The golden age of wasted TVs

Abstract

In recent decades Europe has been increasing its demand and consumption of electronics. This has in turn resulted in major outflows of waste electronics (WEEE) that are usually not properly dealt with. This is especially the case for low to medium grade printed circuit boards (PCBs) which unlike higher grade electronics such as computers are currently not profitable to recycle. Therefore this thesis, as a part of the Peacoc project, investigated the low energy separation methods roll sorting, magnetic separation and magnetic density separation to concentrate the precious and critical metals found in the components of these discarded PCBs. The resulting secondary material flows were then evaluated on their impact in the EU from a material and energetical perspective.The roll sorter was able to significantly increase the concentrations of the precious metal rich target components (Central processing units, IC chips and transistors, MLCC + Ta capacitors, Small transistors and IC chips and Connectors of plastic with golden pins). The machine sorted the feed into multiple width sizes (< 3.0, 3.0 - 5.0, 5.0 - 7.0 and > 7.0 mm) of which all except > 7.0 were used for further processing, increasing the overall grade from 18.66 to 42.61 wt%. This was further increased by the magnetic separator (lightly and non magnetic fractions for < 3.0 mm and only the non magnetic fraction for 3.0 - 7.0 mm) to 53.69 wt% and magnetic density separation (only for non magnetic 5.0 - 7.0 mm)to 66.23 wt%. Recovery for all target categories was near 100% with the exception of Connectors of plastic with golden pins as these were too large for the roll sorter to sort.The thesis also took a broader approach by employing a dynamic material flow analysis to determine the low to medium grade PCBs and their accompanying precious metal flows in the EU. The expected metal flows were low (∼4%) compared to the EU’s overall demand in 2020 and expected to decrease over the years due to miniaturisation (decreasing size and weight) of the components. Furthermore, only around 36.68 wt% of the maximum precious metal flows were expected to be captured due to low collection rates of WEEE and small loses in separation and metallurgical recovery. Nonetheless, a sizeable fraction of the EU’s electronics sector’s demand (over 10%) could be supplied. These results were confirmed by modelling different future scenarios, a Monte-Carlo uncertainty and sensitivity analysis of the model.Lastly, the thesis explored the topic of critical raw materials (CRMs) and the direct energy requirements of Peacoc’s recovery system. It was found that beryllium, antimony, platinum and palladium were the only CRMs that had any significant potential to supply the EU (9.13% for beryllium, 1.58% for antimony,1.32% for platinum and 4.02% for palladium). If only looking at the electronics sector this was also the case for cobalt and vanadium. The newly captured secondary precious metals were shown to require significantly less energy to produce, around an order of magnitude, compared to primary production but were similar to other recycling pathways. Furthermore, the majority of energy was required during metallurgical recovery showing a potential for further mechanical concentration during separation.In conclusion it can be stated that the separation technologies (roll sorting, magnetic separation and magnetic density separation) are effective methods for separating the components of low to medium grade PCBs. However, their impact on the circularity and energetical footprint of the whole EU are expected to be small.