Recovery and separation of rare earths and boron from spent Nd-Fe-B magnets

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Recovery and separation of rare earths and boron from spent Nd-Fe-B magnets. / Liu, Fupeng; Porvali, Antti; Wang, Jin Liang; Wang, Houqing; Peng, Chao; Wilson, Benjamin P.; Lundström, Mari.

julkaisussa: Minerals Engineering, Vuosikerta 145, 106097, 01.01.2020.

Tutkimustuotos: Lehtiartikkelivertaisarvioitu

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@article{b5bcb1bb3f7e4ff3aa18d95a09feb7d6,
title = "Recovery and separation of rare earths and boron from spent Nd-Fe-B magnets",
abstract = "The environmental and economic benefits of recycling spent Nd-Fe-B magnets are becoming increasingly important. Nevertheless, the reprocessing of this type of material by conventional processes remains a challenge due to the difficulties of rare earth elements (REEs) and Fe separation, low products purity and large-scale generation of boron wastewater. This research presents an effective approach for the comprehensive recovery of REEs, iron and boron from Nd-Fe-B magnet wastes. Investigations of the initial roasting pretreatment showed it to be an effective method that aids the subsequent selective separation of REEs, with the most suitable temperature determined to be 800 °C. During the following selective hydrochloric acid pressure leaching of the roasted magnet, the addition of 2 g/L NaNO3 was found to significantly improve the separation of REEs and B from Fe. The results indicated that almost 99{\%} of REEs and 97{\%} of B could be extracted, whilst in contrast, less than 0.1{\%} of iron dissolved, to leave a hematite rich residue. The extracted REEs were then directly precipitated as oxalates with >99{\%} extraction and 99.95{\%} purity at a value n(oxalic acid)/n(REEs) of 1, resulting in significant improvements to oxalic acid consumption and REEs product purity. In the final step, 99.5{\%} of boron was recovered via a three-stage counter current extraction with 30{\%} (v/v) (EHD) and 70{\%} (v/v) sulfonated kerosene. These findings demonstrate that high recoveries of REEs, Fe and B are achievable with hydrochloric acid pressure leaching followed oxalate precipitation and boron recovery.",
keywords = "Boron, Hematite, Pressure leaching, Rare earth elements, Spent Nd-Fe-B magnets",
author = "Fupeng Liu and Antti Porvali and Wang, {Jin Liang} and Houqing Wang and Chao Peng and Wilson, {Benjamin P.} and Mari Lundstr{\"o}m",
year = "2020",
month = "1",
day = "1",
doi = "10.1016/j.mineng.2019.106097",
language = "English",
volume = "145",
journal = "Minerals Engineering",
issn = "0892-6875",

}

RIS - Lataa

TY - JOUR

T1 - Recovery and separation of rare earths and boron from spent Nd-Fe-B magnets

AU - Liu, Fupeng

AU - Porvali, Antti

AU - Wang, Jin Liang

AU - Wang, Houqing

AU - Peng, Chao

AU - Wilson, Benjamin P.

AU - Lundström, Mari

PY - 2020/1/1

Y1 - 2020/1/1

N2 - The environmental and economic benefits of recycling spent Nd-Fe-B magnets are becoming increasingly important. Nevertheless, the reprocessing of this type of material by conventional processes remains a challenge due to the difficulties of rare earth elements (REEs) and Fe separation, low products purity and large-scale generation of boron wastewater. This research presents an effective approach for the comprehensive recovery of REEs, iron and boron from Nd-Fe-B magnet wastes. Investigations of the initial roasting pretreatment showed it to be an effective method that aids the subsequent selective separation of REEs, with the most suitable temperature determined to be 800 °C. During the following selective hydrochloric acid pressure leaching of the roasted magnet, the addition of 2 g/L NaNO3 was found to significantly improve the separation of REEs and B from Fe. The results indicated that almost 99% of REEs and 97% of B could be extracted, whilst in contrast, less than 0.1% of iron dissolved, to leave a hematite rich residue. The extracted REEs were then directly precipitated as oxalates with >99% extraction and 99.95% purity at a value n(oxalic acid)/n(REEs) of 1, resulting in significant improvements to oxalic acid consumption and REEs product purity. In the final step, 99.5% of boron was recovered via a three-stage counter current extraction with 30% (v/v) (EHD) and 70% (v/v) sulfonated kerosene. These findings demonstrate that high recoveries of REEs, Fe and B are achievable with hydrochloric acid pressure leaching followed oxalate precipitation and boron recovery.

AB - The environmental and economic benefits of recycling spent Nd-Fe-B magnets are becoming increasingly important. Nevertheless, the reprocessing of this type of material by conventional processes remains a challenge due to the difficulties of rare earth elements (REEs) and Fe separation, low products purity and large-scale generation of boron wastewater. This research presents an effective approach for the comprehensive recovery of REEs, iron and boron from Nd-Fe-B magnet wastes. Investigations of the initial roasting pretreatment showed it to be an effective method that aids the subsequent selective separation of REEs, with the most suitable temperature determined to be 800 °C. During the following selective hydrochloric acid pressure leaching of the roasted magnet, the addition of 2 g/L NaNO3 was found to significantly improve the separation of REEs and B from Fe. The results indicated that almost 99% of REEs and 97% of B could be extracted, whilst in contrast, less than 0.1% of iron dissolved, to leave a hematite rich residue. The extracted REEs were then directly precipitated as oxalates with >99% extraction and 99.95% purity at a value n(oxalic acid)/n(REEs) of 1, resulting in significant improvements to oxalic acid consumption and REEs product purity. In the final step, 99.5% of boron was recovered via a three-stage counter current extraction with 30% (v/v) (EHD) and 70% (v/v) sulfonated kerosene. These findings demonstrate that high recoveries of REEs, Fe and B are achievable with hydrochloric acid pressure leaching followed oxalate precipitation and boron recovery.

KW - Boron

KW - Hematite

KW - Pressure leaching

KW - Rare earth elements

KW - Spent Nd-Fe-B magnets

UR - http://www.scopus.com/inward/record.url?scp=85073725923&partnerID=8YFLogxK

U2 - 10.1016/j.mineng.2019.106097

DO - 10.1016/j.mineng.2019.106097

M3 - Article

AN - SCOPUS:85073725923

VL - 145

JO - Minerals Engineering

JF - Minerals Engineering

SN - 0892-6875

M1 - 106097

ER -

ID: 38772915