle size distribution and conducting in-depth studies on iron ore mineralogy to obtain briquettes with high quality and performance, reinforcing the potential of this technology as a sustainable alternative for the steel industry.