Characterization of waste materials for optimizing aerodynamic separation steps

To separate residual materials from a heterogeneous material flow an intensive mechanical treatment is necessary. In most cases multistage processes of crushing-, sorting-, and sieving steps are used to meet the quality specifications concerning sorting purity of secondary raw materials. Bulk materials of waste origin have often a fluctuating composition of different material fractions. As a consequent specific behaviors (e. g. flight, particle interaction, and ignition) vary from particle to particle. In mechanical waste treatment plants wind sifting or optical sorting devices are often used to separate a specific fraction from the material flow. In both technologies the material flow is divided into two or more material flows using the separation criteria trajectories of the si ngle fractions. To reach a clean separation a precise knowledge of the flight behavior of the single fractions is required. At Fraunhofer UMSICHT a sink shaft was developed and implemented to determine time-resolved the particle trajectories and particle movement depending at the physical particle properties. Based on the results of sink shaft experiments and further developed simulation tools, well-founded predictions about the behavior of bulk materials are possible.