Abstract: In order to understand the effect of high pressure roller grinding for magnetite ore in Nan⁃ fen Concentrator，the high pressure roller grinding test was carried out on the basis of the analysis of ore sample properties，and the wet magnetic separation test was carried out on the closed-circuit roller prod⁃ ucts under the determined conditions. The results showed that the ore samples with TFe grade of 33.25% and mFe grade of 21.87% were rolled at 20~0 mm. When the working pressure of high pressure roller mill was 8.0，10.0 and 12.0 MPa，the cumulative yield of 5~0 mm grain size of rolled product was 70.60%， 74.83% and 76.61%，respectively. The grain yield of - 0.074 mm accounted for 7.50%，8.28% and 8.50%，respectively. When the working pressure of high pressure roller mill was 8.0，10.0 and 12.0 MPa with feeding particle size of 15~0 mm，the cumulative yield of 5~0 mm grain size was 71.65%，75.51% and 77.24%，respectively，and the yield of -0.074 mm grain size was 7.84%，8.96% and 9.28%，respec⁃ tively. When the screen width was 3 mm and 5 mm，the cyclic load was 71.90% and 38.70%，and the yield of -0.074 mm was 15.41% and 14.29%，respectively. The concentrate from the wet magnetic separa⁃ tion test of high pressure roller grinding closed circuit rolling product（3~0 mm） has a TFe grade of 37.50%，mFe grade of 26.73%，TFe recovery rate of 91.38%，mFe recovery rate of 99.03%，tail casting yield of 18.98%，TFe grade of 15.10% and mFe grade of 1.12%.

Key words: high pressure roller mill, open-circuit roller, closed-circuit process, wet magnetic separa? tion