CARACTERIZAÇÃO DE PELOTAS DE MINÉRIO DE FERRO POR MICROSCOPIA DIGITAL E ANÁLISE DE IMAGENS

Vale evaluates the microstructure of iron ore pellets in order to understand their characteristics and behavior in the agglomeration process, and the correlation with conventional quality parameters. Efforts on image analysis development are in progress between Vale and PUC-Rio in order to improve both the qualitative and quantitative characterization. In the present work, digital microscopy techniques were developed allowing this kind of assessment. Employing a motorized and computer controlled optical microscope, low magnification mosaic images covering complete pellet samples were automatically obtained. The mosaics provide a powerful qualitative overview of the whole sample while allowing low resolution quantitative evaluation and measurement of the porosity mapping. Higher magnification mosaics were also obtained along pellet sample diameters. From these images, hematite, ferrite, slag and pores phase fractions were automatically measured, revealing the typical radial variation expected from pellets.