• Pownceby, Mark
• Haque, Nawshad
• Islam, Khairul

Abstract

Printed circuit boards (PCBs) from antiquated electronic goods were processed by a pyromet-allurgical route to produce and separate alloy and slag phases. The process involved initial size reduction of PCBs, followed by pyrolysis at 500 °C for 6 hours and finally smelting of the solid materials in an electric furnace. A preliminary smelting test was performed at 1600 °C to es-timate the composition of the slag generated. In later kilogram-scale smelting experiments, B2O3 flux was added along with CaO and SiO2 to decrease the liquidus temperature required to smelt the PCBs. The level of fluxing was adapted from earlier phase equilibria studies of the CaO-Al2O3-SiO2-B2O3 slag system. Results showed that the flux decreased the melting temper-ature and assisted the recovery of most valuable metals within the alloy phase. Overall material recovery (93.3 wt.%) was achieved in smelting. More than 99% of Cu, Sn and around 100% of precious metals (Au, Ag, Pt) and Ni were recovered in the alloy phase. A fluxing strategy for smelting high Al2O3 containing e-waste PCBs could be proposed based on the experimental findings of this research.

Topics

• pyrolysis
• phase
• experiment