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What Do We Know About Metal Recycling Rates? What Do We Know About Metal Recycling Rates?
T. E. Graedel
Yale University
, thomas.graedel@yale.edu
Julian Allwood
Cambridge University
Jean-Pierre Birat
Maizieres-les-Metz
Matthias Buchert
Ӧko Institut
Christian Hagelűken
Umicore Precious Metals
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Graedel, T. E.; Allwood, Julian; Birat, Jean-Pierre; Buchert, Matthias; Hagelűken, Christian; Reck, Barbara K.;
Sibley, Scott F.; and Sonnemann, Guido, "What Do We Know About Metal Recycling Rates?" (2011).
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Staff -- Published Research
. 596.
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RESEARCH AND ANALYSIS
What Do We Know About
Metal Recycling Rates?
T. E. Graedel, Julian Allwood, Jean-Pierre Birat, Matthias
Buchert, Christian Hagel
¨
uken, Barbara K. Reck, Scott F. Sibley,
and Guido Sonnemann
Keywords:
end-of-life recycling rate (EOL-RR)
industrial ecology
old scrap ratio (OSR)
recycled content (RC)
recycling input rate (RIR)
recycling metrics
Supporting information is available
on the JIE Web site
Address correspondence to:
Dr. Thomas E. Graedel
School of Forestry and Environmental
Studies
Yale University
195 Prospect Street
New Haven, CT 06511
thomas.graedel@yale.edu
c
2011 by Yale University
DOI: 10.1111/j.1530-9290.2011.00342.x
Volume 15, Number 3
Summary
The recycling of metals is widely viewed as a fruitful sustainabil-
ity strategy, but little information is available on the degree to
which recycling is actually taking place. This article provides an
overview on the current knowledge of recycling rates for 60
metals. We propose various recycling metrics, discuss relevant
aspects of recycling processes, and present current estimates
on global end-of-life recycling rates (EOL-RR; i.e., the percent-
age of a metal in discards that is actually recycled), recycled
content (RC), and old scrap ratios (OSRs; i.e., the share of old
scrap in the total scrap flow). Because of increases in metal
use over time and long metal in-use lifetimes, many RC values
are low and will remain so for the foreseeable future. Because
of relatively low efficiencies in the collection and processing
of most discarded products, inherent limitations in recycling
processes, and the fact that primary material is often relatively
abundant and low-cost (which t hereby keeps down the price
of scrap), many EOL-RRs are very low: Only for 18 metals
(silver, aluminum, gold, cobalt, chromium, copper, iron, man-
ganese, niobium, nickel, lead, palladium, platinum, rhenium,
rhodium, tin, titanium, and zinc) is the EOL-RR above 50%
at present. Only for niobium, lead, and ruthenium is the RC
above 50%, although 16 metals are in the 25% to 50% range.
Thirteen metals have an OSR greater than 50%. These es-
timates may be used in consider ations of whether recycling
efficiencies can be improved; which metric could best en-
courage improved effectiveness in recycling; and an improved
understanding of the dependence of recycling on economics,
technology, and other factors.
www.wileyonlinelibrary.com/journal/jie Journal of Industrial Ecology 355
This article is a U.S. government work, and is not subject to copyright in the United States.
RESEARCH AND ANALYSIS
Introduction and Scope of Study
Metals are uniquely useful materials by virtue
of their fracture toughness, thermal and elec-
trical conductivity, and performance at high
temperatures, among other properties. For these
reasons, they are used in a wide range of applica-
tions in areas such as machinery, energy, trans-
portation, building and construction, informa-
tion technology, and appliances. Additionally,
of the various resources seeing wide use in mod-
ern technology, metals are different from other
materials in that they are inherently recyclable.
This means that, in theory, they can be used
over and over again, which minimizes the need
to mine and process virgin materials and thus
saves substantial amounts of energy and water
while limiting environmental degradation in the
process.
Recycling data have the potential to demon-
strate how efficiently metals are being reused and
can thereby serve some of the following purposes:
• Determine the influence of recycling on re-
source sustainability
• Provide information to governments, the
metals industry, metal users, and the recy-
cling industry on recycling rates and oppor-
tunities for change
• Provide information for research on im-
proving recycling efficiency
• Provide information for life cycle assess-
ments
• Stimulate informed recycling policies.
This article summarizes the results of a work-
ing group of the United Nations Environment
Programme’s (UNEP’s) International Panel for
Sustainable Resource Management (Resource
Panel) on metal recycling rates. We discuss def-
initions of recycling statistics, review recycling
information, identify information gaps, and dis-
cuss the implications of our results. The goal is to
summarize available information (rather than to
generate new data), highlight information gaps,
and fill these gaps through informed estimates.
The elements investigated are not all metals,
according to the chemical meaning of metal, as
metalloids
1
have been included, whereas the ra-
dioactive actinides and polonium are excluded.
From the alkali metals only lithium (Li) has been
included because of its use in batteries, and from
the alkaline metals all but calcium have been
included. Furthermore, selenium has been in-
cluded because of its importance as an alloying el-
ement and semiconductor. The selected elements
(called “metals” hereafter) include the following:
• Group 1: vanadium (V), chromium (Cr),
manganese (Mn), iron (Fe), nickel (Ni),
niobium (Nb), molybdenum (Mo)
• Group 2: magnesium (Mg), aluminum (Al),
titanium (Ti), cobalt (Co), copper (Cu),
zinc (Zn), tin (Sn), lead (Pb)
• Group 3: ruthenium (Ru), rhodium (Rh),
palladium (Pd), silver (Ag), osmium (Os),
iridium (Ir), platinum (Pt), gold (Au)
• Group 4: lithium (Li), beryllium (Be),
boron (B), scandium (Sc), gallium (Ga),
germanium (Ge), arsenic (As), selenium
(Se), strontium (Sr), yttrium (Y), zir-
conium (Zr), cadmium (Cd), indium
(In), antimony (Sb), tellurium (Te), bar-
ium (Ba), lanthanum (La), cerium (Ce),
praseodymium (Pr), neodymium (Nd),
samarium (Sm), europium (Eu), gadolin-
ium (Gd), terbium (Tb), dysprosium (Dy),
holmium (Ho), erbium (Er), thulium (Tm),
ytterbium (Yb), lutetium (Lu), hafnium
(Hf), tantalum (Ta), tungsten (W), rhe-
nium (Re), mercury (Hg), thallium (Tl),
bismuth (Bi).
For our purpose, the metals are designated
as ferrous metals (Group 1), nonferrous metals
(Group 2), precious metals (Group 3), and spe-
cialty metals (Group 4). The principal metals in
each of these groupings are more or less according
to popular use, but the less abundant or less widely
used elements are not necessarily readily catego-
rized (e.g., tellurium [Te] could equally well have
been included in the ferrous metals).
Metals are predominantly used in alloy form,
but not always, and recycling information that
specifies the form of the metal is not commonly
available. Thus, a ll information herein refers to
the aggregate of the many forms of the metal in
question (but as metal, rather than generally in
a nonmetallic form such as a sulfate or oxide,
e.g., barium sulfate [BaSO
4
], titanium dioxide
356 Journal of Industrial Ecology
RESEARCH AND ANALYSIS
Figure 1 The life cycle of a metal, consisting of production, product manufacture, use, and end of life. The
loss of residues at each stage and the reuse of scrap are indicated. (After Meskers 2008.)
[TiO
2
]). This distinction is addressed in the
results where necessary.
Metal Recycling Considerations
Metal Life Cycle
Figure 1 illustrates a simplified metal and prod-
uct life cycle. The cycle is initiated by choices in
product design: which materials are going to be
used, how they will be joined, and which pro-
cesses are used for manufacturing. Choices made
during design have a lasting effect on material
and product life cycles. They drive the demand
for specific metals and influence the effectiveness
of the recycling chain during end of life (EOL).
The finished product enters the use phase and
becomes part of the in-use stock of metals. When
a product is discarded, it enters the EOL phase.
It is separated into different metal streams (recy-
clates
2
), which have to be suitable for raw mate-
rials production to ensure that the metals can be
successfully recycled. In each phase of the life cy-
cle metal losses occur, indicated by the “residues”
arrow in figure 1.
The life cycle of a metal is closed if EOL prod-
ucts are entering appropriate recycling chains,
which leads to scrap metal in the form of
recyclates displacing primary metals. The life cy-
cle is open if EOL products neither are collected
for recycling nor enter those recycling streams
that are capable of recycling the particular metal
efficiently. Open life cycles occur as a result of
products discarded to landfills, products recycled
through inappropriate technologies (e.g., the in-
formal sector) whereby metals are not or only
inefficiently recovered, and metal recycling in
which the functionality (i.e., the physical and
chemical properties) of the EOL metal is lost
(nonfunctional or “open-loop” recycling; see be-
low). A related distinction between open and
closed material systems is made in life cycle as-
sessment (ISO 2006), in which a material sys-
tem is only considered closed when a material
is recycled into the same use (Dubreuil et al.
2010).
Scrap Types and Types of Recycling
The different types of recycling are related to
the type of scrap and its treatment:
• Home scrap is material generated during
material production or during fabrication
or manufacturing that can be directly rein-
serted in the process that generated it.
Graedel et al., Metal Recycling Rates 357
![Figure 2 Flows related to a simplified life cycle of metals and the recycling of production scrap and end-of-life products. Boxes indicate the main processes (life stages): Prod = production; Fab = fabrication; Mfg = manufacturing; WM&R = waste management and recycling; Coll = collection; Rec = recycling. Yield losses at all life stages are indicated through dashed lines (in waste management [WM] referring to landfills). When material is discarded to WM, it may be recycled (flow e), lost into the cycle of another metal (flow f, as with copper wire mixed into steel scrap), or landfilled. The boundary indicates the global industrial system, not a geographical entity. When metal is nonfunctionally recycled (“downcycled”), it enters the cycle of](/figures/figure-2-flows-related-to-a-simplified-life-cycle-of-metals-2dxibcb7.webp)
