A switch from ball mills to Vertimill#174; boosts Miaogou Iron
#0183;#32;The mines original grinding circuit consisted of ball mills exclusively. The primary stage comprised 5 ball mills, the secondary stage 3 ball mills, and the final, tertiary stage 2 ball mills. The original tertiary grinding fineness was 325 mesh with 7173% passing. Iron concentrate grade was 65% and the average recovery rate 87%.