Combination of triboelectrostatic separation and air tabling for sorting plastics from a multi-component plastic mixture : New systems and processes in recycling and high performance waste treatments

This paper examines separation of waste plastics obtained from automotive shredder operations. Thus, a mixture of three kinds of plastic components (i.e. acrylonitrile-butadiene-styrene (ABS), polypropylene (PP), and polyvinyl chloride (PVC)) is sorted by using dry techniques i.e. without using water and hazardous chemicals. The separation process is characterized by the utilization of properties of triboelectric charge and density. Considering the relative position in triboelectric series (TES) and density of the each plastic component of the ABS, PP and PVC mixture, it is concluded that a satisfactory separation could not be obtained by either triboelectrostatic separation or air tabling alone. Thus, a system utilizing a combination of the two processes is developed. The triboelectrostatic separator is initially used to collect the ABS flakes as positively charged fraction and to produce a negatively charged fraction of PP and PVC flakes for further treatment on air table. Hence, at the end of the process, products of ABS, PP and PVC with a grade of 94.3%, 92.5% and 93.7% respectively are collected with a percentage mass distribution higher than 76.7% for all of them.