TECHNICAL NOTES 8 GRINDING R P KingThe geometry of a mill with conical ends is shown in Figure The total volume inside the mill is given by Vm 4 D2 mL 1 2 Lc L L 1 Dt/Dm 3 1 Dt/Dm The density of the charge must account for all of the material in the mill including the media which may be steel balls in a ball mill