Otimização da concentração de minério de ferro em usina de processamento mineral com secagem e concentração magnética

Abstract

Mining faces significant challenges due to the reduction in iron grades and the increase in contaminants in deposits, which requires advanced technologies to keep operational costs low and ensure efficient metal and mass recovery. Environmental issues have also become more relevant, demanding the sustainable use of natural resources, such as reducing water consumption and better utilization of processed ore. Wet beneficiation, although efficient, consumes large volumes of water and presents high operational and environmental costs. In contrast, dry beneficiation has emerged as a sustainable alternative especially in regions with water scarcity. This study aimed to analyze and technologically characterize a dry beneficiation process with a drying stage in the municipality of Sabinópolis, seeking to improve the mass and metallurgical recovery of the current process. Several pilot-scale magnetic concentration tests were carried out, involving the use of drying and hybrid tests, where part of the material was processed through wet beneficiation and another part by dry beneficiation after the drying stage. The tests were conducted with semi-compact and compact itabirite. For the semi-compact itabirite, the best result was obtained with material crushed to less than 1 mm, achieving a final concentrate with approximately 60.4% iron content, 49.2% mass recovery, and 88.8% metallurgical recovery through dry beneficiation with a drying stage. For the compact itabirite, which showed greater resistance to comminution, a hybrid route was proposed, processing the finer material through wet beneficiation and the remaining material through dry beneficiation with a drying stage, obtaining a final concentrate with approximately 65% iron content, 49.7% mass recovery, and 87.7% metallurgical recovery. It is emphasized the importance of drying in the efficiency of the magnetic concentration process. Tests performed with naturally moist material did not reach favorable iron and silica grades, and reducing the particle size had a detrimental effect on separation, opposite to the effect observed in dry separation. The results indicate that small adjustments in particle size and the installation of smaller new equipment could optimize the existing beneficiation unit.