In order to increase metal recovery from discarded printed circuit board assemblies, an additional preprocessing step where its electronic components are presorted before comminution and metallurgy is suggested. The first step in this process is depopulation where the electronic components are removed from the board. However, currently no practical apples to apples comparison has been performed. Therefore, six depopulation methods (both mechanical and thermal) were directly compared on both qualitative and quantitative indicators and evaluated using a multi-criteria analysis. The mechanical methods were faster less energy intensive than the thermal methods but produced lower quality products and had issues with scaling. Overall the best found method was using a pneumatic hammer due to its simplicity and effectiveness.

Critical raw materials (CRMs) are one of the enablers of a sustainable future due to their importance in green technologies. Yet, their own circularity and end-of-life recycling rates have been lacking as their concentrations are too low in waste products to be efficiently recycled. This is not the case, however, for discarded printed circuit boards where different types of electronics components (ECs) use specific CRMs in high concentrations. Furthermore, due to worldwide manufacturing standards these ECs are consistent between different printed circuit boards (PCBs) in their physical characteristics such as size, shape and material composition. Yet at the moment no sorting methods exist that can separate ECs from modern PCBs. Therefore, we aim to evaluate multiple simple yet effective mechanical separation methods to sort said ECs with CRM recovery in mind. First of all, ECs from flat-panel displays were sieved into a small (<4 mm), medium (4 - 10 mm) and large fraction (>10 mm). This was followed by a roll sorter to separate thinner components, like IC chips, from similarly sized thicker ECs. In order to separate the components based on ferromagnetic composition an innovative overbelt ferromagnetic separator was developed where the magnetic field strength continuously decreased over the length of the belt. Lastly, the different types of ECs were analysed by laser-induced breakdown spectroscopy to identify the presence of any CRMs. Our study shows that by combining these three different sorting technologies it is possible to sort the ECs in a way that the majority of CRM containing components are concentrated in only 21.09 wt% of the total weight. This in turn results in significantly higher CRM concentrations, thus removing a major limitation to their recovery and improving CRM circularity for a more sustainable future.

Solid waste sorting is an important pre-treatment in recycling to improve the efficiency of material recovery and reduce costs. Motivated by the PEACOC project on metal recovery from solid wastes, an innovative magnetic density separation (MDS) process has been developed for solid waste sorting. It has intrinsic advantages over conventional gravity separation technologies and the previously industrialized MDS process. The new MDS process applies an inclined planar magnet and a horizontal basin containing a static magnetic fluid as the separation medium. A particle sliding phenomenon is identified as a feature that could help the separation. Experiments have been carried out to demonstrate the role of the MDS in concentrating valuable metals in shredded PCBAs and reducing metallic contaminants in plastic fractions of shredded wires. A pilot scale facility is introduced to show the design to achieve continuous production and to reduce the consumption of ferrofluid.

Elektronica is een snel groeiende stroom van complex afval in Nederland. De huidige technieken zijn echter niet in staat om dit type afval, bekend als afgedankte elektrische en elektronische apparatuur (AEEA), te behandelen tot het niveau van ruwe materialen dat onze duurzaamheidsdoelen vereisen. Als stap op weg naar dit doel bespreken we hier drie vernieuwende mechanische scheidingsmethodes en de daaraan onderliggende natuurkundige principes, zoals scheiding op basis van frictie, magnetisme en drijfvermogen in een magnetische vloeistof. Deze maken het mogelijk om verschillende types elektronische componenten van afgedankte printplaten effectief te scheiden, wat het uiteindelijk mogelijk moet maken om de kritieke metalen beter terug te winnen via energie-efficiënte metallurgische routes.