Investigating the use of vertical vibration to recover metal from electrical and electronic waste

Due to the current and future environmental legislation there is a need to develop cleaner technologies for separating materials in the mineral and recycling industries. This paper discusses the use of vertical vibration to recover valuable materials from electrical wastes. Under vertical vibration granular materials segregate by size and/or density. Previous studies have shown that glass/bronze mixtures [Burtally, N., King, P.J., Swift, M.R., Leaper, M., 2003. Dynamical behaviour of fine granular glass/bronze mixtures under vertical vibration. Granular Matter 5, 57-66] and mixed-plastics/bronze mixtures [Mohabuth, N., Miles, N., 2005. The recovery of recyclable materials from Waste Electrical and Electronic Equipment (WEEE) by using vertical vibration separation. Resour. Conserv. Recy. 45, 60-69] can be separated under vibration. This new separation technique is now extended to recover copper from electrical wires and computer circuit boards. The materials were reduced to a granular state and fed into a specially designed semi-batch cell consisting of two chambers. The cell was placed between a pair of sinusoidally driven loudspeakers which induced vibration. Under vibration the denser materials were found to concentrate into the adjacent chamber leaving the rest of the materials in the original chamber. The separation behaviour was studied at different combinations of frequencies and dimensionless accelerations. Assays were also carried out to assess the efficiency of separation. Understanding the separation behaviour in the batch cell will possibly lead to the design information for the future development of a continuous separation system.