The influence of particle bed configurations and confinements on particle breakage

Particle arrangements and confinements can be classified in the four groups (1) single particle situation, (2) one-particle layer, (3) particle bed confined closely or widely, and (4) ideal particle bed. Any confinement influences the stress distribution inside the bed due to the wall friction, and a complex stress field arises. The size-reduction effect is represented with the fraction of broken particles, the breakage function and the specific surface increases. The breakage functions of the particle bed comminution display as truncated logarithmic normal distributions. The stressing intensity can be quantified by the pressure, the stress field characteristics or the energy absorption. Although the stress field situation can differ extremely, the overall energy absorption has been proven to represent the stressing intensity very well in respect to the size-reduction. The transition from a close to a moderately wide confinement does not affect the size-reduction strongly. Steel balls inserted in a particle bed improve the breakage of coarse particles at a low intensity level. This advantage fades with increasing intensity and decreasing particle size.