Abstract: For the purpose of solving low efficiency and low output per machine-hour of dry magnetic separation for fine powder，a new type of high efficiency dry magnetic separator for fine powder was developed which is called double circular moving magnetic system dry-magnetic separator for fine powder.The device consists of enrichment of particles with magnetism and concentration，and scavenging of nonmagnetic particles，however each working area is relatively independent.The problem of low efficiency of separation owing to great agglomerating force between fine particles has been solved，since fine particles with well dispersed state are not prerequisite in whole separation process.The device possesses long double circular moving magnetic system structure and has the advantage of a long separation area，which is the key to achieve efficient separation.In the separation of the materials containing hydration active ingredient such as steel slag powder by the device，the ingredients is not destroyed by hydration reaction，and the magnetic minerals are efficiently extracted，as a result of raising the quality of the steel slag powder as addition of cement by a level.The separation results on steel slag powder from Taiyuan Iron & Steel Co.，Ltd.with the average particle size 30 μm，the specific surface area 307 m2/kg and the iron grade 14.86%(magnetic minerals content of 30.09%) show that iron grade and recovery of concentrate reaches 32.21%( magnetic minerals content of 65.22%) and 90.30% respectively，and the activity index of tailings is improved over 15 percentage points.The device is good at separation of the fine materials containing hydration active ingredient.

Key words: Dry- magnetic separator, Double circular moving magnetic system, Fine powder, Steel slag powder