Abstract: In order to realize the high-purity preparation of fine-grained magnetite concentrate，aim⁃ ing at the problems of insufficient mineral dissociation，obvious agglomeration of fine particles，serious magnetic entrainment and difficult deep removal of gangue impurities in the high-purity process of fine�grained magnetite concentrate，the magnetic separation concentrate of molybdenum tailings in Shaanxi Province is taken as the research object，and the grinding-dispersion synergistic parameter optimization and multi-stage magnetic separation quality improvement process test are carried out.The response surface method is used to optimize the grinding-dispersion synergistic control parameters，and the effects of demag⁃ netization，desliming，grinding fineness and gradient magnetic separation times on the quality improvement of magnetic separation are systematically investigated.The action law of various process parameters and the optimal process conditions are obtained. The amount of PAA，dispersion time and grinding time have signifi⁃ cant effects on the iron grade and iron recovery of the concentrate，and there are obvious interactions be⁃ tween the parameters.Under the determined optimal process parameters of PAA dosage of 500 g/t，dispersion time of 3 min and grinding time of 3 min，the slurry dispersion state is stable，which can effectively inhibit the entrainment of gangue. The results of single process optimization test show that demagnetization treat⁃ment can weaken the magnetic agglomeration effect and increase the iron grade of concentrate from 70.0% to 70.8%.Desliming treatment can remove argillaceous impurities such as fine mica，quartz and iron-con⁃ taining silicate，and increase the iron grade of concentrate from 69.1% to 70.8%. When the grinding fineness is -23 μm95.0%，the concentrate product with iron grade of 70.80% and iron recovery of 91.49% can be ob⁃ tained.After adopting the three-stage gradient magnetic separation process of 39.79，35.81，31.83 kA/m， the highest iron grade of the concentrate can be increased to 71.6%. The response surface method can effec⁃ tively reveal the synergistic relationship between grinding-dispersion-magnetic separation parameters. The constructed demagnetization-grinding-PAA dispersion-desliming-three-stage gradient magnetic separa⁃ tion process can effectively realize the quality improvement of fine-grained magnetite concentrate，which can provide a reliable technical reference for the high-purity preparation of fine-grained magnetite.

Key words: high purity magnetite concentrate, response surface method, grinding fineness, disper? sion control, demagnetization, desliming, gradient magnetic separation