V. LOPES1, N. COUTO1, A.R. FERREIRA1, E.P. MATEUS1, S. PAMUKCU2, ALEXANDRA B. RIBEIRO1

ELECTRO-ASSISTED EXTRACTION OF CRITICAL RAW MATERIALS FROM COAL ASH

1 CENSE, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal2 Department of Civil and Environmental Engineering, Lehigh University, Bethlehem, PA 18015, USA

HERAKLION 2019 - 7th International Conference on Sustainable Solid Waste Management, 29th June 2019, Crete Island, Greece

Rare Earth Elements (REEs)

59

PrPraseodymium

140.908

60

Nd

Neodymium144.243

62

Sm

Samarium150.36

63

EuEuropium151.964

64

Gd

Gadolinium157.25

65

TbTerbium158.925

66

Dy

Dysprosium162.500

67

Ho

Holmium164.930

68

ErErbium167.259

69

Tm

Thulium168.934

70

YbYtterbium

173.055

71

LuLutetium174.967

57

LaLanthanum

138.905

58

CeCerium140.116

21

ScScandium

44.956

39

YYttrium88.906

61

Pm

Promethium144.913

‘Rare’ because they mix diffusely with other minerals underground therefore difficult and costly to extract‘Rare’ because they mix diffusely with other minerals underground therefore difficult and costly to extract

La57- 71

REEs applications

Chart by netl.doe.gov

ProblemEU overview

** 0 - 1: 1 means non-substitutable EU, 2017 Source: Geology.com using data from the United States Geological Survey

o EU is almost entirely dependent upon imports from China

o The 2011 REE-price crisis pointed to the need to reduce the dependence on China’s

imports

o Substitution Index**: 0.96 (HREE) & 0.90 (LREE)

o End of life recycling rate: 8% (HREE) & 3% (LREE) REE Production

1

1

1

Geopolitical strategy

Final List of 35 Minerals deemed critical to U.S. National Security and Economy

2018 May (Dep. of Interior)

List of Critical Raw Materials for the EU – 27 CRMs

2017 September (European Commission)Y

DyEuTb

Nd

CeLaTm

Sm

Pr

Supply Risk

1

2

3

4

21 43

Imp

ort

ance

to C

lean E

nerg

y

Criticality matrix (2015 – 2025)

(Based on the US Dept. of Energy, 2011)

2011 Critical Materials Strategy - by the U.S. Department of Energy - includes criticality assessments:

• Supply challenges for 5 REE may affect clean energy technology deployment in the years ahead.

Aim

In progress:• Assessment and analysis of the feasibility of electrodialytic recover of REEs

from anthracite ash• Proof of concept

Recovery of REEs from a secondary resource (e.g. coal by-product) through electro-based technologies

Recovery of REEs from a secondary resource (e.g. coal by-product) through electro-based technologies

Recover of REEs from fine anthracite coal ash under the influence of an applied low level direct current

Electrodialytic Process

Matrix compartment: anode

Efficient & environmentally-friendly separation and processing technology Efficient & environmentally-friendly separation and processing technology

• Blaschak Coal Corporation, Centralia,

PA, USA 

• Northern Pennsylvania

• Lat. 40.8° N, Long. 76.36° W

• Mammoth Vein

Anthracite origin

Imagery ©2019 Google, Map data ©2019

Imagery ©2019 Landsat/Copernicus, Data SIO, NOAA, U.S. Navy, NGA, GEBCO, NOAA, Map data ©2019 Google

Methodology

Anthracite

Anthracite ashASTM (D3174-12)

Electrodialytic cell

Fluxing

ICPEDXSEM-EDS

CutCrush

GrindingAshing pH desorption

testED experiments

FluxingICP

Processing

Characterization

Extraction/Analysis

REE recover

CharacterizationRelative REE content in anthracite ash

Critical

Near Critical

Not CriticalOther REE

Sc Y La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

3,71%

10,09%

19,35%

38,07%

4,04%

14,61%

2,39%0,44%

2,10%0,28%

1,90%0,34%1,21%0,10%

1,28%0,09%

59

PrPraseodymium

140.908

60

Nd

Neodymium144.243

62

Sm

Samarium150.36

63

EuEuropium151.964

64

Gd

Gadolinium157.25

65

TbTerbium158.925

66

Dy

Dysprosium162.500

67

Ho

Holmium164.930

68

ErErbium167.259

69

Tm

Thulium168.934

70

YbYtterbium

173.055

71

LuLutetium174.967

21

ScScandium

44.956

39

YYttrium88.906

57

LaLanthanum

138.905

58

CeCerium140.116

LREE

HREE

REE

SEM microphotograph of anthracite ash

CharacterizationParticle morphology of anthracite ash

• Disperse

• Angular

• Size range: 1 to 10 um

CharacterizationParticle morphology of anthracite ash

Trace elements• Carbon• Oxygen• Aluminum• Silicone• Phosphorus• Titanium• Iron

REEs • Lanthanum• Neodymium• Cerium

SEM microphotographs and respective EDS spectra of a) REE particle; b) agglutination of minerals

b)

a)

pH desorption from anthracite ash

0 1 2 3 4 5 6 7 8 9 10 11 12 13 140%

20%

40%

60%

80%

100%

120%

Sc Y La Ce Pr Nd Sm EuGd Tb Dy Ho Er Tm Yb Lu

pH

LREE

HREE

Outlier

%

ED experiments

Ferreira et al. 2019, Water Air & Soil Pollution, 230(4): 78-88. 1

• 2C-ED cell

• L/S = 15

• CEM = cation exchange membrane

• MMO coated titanium bar

• Time: 3 days

• Current intensity: 10 mA

• pH: no adjustment

1

1

1 +

ResultsDesorped REEs after ED

Critical

Near Critical

Not CriticalOther REE

59

PrPraseodymium

140.908

60

Nd

Neodymium144.243

62

Sm

Samarium150.36

63

EuEuropium151.964

64

Gd

Gadolinium157.25

65

TbTerbium158.925

66

Dy

Dysprosium162.500

67

Ho

Holmium164.930

68

ErErbium167.259

69

Tm

Thulium168.934

70

YbYtterbium

173.055

71

LuLutetium174.967

21

ScScandium

44.956

39

YYttrium88.906

57

LaLanthanum

138.905

58

CeCerium140.116

LREE

HREE

REE

1,1%

4,9%

15,5%

12,7%13,0%12,0%

10,8%

13,5%

8,9%

14,4%

5,4%

10,5%

4,9%

14,4%

3,1%

23,4%

ResultsREEs criticality analysis of relative content after ED

Catholyte Anolyte Membrane Ash0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

33,5821,15 23,56 29,34

29,34 66,29 65,60 52,42

37,07

12,56 10,83 18,24

%

Conclusions

REE desorption improved with the ED process

LREE show higher desorption rates

HREE show promising capabilities of passing through the CEM

Critical REEs

Relative % of REEs desorped by ED

Tb 14.4

Eu 13.5

Nd 12.0

Dy 5.4

Y 4.9

ED process is a promising extraction technique for rare earth elements recover from coal ash

• Blaschak Coal Corporation, 2019. Representative analysis Lattimer mammoth vein. Accessed in June 2019 http://www.blaschakcoal.com/wp-content/uploads/Lattimer-Mammoth-Vein-Rep-Analysis.pdf

• European Commission, 2017. (COM(2017) 490) ‘on the 2017 list of Critical Raw Materials for the EU’ 2017.

• Ferreira, A.R.; Couto, N.; Ribeiro, A.B.; Ottosen, L.M. 2019. Electrodialytic arsenic removal from bulk and pre-treated soil. 2019, Electrodialytic arsenic removal from bulk and pre-treated soil. Water Air & Soil Pollution, 230(4):78-88.

• NETL - National Energy Technology Laboratory. REE Program. Accessed in June 2019,  https://netl.doe.gov/coal/rare-earth-elements/program-overview/background

• REE - Rare Earth Elements and their Uses. Accessed in June 2019, https://geology.com/articles/rare-earth-elements/

• US DoE, 2011. Critical Materials Strategy report. US Department of Energy

References

This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045, and from FCT/MEC through grant UID/AMB/04085/2019 to the Research unit CENSE – Center for Environmental and Sustainability Research. N. Couto also acknowledges FCT Investigator Contract CEECIND/04210/2017.

Acknowledgements

pH desorption LREE

0 1 2 3 4 50%20

%40

%60

%80

%10

0%

REE desorption at acidic pH

pH

Deso

rpti

on (

%)

59

PrPraseodymium

140.908

60

Nd

Neodymium144.243

62

Sm

Samarium150.36

63

EuEuropium151.964

57

LaLanthanum

138.905

58

CeCerium140.116

21

ScScandium

44.956

LREE - Stable complexes are the first to desorp- Higher desorption rates compared

to HREE

LREE - Stable complexes are the first to desorp- Higher desorption rates compared

to HREE

Tendency- Desorption starts from lower to

higher atomic number (i.e. inversely related with ionic

radius)

Tendency- Desorption starts from lower to

higher atomic number (i.e. inversely related with ionic

radius)

Scandium- Different electronic and

magnetic properties

Scandium- Different electronic and

magnetic properties

ResultsRelative distribution of REEs in the ash

Before ED

31,57%

17,50%

50,93%

27,31%

57,53%

15,16%

After ED

ResultsREE distribution within the cell

59

PrPraseodymium

140.908

60

Nd

Neodymium144.243

62

Sm

Samarium150.36

63

EuEuropium151.964

64

Gd

Gadolinium157.25

65

TbTerbium158.925

66

Dy

Dysprosium162.500

67

Ho

Holmium164.930

68

ErErbium167.259

69

Tm

Thulium168.934

70

YbYtterbium

173.055

71

LuLutetium174.967

21

ScScandium

44.956

39

YYttrium88.906

57

LaLanthanum

138.905

58

CeCerium140.116

%

ResultsRelative distribution of REEs in the liquid phase after ED

Anolyte Catholyte

11

14

20

5

7

11

ResultsREE in the catholyte after ED

Critical

Near Critical

Not CriticalOther REE

59

PrPraseodymium

140.908

60

Nd

Neodymium144.243

62

Sm

Samarium150.36

63

EuEuropium151.964

64

Gd

Gadolinium157.25

65

TbTerbium158.925

66

Dy

Dysprosium162.500

67

Ho

Holmium164.930

68

ErErbium167.259

69

Tm

Thulium168.934

70

YbYtterbium

173.055

71

LuLutetium174.967

21

ScScandium

44.956

39

YYttrium88.906

57

LaLanthanum

138.905

58

CeCerium140.116

LREE

HREE

REE

2,8%4,7%

0,7%0,5%2,5%

0,6%2,2%

12,3%

2,9%

24,0%

4,7%

24,4%

12,3%

32,6%

5,3%

33,5%

Future Work

• 7 days

Higher desorption rates

TT

pH adjustment

Increase current intensity

Experiment duration

• 50 mA Higher desorption rate

Higher migration speed of the REE from the anolyte to the catholyte

• In the catholyte (pH ~2)

Prevention of ion element precipitation

Prevention of the formation of aggregated elements around the electrodes and the membrane

Prevent membrane obstruction