Exploration of alternative routes for recycling critical metals from waste PCB and tantalum capacitors

Abstract

Abstract Printed Circuit Boards (PCB), secondary source of critical metals, are usually recycled to recover precious metals. Alternative routes, aiming to pre-concentrate critical metals, were tested at lab scale. An up-scaling process is proposed involving a thermomechanical separation of PCB and surface mounted devices (SMD). PCB without SMD are treated by solvolysis for desilication and debromination. Further calcination provides a presumably leachable metallic mix. Tantalum capacitors, a specific type of SMD, are treated by pyrolysis, to isolate metallic cores, which are further leached to obtain 92% pure tantalum oxide. LCA data show that tantalum recycling process is profitable for the environment.