rare earth recovery and separation using diglycolamides

1E. Andreiadis - Rare earth recovery and separation using diglycolamides Perth, 23 May 2019

DE LA RECHERCHE À L’INDUSTRIE

French Alternative Energies and Atomic Energy Commission - www.cea.fr

Rare Earth Recovery and Separation Using Diglycolamides

ALTA Conference23/05/2019, Perth, Australia

E. Andreiadis, M. Miguirditchian, V. Blet

CEA, Atomic Energy and Alternative Energies Commission,Research Department on Mining and Fuel Recycling Processes, Marcoule, France

eugen.andreiadis @ cea.fr

http://www.altamet.com.au/conferences/alta-2019/


Critical supply of rare earth elements

Are rare earth elements (REE) critical raw materials?

Demand growing, especially for magnets (> 8% per year)Accelerated growth of HEV/EV market (+30% in 2017)Global REO production in 2018 at 175 kT/yrProduction chain concentrated in China (mining, separation,

downstream manufacturing, R&D capacity): 80% world REO supplyCurrently no European mine in operationSignificant price volatility during the last 10 years

Impo

rtanc

e

Supply riskSource: report US Department of Energy 2010

Tb

Sm

Y

REO consumption by application 2012-2016

References: Roskill 2015, IMCOA 2017

Permanent magnets

31%Metal alloys18%

Catalysts18%

Glass andceramics

11%

Polishing 13%

Phosphors4%

Others5%

Possible solutions to decrease REE criticalityReducing consumption (shift in technology)Substitution by other non-critical metalsDiversifying supply

Primary and secondary sources (new mines, tailings…)Recycling (scraps, urban mine)



REE recycling: closing the materials loop

Advantages of recyclingTarget only the most critical rare earths (highest demand)No issues with radioactive elements (235U, 238U, 232Th)Lower environmental footprint ( public acceptance)

ChallengesInsufficient and untargeted collection of waste sources Difficult recovery of REE-containing fractions Difficult separation of individual REE No regulatory incentives for recycling WEEELow economic interest in line with current market prices

OpportunitiesCompetences and expertise of the European recycling industryLeveraging on the urban mineDevelopment of a circular economyPositive economic and environmental impact

500 kg Nd/MW in the magnet of a wind turbin

Very low recycling rates

6-7% in EU

Source: EU 2018 Report on CRM



Recycling NdFeB permanent magnets

Why NdFeB magnets?Most important market, driving REE demand Present in a large variety of products

Characteristics of NdFeB magnetsHigh REE concentration (25% Nd, 5% Pr, 2-8% Dy) Different life cycles, depending on application :

(2-3 years in WEEE up to 20-30 years in wind turbines)Various sizes :

(g in electronics, kg in EV/HEV, ton in wind turbines)

NdFeB magnet applications

Reference: Shaw 2012



Permanent magnet recycling strategies

Y. Yang, Extraction 2018

No commercial process for REE recycling from EoL products

<<~ 200 t/yr in Europe



Flowchart for REE recovery from NdFeB magnets

Magnet scraps EoL magnets

Thermal treatmentH2 decrepitation

Mechanical treatment

Leaching

Fe + impurities

REE separation by solvent extraction

REO conversion REE conversion to metal

Dy Nd+Pr Recovery > 99%Purity > 99.5%

R. Laucournet (CEA/DRT)Patent WO2014/06459

High REE concentration (25% Nd, 5% Pr, 2-8% Dy)

M. Miguirditchian (CEA/DEN)Patent WO2016046179

Selective precipitationREO mixed concentrate

Fe(OH)3



• Development of extraction models and flowsheets

• Optimization

• Design and synthesis of extracting molecules

• Optimization of extractant formulation

• Measurement of batch data• Understanding the extraction

mechanisms (affinity, selectivity)• Structure-activity relations

• Qualification of the process on real solutions

• Industrial extrapolation using simulation

Specificobjectives

Extractant system selection

Molecularscale chemistry

Process modelling

Integrated experiments

PAREX simulation code

Our approach to SX process development



Selection and evaluation of the extractant system

Challenge: excellent affinity and selectivity for REE in the presence of Fe3+

Screening of several commercially-available extracting molecules Selection of diglycolamides (TODGA) class of solvating extractants

NO

N

O O

TODGA

HNO3 3 M, 0.1 M TODGAHNO3, 0.1 M TODGA

OPO

O

D2EHPA

OH

POO

PC88A

OH

PO

TOPO

Extraction capacity inversely proportional to RE3+ ionic radius Excellent extraction of heavy RE (Dy),

less for light RE (La, Ce, Pr)

Excellent selectivity with respect to transition metalsReduced extraction capacity in sulfuric and chlorhydric acid media Y. I. Sasaki, G. R. Choppin, Anal Sci 1996, 12, 225-30

Z.-X. Zhu, Y. Sasaki, H. Suzuki, S. Suzuki, T. Kimura, Anal. Chim. Acta 2004, 527, 163-8.H. Narita, M. Tanaka, Solvent Extr. Res. Dev. Jpn. 2013, 20, 115-21



Solvent extraction of REE using TODGA

Tests on synthetic and genuine magnet solutions in nitric acidQuantitative extraction of Dy (D > 100)Efficient separation of RE / transition metals (Fe, Co, Ni…) and RE/RE in a large range of acidity (0.4 to 5 M)No 3rd phase formation in process conditionsQuantitative stripping of Nd and Dy at low acidity (pH 2-3)

Confirmation of the potential of TODGA for selective Dy recovery from NdFeB magnet solutions

Distribution coefficients DM Separation factors SFM/M

Elément B Fe Co Ni Cu Pr Nd Dy

g/l 0.5 35 0.2 0.8 0.5 3.1 12.5 0.3

Solvent formulation: 0.2 M TODGA + 5% octanol / HTP

Synthetic aqueous solution composition:



Process modelling

Elaboration of a phenomenological model from experimental batch data

Representation of distribution equilibriaHNO3-Oct, HNO3-TODGA, Ln-NO3-TODGA

(HNO3)(octanol)2

(HNO3)m(TODGA) with m = 1 to 3

M(NO3)3(TODGA)n with n = 3 for Dy, Nd, Pr, Fe

𝐾𝐾′𝑛𝑛 =

�{𝑇𝑇𝑇𝑇(𝑁𝑁𝑁𝑁3)3,𝑇𝑇𝑁𝑁𝑇𝑇𝑇𝑇𝑇𝑇𝑛𝑛 }��𝛾𝛾𝑇𝑇𝑇𝑇(𝑁𝑁𝑁𝑁3)3 ∙ [𝑇𝑇𝑇𝑇(𝑁𝑁𝑁𝑁3)3] ∙ [𝑇𝑇𝑁𝑁𝑇𝑇𝑇𝑇𝑇𝑇��]𝑛𝑛

Activity coefficients taken into account in aqueous phase

Good agreement between extraction experiments and calculated values for both synthetic and real solutions

Implementation of the model in the CEA PAREX+ simulation code and calculation of flowsheets



Pilot test n°1Selective extraction of all REE followed by Dy/Nd partitioning Compact 24-stage lab-scale mixer-settler setup at 100 mL/h

Solventrecycling

Pilot demonstration tests on real magnet solution

Test runned for 32 hVery good hydrodynamic behaviorUV-vis on-line analysis (for Nd) and

ICP-AES measurements for Dy, Nd, Fe

Excellent recovery of REE with very high purityNd+Pr recovery > 99.98% with purity > 99.99%

Dy recovery 96.7% with purity 99.96%



Pilot test n°2Selective extraction of only Dy followed by strippingNd & Pr collected in the raffinate for further 2nd cycle processCompact 16-stage lab-scale mixer-settler setup at 200 mL/h


Test runned for 20 hVery good hydrodynamic behaviorUV-vis on-line analysis (for Nd) and

ICP-AES measurements for Dy, Nd, Fe

Excellent recovery of Dy (99.7%)with very high purityUpgrade Dy from 0.69 to 4.05 g/L (×6)

Solventrecycling

Validation of hydrometallurgicalprocess flowsheets at TRL 5 level



Recovery of RE-rich fractions from Ni-MH batteries

Black mass Composition : 40%wt Ni, 15%wt REE

Physical and mechanical treatment of batteriesAdapting an existing NiMH recycling process for the recovery of RE-rich fractions

Production of a 10 kg final sample

Disassembling

Hydrometallurgical processes

Thermal treatment

Crushingsieving

Pyrometallurgical process

Hydrometallurgical treatment of the black massChoice of acids and leaching conditions compatible with an industrial approach

Total digestion (REE + Ni, Co…) Quantitative yield for HNO3 and HCl acid digestion

Selective leaching (only Ni, Co…) Precipitation of REE in sulfuric acid solution Redissolution of sulfate precipitates and further conversion

Good extraction of light REE upon increasing TODGA concentration

Very high selectivity (Ni, Co, Mn, Fe)



Conversion of purified REE to oxides

Precipitation and calcination to REO

Effluent treatment



Novel dissymmetrical DGA extractants

Increase the amphiphilic character Short (hydrophilic) alkyl chains: R1

Long (lipophilic) alkyl chains: R2

Andreiadis, patent pending FR1853263

Improving the extraction of light REE Increasing the selectivity towards transition metals (e.g. Fe, Ni) Improving the REE extraction in sulfuric and hydrochloric acid media

NO

N

OOR

R

RN

ON

OOR

OO

NN

OC12H25

C12H25

OO

NN

O

C12H25

C12H25

N,N,-diethyl-N',N'-didodecyl DGA(N,N-E)

N,N,-dipropyl-N',N'-didodecyl DGA(N,N-P)

OO

NN

OC12H25

C12H25

N,N,-diisopropyl-N',N'-didodecyl DGA(N,N-iP)

OO

NN

O

C12H25

C12H25

N-pyrrolidinyl-N',N'-didodecyl DGA(N-Py)

OO

NN

O

C12H25C12H25

OO

NN

O

C12H25C12H25

N,N',-dibutyl-N,N'-didodecyl DGA(N,N'-B)

N,N',-diisobutyl-N,N'-didodecyl DGA(N,N'-iB)

OO

NN

O

C12H25C12H25

N,N',-dipropyl-N,N'-didodecyl DGA(N,N'-P)

NO

N

O O

C8H17

C8H17

C8H17

C8H17

TODGA

Reference extractant



2

15

42

> 1000

15

206

618

0,1

1,0

10,0

100,0

1000,0

La Pr Nd Dy

Dist

ribut

ion

ratio

TODGA

N1-E

N1-IP

N1-P

N1-PY

N2-P

N2-IB

N2-B

Solvent extraction by DGA in nitric acid solution

Excellent extraction of heavy REE (DDy >1000)Increased extraction (x 15) of light REE for N,N-E compared to TODGA

N,N-EDistribution ratios

Conditions HNO3 3 M solution containingREE, Ni, Co 1 g/L, Fe 10 g/L0.1 M DGA in HTP + 10% n-octanol

OO

NN

OC12H25

C12H25

N,N-E

Novel DGA



180

1500

4000

> 100 000

1280

17500

52500

10

100

1000

10000

100000

La/Fe Pr/Fe Nd/Fe Dy/Fe

Sepa

ratio

n fa

ctor

Excellent selectivity REE / impurities (Fe, Co, Ni)N,N-E is 6-15 times more selective than TODGA

Very high intra-REE selectivity (Nd/Pr) for N,N-iPWorking on understanding the influence of minor chain variations on the extraction properties

Separation factors REE / Fe(III) HNO3 3 M

1,0

2,0

3,0

4,0

5,0

Sepa

ratio

nfa

ctor

Nd/Pr

N,N-iP

Solvent extraction by DGA in nitric acid solution

N,N-E

OO

NN

OC12H25

C12H25



Solvent extraction by DGA in sulfuric acid solution

Much lower extraction in 2 M sulfuric acid compared to 3 M nitric acid solutionsOnly heavy REE can be selectively extracted, no light-REE extractionRemarkable improvement (x 100) of HREE extraction for N,N’-P (DDy = 25)compared to TODGA Excellent separation factors Dy / Fe, Co, Ni

0,2

25,3

0

5

10

15

20

25

30

La Pr Nd Dy

Dist

ribut

ion

ratio TODGA

N,N-P

N,N'-P

N,N'-iB

N,N'-B

Distribution ratios N,N’-P

0

500

1 000

1 500

2 000

2 500

Sepa

ratio

n fa

ctor TODGA

N,N-P

N,N'-P

N,N'-iB

N,N'-B

Separation factors

Dy/Fe Dy/Co Dy/Ni

N,N’-P

OO

NN

O

C12H25C12H25

Conditions: H2SO4 2 M solution; REE, Ni, Co 1g/L, Fe3+ 10 g/L0.1 M extractant in TPH + 10% octanol



Solvent extraction by DGA in hydrochloric acid solution

Rather low La extraction but good (Nd, Pr) to excellent (Dy) extraction of HREEIncreased extraction (2-4 x) for N,N’-B compared to TODGANo extraction of Ni or Co however 40% of Fe is extractedWe need to improve the selectivity with respect to Fe3+

1,0

31,1

92,2

> 265

0,7

2,9

132,9213,8

0,8

0,100

1,000

10,000

100,000

1000,000

La Pr Nd Dy Ni Co Fe

Dist

ribut

ion

ratio

TODGA

N,N-P

N-Py

N,N'-P

N,N'-iB

N,N'-B

N,N’-B

Distribution ratios

Conditions: HCl 2 M solution0.1 M extractant in TPH + 10% octanolREE, Ni, Co 1g/L, Fe3+ 10 g/L

Formation of FeCl4- complexextracted by protonated DGA

OO

NN

O

C12H25C12H25

N,N’-B



- Non optimised conditions- RoI = 3 years- Careful hypothesis for REEs pricesNd2O3 50 US $/kg; Dy2O3 = 300 US $/kg- Work in 5 shifts for throughput > 5 m3/h- 15% uncertainty on operating costs

The profitability limit can be shifted to a lower capacity (300 t/yr) with an optimised processLiquid waste treatment cost has to be further assessed, depending on local regulations (discharge of NO3- is strictly supervised)

-10000

-5000

0

5000

10000

15000

20000

25000

30000

35000

40000

0 2 4 6 8 10 12 14 16

(k€/

year

)

Capacity (m3/h)

Annual capital costsTurnoverOperating costsProfit

Profitability limit: 2,000 t/yr

Profit = Turnover – CAPEX/ROI – OPEX

Technical-economic assessment for REE recovery from magnets

Hydrometallurgical recovery of REO from NdFeB magnet scraps



Conclusions and outlook

Demonstration of the scientific feasibility of REE recovery by SX using TODGA without preliminary separation of transition metal impurities by precipitation

Pilot scale production (TRL 5) of highly pure Dy and Nd/Pr solutions from used magnetsExperiments in progress on NiMH battery recycling process

Technical-economic study of the process for cost and rentability evaluationDesign of an optimized process limiting investment and operational costs

Limiting the volume of acid in the leaching stepIncreasing extractant concentration / novel DGA and optimizing stripping conditionsSwitching to less expensive precipitation reagents (carbonate vs. oxalate)Optimize the secondary fluxes (recycling nitric acid, valorize Fe residues…)

Novel dissymmetrical DGAs were designed and tested in nitric, sulfuric and hydrochloric acid solutionsRemarcable improvement of REE extraction (espeacially Dy/sulfuric acid) compared to TODGAUnderstanding the behavior of novel dissymmetric DGAs compared to TODGA

Remaining challenge: improve WEEE collection and physical treatment to better liberate REE

Short to medium term perspective: unavailability of easily collectable and dismantable WEEE prevents recycling. Direct scrap generated volume is not sufficient to support a recycling unit in Europe.

Long term perspective (25-30 yrs): flourishing HEV/EV market + regulatory incentives could drive recycling…but will the REE still be technologically relevant?


Nuclear Energy DivisionResearch Department on Mining and Fuel Recycling Processes

Commissariat à l’énergie atomique et aux énergies alternativesCentre de Marcoule | BP17171 | 30207 Bagnols-sur-Cèze Cedexeugen.andreiadis @ cea.fr

Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 019

Thank you for your attention

Acknowledgments

V. HaquinM-T. Duchesne

V. PacaryM. MontuirD. Rinsant

G. MossandD. Hartmann

ANR REPUTER projectgrant 15-CE08-0017-01

rare earth recovery and separation using diglycolamides

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