Effect of cone angles of a hydrocyclone for the separation of waste plastics with low value of density difference

The cone angle of a hydrocyclone is believed to be an important parameter to affect the separation performance. For the recycling of waste plastics, this paper focused on the study of the influence of cone angles on the separation of light dispersed plastics (PET) and heavy dispersed plastics (PVC) by experiments and numerical simulations. The cone angle was changed from 3° to 28° either at given length of the cylindrical section or at fixed total length of the hydrocyclone. The separation performance varied with cone angles at given length of the cylindrical section more greatly than that at fixed total length of the hydrocyclone. Results show that particles with different sizes in mixture exhibited discrepant separation behaviors at various cone angles. There was an optimum cone angle at which the Newton efficiency peaked as 90.2%, while the purity of PET could also reach the highest. The proportion of cylindrical section could be properly small for the enhancement of Newton efficiency.