Sag Mill Vs Ball Mill SAG MILL GRINDING DESIGN VERSUS GEOMETALLURGY It is important to note that the Bond Ball Mill Work Index on SAG ground ore is similar to but not the same as a crushed Bond Ball Mill Work Index It is 7 higher because the SAG mill grinds the softest ponents quickly and leaves the harder material to be ground in the ball mill Figure 3 presents the graph of SAG pinion energy vs BWi