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COMMENT
COMMENT How green is your aluminium?
Phil Slinger from the Council for Aluminium in Building provides expert insights on the current green credentials provided by aluminium production, and how EPDs and collaboration are supporting its specification
A
luminium has enjoyed an extensive recycling lifespan since its commercialisation in the 1880s with the advent of the Hall–Héroult process for the economic production of
aluminium, in fact, 75% of all the aluminium produced since that 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 today is driven by the demand for ‘low-carbon’ aluminium, as recycling aluminium uses just 5% of the energy needed to produce ‘prime’ aluminium from surface mined bauxite. Today ‘low-carbon’ aluminium can be produced at less than 3.0 equivalent per production tonne) when prime
tCO2e (tonnes of CO2
is mixed with 60% to 70% of recycled aluminium. The process of reducing carbon in production is ongoing with some producers now gearing up to produce aluminium using hydrogen energy. No more than a couple of decades ago we were specifying the use of ‘prime’ aluminium for projects at 20.0 tCO2
e carbon content.
As you would expect, there is a high demand for this ‘low- carbon’ 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 dilemma we face, is the difficulty in obtaining scrap, which is due to the aluminium product still being in active use which is down to aluminium’s in use 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 deconstruction of our structures 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 easily recycle aluminium back into their original ‘grades’. Pure aluminium is relatively soft and rarely used in production, it is normally formed into an aluminium alloy which contains other materials that give the alloy special characteristics. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are
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many globally recognised grades of aluminium alloy which are placed into a long list or ‘series’ of different characteristics which are used in various applications. 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
ADF OCTOBER 2023
Selfridges, Birmingham, designed by Future Systems Photo by Simone Hutsch on Unsplash
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