F = Filling percentage in % Feed materials: Mill liner thickness = 40mm = 0.04m Clinker = 772 t/hr Mill speed = 77% of the critical speed Dry flyash = 116 t/hr Gypsum = 36 t/hr Critical speed (Nc) is the speed at which the centrifugal force Performance enhancer = 28.5 t/hr is equal to the gravitational force.