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Recycling Recycling12 AluReport 02.2012 13AluReport 02.2012
Aluminium recycling on the highest technical level
Shaft furnaceGear boxes
Dross
Pressed aluminium chips
Aluminium cans
Lithographic plates
Window profiles Hearth furnace
Rotary furnace
Tiltable rotary furnace
Illustration 1: Aluminium scrap – A valuable material delivered in various forms, recycled by AMAG in
various melting furnaces for optimum material yield in an environmentally friendly manner
Its knowledge of recycling, developed
over nearly 35 years, enables AMAG
to process aluminium scrap into high-
quality alloys. The ever-increasing de-
mands being placed on the products will
continue to require AMAG to deal, com-
prehensively and in depth, with scrap as a
valuable material. At the Ranshofen loca-
tion, 260,000 tons of scrap were used as
input material last year. The material is de-
livered in various forms (see illustration 1),
from correctly sorted, clean, external indus-
trial waste, which has similar properties and
values as ingot material, to highly oxidic and
organically contaminated dross skimmings
and chips, which are cheaper to buy but
place high demands on process control and
output. In that area of conflicting priorities,
AMAG attempts to process the input ma-
terial in an optimum manner. This means,
for example:
1) Professional checking of incoming raw
materials in a professional manner
2) Storing correctly sorted raw material un-
der roof
3) Adding as much value as possible
through alloy-to-alloy recycling
4) Maximizing output by means of batch
calculation for each melting furnace
5) Ensuring sustainability in all production
processes
6) Detailed knowledge of the influence of
the chemical composition on material
properties
7) Developing recycling-friendly materials
Recycling at AMAG Goal: alloy-to-alloyIf one consistently practices the above
points, alloy-to-alloy recycling is possible.
That is, scrap is not used to produce alu-
minium of unspecific composition but, in-
stead, the recycled material has the same
composition that the starting material had,
or one very similar to it. The second point is
accepting a certain level of impurities wit-
hout a negative effect on properties. These
recycling-friendly cast and wrought alloys
are being developed in cooperation with
partners.
1) Checking of incoming materials
Before entering AMAG's premises, any
materials are automatically checked for ra-
dioactivity. It is only after passing that test
that further samples of the material are in-
spected, especially as regards its composi-
tion.
Whereas for many cast alloys AMAG chiefly
uses scraps it is obvious that for certain
wrought alloys where a high degree of pu-
rity is required these can be employed to
a limited extent only. Optimum use of the
charged material presupposes thorough in-
spection of samples and proper separation.
For this reason, a representative sample is
drawn from each delivery, and a chemical
analysis is performed.
It is mostly objects of everyday use - often
not recognizable as valuable recyclables by
the layman - that are processed in Ransho-
fen to obtain high-grade cast and wrought
alloys. Motor cars, for instance, are a rich
source of raw materials: engine blocks,
gear boxes, wheel rims, radiators, body
sheets, license plates, etc., even production
waste (e.g. gating systems), are recycled at
AMAG.
This also applies to the civil engineering
and building industries; take, for example,
casements (whether pre-consumer scrap or
post-consumer scrap from building demo-
lition and renovation), or aluminium molds
for clay roof tiles, supports, casings, tread-
plates, etc.
Modern printing processes, e.g. for maga-
zines, use aluminium lithographic plates.
After use, they are melted down in Rans-
hofen and used in alloy-to-alloy recycling.
Products of daily use such as wine closures,
cans, tubes, yogurt lids, bottle caps and
foils are processed as well. Due to their
high plastics content, such materials make
very high demands on the melting process.
Even aluminium that is tossed into the trash
bin (e.g. cans) ultimately finds its way to
AMAG as the ashes from waste incinerati-
on are sorted and the corresponding alumi-
nium fraction can be recycled. However, it
is more expedient to separate beforehand.
2) Storing correctly sorted raw materi-
al under roof
Subsequently, the scrap is sorted both
according to chemical composition and
morphology, and stored in dedicated sto-
rage areas. Particularly small-sized scrap
with large surface portions must be stored
in a dry place; otherwise the aluminium
would corrode and be lost. Pure scrap in
lumps can be stored in the open for a short
period of time. The logistics behind this is
one of AMAG's core competences.
15Recycling14
Literature[1] AMAG AluReport 1/2008, page 15[2] Suppan, Umweltfreundliche Schmelzöfen in der Aluminiumindustrie, 5. Ranshofener Leichtmetalltage, Seite 25ff,ISBN-13: 978-3-902092-05-2
From aluminium scrap to
alu
min
ium
coil
Aluminium scrapScrap from cans, foils, wheel rims, win-
dow frames, façades, engine blocks, body
sheets, chips, process scrap, etc., is col-
lected, classified and stored sorted by type
to the greatest possible extent.
limits, however, can only be carried out in
close coordination with the user because
each finished product places individual de-
mands on the material.
It is AMAG's declared intention to increas-
ingly work on the development and im-
provement of recycling-friendly alloys,
jointly with customers and research in-
stitutes, to continue encouraging the re-
source-efficient production of lightweight
components through the recycling route.
Outlook
The "AMAG 2014" investment project
will cause AMAG to grow signifi-
cantly. The current scrap charge rate
will be maintained, which will lead
to more aluminium scrap being
processed. For this reason, the
Ranshofen Recycling Center is
being further expanded.
MeltingAt Ranshofen, approximately 80% of
AMAG's high-quality products are made
from scrap material. This high scrap charge
rate can only be achieved through special
know-how and sophisticated metal analysis.
CastingAdvanced casting technology provides high-quality
basic material for subsequent processes. For
instance: rolling slabs of optimum form,
dimension and chemical composition.
Optimally tailored to customer
requirements.
Rolling and heat treatmentNumerous production stages - e.g.
rolling, heat treatment, cutting,
testing - are needed in the roll-
ing mill in order to produce
aluminium strip.
Final stepsCutting and packing accord-
ing to customer specifications
and dispatch conclude the
processing of the order.
tion [1]. 16 differentiated analysis programs
ensure that the chemical composition can
be measured correctly.
At this point, all AMAG customers benefit
from the rigorous certification standards of
the aircraft industry. For example, approval
analyses of cast alloys are kept for at least
two years, those of wrought alloys for at
least ten years. Even test specimens that
describe the melting history of the material
up to the product, so-called approval sam-
ples, are retained for one month to be able
to answer questions, if any. The test speci-
men is automatically labeled for traceability
with the batch number, material number
and equipment number, as well as date and
time of measurement, using a marking sys-
tem, and entered in the database.
For special elements or to be on the safe
side, AMAG can also perform wet-chemical
ICP (induced coupled plasma) analyses. At
any rate, it is ensured that the sampling
standards used are always the same, from
the inspection of samples to the finished
product. This way a 6xxx alloy can again be
recycled into a 6xxx alloy.
4) High-quality recycling by charge cal-
culation for each melting furnace
Adequate melting technologies are the key
to optimum recycling. AMAG has a wide
range of melting furnaces (shaft furnaces,
hearth-type furnaces, rotary drum-type
furnaces, rotary-drum tilting-type furnaces;
see Illustration 1). The art of recycling con-
sists in allocating the optimum scrap mix to
the appropriate melting unit, based on the
requirements of the finished product. A da-
tabase-aided charge calculation that takes
into account the types and amounts of the
3) Alloy-to-alloy recycling
An important aspect in alloy-to-alloy re-
cycling is sophisticated metal analysis by
which the chemical composition of alloys
can be determined. AMAG has recently
invested in this important area. This fully
automated facility includes two spark emis-
sion spectrometers of maximum precision
(Illustration 2). Additionally, samples from
the melting furnace undergo another radio-
activity check.
AMAG's Ranshofen site is the only produc-
tion facility worldwide to process all alloy
families from 1xxx to 8xxx at a single loca-
scraps described in item 2 is an essential
condition. Organic contamination (coat-
ings, paints, foils, etc.) can be a particular
problem when scrap is to be recycled into
high-quality materials. Correct charging al-
lows the contaminants to be burned off in a
controlled manner and reduces the expens-
es related to the required post-combustion
to comply with Austria's stringent emission
regulations. Moreover, the heat generated
can be used for the melting process, thus
saving CO2 [2].
5) Sustainability in all processes
AMAG gives top priority to minimizing envi-
ronmental impact and energy input. During
recent years, all melting furnaces have been
converted to regenerative burner technol-
ogy [3] (install FILTER). As a result, the emis-
sion values are well below the Austrian limit
values, which are among the strictest in the
world. Besides, the cooling water for the
continuous casting process is recirculated to
minimize environmental impact. AMAG is
certified according to ISO 14001.
6) Detailed knowledge of the influence
of the chemical composition on mate-
rial properties
When scrap is processed into alloys, undesir-
ably high amounts of trace elements and al-
loying elements, if any, are bound to be car-
ried into the material. Therefore, it is particu-
larly important to know their impact on the
material properties. Such elements can have
an influence on the mechanical properties,
such as yield point, tensile strength, elonga-
tion, dynamic characteristics, as well as on
the correct heat treatment parameters and
workability at AMAG and at the customer.
The process parameters and properties of the
finished product can only be specifically set if
the chemical composition is fully known.
Illustration 2: fully automated metal analysis
7) Enhancement of recycling expertise
and development of recycling-friendly
materials
Despite considerably larger quantities pro-
cessed at the Ranshofen location, AMAG
is aiming to maintain or, if possible, even
increase the high scrap charge rate. To
achieve this goal, AMAG needs larger quan-
tities of scrap, which is converted to high-
quality cast and rolled products. So, when
expanding its plant, AMAG will also expand
the Recycling Center Ranshofen.
AMAG is focusing on increasing the range
of recyclable input materials, thus enhanc-
ing its recycling expertise step by step. This
means that AMAG also processes scraps
containing large amounts of organic con-
taminants and other nonmetallic impurities
(oxides, dust, etc.), and returns them to the
product cycle.
Recycled aluminium normally contains trace
elements that do not occur in the electrolytic
metal, and may also contain alloying ele-
ments such as iron, copper and zinc that ex-
ceed the tolerance limits of alloy standards.
To be able to use recycling alloys even more
widely in sophisticated aluminium compo-
nents, it is essential to have full knowledge of
the effects of these elements, including their
interactions, to then challenge the necessity
of the close tolerance limits. For example,
a slight increase of the permissible copper
content can lead to a marked increase
of the possible scrap charge, without
having a noticeable impact on
the corrosion properties.
This deliberate exten-
sion of the alloy
tolerance
AluReport 02.2012
Contact for more information:
Dr. Werner Fragner
Phone: +43 7722 801 2835
werner.fragner@amag.at