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