By Phil Slinger – CAB chief executive
Aluminium has enjoyed an extensive recycling lifespan since its commercialisation in the 1880s with the advent of the Hall–Héroult process.
In fact, 75% of all the aluminium produced since this time is still in active use today. Aluminium has an enviable scrap value and ‘clean’ scrap can cost almost the same as new ‘prime’ aluminium. The industry demand for recycled aluminium is driven by the demand for low-carbon aluminium, as recycling aluminium uses just 5% of the energy needed to produce ‘prime’ aluminium from mined bauxite.
Low-carbon aluminium produced into billet or logs, the raw material used in the extrusion press, can be produced to less than 3.0 tCO2e (tonnes of CO2 equivalent) when 60% to 70% of recycled material is mixed with a low-carbon prime aluminium.
As you would expect, there is a high demand for this billet which comes at a premium. In reality, all new aluminium used globally, across all industries, on average contains by volume one third recycled aluminium.
The difficulty in obtaining scrap is due to the volume of aluminium product – be it in transport or construction – still in active use, due to its extensive life expectancy. Some of the oldest installed aluminium windows, installed at the Bodleian Library in Oxford, are over 80 years old and still going strong.
Today we recycle a higher percentage of our scrap aluminium as extraction rates from old buildings has increased to almost 100%, such is the value of the metal. In fact, many aluminium supply chains now see our cities as ‘urban mines’ for the future extraction and re-use of aluminium used in both construction and transport infrastructure.
What is new today is the ability to recycle aluminium back into its original ‘grades’.
For wrought aluminium used in the architectural aluminium extrusion process, we generally use an alloy grade 6063. The ability to recycle in a single grade is helped by using modern, handheld alloy analysers. These XRF (x-ray fluorescence) analysers perform a quick, non-destructive analysis of scrap so grades can be grouped together for recycling.
Keeping the grades segregated means that the scrap aluminium, both pre-consumer and post-consumer, has a higher value to a re-processor.
The value of the scrap is based on how ‘clean’ it is, that is to say free from thermal breaks, screws, fittings, gaskets, etc. Modern processes can clean any scrap aluminium by removing these unwanted materials.
Whilst pre-consumer scrap can easily be collected and fed back into the aluminium supply chain, post-consumer scrap often lies outside the traditional aluminium fenestration supply chain and is more challenging to ensure it is recycled through the correct channels.
The Council for Aluminium in Building (CAB) has been pioneering a ‘closed-loop’ recycling initiative which encourages its members to recycle through the initiative to ensure that scrap aluminium remains in the UK and remains in the 6063 extrusion grade alloy.
Any member of CAB can join the scheme for free and more information is available on the association website. Whilst the scheme is currently voluntary, in Germany such schemes have become mandatory, such is the importance of forming closed-loop recycling. The Glass and Glazing Federation (GGF) has recently adopted the CAB initiative and is promoting the scheme to its own members.
CAB member, Alutrade, is an advanced scrap re-processor who collects scrap from across the UK from the aluminium fenestration supply chain and from construction refurbishment and deconstruction sites.
Together with CAB, the aim is to track more architectural aluminium scrap back into a single grade alloy.
