Comparison of different routes for recovery of metals from electronic scrap

Abstract

There is an exponential demand for electronic equipment but, unlike other consumer products, the useful lifetime is relatively short which calls for the recycling of electronic scrap. Considering the inflow of illegally imported discards from the West, the electronic waste is expected to reach a total of around 30 million tonnes by 2020. Waste printed circuit boards (WPCB) are valuable secondary raw material for critical and precious metal industries. In this work, WPCB of different sizes were dissolved in different lixiviants for metal dissolution. The leach solution contains different metals due to a differential solubility of metals and associated attachments. With organic solvent DMF, plastic, baseboard, and metallic values are easily detached and separated without any contamination of plastic and metal. The coarse ground PCB material subjected to dense medium separation resulted in the clear separation of plastics and metals. Further, the metal fraction is magnetically separated to recover iron-steel values. With all the three processes almost 90% of metal values are recovered from PCB’s. Based on three processes examined, it can be concluded that organic solvent processing and physical beneficiation process are better than hydrometallurgical route as the latter includes extra concentration and separation step.