Ball Mill Operating Speed Mechanical Operations Solved In a ball mill of diameter 2000 mm 100 mm dia steel balls are being used for grinding Presently for the material being ground the mill is run at 15 rpm **-ball rpm grinding-**,Ball Mill Critical Speed Mineral Processing & MetallurgyA Ball Mill Critical Speed actually ball rod AG or SAG is the speed at which the centrifugal forces equal gravitational forces at the mill shell's inside surface and no balls …… Get more