关键词: 提铁降硅, 弱磁选, 反浮选, 高品质铁精矿, 尾矿再选

Abstract: Aiming at the problems of overgrinding of iron minerals，inclusions in the separation pro⁃ cess and low separation efficiency in the existing stage grinding-low intensity magnetic separation-fine screening classification-magnetic gravity combined process of a Anshan-type sedimentary metamorphic rock type lean magnetite in Daixian County，combined with the characteristics of uneven particle size dis⁃ tribution of magnetite in the ore，quartz-based gangue and high content of intergrowth，the iron-increasing and silicon-reducing tests of the grinding-low intensity magnetic separation-reverse flotation-tailings mag⁃ netic separation and re-separation process were carried out. The results show that when the grinding fine⁃ ness is -0.045 mm accounting for 90%，the flotation concentrate with iron grade of 71.05%，iron recovery of 92.00% and SiO2 content of only 1.10% can be obtained by the closed-circuit process of low intensity magnetic separation-anion reverse flotation. The quality of the concentrate fully meets the raw material re⁃ quirements for the production of high-quality pellets. Aiming at the problem that the grade of flotation tail⁃ ings is high and it is difficult to directly discard the tailings，under the condition that the regrinding fine⁃ ness of flotation tailings is -0.030 8 mm accounting for 90.18%，one roughing and one cleaning low intensi⁃ ty magnetic separation can be used to obtain a re-concentration concentrate with iron grade of 64.29%，op⁃ eration recovery of 89.98% and process recovery of 5.56%. The research results provide technical reference for the same type of magnetite iron and silicon reduction and plant process optimization，and have positive significance for promoting the low-carbon green development of the iron and steel industry.

Key words: iron upgrading and silica reduction, low intensity magnetic separation, reverse flotation, high-quality iron concentrate, tailings reprocessing