Jan 01, 2013· To calculate Bond rod-mill work indices, the four samples were screened and the particle size distributions plotted in Fig. 2.The plot was used to find F 80 of the samples for calculations. Fig. 3, Fig. 4 show the grinding kinetics of Pb, Cu, Fe, and Mn ores in the Bond rod-mill in different test-sieves. The slopes of all lines in the figures are equal to the k value of Eq.