ball mill rotating critical speed - grinding mill china. ball mill wikipedia, the free encyclopedia a ball mill is a type of grinder used to grind materials into,ball mill rotating speed,ball mill china, ball mill manufacturer, dry ball mill-sbm machinery. ball mill grinds material by rotating a cylinder with steel grinding balls, causing the balls to fall back into the cylinder and onto the material to be ground.the point where the mill becomes a centrifuge is called the critical speed, and ball mills usually operate at 65 to 75 of the critical speed.