Abstract: Researched the effects on the properties of green balls, preheated balls and roasted balls when the raw materials, magnetite concentrates, were pretreated by high pressure roller grinding（HPRG), from which reached the conclusion that HPRG was beneficial for pelletization of magnetite concentrates, as well as the drop strength and compressive strength of its green balls.However, the improvement of the compressive strength of preheated balls and roasted balls after HPRG was negligible, due to the decreasing of porosities in the ball when the fine particles were drastically increasing and the mutual restriction between the oxidization of magnetite and the solid phase crystallization reaction when the balls were preheated and roasted.

Key words: High Pressure Roller Grinding, magnetite, oxidized pellets