Abstract: In order to reduce the content of silicon dioxide in an iron ore in Brazil and improve the iron grade of concentrate，a magnetic separation test of one roughing and one scavenging was carried out. Through the separation study of Brazilian purchased raw ore samples with iron grade of 57.94% and silicon content of 11.68% under different magnetic field intensities when grinding to -0.074 mm particle size con⁃ tent of 77.0%，the iron grade is 61.50%，the yield is 91.30%，the iron recovery is 96.91%，and the content of SiO₂ is 7.23% iron concentrate. The iron grade of tailings after separation is 20.60%，which meets the control target value of Meishan Beneficiation Production tailings iron grade ≤21%. The Brazilian raw ore is mixed into the beneficiation production process of Meishan self-produced ore.It is mixed according to 100 tons per hour and the grade of comprehensive iron concentrate is controlled on the premise of 57%，each ton of Brazilian raw ore can produce 1.10 tons of Meishan comprehensive iron concentrate with an iron grade of 57.00%.

Key words: grinding, magnetic field intensity, productivity, metal recovery rate