BK 10/08/2009 19:18:51 How much velocity to be maintaine across the ball mill Hai friendsAny body help me to estimate the Velocity across the Ball Mill for Cement Fine grinding in 1st chamber and 2nd chamber.ThankQby Bandari. AN - Kuwait 11/08/2009 06:44:43 1.5m/sec.for closed circuit and 1 m/s for open circuit.