Selective recovery of rare earth elements by smelting of magnets  

作　　者：Venkata Lakshmi Borra Prasanta Jana PPSahoo Prakash Venkatesan Mehmet Ali Recai Onal Chenna Rao Borra 

机构地区：[1]Department of Metallurgical and Materials Engineering,Indian Institute of Technology Kharagpur,West Bengal,721302,India [2]R&D,Tata Steel Ltd.,Jamshedpur,831001,India [3]Department of Materials Engineering,Synthesis and Recycling(4MAT),Universite Libre de Bruxelles,CP165/63,1050,Brussels,Belgium [4]GenoMines,630 Rue Noetzlin,91190,Paris,France

出　　处：《Journal of Rare Earths》2025年第1期209-217,I0008,共10页稀土学报(英文版)

基　　金：Project supported by the Science and Engineering Research Board of India(SRG/2020/002096)。

摘　　要：Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs production and have high recycling value.In this study,smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe_(2)O_(3).This separates REEs into a slag phase from an iron-rich metallic phase.B_(2)O_(3) was also added to the system as a flux to lower the slag melting temperature.This minimizes REEs loss to the metallic phase and allows a more efficient phase separation.The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB(NdCeFeB)magnets.At 1350℃and for 1 h,the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe_(2)O_(3) and 40 wt%of B_(2)O_(3).Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX)analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron.After the selective removal of iron into the metallic phase,REEs are recovered from the slag phase through an acid leaching process allowing>99%of REEs recovery.Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique.The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.

关 键 词：RECYCLING Rare earth elements NdFeBmagnets SMELTING LEACHING 

分 类 号：TF845[冶金工程—有色金属冶金]