PARTICLE CHARACTERIZATION BY PROJECTED AREA DETERMINATION

The projected areas of non-spherical particles do not represent an una mbiguous particle characteristic. Depending on the orientation towards a constant observational direction, different projected areas result. The spectrum of all projected area values of a particle, if determine d representatively, gives the probability with which a certain value i s obtained by a single measurement. In this work, the frequency distri butions of different examples of test objects were both calculated and measured. The objects were a cube, a rectangular parallelepiped and a lso three model agglomerates consisting of spheres of the same size. I nstead of just one projected area, during each measuring procedure thr ee projected areas from three orthogonal directions can be obtained. A mean value is then calculated to reduce the ambiguity of the particle characteristic and enhance the resolution. A suitable measurement set -up is introduced. The results of calculation and measurement are comp ared for observation from just one direction and also simultaneous obs ervation from three directions. The frequency distributions of the equ ivalent diameters of the particle projected areas show a characteristi c trend of the total curve with remarkable properties. The simultaneou s measurement of three values from mutually orthogonal directions and their mean value calculation result in a much narrower distribution. I n this case, a nonsphericity factor can additionally be calculated, wh ose frequency distribution contains information in a characteristic ma nner about the degree to which the particle shape differs from a spher e.