Permanent Magnets
for Energy Applications
Part 2
Stan Trout
August 11, 2014
Permanent Magnets
for Energy Applications Part 2
• Rare Earths
– Basic facts
– The crisis
– Mines
– Applications
•
•
•
•
Magnet Recycling
Permanent Magnet Selection & Specification
Case Studies
The Future
Rare Earths
Sc
Y
La
Ce
Pr
Nd Pm Sm Eu Gd Tb
Dy Ho
Er
Tm Yb
Lu
Rare Earths 101
• Ores contain all rare earths except Pm
• The rare earths are chemically very similar
• There is no shortage of ore for light RE’s
– Bastnasite & Monazite are the most common
• Most ores are rich in Ce, La, Nd and Pr
– Not all rare earths are rare in the Earth
• Magnetic, optical, electronic and catalytic
properties vary widely
• The lanthanide contraction
• Producers try to balance supply and demand
– And are rarely successful!
Dilbert, February 28, 2011
Critical Materials Institute
• DOE Program
– $120 million, 5 years
– National Labs
– Academe
– Industry
• Reduce criticality
• CMI opened officially
on Sept. 10, 2013
Source: DOE Announcement May 2012
Recent RE Metal Prices
Source: U.S. Geological Survey
Two Confusing Points
• Analysis and Recovery, are not the same
thing
• Balance
– What is it?
– Why it is important to the RE industry and to
customers
Rare Earth Analysis
Source: Castor, Resource Geology vol. 58,
No. 4, 337-347 (2008)
The Castor Analysis
•
•
•
•
Original report 1986, almost 30 years old
First Mass Spec-ICP
A single sample
Widely quoted, sometimes abridged to
omit heavy RE’s
• Widely believed to predict recovery
accurately
– At best only an upper limit
Analysis vs. Recovery
Analysis
• Goal: understand
composition
• Scale: 10 gram
• Digestion: complete as
possible
• Separation: no
Recovery
• Goal: sell into
marketplace
• Scale: 1010 gram
• Digestion: appropriate for
scale and market
• Separation: appropriate
for market conditions
Balance
• The attempt by each rare earth processor
to balance the available ore with the needs
of the marketplace.
Source: Kingsnorth
1 km
Bayan Obo mine ,
near Baotou, China
Photo from Google Earth
~1 km
Mountain Pass, CA,
Source: Molycorp
Rare Earth Sources
• Active mines
– China
• Baotou
• Ionic Ores
• Mines coming on
stream
– USA
• Mountain Pass, CA
– Australia
• Mt. Weld
• Under Development
– Australia
• Nolan’s Bore
– Canada
• Hoidas Lake
• Nechalacho
–
–
–
–
–
India
Brazil
USA
Vietnam
Russia
Early Lighting Options
Welsbach
Candoluminescence
Edison
Incandescence
Source:
Gas Light Guys
Source: Wikipedia
Source: Auer Licht
Lighting Phosphors
Lighting Phosphors
• What we see depends on
the phosphors
• Red: Y2O3: Eu
• Green: (La, Ce, Tb) PO4
• Blue: BaMgAl10O17:Eu
Compact Fluorescent Lights (CFL)
Source: GE Lighting
Fluorescent Lighting
• Advantages
– Higher output
• 58 lu/W vs. 13.5 lu/W
– Lower operating cost
• 10 W vs. 40 W
– Longer life
• 12,000 hrs vs. 1,000 hrs
Data source: GE Lighting
• Disadvantages
– Slightly higher price
– Difficulty dimming
– Unappealing light?
• Cheap bulb = cheap
phosphors
– Hg in bulb, special
disposal
Automotive Catalysts
Source: BASF
The metal oxide is cerium
Refining Catalysts
• Fluid Cracking Catalyst (FCC)
– A traditional use of lanthanum
– Ideal for heavy crude to make gasoline
– Ion-exchanged zeolite (cat litter)
– Variable demand
• Driving season and heating season
• Available crude oil
Current Magnet Applications
• Hard drive
– Voice Coil Motor (VCM)
– Spindle motors
– 5 x 108 per year
Source: Western Digital
Current Magnet Applications
Tailgate
Motor
Anti-skid
Sensor and
Motor
Door Lock
Motor
Four
Wheel
Steering
Window
Lift
Motor
Suspension
System
Head
Speakers Automatic
CD Windshield
Temperature
Rest
Control Lumbar
Motor Player Washer
Sun
Defogger
Support
Pump
Roof
Motor
Mirror Gauges
Motor
Cruise
Motors
Control
Door
Liquid
Electric
Gasket
Level
Power
Indicators Steering
and Sensor
Economy
and
Pollution
Control
Ignition
Headlight
Systems
Door
Motor
Starter
Motor
Fuel
Pump
Motor
Seat
Belt
Motor
Windshield
Wiper
Motor
Heater-A/C
Seat
Blower
Throttle
Adjust
Traction
and
MotorsAntenna
Control
Lift
Crankshaft
Motor
Position
Sensors
Source: Magnequench
Coolant
Fan
Motor
New Rare Earth Magnet Applications
• Automotive
– Hybrids
– Electric vehicles
Source: Toyota
Emerging Magnet Applications
The basic components of a wind turbine.
Source: Department of Energy
Emerging Magnet Applications
• Wind Turbines
– Reliability
– The gearbox
– About 500 kg of
magnet per MW
– Small % use magnets
– 260 GW more in US by
2030*
*Source: AWEA.org
Source: Vestas AS
Recycling
• Historically unimportant
– Value
– Difficulty
• Interest rises and falls with prices
• Two areas of interest
– Eu, Tb and Y oxides from lighting phosphors
– Nd and Dy from magnets, mainly hard drives
Material Selection & Specification of
Permanent Magnets
•
•
•
•
•
Motivation
Basic Considerations
Advanced Considerations
Specification
Checklist
Motivation
• Gross oversimplification
• Errors of omission
• Lack of protocol
Basic Considerations
Ferrite Alnico
Ceramic Alnico
Property
8
5
Br (kG) 4.0
12.5
-0.02
 (%/C) -0.18
(BH)max
3.8
5.5
MGOe
Hci (kOe) 3.3
0.64
 (%/C) +0.4 -0.015
Hs (kOe) 10
3
890
Tc (C) 460
SmCo
NdFeB
1-5
1-5 TC
2-17
Bonded Sintered
9.0
-0.045
6.1
-0.001
10.4
-0.035
6.9
-0.105
13.4
-0.12
20
9
26
10
43
30
-0.3
20
727
30
-0.02
40
729
25
-0.3
30
825
9
-0.4
35
360
15
-0.6
35
310
Advanced Considerations
•
•
•
•
Physical
Mechanical
Corrosion
Magnetizing
• Assembly
• Adhesives
• Testing
Writing a Specification
• Two Approaches
–What I happen to have
–What I actually need
• Avoid Contradictions
• IEC or IMA (MMPA) standards
• Supplier Reference, or equivalent
Checklist
•
•
•
•
•
Magnetic parameters
Flux variations
Dimensions/Tolerances
Testing
Magnetizing
•
•
•
•
Coating
Adhesive
Assembly
Others
Case Study 1
• Direct substitution of bonded NdFeB for ferrite
– Saturated return structure
– Poor performance
• Increase the thickness of the return path, more poles
Case Study 2
B = Br ln (do/di)
• Bonded NdFeB ring for angle sensing application
– Incorrect magnetization (axial) yields poor performance
– Correct magnetization, with hairpin fixture, yields good signal
and contained flux
Case Study 3
Window Lift Motor
Toyota Prius and Toyota Harrier
Source: Dr. B. Grieb
Magnequench
3D Model of Benchmark
2 Pole PMDC (Brush Motor)
Skewing on the armature teeth
Torque-Speed and Torque-Current
Characteristics for the Benchmarked and
Redesigned Motors
Torque-Efficiency Characteristics for the
Benchmarked and Redesigned Motors
Benchmarked Motor
Redesigned Motor
2-Pole Ferrite
1
1
1
4-Pole Bonded Neo
1
1
1 0.99
0.88
0.74
0.74
0.38
Diameter
Length
Width
Weight
0.44
Volume
Cost
The Future
• Niels Bohr, “Prediction is very difficult,
especially about the future.”
• Supply and Demand are dynamic
• Overreacting and underreacting are normal
– Supply
– Demand
– Government
• Finding equilibrium is difficult & takes time
• Energy conservation is a major driver
• We need to use these materials wisely
Permanent Magnets
for Energy Applications Part 2
• Rare Earths
– Basic facts
– The crisis
– Mines
– Applications
•
•
•
•
Magnet Recycling
Permanent Magnet Selection & Specification
Case Studies
The Future