A life cycle perspective for hydrometallurgical and biohydrometallurgical metal recovery from weee

Abstract

Rare earth elements (REEs) are being employed in an increasing number of critical or widely popular consumer/ industrial products leading to increase in their demand particularly in the last few decades. Since almost all of REEs are produced in China, the European Commission and US energy department have identified REEs as critical elements and have directed special efforts to obtain sustainable resources of REE. End of life consumer electrical products contain significant amounts of metals and plastics. Thus the aim of this study is focused on recycling metals from waste electric and electronic equipment (WEEE). WEEE contains high amounts of base metals, precious metals and REEs. The concentration of metals in waste streams is higher than that of natural ores. Current recycling methods consume high amounts of energy and chemicals. Economically feasible industrial facilities (waste incineration) perform poorly for environment. In this study life cycle assessment (LCA) of two metal recovery systems were examined: biohydrometallurgical recovery of copper and hydrometallurgical recovery of neodymium from WEEE. Biohydrometallurgical methods are identified as environmentally friendly and low cost operation methods. An ex-ante scaled-up life cycle assessment (LCA) model was created for copper metal recovery. Results show that recovering only copper metal from WEEE is neither economically feasible nor environmentally friendly. The feasibility and environmental performance of neodymium metal recycling experiment model was investigated with a LCA scenario of neodymium iron boron magnet production model. It was found that neodymium metal recycling economically and environmentally performed better than virgin magnet production.