#### TECHNICAL NOTES 8 GRINDING R. P. King

Ball Mill Critical Speed Of Formula. Ball mill critical speed mineral processing metall.ball mills have been successfully run at speeds between 60 and 90 percent of critical speed, but most mills operate at speeds between 65 and 79 percent of critical speed rod mills speed should be limited to a maximum of 70% of critical speed and preferably should be in the 60 to 68 percent critical speed range.