Pilot-scale combined pyrolysis and decoupling biomass gasification for energy and metal recovery from discarded printed circuit board and waste cable

Abstract

This paper aims to the design innovation concept of e-waste pyrolysis and decoupling biomass gasification in pilot-scale for e-waste recycling and metal recovery. The syngas product and exhaust gas from decoupling gasification were injected to the pyrolysis burner for fuel reduction in sustaining the pyrolysis process. Results showed that the PCB (printed circuit board) and WC (waste cable) materials had pyrolysis oil yield of 20% and 27.3%, respectively, and pyrolysis char yield of 48% and 42%wt, respectively. Single ring compounds were the major compositions of the pyrolysis oil. The main composition of the synthesis gas product was 10.91%vol (H2), 23.4%vol (CO), and 5.68%vol (CH4). The methane content of the decoupling process was higher than that of conventional gasification. Precious metal content in the PCB char comprised Au, Ag, and Cu. Metal recovery from PCB char and ash via ultrasonication was 83.8–89.8%. The combined pyrolysis and decoupling gasification process offered a reduction in LPG (liquefied petroleum gas) consumption (36.1–41.7%), and high energy recovery from the pyrolysis products (53.4–81.6%). This could save the cost of e-waste recycling by about 25.7–28.7% compared to traditional pyrolysis. Therefore, the combined pyrolysis and decoupling gasification has a very good potential for e-waste conversion and metal recovery.