AMDREYExtraction of Rare Earths Elements from Acid Mine Drainage

State of Art

Rare Earth  / Transition metal Some L/L separation issues

Daniel Meyer

PrometiaScientific SeminarDecember 2016

CSIC (Consejo Superior de Investigaciones Científicas) SpainCarlos Ayora

The University of Huelva (UHU) SpainJose‐Miguel Nieto

The “Institut de Chimie Séparative de Marcoule” FranceStephane Pellet‐Rostaing

University in the Free State. South AfricaEsta van Heerden

Chemec Oy. FinlandLasse Moilanen

AMDREY Partners

ContextWaste from Mine Activity (Pyrite)

Mining Activity

FeS2 + 7/2 O2 + H2O   Fe2+ + 2 SO4

2‐ + 2 H+

Acid mine Drainage (AMD)

Waste containing traces of elements : Al, Cu, Zn, As, Cd, Pb, etc.

and interesting metals like Lanthanides and Yttrium

Draining wastepH 2.5 Fe precipitate

Al precipitate

“clean” river pH 6.8Precipitation of metals depending on the pH

Fe precipitates around pH 3

Al precipitates around pH 4,4

AMD SolutionLanthanides (Ln)Yttrium (Y)ppb to some ppm levelOther elements, valuable (VE)  unwanted (UE)

Precipitation

DissolutionAs specific as possible 

PrecipitatecontainingLn, Y, VE, UE

Solid treatmentLow temperatureWater removing

Solid 1Ln, Y, VE, UE

Solid treatmentHigh temperature

Solid 2Ln, Y, VE, UE

Ln+Y Other

ChemicalSeparation

Concentratesolution

Ln1 Ln2

Ln.. Y

Valuableelements

Fine Chemical Separation

NovelSolutions

NovelSolutions

3. Schwertmannite Fe8O8(OH)6(SO4)∙nH2O2. Hydrobasaluminite Al4(SO4)(OH)10∙15(H2O)1. Unreacted limestone Ca2CO3

using CaCO3

Concentratesolution

General  Proposed Approach

Overview of the chemical separation

AMD samples: metalseparation

Direct extractionLiquid‐liquid extraction:

• Caracterisation of aqueous phases

0.001

0.01

0.1

1

10

100

1000

10000

100000

La Nd Gd Yb Y Fe Zr Ca Al Zn Mg Cu As

[M] ppm

Metals concentrations estimated by ICP‐OES

AG

BE

PHPH is the solution which is the mostconcentrated with concentration of 

light REE over 1ppm

Very low concentration of REEbut high concentrations in Fe, Al 

and Mg

0.0

0.2

Nd1.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

2 5.2 7.5

[M] ppm

[H2SO4]

La

Nd

Gd

Y

Fe

Ca

Al

AMD samples: metalseparation

Direct extractionLiquid‐liquid extraction:

• Caracterisation of aqueous phases• Solvent Extraction

• Impact of adding H2SO4

We managed to recover up to 1.2ppm Nd in PH solution, 

using 7.5M H2SO4

La 20‐30%

Nd 80‐100%

Gd 5‐30%

Y 70‐100%

Fe 0.0095%

Al 0.0053%

Mg 0.0000%

Ca 0.52%

With this condition we are able to recover up to 100% of Nd 

and 100% of Y with a very good selectivity toward other

elements.Less than 0.01% of Fe, Al and Mg and less than 1% of Ca

is extracted

AMD samples: metalseparation

Direct extractionLiquid‐liquid extraction:

• Caracterisation of aqueous phases• Solvent Extraction

• Impact of adding H2SO4• Modifications of O/A ratios• Multiple contacts

Multiple contacts help increase the concentration of 

recovered metals

Modification of O/A ratios decrease the recovery of REE but increase the selectivitytoward the other elements, 

especially Ca

• Shimojo, K.; Kurahashi, K.; Naganawa, H. Extraction Behavior of Lanthanides Using a Diglycolamide Derivative TODGA in Ionic Liquids. Dalton Trans. 2008, No. 37, 5083–5088

Prospects

• Screening of other inorganic acids: HNO3, HCl, H3PO4…• Develop an extraction process for REE without the addition of acid

For exemple with ionic liquids

• Working on concentrated metals• Specific leaching

Al oxydes + REE ?• REE recovery from leaching solution: key step REE / Ca selectivity

• Prospective extractants

CMPO

DMDOHEMA

terpy

BTP

BTBP

Rare Earth  / Transition metal Some L/L fundamental  separation issues

Extraction and separation of Pd, Ln by diamides from nitric waste

Ln-Pd supramolecular behavior

Aggregation is not a prerequisite for Pd(II) extraction Aggregation is a prerequisite for Nd(III) extraction

" Metal Recognition Driven by Weak Interactions: a Case Study in Solvent Extraction. "R. Poirot, X. Le Goff, O. Diat, D. Bourgeois, D. Meyer; ChemPhysChem , 17(14), 2112, 2016. Pacifichem 2015 Honolulu, dec. 15th, 2015

Weaker coordination of malonamide to La & need for 2 ligands in coordination sphere

Ln-Pd Coordination Behavior

Low pre-organisation (toluene, heptane HNO3 1M)

Nd-Pdhi-loGext = -2 kT

Nd-PdGext)lo Nd-PdGext)hi

Pdd‐metals?

Ln (Nd)

NN

CH3

C7H15C7H15

CH3

O

C5H11

OO

NO3

NdNO3

NO3NO3

NdNO3

NO3

Thermodynamic consideration

Pacifichem 2015 Honolulu, dec. 15th, 2015

High pre-organisation (heptane HNO3 5M)

Acidity and concentration of extractant

Nature of the extractant

Diluant Effect

Pd and RE extraction behaviour in the presence of 

other metal

Leading to controlled mixed extraction

Liquid‐Liquid separation Pd, Ln, other M

RE Co Ni Fe Zn

Kinetic can help

3 metal separationKinetic removal Mgreen

(confidential)