Abstract
The mechanism of part detachment and board breakage process in a drum-typed impact mill to recover valuable metals by removing components from printed circuit boards (PCBs) was investigated. Experimental results using test PCBs showed that parts detachment was enhanced by the increase of input number of PCBs in the mill and board breakage was enhanced by the increase of rotational speed of the agitator. DEM simulation results using spherical particles model showed that board breakage was achieved by the collision of boards with drum wall and agitator, and part detachment was achieved by the interaction between PCBs.
To simulate part detachment and board breakage process more briefly, particle-based rigid body model, in which model PCB geometry was constructed consisting of bonded particulates, was included to DEM simulation. Simulation results showed that board breakage was obtained from the impact of boards with the drum wall and part detachment was obtained from the collision of the boards with each other. These simulation results were successfully corresponded to experimental observations.
