Recycle of rare earth magnet with pyrochemical process · Demonstration test with actual used RE...

© 2016 Toshiba Corporation

Hisao OHMURAToshiba Corp.Dec 8, 2016

Recycle of rare earth magnet with pyrochemical process

© 2016 Toshiba Corporation 2

Background

Industrial device@ 2015

Automobile@ 2019

Home electronics@ 2018

43%

22%

35%General Industry(Small, Middle motor)

Elevator Hoisting machine(Large motor)

508 t/y Air conditioner

39.4%

36.4%

23.6%

Others 0.6%

Amount of rare earth magnet embedded each product (estimate)

Breakdown

• 【Rare Earth(RE) magnet】Recycle of RE magnet from home electronics has been focused in JAPAN.– Amount of RE magnet embedded in industrial device is comparable to

home electronics. (508 ton/year)– Simple distribution route → Easy collection of waste product

(for product maker)


Concept• 【RE magnet recycle system】

– Solution to uneven distribution of RE and high environmental load in RE production from ore

– RE recycle system from urban mine to product– Less-waste and economical process by applying nuclear technology

Hoisting Machine(motor)

Coil（Copper）

Used RE magnet

Other parts（Steel）

High purityRE alloy

Recycled RE magnet


Outline and Features of TSB process

- Processing capacity: 3000 motors/year (motor weight: 230kg/unit)- Recovered RE alloy to recycled RE magnet,

other metal parts (steel, copper) to raw material for product- No liquid waste (acid, alkaline and organic solvent) process with molten salt*1

Recovery of 99%-component of industrial motor

*1Molten salt: Conductive melted salt, such as NaCl, at high temperature

Copper: 62 t/yearSteel: 621 t/year

Magnet : 7 t/year


Analysis of RE magnetElement composition analysis by XRF, ICP-AES, IR and TCD

The composition of RE magnet recovered from industrial motor was almost equal to from compressor.

The RE magnet was not almost oxidized.

The RE magnet contained additive substances such as Al, Co and Cu.

Element composition RE magnet (wt%)

Element Industrialmotor Compressor

Fe 65.4 65.4Nd 24.6 26.2Dy 5.6 5B 1 0.97Al 0.19 0.23Si 0.08 0.15Co 2.2 1.5Cu 0.13 0.23O 0.21 0.25N 0.005 0.01C 0.071 0.066

RE magnet recovered from industrial motor (after thermal demagnetization)

33 mm

33 mm

Thickness: 4 mm


RE metal recovery from RE magnet

温度：400～900℃

RE magnet

Extraction

Extractant

Molten salt extraction

Residue

RE3+

(Nd3+, Dy3+, Pr3+)

Molten salt electrolysis

Cathode Anode

RE3+Molten salt

Electrolysis

RE-Fe liquid alloy

Formation of RE-Fe liquid alloy

T > 685 ºC

Selective Extraction of RE ions from RE magnet by extractant addition

Electrowinning of RE-Fe liquid alloy from molten salt after extraction

Conc

entr

atio

n of

RE

ions

Time

Extraction Electrolysis Extraction Electrolysis


Principle of molten salt extraction

NdDyMolten

salt

MClx

RE magnet

Nd3+, Dy3+

• Extraction of RE ions from RE magnet• Elimination of undesirable elements by volatilization

Volatilization

LiCl

CaCl2

NdCl3

MgCl2 DyCl3

MnCl2

FeCl2NiCl2

FeCl3

Candidate extractant

AlCl3e.g. FeCl3, NiCl2, FeCl2, AlCl3, MnCl2, MgCl2

Extraction ReactionxNd(in magnet) + 3MClx

= xNd3+ + 3xCl- + 3Me.g. M= Fe, Mg


Molten salt extraction(1)

Extraction ratio = Mass of RE ion in molten salt

Mass of RE metal in initial RE magnet×100

After extraction (2 hours)

Before extraction

•RE ions were extracted by addition of MClx.•There were no differences in the extraction behavior of RE ions.•Al ion was also extracted into the melt.

Molten salt: LiCl-KCl (59:41mol%)Temperature: 500 ºCExtractant: MClx (Mole ratio; MClx/RE=1-3)Atmosphere: ArAgitation: No


Molten salt extraction(3)

•RE ions were extracted into CaCl2 melt by addition of MClx•Al ion was not detected in the melt.→ Al ion was eliminated as AlCl3 by volatilization.

Molten salt extraction is applicable to RE recovery from RE magnet.

Molten salt: CaCl2Temperature: 850 ºCExtractant: MClx (Mole ratio; MClx/RE=1.8)Atmosphere: ArAgitation: No

B, Al, Co ions were not detected.


Principle of molten salt electrolysis

Molten salt

Cathode(Fe)Anode(C)

Crucible

Liquid alloy(RE-Fe)

Formation of RE-Fe liquid alloyT > 685 ºC

Eutectic pointT = 685 ºC, XNd = 0.795

Expected reactionRE3+ 3e- + = RE-Fe alloy

Molten salt electrolysis with fluoride melt is applied to Nd-Fe metal production on a commercial scale.

Is it possible to product RE-Fe metal in the chloride melts after molten salt extraction ?

G. Schneider, E.T. Henig, G. Petzow, and H.H. Stadelmaier, Z. Metallkd., 78(10), 694-696 (1987).

Fe Nd



wt% mol%

Nd 89.04 75.88

Fe 10.96 24.12

O ND ND

Ca ND ND

Cl ND NDΣ 100 100

wt% mol%

Nd 21.66 9.59

Fe 78.06 89.27

O 0.29 1.14

Ca ND ND

Cl ND ND

Σ 100 100

wt% mol%

Nd ND ND

Fe 99.64 99.94

O ND ND

Ca ND ND

Cl 0.36 0.56

Σ 100 100

Fe electrodeNd-Fe alloy

Molten salt: CaCl2 - NdCl3Temperature: 850 ºCPotential: 0.27 V vs. Ca2+/CaElectrolysis time: 6 hoursAtmosphere: Ar

High pure Nd-Fe metal was obtained from CaCl2 melt.

Image of the cathode after electrolysis


Demonstration test with actual used RE magnet(1)

温度：400～900℃

RE magnet

Extraction

Extractant

Molten salt extraction

Residue

RE3+

(Nd3+, Dy3+, Pr3+)


Cathode Anode

RE3+Molten salt

Electrolysis

RE-Fe liquid alloy

Formation of RE-Fe liquid alloy

T > 685 ºC



NdDy

Molten salt

• Molten salt: CaCl2• Temperature: 850 ºC• Extractant: MClx (Mole ratio; MClx/RE=1-3)• RE magnet: NdFeB + Dy• Atmosphere: Ar• Agitation: No

RE magnet

MClx

B, Al, Co ions were not detected.

RE ions were extracted selectively from actual used RE magnet.

RE magnet crushed under Ar atmosphere



Molten salt

Cathode(Fe)Anode(C)

Crucible

Liquid alloy(RE-Fe)

• Molten salt: CaCl2 containing extracted RE ions

• Temperature: 850 ºC• Current density: 1-3 A cm-2

• Atmosphere: Ar

Reference(Ag+/Ag)

Obtained RE-Fe alloy

RE-Fe metal was obtained from the melts after molten salt extraction.



Element composition (wt%)Fe Nd Dy B Al Si Co Cu N C

Actual used RE magnet

65.4 24.6 5.6 1.0 0.19 0.08 2.2 0.13 0.005 0.071

Recovered RE-Fe metal

9.8 63 14 N.D.<0.1

N.D.<0.1

N.D.<0.1

N.D.<0.1

N.D.<0.1

N.D.<0.02

N.D.<0.05

Actual used RE magnet Recovered RE-FE metal


Summary

•High purity RE-Fe alloy was recovered from actual used RE magnet by pyrochemical process.

•RE recovery test was conducted using actual used RE magnet by pyrochemical process.

•RE ions were selectively extracted from RE magnet into chloride melts by addition of MClx.

•RE-Fe alloy was obtained by molten salt electrolysis from the melts containing extracted RE ions.


Acknowledgment

This presentation is partly based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

Recycle of rare earth magnet with pyrochemical process · Demonstration test with actual used RE...

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