DEVELOPMENT of ALLOY RECYCLING INDICES
for AEROSPACE ALUMINUM ALLOYS
Dr. Subodh K. Das
J.G.Kaufman , Dr. J.A.S.Green
Phinix , LLC
Lexington, Kentucky, USA
Dr. D.Emadi, McGill University, Montréal, Quebec, Canada
Dr. M. Mahfoud, College of the North Atlantic - Qatar, Doha, Qatar
AeroMat 2009
June 9, 2009
Dayton , Ohio, USA
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OUTLINE
• Background : Recycling & Aerospace Aluminum Alloys
• Alloy Recycling Index & Recycling Production Index
• Conclusion & Future Work
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Aluminum Industry emits 1 % of Global GHG
500 Billion Tonnes per Year
• Recycling lowers energy & carbon footprint
– Requires only 5% of energy
• ~2.8 kWh/kg Al vs. ~45 kWh/kg Al
– Produces only 5% of CO2
• ~0.6 kg/kg Al vs. 12 kg/kg Al
– Alloying Elements Conservation ( Mg, Mn , Cu , Zn, Si ) ,
higher energy & carbon footprints than Al
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Why Recycle Aluminum Aircrafts ?
• Thousands of obsolete aircraft stored in
“graveyards” around the world
• “ Graveyards” are large, located in dry / hot
places, establishment of recycling center practical
• Older aircraft are 90%-plus aluminum recovery
feasible
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Recycling Driving Alloy Development
• Previous approach to alloy development
– Driven solely by desired performance
– Limited considerations of end-of-product-life
– Less considerations for cost, carbon footprint and
availability of alloying elements
• Beginning to recognize impact of recycling
– How will product be recovered for recycling ?
– How will composition impact cost & recyclability?
– What will be it's carbon footprint?
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ALLOY RECYCLING INDEX (ARI)
RECYCLING PRODUCTION INDEX(RPI)
• ARI – Recyclability for recovering the maximum
stored energy invested in the alloy ,carbon
footprint ( Quantative)
• RPI – Ease of producing from recycled
remelts(Qualitative)
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ALLOY RECYCLING INDEX (ARI)
• Nominal alloy content is sum of the nominal
alloy additions ( mid-range)
• Sum of the mid-range of the impurity limits
• Total of nominal alloying content plus
nominal total impurity content subtracted
from 100% = ARI.
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RPI - Classification
• High (H) – Readily produced from recycled
remelts in the same alloy
• Medium (M) – Readily produced from recycle
remelts of scrap segregated at least by alloy
series
• Low (L) – More difficult to recycle from recycle
remelts
• Unlikely (U) – Composition doesn’t lend to
production from recycled remelts ( Ag, Be, or Li )
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ARI and RPI for Aerospace Aluminum Alloys
Alloy
2011
2014
2024
2195
2219
2324
2524
7010
7039
7040
7049
7050
7055
7068
7075
7085
7175
7178
7250
7349
7475
8090
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Nominal
Nominal
Alloying
Impurity
Content
%
5.5
6.5
6.5
6.0
6.9
6.2
6.2
10.7
7.2
10.4
11.8
10.8
12.3
12.5
9.9
12.5
7.7
11.8
10.5
12.3
9.7
6.0
Content
%
0.8
0.6
0.8
0.5
0.4
0.4
0.3
0.3
0.5
0.2
0.5
0.3
0.3
0.3
0.7
0.2
0.3
0.7
0.2
0.2
0.2
0.6
Sum
Eleme
nt
Conten
t
%
6.3
7.1
7.3
6.5
7.3
6.6
6.5
11.0
7.7
10.6
12.3
11.1
12.6
12.8
10.6
12.7
8.0
12.5
10.7
12.5
9.9
6.6
Nominal
Potential
Aluminum
From
Content
ARI, %
93.7
92.9
92.7
93.5
92.7
93.4
93.5
89.0
92.3
89.4
87.7
88.9
87.4
87.2
89.4
87.3
92.0
87.5
89.3
87.5
90.1
93.4
Recycle
RPI
M
M
M
U
M
L
L
U
L-M
U
U
U
U
U
M
U
L
L
U
U
U
U
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Remelt Compositions of Recycled Aircraft
Components Assuming Pre-Sorting of 2xxx & 7xxx
Al
%
Cu
%
Fe
%
Mg %
Mn %
Si
%
Zn %
2xxx
~93
4.4
0.5
1.0
0.7
0.5
0.1
7xxx
~90
2.0
0.4
2.5
0.2
0.2
6.0
Mix
~92
3.0
0.4
1.8
0.4
0.4
3.0
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ARI & RPI for Key Aerospace Alloys
ALLOYS
ARI
RPI
• 2XXX
94
M
• 7XXX
91
M/L
• 2XXX/7XXX
91
U
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Conclusions
• Aging / obsolete aircraft = “urban aluminum mine” , reuse
will lowering carbon footprints
•
Alloy Recycling Index and Alloy Recycling Production Index
have been developed
• Alloys with high Cu / Zn difficult to recycle together, preshred segregations into 2xxx and 7xxx groups for remelting
• Manage alloying elements Ag, Be, Bi, Pb, Li and grain refiners
Cr, Zr, V
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Aluminum Industry Flow Chart
Production
Carbon Trading
End Use
Recycling
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