CFD–DEM simulation of fluid–solid flow of a tapered column separation bed

Research on recycling waste Printed Circuit Boards (PCB) is at the forefront of preventing environmental pollution and finding ways to recycle resources. The Tapered Column Separation Bed (TCSB) is invented aiming at disposing the problem that fine particles of waste printed circuit boards cannot be separated efficiently so as to obtain further insight about the underlying mechanisms and demonstrate the separation feasibility in the tapered column separation bed. In this work, a Computational Fluid Dynamics (CFD) coupled with Discrete Element Method (DEM) model for two-phase flow has been extended to simulate the fluid–solid flow in the tapered column separation bed. Its validity is demonstrated by its successful capturing the key features of particles’ flow pattern, velocity, the pressure distribution, the axial position with time and axial force for particles with different densities. Simulation results show that the plastic particles and resin particles become overflow, while copper particles, iron particles and aluminum particles successively become underflow, with a discharge water flow rate of 1 m3/h, an obliquity of 30°. The simulated results agree reasonably well with the experimental observation. Using this equipment to separate waste PCBs is feasible, theoretically.