Pyrolysis-Based Technology for Recovering Copper from Transistors on Waste Printed Circuit Boards

Waste electronic components (ECs) recycling is a crucial part of waste printed circuit boards (WPCBs) recycling system. Waste transistors (WTs) are one of the largest obsolete ECs whose recycling technology has been poorly developed. This study presented a pyrolysis-based technology for recovering copper from WTs disassembled from WPCBs, including coarse crushing, pyrolysis, pulverizing, and sieving. First, the WTs were coarsely crushed to reduce the particle size of the epoxy molding compound (EMC). Second, the coarsely crushed WTs were pyrolyzed to damage the cross-linking network structure of EMC and reduce the hardness of EMC. Third, all of the pyrolysis residues were crushed and sieved to separate metals and nonmetals. Finally, an integrated recycling process was proposed based on above studies. In addition, the mechanism of the pyrolysis was analyzed based on bond theory and product analysis to deeply understand the recycling process. Under optimal conditions, 99.16% of copper in WTs were recovered with a purity of 92.75%. This paper provides a method for waste transistors recycling in an efficient and environmentally friendly way