ASPEN PLUS Predictive Simulation of Printed Circuit Boards Pyrolysis and Steam Gasification for Organic Fraction Valorization

Abstract

Printed circuit boards are considered a secondary source of raw materials, such as precious or base metals. One of the most promising solutions for recovering these metals is certainly hydrometallurgy. However, the leaching of different metals from PCBs is hindered by the presence of an organic fraction that lowers the extraction yields. One solution to this problem is a pyrolysis pre-treatment which removes the organic fraction and enhances it through conversion into syngas. A steady-state simulation model was developed using ASPEN PLUS to describe the thermodynamic behavior of PCB pyrolysis. The pyrolysis reactor was modeled as a combination of the Yields reactor and the Gibbs reactor. The model has been validated using various data present in the literature. The composition of the different products was estimated through the minimization of Gibbs’s free energy. A sensitivity analysis was performed to investigate the influence of different parameters on the conversion yield and the syngas quality produced. Thanks to the study, it was possible to describe and analyze the pyrolysis of PCBs without requiring numerous experimental tests. The results show how steam gasification appears to be the most efficient technology for the pre-treatment of PCBs within a hydrometallurgical process.