GU I D E TO ALUMINIUM
Urban mines – fact or fi ction
Adrian Toon, Council For Aluminium in Building (CAB) board director, discusses CAB's closed
loop recycling initiative, and says we should be looking at our built landscape as an 'urban mine' for
Scrap aluminium has long been
recognised for its ability to be easily
collected and recycled into new
Together with its high scrap value, aluminium
is rarely wasted as it feeds back via wellestablished
recycling processes. The EAA/Delft
study in confi rmed that between % and
8% collection rates at the time were achieved
in the UK’s building demolition. What is less
well known is that if not appropriately separated
and sorted, collected scrap can include a mix of
various aluminium alloy grades.
While this mixed recyclate may be used
for cast aluminium products, for example,
it is usually harder to recycle it into wrought
aluminium alloy grades in a ‘closed loop’. Add to
this, it is known that a lot of our valuable scrap
metals are shipped overseas, thus losing a very
valuable resource from the UK.
With these issues in mind, the Council for
Aluminium in Building (CAB) has set up a closed
loop recycling initiative for the UK, an initiative
to encourage the recycling of aluminium alloys
within the same alloy grades. For the CAB
scheme we require that extrusion grades of
aluminium, namely xxx series alloys for the
architectural aluminium market, are recycled
back into the same 6xxx series alloys.
The same can be said for sheet aluminium
recycling, namely with 1xxx series alloys. It is
important to reiterate that in a ‘closed loop’, an
aluminium alloy can be recycled infi nitely without
loss of its specifi c characteristics.
Pre-consumer scrap can easily be recycled
before it leaves the factory as it is often ‘clean’
and of a known alloy. Post-consumer scrap is
where the challenge really lies. With the many
thousands of tonnes of alloy extrusion and
sheet used in our buildings across the UK, we
should be looking towards the advantages of
deconstruction, separation and recycling, and
the ability to see our built landscape as an ‘urban
mine’ for raw materials.
As already stated, we have recycled aluminium
over many decades, primarily as it has a high
recycle value, but without a ‘closed loop’ we can
‘lose’ the specifi c grades we require to recycle the
aluminium back into the same product type.
If we constrain recycling to specifi c alloy
grades, we can recycle extrusions back into new
extrusions and offer a true circular economy for
our aluminium products in the UK construction
One of the keys to this capability is the advent
of the handheld spectrometer for identifying the
content of an aluminium alloy. Easily portable
and very quick to use, grades can easily be
checked prior to recycling.
This means that the aluminium grades could
easily be checked and identifi ed on a building site
prior to deconstruction.
The quantity available on a given site can also
be relatively easily calculated before removal,
as aluminium extrusions and sheets are usually
uniform in shape and easily measured. Skips
for the scrap, clearly labelled for the identifi ed
grades being removed, can be obtained from
GUIDE TO ALUMINIUM www.ggpmag.com
recyclers to be placed on site for collection of
this valuable post-consumer scrap.
The second challenge is to remove nonaluminium
components from the aluminium
frames of windows and curtain walling, such as
hinges, handles, gaskets, screws and weather
Done manually, this could take some time, and
we must also consider the removal of thermal
breaks made of materials such as polyamide and
polyurethane. Fortunately, the technology has
advanced considerably, and this process can be
What is supplied back to the smelter is
‘chipped’ aluminium, with minimal contaminants
such as paint and thermal breaks which are
mostly removed in the process.
Aluminium scrap in this form can easily
be reintroduced back into the UK aluminium
smelting industry to meet the growing demand
With just % of the energy needed to recycle
aluminium in this way compared to producing
prime aluminium from bauxite, we can make
best use of the embodied energy present in
aluminium that exists in our building stock.
CAB’s closed loop recycling scheme is open to
members as part of their membership package.
While such closed loop recycling of construction
materials is currently voluntary, requirements
could be placed on ‘embodied carbon’
content in the future and main contractors are
increasingly seeking evidence to demonstrate the
sustainability credentials of their supply chain.
Aluminium scrap is an important resource and
we should maximise the quantity and quality of
recovered aluminium scrap in the UK to build the
circular economy of the future.