Aplicação de separação magnética de alta intensidade (WHIMS) no beneficiamento de itabiritos pobres

Abstract

The reduction of iron content in ores that feed the processing plants requires the development of appropriate procedures for processing low-grade ores and / or able to recover the iron contained in the tailings. The need to process low grade ores associated with the reduced particle size required for liberation and the development and use of substitute materials increase the pressure to reduce costs and improve the efficiency of processing operations. In this context, the opportunity arises for the application of high intensity magnetic separators in the recovery of even finer ferromagnetic and paramagnetic particles. The objective of this study consists in comparing the results of mass and metallurgical recoveries and concentrate quality, especially regarding the content of SiO2 in the final concentrate, obtained in technological tests that simulate the current process route characterized by the steps of desliming and flotation and the alternative process route characterized by magnetic separation step preceding flotation. The comparison of the results achieved with the two process routes as described above was made using a representative sample of the future ore of Alegria mine, located in the towns of Ouro Preto and Mariana, owned by Samarco Mineração S.A. The results support the potential of the alternative process route characterized by magnetic separation preceding flotation. The mass and metallurgical recoveries obtained with the alternative route (magnetic + flotation separation) in absolute values was 3.3% and 4.4% higher than the respective recoveries obtained with the reference route (desliming + flotation). Considering the flotation kinetics tests, even with the smaller degree of liberation of quartz in the fraction retained in 149m (68.0% for the magnetic pre-concentrate and 78.0% for the desliming underflow), the content of SiO2 in the concentrate achieved in the alternative mixed route were below the levels of SiO2 in the concentrate obtained with the reference route. The results achieved with mixed (magnetic separation + flotation) route namely higher mass and metallurgical recoveries and lower SiO2 contents in the flotation feed and final concentrate render this route an alternative for the processing of low iron grade ores. With the demonstrated potential to increase the mass and metallurgical recoveries process and to reduce the content of SiO2 in the feed of flotation step and allows to obtain lower contents of SiO2 in concentrate, the process alternative route (magnetic separation + flotation) becomes an alternative for the processing of lower-grade ores.