Characterisation of printed circuit boards and particle based simulation for recycling purposes

Printed circuit boards (PCBs) play a crucial role in recycling of WEEEs (waste from electronical and electronic equipment), containing valuable elements like copper, gold, nickel, palladium and many others. While e.g. copper and gold are being recycled via well-established pyrometallurgical routes (Hagelüken, 2006), others are lost in the waste stream. Additionally, hazardous contents like flame retardants and persistent organic compounds comprise further issues for recyclers. In an attempt to contribute to the improvement of recycling rates, we used a combination of different analytical tools to investigate unpopulated PCBs, such as Computer Tomography (CT), SEM-based image analysis (i.e. automated mineralogy, AM), X-ray diffraction and wet chemical methods in order to perform a case study eventually including the usage of heavy liquid separation, a new type of eddy current separator and hydrometallurgical techniques. Furthermore, we trained a particle-based separation model (PSM, Pereira et al. 2021), which has successfully been applied to primary raw materials, to predict the probabilities of individual particles reporting to different processing products. Our results indicate that PSMs are valuable tools to predict recycling efforts, we suggest to use rather 3D-methods (e.g. CT) for complex particle shapes rather than 2D-techniques (e.g. AM) to obtain particle data necessary for simulations.

Hagelüken, C. (2006). Improving metals returns and eco-efficiency in electronics recycling. In Proceedings of the 2006 IEEE international symposium on electronics and environment, San Francisco.

Pereira, L., Frenzel, M., Khodadadzadeh, M., Tolosana-Delgado, R., & Gutzmer, J. (2021). A self-adaptive particle-tracking method for minerals processing. Journal of Cleaner Production, 279, 123711.