Theory and practical application of multicomponent separation in solid waste technology, illustrated by a process for recovering materials from car shredder waste

Abstract Multicomponent separation is applied in solid waste technology to recover usable materials from a waste stream. Each material in the waste mixture consists of solid particles with different properties. Component separation is, therefore, the complex result of separator performance and particle properties of the various materials. A mathematical formulation of the relation between component separation efficiency, separator performance and particle properties of the various components in the feed stream is given. On the basis of theoretical considerations, the rationale of the combination of dry mechanical separation techniques such as sieving and air classification is shown. A strategy is proposed for the design of separation processes that is based on the characterization of the particle properties in the solid waste feed stream. Possibilities and limitations of this strategy in practice are shown in developing a separation process for the recovery of materials from car shredder waste. In this practical problem the feed properties were characterized in the same apparatus in which the actual separation process is to be carried out. This fact interrelates feed properties and apparatus performance under analyzing conditions which, from a theoretical point of view, interferes with the desired uncoupling of separator performance and feed properties. Nevertheless it is shown that this analysis leads to a well justified design of the separation process.