Recycling the Rare Earth Elements from Waste NiMH Batteries and Magnet Scraps by Pyrometallurgical Processes Kai Tang, Arjan Ciftja, Ana Maria Martinez, Casper van der Eijk SINTEF Materials and Chemistry, N-7465 Trondheim, Norway Yuyang Bian, Shouqiang Guo, Weizhong Ding Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 20072, China Abstract: The rare earths (REs) are now considered as the most critical, with the highest supply risk raw materials in EU. Because there exist only few exploitable natural resources of rare earths in Europe, the EU will have to rely on recycling of REs from pre- and post-consumer scraps and especially end-of-life products. Nickel- metal hydride (NiMH) batteries and rare earth magnets are the typical urban mining resources. High temperature processes designed for recovery of rare earth elements from the waste nickel-metal hydride batteries and magnet scraps have been developed recently. The calcium silicate slags and FeO-B 2 O 3 fluxes were chosen to recover the REEs from the waste flows. The key parameters for high temperature recycling of rare earth elements (REEs) have been extensively studied both theoretically and experimentally. The pyrometallurgical processes are able to separate and recover almost 99% of REEs from the waste NiMH batteries and NdFeB magnet scraps. Experimental results also show that the RE oxides obtained from the high temperature treatment can reach as purity as 96 wt%. Key words: Rare Earth Elements, Recycling, NiMH Battery, Magnet Scraps, Pyrometallurgical Process 1. Introduction The increasing popularities of electronic consumer goods, hybrid and electric cars, and wind turbines lead to an unprecedented increase in the demand of rare earth elements (REEs). The rare earths are now considered as the most critical, with the highest supply risk raw materials in EU. Because there exist only few exploitable natural resources of rare earths in Europe, the EU will mainly have to rely on recycling of REEs from pre- and post-consumer scraps and especially End-of-Life (EoL) products, known as “urban mining”. Nickel-metal hydride (NiMH) batteries are currently used in many mobile applications: hybrid and electric cars, laptops, and mobile phones etc. Because NiMH batteries have about twice the energy density of Ni -Cd batteries and a similar operating voltage as that of Ni -Cd batteries, they are expected to become a mainstay in the current rechargeable batteries. The most common rare earth magnets are based upon a neodymium-iron-boron alloy (Nd 2 Fe 14 B as matrix phase, surrounded by a Nd-rich grain boundary phase), with small additives of Pr, Tb, and especially Dy. The heavy rare earth elements (HREEs) are added to magnets to increase their temperature resistance. The NdFeB magnets contain more than 30 wt% of REEs. It is estimated that 20-30% NdFeB scraps will be produced in the manufacturing process[1]. Furthermore, NdFeB magnet is easily to be oxidized at higher temperatures[2]. The oxidized scraps are not able be reuse in the conventional magnet production. It is essential to recycle the magnets and particular to extract the rare earth elements from the oxidized magnet scraps. Sustainable industrial recycling processes for the EoL NiHM batteries and pre-/post-consumer NdFeB magnets are still under developing. Several hydrometallurgical recycling processes for the discarded NiMH batteries have been reported in the literature[3-7]. The conventional ways to extract REEs from permanent magnets were also based mainly on the hydrometallurgical treatment[8]. However, huge amount of water and chemicals have to be used in the hydrometallurgical treatments. These processes are no longer considered as sustainable in the future. The processes based primary on the high temperature pyrometallurgical processes are now attracted more attention for their less environmental impact[9-11]. The existing state-of-the-art technologies for recycling of precious and other metals from electronic waste are based on high temperature smelting processes using Pb, Cu and Ni as collectors for the valuable metals. However, the smelting flow sheets are not developed yet for the REEs recovery, as they revert to the oxide phase (slags or fluxes) in a diluted form. One of