Preliminary tests on fluid-dynamic features and plastic separation feasibility of a hydraulic separator

Plastic materials recovery and recycling is assuming growing relevance in industrialized countries. The main problem in plastics recovery and recycling is related to the variety of plastic waste, even if a selective collection occurs. Therefore, plastic materials can be recycled either as mixtures or as single kinds, separating the different typologies by physical (size, specific mass, etc.) and/or chemical properties. However, separation of plastics in single typologies by traditional processes and devices is difficult due to their typical low variability in properties. This work focuses on the set up of the so called "Multidune" separator, a hydraulic separator, whose particular profile determines differential transport of particles of low specific mass, near to 1 g/cm3, allowing their separation. The experimental set-up has been designed to investigate the solid transport phenomena settled in the apparatus. Particle Tracking Velocimetry (PTV) was employed to reconstruct tracer particle trajectories to compute the velocity field. Preliminary tests on monomaterial samples have been performed, choosing several operative parameters of the Multidune separator, to determine the best operative conditions. Therefore, separation tests have been executed on composite samples, obtaining satisfactory results in terms of plastic separation feasibility.