Exploration of Feed Shape, Size, Infill, and Aspect Ratio on the Cyclone Separation Process for Small-Format Plastics

Small-format plastics are defined as being <2 in. in two or more dimensions and account for up to 10% of plastic waste by weight. Due to their size, they are often not recovered within the current material recovery facilitie infrastructure because they typically fall through screens in the glass separation process. A previous study demonstrated the feasibility of implementing a cyclone separation process to improve retention of small-format plastics that fall through with the glass. This work explores how the cyclone’s sorting is impacted by feed shapes, feed size, feed infill, and feed aspect ratio through experimental trials and computational fluid dynamics. It was demonstrated that the cyclone is also capable of sorting spheres, cubes, cylinders, and cones with separation efficiencies >90% at lower particle sizes. Three different infills were tested, demonstrating that solid particles tend to perform worse due to their larger mass compared to their hollow counterparts. While the cyclone can handle 1:2, 1:1, and 2:1 aspect ratios, it performs most consistently with isometric particles and shorter, wider particles. Finally, contamination studies were conducted revealing that the cyclone separation process has tolerance to some contamination before clogging is observed. Overall, the potential of a cyclone separation process was demonstrated within the context of improving recovery of small-format plastics.