Grouping of mixed waste plastics according to chlorine content

This research aimed to simply classify pre-sorted mix plastics of 2.2% Cl into two groups—Cl-poor plastics (≤0.5%) for waste-to-energy application and Cl-rich plastics for selective landfilling. Using three processes (sink-float tank, centrifugation and hydrocyclone) and a number of operating conditions (liquid density and input pressure), 10 different tests were carried out to achieve the above-mentioned purpose.The hydrocyclone separation had a larger amount of the Cl-rich group than the sink-float process and the centrifugation. The centrifuge separation showed that the Cl contents in both the overflow (2.0% Cl) and the underflow (9.4% Cl) were greater than the target value of ≤0.5%. The sink-float process with 1.1 g cm−3 liquid density showed a comparatively small amount of the Cl-rich group and a great amount of the ≤0.5% Cl group; however, special attention is required to use the obtained Cl-poor group in the cement industry because standards regarding cement quality strictly limit the Cl content.Although it is important to individually separate various waste plastics, it must also be environmentally helpful to sort mixed waste plastics according to their final destination by a simple separation approach.