A Method of C alculating Autogenous/ Semi Autogenous mills with the rod mill and ball mill laboratory work indices Note in Figure 1 that the rod mill product slope is less than due to an extra amount of nes present being ﬁ ﬁ ner than 650 μm These ﬁ nes proceed to the ball mill improving the ball mill efﬁ ciency Also the plotted rod mill P80 value as shown in Figure 1 is 2900 μm If the rod mill ﬁ nes are taken into