An evaluation of hydrocyclones and the LARCODEMS cylindrical cyclone for the separation of waste plastics of proximate densities

Abstract Results of an evaluation of hydrocyclones and the LARCODEMS version of Density Medium Separation (DMS) cyclones for the separation of plastics are presented. This study presents the results of tests of the precision of density separations and the effect of flakiness of particles on the quality of density separations obtained in these devices. The cylindrical DMS cyclone (LARCODEMS) tested produced significantly more precise density separations of both flaky particles of varying size and of equidimensional particles of similar size than did a hydrocyclone of similar diameter. Particles with densities approximating that of the real separation density fed into the cyclone along with the separation medium are susceptible to misclassification into both the dense “sinks” and light “floats” products. In such instances, it appears that the only pure dense product that can be obtained is with the LARCODEMS and this only when particles to be processed are fed into its vortex. It is shown that the cylindrical DMS cyclones such as the LARCODEMS are indicated to be the most suitable for precise density separations of waste plastic particles. This device is also the most versatile cyclone density separation process as it is suitable for conducting density separations by either feeding material to be processed either dry or moist directly into its vortex or submerged along with the separation medium.