Abstract: In order to solve the problem of the high grade of high intensity magnetic tailing in Donganshan， and the existing high intensity magnetic equipment cannot effectively recover fine iron ore. Based on the process mineralogy of samples and the theory of agglomeration separation， the effects of reagent dosage and magnetic separation parameters on the magnetic separation index were investigated through agglomeration-magnetic separation test， and the effects of selective agglomeration pretreatment on reverse flotation index were also investigated through reverse flotation test. The agglomeration-magnetic separation test results indicated that under the conditions of sodium silicate dosage of 500 g/t， DLA dosage of 250 g/t， stirring speed of 900 r/min， stirring time of 5 min， pulp pH value of 10.0， frequency of 170 times/min， pulp flow rate of 120 mL/s and magnetic separation background field strength of 1.0 T， the magnetic separation index with iron grade of 47.65% and iron recovery of 71.54% can be obtained. Compared with non-additive agent， the magnetic separation recovery was increased by 4.58 percentage points，and the beneficiation efficiency was increased by 2.42 percentage points. The reverse flotation test results of mixed magnetic concentrate show that: compared with the conventional high gradient high intensity magnetic separation reverse flotation process， the final concentrate grade obtained by selective agglomeration high gradient high intensity magnetic separation reverse flotation process has little change， while the iron recovery of mixed magnetic concentrate has increased by 2.05 percentage points， and the iron recovery of final flotation concentrate has increased by 4.37 percentage points.

Key words: fine iron ore, flocculation, high gradient magnetic separation, agglomeration-separation