DEVELOPMENT of ALLOY RECYCLING INDICES for AEROSPACE ALUMINUM ALLOYS

Dr. Subodh K. DasJ.G.Kaufman , Dr. J.A.S.Green

Phinix , LLCLexington, Kentucky, USA

Dr. D.Emadi, McGill University, Montréal, Quebec, Canada

Dr. M. Mahfoud, College of the North Atlantic - Qatar, Doha, Qatar

AeroMat 2009June 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 GHG500 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

    Nominal Nominal Sum Nominal   Potential

Alloying ImpurityEleme

nt Aluminum From

Alloy Content ContentConten

t Content Recycle    % % % ARI, %   RPI

2011 5.5 0.8 6.3 93.7 M2014 6.5 0.6 7.1 92.9 M2024 6.5 0.8 7.3 92.7 M2195 6.0 0.5 6.5 93.5 U2219 6.9 0.4 7.3 92.7 M2324 6.2 0.4 6.6 93.4 L2524 6.2 0.3 6.5 93.5 L7010 10.7 0.3 11.0 89.0 U7039 7.2 0.5 7.7 92.3 L-M7040 10.4 0.2 10.6 89.4 U7049 11.8 0.5 12.3 87.7 U7050 10.8 0.3 11.1 88.9 U7055 12.3 0.3 12.6 87.4 U7068 12.5 0.3 12.8 87.2 U7075 9.9 0.7 10.6 89.4 M7085 12.5 0.2 12.7 87.3 U7175 7.7 0.3 8.0 92.0 L7178 11.8 0.7 12.5 87.5 L7250 10.5 0.2 10.7 89.3 U7349 12.3 0.2 12.5 87.5 U7475 9.7 0.2 9.9 90.1 U8090 6.0 0.6 6.6 93.4 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, pre-shred 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

End Use

Recycling

Carbon Trading

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