Abstract: The grade of iron in Anqian magnetite is 29.25%， and the iron mainly exists in the form of magnetite with the distribution rate of iron in magnetite of 79.02%. The main gangue mineral is quartz. In order to develop and utilize the low-grade iron ore efficiently and enhance the magnetic separation efficiency， the short process optimization test was carried out. Analysis methods， such as chemical multi-elements analysis， iron phase test and XRD analysis were adpoted to study the ore properties for basis of the new process design. One-stage low- magnetic preconcentration， regrinding and reselection of concentrate from low-magnetic preconcentration and high-magnetic reselection of tailings from low-magnetic preconcentration were carried out with faction of -1 mm， -2 mm， -3 mm and -4 mm prepared from high pressure roller mill. The results showed that: ①The finer the particle size of the material is， the higher the grade and recovery rate of the concentrate of the low-magnetic preseparation is. Since the high pressure roller grinding equipment has poor effect on the fine particle size， -3 mm is determined as the best crushing size. At this time， the iron grade of the concentrate is 38.03%， and the iron recovery rate is 88.12%. ②The iron grade of low-magnetic separation increased and the iron operation recovery rate decreased with the increase of regrinding fineness in the regrinding test of preconcentration concentrate. The optimal grinding fineness is - 0.038 mm accounting for 94.30%， in which the total recovery rate of iron is 81.99%. ③The iron grade of the four particle sizes of the high-magnetic concentrate gradually decreased with the increase of magnetic field intensity in the high-magnetic exploration test. The iron recovery rate gradually increased and then became stable， while the tailings yield gradually decreased. ④The high-magnetic separation tests were carried out with low-intensity magnetic tailings of -3 mm under the conditions of the background magnetic induction intensity of 1.0 T， the feeding speed of 1.3 kg /min， the feeding water flow rate of 6.5 L/min， the rotating speed of 2.0 r/min and the fluctuation of 200 times/min. The high-magnetic concentrate with the iron grade of 16.54% and the iron recovery rate of 80.93% could be obtained finally. The recovery value was not high， thus the high-magnetic process was abandoned. Finally， the technological process of "high pressure roller crushing， weak magnetic pre concentration， fine grinding and weak magnetic separation" was determined to replace the original complex long process of "stage grinding， coarse and fine separation， gravity separation， strong magnetic and anion reverse flotation". The experiment has completed the optimization of the original process of Anqian Mining Company， which is of reference significance to the improvement of magnetite beneficiation process indexes in Anshan area and Anqian Mining Company.

Key words: magnetite, optimization of short process, fraction, low-intensity magnetic preselection, regrinding of concentrate, high-intensity magnetic separation