3.3 Angle of repose
The courses of the angles of repose as a function of
the particle size also correspond to those of the flow
properties and the bulk density. In the case of the
smallest particle size fraction 100 < x < 160 µm, the
values of the angles of repose are similarly high for both
grinding methods. With increasing particle size, the
angle of repose for the samples after grinding with a
hammer mill is reduced more than for the samples after
grinding with a roller mill. This too can be explained in
line with the fractal dimension by the greater surface
roughness of the particles after grinding with the roller
mill (Table 1) (Figure 5):