Hydrometallurgical recovery of neodymium from spent hard disk magnets: a life cycle perspective

Abstract

Rare earth elements (REEs) are commercially used in an increasing number of critical or widely popular consumer and industrial products. Neodymium (Nd) element has emerged in recent years as one of the most critical REE, due to risks associated with its security of supply at required amounts. It has been widely reported that end of life (EoL) consumer electrical products contain significant amounts of metals and plastics. Thus, recovery of Nd from magnet scraps, EoL appliances or industrial applications is gaining even more strategic importance nowadays. In this study, an ex-ante life cycle assessment (LCA) of the hydrometallurgical recovery of Nd from waste electric and electronic equipment (WEEE) was conducted. The hydrometallurgical Nd recovery route consists of pretreatment, chemical leaching and Nd metal precipitation The feasibility and environmental performance of Nd metal recycling experiment model was investigated with an LCA scenario focusing on neodymium-iron-boron (Nd-Fe-B) magnet production. The LCA results were compared to that due to Nd-Fe-B magnet production from bastnäsite/monazite mineral ores using the traditional sintered magnet route. LCA sensitivity analysis and cost analysis were also performed. It was found out that, from both an economical and environmental point of view, magnet production from recovered Nd performed better than that of virgin magnet production. The scaled-up Nd metal recovery system reduced environmental impacts of Nd-Fe-B magnet production system by up to 65% for eight of the eleven environmental impact categories. Nd recycling reduced production cost from 8.55 to 3.98 USD/kg.