An Experimental Study on Recycling Waste Printed Circuit Boards with Pyrolysis Technique

A fixed-bed experimental apparatus was used to pyrolyze large-size (20cm(2)) multilayer FR4-type printed circuit board(PCB) whose substrate materials were glassfibre reinforced epoxy resins with pyrolysis final temperature of 500 C. The products were detected by GC-MS, FT-IR and SEM. Gas products mainly consisted of CO, CO2, propylene, bromomethane, and a small amount of acetone, C-1-C-3 halogenation alkyls.Pyrolysis oil consisted of 32.9wt% light oil and 44.04wt% heavy oil and 0.083wt% water and 0.066wt% wax. Light oil contained high concentrations of phenol, followed by acetone, 4-ethylphenol, 3-(1-methyl-ethyl)-phenol.Other components were alkyl phenols and alkyl benzenes. Low concentration of bromine was also presented in light oil. The heavy oil was aromatics compound, with the main contents of phenol and alkyl phenols. Solid products contained metals and fiberglass, pyrolysis residues of organic compounds in PCB. Most of metals and glassfibre kept flake jointed together with thin copper wires and plating coppers on the holes of PCB.It was easy to seperate and enrich the metals and glassfibre respectively by manual operation. The accumulated metals contained abundant copper, as well as a small quantity of precious nickel, gold. The enriched glassfibre contained carbon, silicon, oxygen, calcium, aluminum.