Effects of high pressure roller grinding on size distribution of vanadium-titanium magnetite concentrate particles and improvement of green pellet strength

The vanadium-titanium magnetite concentrate from Panxi region of China was pretreated by high pressure roller grinding (HPRG) and then used in pelletization. Size distribution change of the vanadium-titanium magnetite concentrate after HPRG and the improvement of its green pellet strength were investigated. The results indicated that, besides the increase of fine particles, the vanadium-titanium magnetite concentrate after HPRG had a smaller size ratio of fine particle to coarse particle of 0.126, meaning a lower porosity, compared with the size ratio of raw material of 0.157. The concentrate particles were more closely packed when there was a smaller size ratio of fine particle to coarse particle. The particle packing in the green pellets was closer after HPRG, which strengthened the green pellets with an average drop number of 5.1 (drop height of 0.5 m) and average compressive strength of 13.1 N per pellet of 11 mm in diameter.