Keigo Nishimura , Toru H. Okabe Introduction Experimental Results

Keigo Nishimura , Toru H. Okabe Introduction Experimental Results

Dry Recycling Process of Rare Earth Elements
from Alloy Magnets
Keigo
Toru H.
2
Okabe
Division of The College of Arts and Sciences, The University of Tokyo, Japan;
2Institute of Industrial Science, The University of Tokyo, Japan.
Introduction
Rare earth elements
Application of Nd-Fe-B magnet
Production of
rare earth ore
Other 19%
Other
4.2%
India
2.6%
MRI 5%
Motor
Total
10400 t 31%
United
States
6.4%
VCM 31%
140
China
87%
Total
109 kt
Demand for Nd-Fe-B sintered magnet by use in Japan (2008).
The representative component of
rare earth ore
Used for Nd-Fe-B alloy magnet
Mt. Pass (USA)
Bastnaesite
Baiyun Obo (China)
Bastnaesite
Nd-Fe-B magnet is
the strongest permanent magnet in the world.
Ion clay
Rongnan (China)
20000.0020
: Nd
: Dy
15
15000.0010.0
10
10000.00
5.0
5
5000.00
0
0.000.0
2006
2010
11 3 5 6 7
92015
11 Year
13 2020
1516 17 192025
21 23 25
11
21
Price chart of Nd and Dy
120
US$ ・kg-1
Price
100
80
40
now
~$1,000/kg Dy metal
Dy
60
Nd
20
0
2005.1
2006.1
Year. Month
2006.12
Change in prices of Nd, Dy.
(Industrial rare metals (2007))
Price of Nd and Dy is increasing
Mg as an
extractant
Pulverization
Oxidation
Filtration
L
H 2 C 2 O4
FeOx, abrasives, etc.
S
Nd, Fe (in solution)
Fractional precipitation
Fractional precipitation
Filtration
Filtration
Fe (in solution)
Fe (in solution)
Nd2(C2O4)3
NdF3・nH2O
Calcination
Calcination
Nd2O3
NdF3
× Discarding large amount of
highly toxic waste solutions
SEM-EDS analysis of sample
Fe
Top view of
sectioned crucible
Magnet
phase
Reaction
phase
Mg-rich
phase
Fig. Samples obtained after the extraction experiment.
Other
1985
1990
1995
Year
2000
2005
2010
Change in amount of production of REE
Nd
Alloy magnet used in this study
Dy
6%
Nd
Mg
Nd
ICP-AES analysis of sample
Result in magnet alloy phase
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
Result in Mg phase
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
B
1%
Fe
49%
Nd
44%
Fig. Composition of alloy
magnet (mass%)
Mg
Experimental procedure
1. Experimental setup
Extract only Nd and Dy from
Nd-Fe-B alloy magnet by using
molten Mg.
TIG welding
Fe lid
Mg shot
Nd-Fe-B magnet
alloy lump
Iron crucible
Stainless steel vessel
Ti sponge
Objectives
Development of environmentally
friendly dry recycling process for
rare earth.
Weight ratio of alloy magnet lump and Mg shot
Stable supply of rare earth.
SEM
(Nd, Dy)-rich phase
0
India
Experimental
Nd-Mg alloy
HF
Results
Nd-Fe-B magnet alloys were reacted
with Molten Mg at 1000℃ for 24 hours.
United States
High affinity
between
Nd and Mg
Nd-Fe-B
magnet
Recycling of Nd from scraps is important.
2. Nd extraction at elevated temperature.
20
Serious environmental pollution occurs.
1,000 ℃
Fe
Acid dissolution
(Annual Energy Outlook 2008: US DOE EIA, http://www.eia.doe.gov/oiaf/ieo/)
Large amount of scraps will be
generated in the future.
China
40
But·····
Concept of our new process
Nd2Fe14B magnet scrap
Production of EV, N (million)
Demand for Nd-Fe-B magnet and
the ratio of materials for EV, W / kt
15.0
60
Sm
Other heavy REE
(Eu, Gd, Tb, Ho, Er, Yb, Lu)
Current recycling process
20
18
16
14
Dy Nd
12
10 系列1
他
8
6
4
2
0
2030
: other materials
Ion clay
80
Ion clay which contains large amount of Dy and
other heavy rare earth exsist only in China.
Nd and Dy are vital elements for strong magnets.
30
30000.0020.0
95 kt
Dy
Ion clay
Nd is an essential element for high performance alloy magnet.
Addition of Dy or Tb improves heat resistance of magnet.
自動車生産に必要なNd磁石量(保有台数から)
Demand
for 自動車保有台数(百万台)
Nd-Fe-B magnet
Y
Xinfeng(China)
Total supply
of China
Nd
Pr
Xunwu(China)
100
Almost all rare earth are produced in China.
4 kt
Monasite
120
1980
Supply of REE in 2012
7 kt
Ce
Mt. Weld (Australia)
Nd-Fe-B magnets
25000.0025
La
In 2010, China accounts for 97% of
world rare earth production.
Amount of production of RE oxides, W / kt
1Freshman,
1
Nishimura ,
A
B
C
Extracted Nd
ratio (%)
93.2
88.5
85.0
Magnet alloy lump
A
1
1.5
B
C
1
1
2.0
2.5
Conclusion
Extraction rate of Nd
(On assumption that Mg is not flowing
outside as gaseous phase)
Sample
Mg shot
• 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.
*1 The value was
determined from the
composition of
magnet alloy after
extraction.
Over 90 % of Nd was extracted from
Nd-Fe-B alloy magnet.
Most of Nd was extracted from alloy
phase to Mg phase.
On the other hand, Fe was not
extracted into molten Mg.
Nd can be extracted and separated
directly from magnet alloy
Keigo Nishimura is expert of Taido, martial arts.