An Innovative Enhanced Flotation Approach of Non-Metallic Components in Waste Printed Circuit Boards: Application of Pyrolysis Oil As Self-Generated Collector

The generation of waste printed circuit boards (WPCBs) is increasing due to the global consumption of electronic devices. In this study, a novel approach has been proposed by employing pyrolysis oil derived from the pyrolysis of non-metallic particles (NMPs) as self-generated collector for WPCBs flotation, thereby improves the flotation effect of WPCBs, which not only circumventing the consumption of non-regenerative collectors but also offering a viable means for the clean utilization of non-metallic components (NMCs). The surface morphology and phase composition of WPCBs and NMPs were analyzed respectively. The SEM and XRD results indicate that the dissociation degree of NMPs is limited, thereby exacerbating the challenges associated with flotation of WPCBs. Additionally, FTIR analysis was conducted to investigate the adsorption mechanism between pyrolysis oil and NMPs. The results show that both NMPs and pyrolysis oil contain-CH3, 3 , C--C -- C diffraction peaks, which is conducive to the adsorption of pyrolysis oil. The floatability of NMPs before and after conditioned by pyrolysis oil, as well as the mechanism of particle-bubble interaction, were investigated through contact angle and wrap angle measurements. The results demonstrate a substantial increase of over 45 degrees degrees in the contact angle of NMPs. Additionally, the results show that the wrap angles of NMPs conditioned by pyrolysis oil also significantly increase. Flotation tests with pyrolysis oil were conducted on WPCBs and NMPs to validate the effectiveness of pyrolysis oil on flotation. The flotation results of WPCBs show that when 8 kg/t pyrolysis oil is added, the Cu grade for concentrate of 1-0.5, 0.5-0.25, 0.25-0.125, 0.125-0.074,-0.074 mm increases by 4.24 %, 10.26 %, 17.86 %, 17.20 %, and 22.21 %, respectively. This study presents a viable approach to address the challenges of achieving higher separation accuracy for WPCBs and optimizing resource utilization of NMPs.