Recovery of residual metals from − 0.5 mm non-metallic fractions in WPCBs using electrostatic separation enhanced by air classification

• Published in: Journal of material cycles and waste management Vol. 24; no. 3; pp. 980 - 991
• Main Authors: Wang, Zhe, Li, Hong, Chen, Haiyan, Xiao, Junhui, Zhang, Qing
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.05.2022; Springer Nature B.V
• Subjects: Adhesion; Air flow; Circuit boards; Civil Engineering; Classification; Efficiency; Engineering; Environmental Management; Fibers; Glass fibers; Materials recovery; Metal concentrations; Metal particles; Metals; Original Article; Separation; Waste Management/Waste Technology; WPCBs; Air classification; Electrostatic separation; Metal recycling
• ISSN: 1438-4957; 1611-8227
• DOI: 10.1007/s10163-022-01373-1

Electrostatic separation is a cleaning physical method to recover metals from waste printed circuit boards (WPCBs), but it has poor separation efficiency for finer sized fractions. In this study, electrostatic separation enhanced by air classification was used to recover residual metals from − 0.5 mm non-metallic fractions in WPCBs. Under the optimal operational factors, concentrate with metal content of 71.55 wt% and recovery of 64.79% was obtained by “air classification + electrostatic separation” process. Morphology analysis showed that large amounts of fine glass fibers adhesion to the surface of metal particles, resulting in low separation efficiency of fine fractions. Air classification can realize separation of metallic particles and non-metallic particles according to the difference of density. And pre-concentration of metal particles in coarse fraction can reduce the load of subsequent separation process. Moreover, the air flow can effectively remove fine non-metallic particles and reduce the influence of adhesion and agglomeration of fine particles on electrostatic separation, so as to improve the separation efficiency of electrostatic separation.