Review on zigzag air classifier

The zigzag (ZZ) classifier is a sorting and classification device with a wide range of applications (e.g. recycling, food industry [1, 2]). Due to the possible variation of geometry and process settings, the apparatus is used for various windows of operation regarding the specifications of the separation (e.g. cut sizes from 100 μm to several decimetres, compact and fluffy materials as well as foils). Since the ZZ-classifier gains more and more interest in recycling applications, it is discussed in this paper, regarding its design, mode of operation, influencing parameters and the research to date. Research on the ZZ-classifier has been going on for more than 50 years and can be divided into mainly experimental studies and modelling approaches.