REE
Source
REEs wt%
Chelating
agents
Pressure (MPa)
Temperature
(°C)
Residence
Time
(h)
Efficiency (%)
Pre-treatment/
Other Additions
Reference
NdO
2
3 CeO
2
3
TBP/HNO
3
21
60
3
Nd
(95)
Failed
to extract
Ce
(Duan,
Cao
et
al.
2010)
NdO
2
3
TBP/HNO
3
21
60
1
Nd
(96)
(Zhu,
Duan
et
al.
2009)
Lanthanide
oxide NdO
2
3 GdO
2
3
10–3
mol
each
TBP/HNO
3
12
40
Nd
(51)
Gd
(46)
(Tomioka, Enokida
et
al.
1998)
Lanthanide
oxides
(YO,
2
3
CeO
2 ,
EuO,
2
3
TbO
2
3 ,DyO
2
3
)
TBP/HNO
3
34.5
65
1.5
Y
(99)
Ce
(0.12)
Eu
(99)
Tb
(92.1)
Dy
(98.5)
(Baek,
Fox
et
al.
2016)
NdFeB
Nd
(18.5)
Pr
(3.6)
Dy
(0.1)
TBP/HNO
3
20.7
55
1
Nd
(94)
Pr
(91)
Dy
(98)
Methanol
added
(Zhang, Anawati
et
al.
2018)
NdFeB
Nd
(32.36)
Malic
acid
12
90
0.5
Nd
(99.4)
(Reisdörfer, Bertuol
et
al.
2020)
Nd
(32.36)
Citric
acid
Nd
(50.5)
NdFeB
Nd
(25.19)
Malic
acid
10
90
2
Nd
(99.5)
Roasted
at
900
°C
for
480
min
Nd
(25.19)
Citric
acid
Nd
(30.6)
Acronyms
NiMH:
Nickel-metal
hydride
battery
TBP:
Tributyl
phosphate
TTA:
Thenoyl
tri
fluoroacetone
HNO
3 :
Nitric
acid
NdFeB:
Neodymium
magnet
made
from
alloy
of
neodymium,
iron,
and
boron
NaOH:
Sodium
hydroxide
NaCO:
2
3
Sodium
carbonate
Table
1.
Summary
of
recent
literature
studying
the
use
of
scCO
2
extraction
for
the
recovery
of
REEs
(continued)
1370 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Source
REEs wt%
Chelating
agents
Pressure (MPa)
Temperature
(°C)
Residence
Time
(h)
Efficiency (%)
Pre-treatment/
Other Additions
Reference
NdO
2
3 CeO
2
3
TBP/HNO
3
21
60
3
Nd
(95)
Failed
to extract
Ce
(Duan,
Cao
et
al.
2010)
NdO
2
3
TBP/HNO
3
21
60
1
Nd
(96)
(Zhu,
Duan
et
al.
2009)
Lanthanide
oxide NdO
2
3 GdO
2
3
10–3
mol
each
TBP/HNO
3
12
40
Nd
(51)
Gd
(46)
(Tomioka, Enokida
et
al.
1998)
Lanthanide
oxides
(YO,
2
3
CeO
2 ,
EuO,
2
3
TbO
2
3 ,DyO
2
3
)
TBP/HNO
3
34.5
65
1.5
Y
(99)
Ce
(0.12)
Eu
(99)
Tb
(92.1)
Dy
(98.5)
(Baek,
Fox
et
al.
2016)
NdFeB
Nd
(18.5)
Pr
(3.6)
Dy
(0.1)
TBP/HNO
3
20.7
55
1
Nd
(94)
Pr
(91)
Dy
(98)
Methanol
added
(Zhang, Anawati
et
al.
2018)
NdFeB
Nd
(32.36)
Malic
acid
12
90
0.5
Nd
(99.4)
(Reisdörfer, Bertuol
et
al.
2020)
Nd
(32.36)
Citric
acid
Nd
(50.5)
NdFeB
Nd
(25.19)
Malic
acid
10
90
2
Nd
(99.5)
Roasted
at
900
°C
for
480
min
Nd
(25.19)
Citric
acid
Nd
(30.6)
Acronyms
NiMH:
Nickel-metal
hydride
battery
TBP:
Tributyl
phosphate
TTA:
Thenoyl
tri
fluoroacetone
HNO
3 :
Nitric
acid
NdFeB:
Neodymium
magnet
made
from
alloy
of
neodymium,
iron,
and
boron
NaOH:
Sodium
hydroxide
NaCO:
2
3
Sodium
carbonate
Table
1.
Summary
of
recent
literature
studying
the
use
of
scCO
2
extraction
for
the
recovery
of
REEs
(continued)
1370 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3