The courses of the bulk density values as a function of the particle size correspond to those for the flow properties. For the smallest fraction 100 < x < 160 µm, the bulk densities for the samples of both grinding methods are the same. This in turn is due to the certainly higher value of adhesive force/mass force. With further increasing particle size, the rise in bulk density values for samples ground in a hammer mill is larger than for samples ground in a roller mill (Figure 4). This too can be attributed to the rougher particle surface, expressed by the fractal dimension. The elongation evidently exerts less influence in this sector.