Abstract: One new type of HGMS was designed|which has a feature of introducing airflow into the separation process to increase the concentrate grade.This new device was applied to the tests on improving low grade hematite (18.2%) which were generated from oxidized ores by low intensity magnetic separation in Baosteel Dressing Plant.The results indicated that with the air flow rate of 0.16 m3/h, iron concentrate grading at 48.2% with a recovery of 53.39% was obtained by the process of roughing-grinding-two cleanings.Compared the tests without airflows, the grade of iron concentrate was increased by above 3% and its recovery decreased by less than 1%.The analysis ascribed the increase of iron concentrate grade by airflow to the air-flow agitation and the negative pressure or strong disturbance as gas bubbles broke down.

Key words: Low grade hematite, High gradient magnetic separation, Air-flow agitation, Iron concentrate grade