# US 2019/0244733 A1 · Processing of NdFeB Magnetic Material

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- Number: US 2019/0244733 A1
- Document ID: US20190244733A1
- Status: Published application
- Kind: A1
- Application number: 16/327,747
- Filed: 2017-08-25
- Published: 2019-08-08
- Earliest claimed: 2016-08-25
- Assignees: The University of Birmingham
- Applicants: The University of Birmingham
- Inventors: Allan Walton; Neil Rowson; Enrique Herraiz Lalana
- Web page: https://patentgrep.com/patent/US20190244733A1

## CPC

- H01F 1/0573: {obtained by reduction or by hydrogen decrepitation or embrittlement}
- B22F 8/00: Manufacture of articles from scrap or waste metal particles
- B22F 9/023: {Hydrogen absorption}
- C22B 7/005: {Separation by a physical processing technique only, e.g. by mechanical breaking}
- C22B 59/00: Obtaining rare earth metals
- H01F 1/0571: {in the form of particles, e.g. rapid quenched powders or ribbon flakes}
- H01F 41/0253: {for manufacturing permanent magnets}
- Y02P 10/20: Recycling
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method of processing NdFeB magnetic powder comprises: providing a source of hydrogenated NdFeB powder (101, 102, 103); feeding said powder into an inlet of a cyclone separator (104); separating the powder into an overflow enriched in Nd-rich grain boundary phase and an underflow enriched in NdxFeyBHz matrix phase particles (106); optionally feeding the underflow back into the inlet of the cyclone separator whereby to further enrich the underflow in the NdxFeyBHz matrix phase particles (108a); and collecting the underflow (108).

## Claims

### Claim 1

A method of processing NdFeB magnetic powder comprising:
(i) providing a source of hydrogenated NdFeB powder;
(ii) feeding said powder into an inlet of a cyclone separator;
(iii) separating the powder into an overflow enriched in Nd-rich grain boundary phase and an underflow enriched in NdxFeyBHz matrix phase particles;
(iv) optionally feeding the underflow back into the inlet of the cyclone separator whereby to further enrich the underflow in the NdxFeyBHz matrix phase particles; and
(v) collecting the underflow.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the hydrogenated NdFeB powder is obtained by carrying out hydrogenation decrepitation on a sintered NdFeB magnet.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the underflow is fed into the inlet of the cyclone separator sufficient times until the underflow is at least 95 wt % NdxFeyBHz matrix phase particles.

### Claim 4 (depends on 1)

The method according to claim 1, further comprising an additional step of blending the underflow collected in step (v) with fresh Nd particles to produce an Nd-enriched powder and sintering and magnetising the Nd-enriched powder to form a NdFeB magnet.

### Claim 5 (depends on 4)

The method of claim 4, wherein the Nd particles are elemental Nd, Nd-hydride or an alloy of Nd.

### Claim 6 (depends on 1)

The method according to claim 1 wherein the cyclone separator is a hydrocyclone separator and the hydrogenated NdFeB powder is formed into an aqueous slurry before being fed into the inlet of the separator.

### Claim 7 (depends on 6)

The method of claim 6 wherein the underflow collected in step (v) is dried.