Next Article in Journal
Analyzing How Governance of Material Efficiency Affects the Environmental Performance of Product Flows: A Comparison of Product Chain Organization of Swedish and Dutch Metal Packaging Flows
Previous Article in Journal
Materials Stock of the Civilian Aircraft Fleet
Previous Article in Special Issue
Leaching of Metals from Spent Lithium-Ion Batteries
Article Menu

Export Article

Open AccessArticle
Recycling 2017, 2(4), 22; doi:10.3390/recycling2040022

Hydrocyclone Separation of Hydrogen Decrepitated NdFeB

1
School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
2
School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
This paper is an extended version of our paper published in 6th International Conference Quo Vadis. Recycling, High Tatras, Slovak Republic, 6–9 June 2017.
*
Author to whom correspondence should be addressed.
Received: 23 August 2017 / Revised: 31 October 2017 / Accepted: 13 November 2017 / Published: 14 November 2017
(This article belongs to the Special Issue Quo Vadis Recycling 6)
View Full-Text   |   Download PDF [6973 KB, uploaded 14 November 2017]   |  

Abstract

Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the NdFeB breaks down into a matrix phase (Nd2Fe14BHx) and RE-rich grain boundary phase. The grain boundary phase in the HD powder is <2 μm in size. Recycled NdFeB material has a higher oxygen content compared to the primary source material. This additional oxygen mainly occurs at the Rare Earth (RE) rich grain boundary phase (GBP), because rare earth elements oxidise rapidly when exposed to air. This higher oxygen level in the material results in a drop in density, coercivity, and remanence of sintered NdFeB magnets. The particle size of the GBP is too small to separate by sieving or conventional screening technology. In this work, an attempt has been made to separate the GBP from the matrix phase using a hydrocyclone, and to optimise the separation process. HD powder, obtained from hard disk drive (HDD) scrap NdFeB sintered magnets, was used as a starting material and passed through a hydrocyclone a total number of six times. The X-ray fluorescence (XRF) analysis and sieve analysis of overflows showed the matrix phase had been directed to the underflow while the GBP was directed to the overflow. The optimum separation was achieved with three passes. Underflow and overflow samples were further analysed using an optical microscope and MagScan and matrix phase particles were found to be magnetic. View Full-Text
Keywords: hydrocyclone; centrifugal separation; fine particle separation; NdFeB; recycling; rare earth elements hydrocyclone; centrifugal separation; fine particle separation; NdFeB; recycling; rare earth elements
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Awais, M.; Coelho, F.; Degri, M.; Herraiz, E.; Walton, A.; Rowson, N. Hydrocyclone Separation of Hydrogen Decrepitated NdFeB. Recycling 2017, 2, 22.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Recycling EISSN 2313-4321 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top