Dynamics of separation characteristics of sieving and flow classification processes

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Existing models for dry classification are based on simplifications which hinder the adequate description of the dynamic behavior of the classifying apparatus under varying operational conditions. Therefore, the dynamic behavior of a counter current flow classifier, i.e. deflection wheel classifier, will be studied here in a time resolved manner. It was shown that the existing models, which are based on centrifugal and frictional forces on single particles, need to be extended in order to incorporate particle-particle and particle-paddle collisions. While in the first two funding periods the stationary behavior was targeted, in the third period also the separation behavior under non-steady conditions will be included in the model which will be at the center of a complete dynamic representation of the deflection wheel classifier. Besides particle collisions this model will also take into account streaks and a particulate ring, which is orbiting the wheel, thereby extending the characteristic time constants (hold-up) to much higher values than expected. By the comparison of the experimental results with DEM simulations the input parameters of the model, such as the coefficient of restitution and the effective viscosity, will be extracted.