Handbook of Recycling

Appendix 1

Physical Separation 101

Kari Heiskanen,     Aalto University, Espoo, Finland

A1.1. Breakage

Breakage at recycling is a composite outcome of brittle, ductile or viscous behavior.

The brittle particles can be broken by compression or impact. Most slags, minerals and rocks are brittle, as often are many types of coating. Fine particles (smaller than 50 μm) are easy to produce. Particle size distributions tend to follow roughly simple distributions (log-normal or Weibull). Ductile materials, like metals, need to have a shear force for breaking. It can be created also by impacting crushers. Particles tend to become bent and folded depending on their dimensions and plasticity. Compressive stress results in major deformation before breakage. Very ...