REE Processing | A South African perspective
REE Beneficiation What are they…..
“The rare earth elements perplex us in our researches, baffle us in our speculations, and haunt us in our very dreams. They stretch like an unknown sea before us
mocking, mystifying and murmuring strange revelations and possibilities. ”
Sir William Crookes
REE Beneficiation What are they…..
REE Beneficiation How rare are they…..
U.S. Geological Survey Fact Sheet 087-02
cerium is the 25th most abundant element at 68 parts per million, more abundant than copper
REE Beneficiation Where do we find them…..
Karin Soldenhof – Ansto Minerals – ALTA 2013
REE Beneficiation Largest deposit…..
Rare Earth Element deposits – GSSA 2011 – Jock Harmer
Bayan Obo, China (Inner Mongolia) 48 Mt contained REO
China’s Rare Earth Elements Industry: What can the West learn? IAGS 2010
REE Beneficiation China syndrome...
• China possesses 40% of global REE reserves
• China Produces >80% of Global REE
In July 2010 Chinese Ministry of Commerce reduces REE export quotas
= REE prices increase of over 1500% in space of a few months!
In July 2013 Chinese Ministry of Commerce relaxes REE export quotas
= REE prices tumbled to pre-2010 levels in space of a few months!
• Rare earths – strategic elements
• Total dominance of China as a producer => alternative sources of
supply
• Two new world class REE refineries – Lynas and Molycorp
• Non-Chinese production - a strategic rather than cheaper alternative
REE Beneficiation Outside of China?…..
Rare Earth Element deposits – GSSA 2011 – Jock Harmer
Mountain Pass, USA Mount Weld, Australia
1.4 - 2 Mt contained REO 1.78 – 4.2 Mt contained REO
REE Beneficiation South Africa ?…..
Phosphogypsum waste dumps
LnPO4∙nH2O), (NaLn(SO4)2∙H2O
REE Beneficiation South Africa ?…..
Monazite – Namaqua Sands and Richards Bay
(Ce, La, Pr, Nd, Th, Y)PO4
REE Beneficiation South Africa ?…..
Monazite-apatite-quartz - Steenkampskraal
(Ca, REE)PO4(F,Cl,OH)x
(REE, Th)PO4
REE Beneficiation South Africa ?…..
Carbonatite - Zandkopsdrift
Ca5(PO4)3(F,Cl,OH)
CaAl3(PO4)2(OH)5•(H2O)
LnPO4
(Ce,Ca,Th)(P,Si)O4
REE Beneficiation South Africa ?…..
Pegmatite - Naboomspruit
REE Beneficiation What minerals?…..
REE mineral Formula
Bastnäsite LnCO3F
Monazite (Ln, Th)PO4
Xenotime YPO4
Minerals of major economic significance
Parisite
Synchisite
Allanite
Apatite
Britholite
(Ln)2Ca(CO3)3F
Ln Ca(CO3)2F
(Ce, Ca, Y)2 (Al, Fe)3 (SiO4)3 (OH)
Ca5(PO4,CO3)3(OH,F) (Ln, Ca) (SiO4, PO4)3(OH, F)
REE Beneficiation What is the targeted product…..
Mining/ concentration
RE Mineral concentrate
RE Chemical concentrate
Ref
ine
ry
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Y
Metal/Alloy production
Speciality applications
Increasing value
REE Beneficiation High level processing route…..
Cracking of ore matrix
Solubilizing/leaching of REE
Solid/Liquid separation
Recovery purification
REE Beneficiation How rare are they…..
So “Rare Earth Elements” are not all that rare ! “…but their extraction as pure elements requires a higher technology than the winning of gold.” Mariano (1989)
REE Beneficiation How difficult to process?…..
Buzzle.com
REE Beneficiation Why are they so difficult to process…..
Ore Type 1
Ore Type 2
Ore Type 3
Ore Type 1: Complex monazite ore, REE mineralised
as phosphates: (La,Ce,Nd,Th)PO4 , YPO4
Ore Type 2: Complex bastnaesite ore, REE
mineralised as Fluoro-carbonates: (Ce,La)(CO3)F
Ore Type 3: Complex synchysite ore,
REE mineralised as Ca-fluoro-
carbonates: Ca(Ce,La)(CO3)2F
Complex mineralogy and/or low REE grade
• Difficulties in conventional physical upgrading of REE bearing minerals
Phosphogypsum: Very low grade, REE
hardly soluble phosphates and double
sulphates: LnPO4∙nH2O,
NaLn(SO4)2∙H2O
Phosphogypsum
REE Beneficiation Why are they so difficult to process…..
e-
e-
e-
e-
[Xe] 4fn-15d16s2
or
[Xe] 4fn6s2
[Xe] 4fn-16s2
REE Beneficiation Why are they so difficult to process…..
#1 Chemistry of the Rare Earth elements are determined by their ionic radii
#2 Chemistry of the Rare Earth elements are determined by their valence state
Almost exclusively +3
REE Beneficiation Why are they so difficult to process…..
Similar ionic radius + Same valence
state = Same chemical behaviour
………………..(2)
Same chemical behaviour ≈ Difficult inter-element
separation ………………..(3)
Number of f – orbital electrons + Nature of f -orbitals = Unique chemical
behaviour ………………..(1)
Unique chemical behaviour
• unusual spectroscopic properties due to shielding of the 4f orbitals by the filled 5s2 and 5p6 sub-shells
• large number of unpaired magnetic moments
• high magnetic anisotropy
• high coordination numbers
REE Beneficiation How do we separate them from one another?…..
Nature provides some assistance!
#1
Light REE Middle REE Heavy REE
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
#2
III IV II III
#3
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Electronegativity
REE Beneficiation How do we separate them from one another?…..
R P
O
R O
OH
PC88A
[RE3+]aq + 3[(HA)2]org↔ [RE(HA2)3]org + 3[H+]aq
Aqueous phase
Organic phase
REE3+
aq
REE3+ org
Extractability
Equilibrium pH
REE Beneficiation How do we separate them from one another?…..
Separation scheme – using pH and redox
#1 ppt REE as hydroxide
REE leach liquor
#2 Oxidative drying
#3 Redissolution
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
La Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
#4 pH controlled SX La Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
#5 pH controlled SX La Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
#6 SX/IX La Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
REE Beneficiation How do we separate them from one another?…..
Lanthanide solution Filter
SX Mixer
SX Mixer
SX Mixer
SX Loading
SX Loading
SX Loading
SX stripping
SX stripping
SX stripping
La-Nd-Pr-Sm-Eu-Gd
solution Sm-Eu-Gd solution
Sm-Eu-Gd
solution
Eu – redox
separation
Eu purification SX Loading
SX Loading
SX Loading
SX stripping
SX stripping
SX stripping
SX Sm-Gd
separation
precipitate, filter
calcine
Eu2O3
precipitate, filter
calcine
Sm2O3
Sm solution
precipitate, filter
calcine
Gd2O3
SX Mixer
SX Mixer
SX Mixer
SX Mixer
SX Mixer
SX Mixer
SX Loading
SX Loading
SX Loading
SX stripping
SX stripping
SX stripping
SX La-Nd-Pr
separation
SX Mixer
SX Mixer
SX Mixer
SX Loading
SX Loading
SX Loading
SX stripping
SX stripping
SX stripping
SX Nd-Pr
separation
La-Nd-Pr
solution
La-Ln concentrate
La(NO3)3
precipitate, filter
calcine
Pr2O3
precipitate, filter
calcine
Nd2O3
REE Beneficiation Can it be done in South Africa?...
REE processing plants and refineries in particular:
• complex,
• capital-intensive =>
• in order to be globally competitive => an economy of scale in the region of ≥20,000 tpa TREO production
Refinery Molycorp
Mountain Pass (USA) Lynas
Mount Weld (Australia)
Size, t/a 19,500 – 40,000 22,000
Products All All Cost $ 531 000 000 $AUS 478 000 000
Size and investment for building a REE refinery
Problem Statement #1
REE Beneficiation What does it cost?…..
Citizen Journalists Malaysia
Capacity – 22 000 t REO/a
CAPEX – $ 478 000 000
REE Beneficiation Can we do this in South Africa?...
Problem Statement #2
Mine or Prospect Name REO, mLn
t Ore reserves,
mLn t Grade REO, %
Mountain Pass, USA 1.8 13.59 8.2
Mount Weld, Australia 1.7 17.49 8.1
Kangankunde, Malawi 0.12 2.53 4.9
Steenkampskraal, South Africa 0.03 0.25 17
Zandkopsdrift, South Africa 0.53 22.92 2.32
Glenover, South Africa 0.013 1.64 0.8
Loftdal, Namibia 0.12 9.6 1.2
Mount Muambe, Mozambique 0.015 1.6 0.94
Songwe, Malawi 0.065 4.4 1.47
Tantalus, Madagascar 0.09 2.9 3.08
Wigu Hill, Tanzania 0.07 3.3 2.17
Nolans Bore, Australia 0.85 30.3 2.8
Holidas Lake, Canada 0.057 2.85 2.0
Kvanefjeld, Greenland 4.91 457 1.1
Nechalacho, Canada 0.9 57.49 1.56
REE Beneficiation Can we do this in South Africa?...
Problem Statement #3 Complex technology
REE Beneficiation Centralized refinery
Deposit 1
Deposit 2
Deposit 3
Deposit 4
Physical
Concentrate 1
Physical
Concentrate 2
Physical
Concentrate 3
Physical
Concentrate 4
Processing
Option 1
Processing
Option 2
Processing
Option 3
Processing
Option 4
Chemical REE
Concentrate 1
Chemical REE
Concentrate 2
Chemical REE
Concentrate 3
Chemical REE
Concentrate 4
R
E
F
I
N
E
R
y
La
Ce
Pr
Nd
Sm
Eu
Gd
Tb
Dy
Ho
Y
Er
Tm
Lu
On siteCentralized facility
Variable concentrates Economy of scale Infrastructure
Chemical supply Established area Transportation …
Problem Statement #1
Problem Statement #2
REE Beneficiation Centralized refinery
•Centralized => dependent on feed => planning of the feed supply is critical => know your feed before process parameters generation
•Secure off-take agreements:
REE prices - volatile
Difficult to market
•Project development & execution - equity-financed by the key partners or through a strategic national investment
•Transport, disposal and storage of radioactive waste
Critical issues to be addressed
REE Beneficiation Centralized refinery
• Economies of scale => costs of reagents & processing;
• Developed infrastructure => sophisticated operational
support;
• Access to reagent production & recycling facilities;
• Qualified staff <= well-established area;
• Centralized storage facility for wastes.
Benefits of a centralised facility
REE Beneficiation Process technology…
Problem Statement #3
Late 60s to late 70s
Development
work in REE
analytical and
mineralogical
methods to be
used for clients
• R&D test work on
separation of REE
• Project on phosphogypsum
sludge (Phalaborwa) for
leaching and separation of
certain targeted REE
• From bench-scale to pilot-
plant scale followed by
demo plant for production of
tonnes of mixed REO
• Including the design of REE
plants and cost estimates
Late 80s to late 90s
More R&D
test work on
REE
(synergistic
systems)
Late 90s to early 2000
Marubeni enquiry
on evaluation of
phosphogypsum
dumps
(Phalaborwa) for
REE recovery
2009 2010 onward
R&D test work on REE
restarted and on-going to
develop flow sheets for
REE recovery, impurity
removal from REE
solutions and separation
of targeted REE
Montero, Marubeni and
other commercial
projects on REE recovery
and separations started
and on-going
REE Beneficiation Process technology…
Problem Statement #3
REE Beneficiation Can South Africa build and operate a centralized REE facility?
Technical expertise to develop a robust flow sheet and supply wide ranging technical
support once operation is running
Governmental support
Infrastructural support
Wastes and radioactive materials storage
South Africa may not have world class REE resources
There is probably space for one more world class producer in the next 10 years
THE QUESTION IS: WHY NOT SOUTH AFRICA?
37
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