2017-Sustainable Industrial Processing Summit
SIPS 2017 Volume 1. Barrios Intl. Symp. / Non-ferrous Smelting & Hydro/Electrochemical Processing
| Editors: | Kongoli F, Palacios M, Buenger T, Meza JH, Delgado E, Joudrie MC, Gonzales T, Treand N |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2017 |
| Pages: | 264 pages |
| ISBN: | 978-1-987820-61-4 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Selective Recovery of Rare earth elements from NdFeB powders by using caustic digestion and oxidation roasting
Ho-Sung Yoon1; Chul Joo Kim1; Kyeong Woo Chung1;1KOREA INSTITUTE OF GEOSCIENCE AND MINERAL RESOURCES (KIGAM), Daejeon, Korea (Republic of [South] Korea);
Type of Paper: Regular
Id Paper: 50
Topic: 11
Abstract:
With increasing use of NdFeB magnets, an abundance of waste magnets has been gradually released from end-of-life devices and systems. In addition, the generation of scrap materials is simultaneously increasing because more than 20% of the input amount is discharged as waste scrap during the manufacturing process. Therefore, their recycling has attracted much attention and several methods based on pyro/hydro-metallurgy for recovering valuable metals from magnet alloys have been developed.
Hydrometallurgical process consists of leaching, separation and purification and recovery of rare earth elements(REEs) as compounds and metals. Upon the application of NdFeB powders to acid leaching without pretreatment, iron as well as REEs are leached, which consumes large amount of acid and generated the large amount of FeSO4 waste solution. To avoid this, oxidation roasting and acid leaching of NdFeB powders have been suggested, however, this methods shows still relatively high leaching of iron due to the formation of mixed oxide, FeNdO3.
In this work, caustic digestion and oxidation roasting method is suggested. In alkaline region, neodymium and iron can be transformed to neodymium hydroxide and magnetite like this. Then oxidation roasting of these powders gives rise to the formation of neodymium oxides and iron oxides, respectively. The leaching of resultant powders reveals high recovery yield of REEs of more than 90% and very low recovery yield of iron of below 1%.
More details will be discussed in the presentation.