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TRANSCRIPT
Dry Recycling Process of Rare Earth Elements
from Alloy Magnets Keigo Nishimura1, Toru H. Okabe2
1Freshman, Division of The College of Arts and Sciences, The University of Tokyo, Japan; 2Institute of Industrial Science, The University of Tokyo, Japan.
Introduction
Experimental
Results Conclusion
Total
109 kt
Rare earth elements Production of
rare earth ore
Nd-Fe-B magnets
Application of Nd-Fe-B magnet
China China
87%
India
2.6%
Other
4.2%
India
Other
United States
1985 1980 1990 1995 2010 2000
140
120
100
80
60
40
20
0
Am
ou
nt o
f p
rod
uctio
n o
f R
E o
xid
es, W
/ k
t
Year
Change in amount of production of REE
United
States
6.4%
2005
Current recycling process
Nd-Fe-B magnet alloys were reacted
with Molten Mg at 1000℃ for 24 hours.
(Nd, Dy)-rich phase Top view of
sectioned crucible
Fig. Samples obtained after the extraction experiment.
Magnet
phase
Reaction
phase
Mg-rich
phase
Demand for Nd-Fe-B sintered magnet by use in Japan (2008).
VCM 31%
MRI 5%
Other 19%
In 2010, China accounts for 97% of
world rare earth production.
Almost all rare earth are produced in China. Used for Nd-Fe-B alloy magnet
Nd-Fe-B magnet is
the strongest permanent magnet in the world.
Demand for Nd-Fe-B magnet
Alloy magnet used in this study
Experimental procedure
Nd is an essential element for high performance alloy magnet.
Addition of Dy or Tb improves heat resistance of magnet.
Nd and Dy are vital elements for strong magnets. Ion clay which contains large amount of Dy and
other heavy rare earth exsist only in China.
Large amount of scraps will be
generated in the future.
Supply of REE in 2012
Serious environmental pollution occurs.
But·····
Change in prices of Nd, Dy. (Industrial rare metals (2007))
Year. Month 2005.1 2006.1 2006.12
0
20
40
60
80
100
120
Pri
ce
U
S$ ・
kg
-1 Dy
Nd
Price chart of Nd and Dy
Price of Nd and Dy is increasing
Recycling of Nd from scraps is important.
Concept of our new process
Development of environmentally
friendly dry recycling process for
rare earth.
Stable supply of rare earth.
1. Experimental setup
2. Nd extraction at elevated temperature.
TIG welding
Fe lid
Mg shot
Nd-Fe-B magnet
alloy lump
Iron crucible
Stainless steel vessel
Ti sponge
SEM-EDS analysis of sample
ICP-AES analysis of sample
95 kt
Total supply
of China
自動車生産に必要なNd磁石量(保有台数から)
0.00
5000.00
10000.00
15000.00
20000.00
25000.00
30000.00
1 6 11 16 21
Dy Nd
他
0.0
5.0
10.0
15.0
20.0
1 3 5 7 9 11 13 15 17 19 21 23 25
自動車保有台数(百万台)
系列1
0
5
10
15
20
25
30
De
ma
nd
fo
r N
d-F
e-B
ma
gn
et a
nd
the
ra
tio
of m
ate
ria
ls fo
r E
V, W
/ k
t
0
2
4
10
12
18
20
6
8
14
16
Year
Pro
du
ctio
n o
f E
V,
N (
mill
ion
)
2006 2010 2015 2020 2025 2030
: Nd
: Dy
: other materials
(Annual Energy Outlook 2008: US DOE EIA, http://www.eia.doe.gov/oiaf/ieo/)
Extract only Nd and Dy from
Nd-Fe-B alloy magnet by using
molten Mg.
Nd
Fe
Nd Mg
Nd-Mg alloy
Mg as an
extractant
Nd-Fe-B
magnet
1,000 ℃
High affinity
between
Nd and Mg
Fe
49%
Nd
44%
Dy
6%
B
1%
Most of Nd was extracted from alloy
phase to Mg phase.
On the other hand, Fe was not
extracted into molten Mg.
Over 90 % of Nd was extracted from
Nd-Fe-B alloy magnet.
• Nd was extracted directly
from Nd-Fe-B magnet by
dry recycling process.
• Not any highly toxic waste
solution was generated by
this dry process.
Discarding large amount of
highly toxic waste solutions
×
The representative component of
rare earth ore La Ce
Y
Pr
Sm
Dy
Mt. Pass (USA)
Baiyun Obo (China)
Mt. Weld (Australia)
Rongnan (China)
Xinfeng(China)
Xunwu(China)
Ion clay
Bastnaesite
Bastnaesite
Monasite
Ion clay
Ion clay
7 kt
4 kt
Nd
Motor
31%
Nd2Fe14B magnet scrap
Pulverization
Oxidation
Acid dissolution
L S
Filtration
Nd, Fe (in solution)
FeOx, abrasives, etc.
Fractional precipitation Fractional precipitation
Filtration Filtration
Calcination Calcination
Nd2O3
HF
Fe (in solution) Nd2(C2O4)3 NdF3・nH2O
Fe (in solution)
NdF3
H2C2O4
Objectives
Fig. Composition of alloy magnet (mass%)
Mg shot Magnet alloy lump
A 1 1.5
B 1 2.0
C 1 2.5
Weight ratio of alloy magnet lump and Mg shot
Mg SEM
Nd Fe
Composition, Ci (mass%)
Mg Fe Nd
A 0.82 96.1 3.07
B 1.11 93.7 5.19
C 0.64 92.6 6.75
Composition, Ci (mass%)
Mg Fe Nd
A 62.65 0.87 35.79
B 62.38 0.00 36.97
C 53.35 0.35 45.41
Result in magnet alloy phase
Result in Mg phase
Extraction rate of Nd (On assumption that Mg is not flowing
outside as gaseous phase)
Sample A B C
Extracted Nd ratio (%)
93.2 88.5 85.0
now
~$1,000/kg Dy metal
*1 The value was
determined from the
composition of
magnet alloy after
extraction.
Keigo Nishimura is expert of Taido, martial arts.
Nd can be extracted and separated
directly from magnet alloy
Other heavy REE
(Eu, Gd, Tb, Ho, Er, Yb, Lu)
Total
10400 t