‘Urban mined’ aluminium refers to reusing existing aluminium sourced from dismantled buildings and other urban waste streams for windows, doors, and facades in cities. This approach supports a circular economy, reduces the need for prime aluminium (which has a high carbon footprint due to bauxite mining and refining), and contributes to sustainable urban development.
The benefits of recognising urban mining for aluminium are manyfold and include: lowering the carbon footprint of aluminium, reprocessing waste aluminium using 95% less energy than using prime aluminium. Waste reduction diverts valuable materials from landfills. Resource security reduces reliance on imported raw materials. Promoting sustainable cities supports green building certifications like LEED and BREEAM.
Many cities are embracing urban mining as part of their green building initiatives, integrating reclaimed materials into new construction and retrofit projects. This reduces embodied carbon, supports local material loops, and aligns with net-zero building
How Urban Mining Works:
1. Material Collection. Taken from demolished buildings or refurbished projects, vehicles, electronic waste, and industrial leftovers are identified as sources of valuable materials like aluminium, steel, copper, and rare earth metals.
2. Dismantling & Sorting. Materials are carefully extracted, sorted, and processed to maximise recovery and minimise contamination.
3. Recycling & Processing. Advanced technologies refine and repurpose these materials into high-quality raw inputs for new products.
4. Reintegration into Manufacturing. Recovered materials are then used in construction, electronics, and manufacturing industries, replacing virgin materials.
So why Aluminium? Aluminium can be highly recyclable without losing its properties. Urban mining helps recover aluminium from old windows, doors, and facades, reducing the need for energy-intensive primary aluminium production, however, it is crucial to recycle within the many grades of aluminium alloy, creating a ‘closed loop’. This increases the scrap value and allows windows to be recycled back into windows in a short, local, closed loop cycle.
CAB have been running a scheme such as this for several years which is now gaining traction with several UK main building contractors.
The CAB’s closed loop recycling recycles scrap within recognised aluminium grades. By using an XRF analyser (X-ray fluorescence) which is a powerful, nondestructive technique for measuring elemental composition from magnesium (Mg) to uranium (U), these handheld XRF analysers are portable devices that offer immediate composition of an alloy revealing its grade. Incorporating modern techniques that remove unwanted items such as screws and thermal breaks, the resultant, chipped aluminium is ready to be remelted for new product whilst maintaining its original grade.
The aim of the initiative is to encourage the recycling of aluminium alloys within the same alloy grades. For the CAB scheme, we require that extrusion grades of aluminium, namely 6000 series alloys for the architectural aluminium market, are recycled back into the same 6000 series alloys. The same can be said for sheet aluminium recycling, namely with 1000 series alloys. It is important to reiterate that in a ‘closed loop’, an aluminium alloy can be recycled infinitely without loss of its specific 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 specific grades we require to recycle the aluminium back into the same product type, introducing other grades reduces its resale value. If we constrain recycling to specific alloy grades, we can recycle extrusions back into new extrusions and offer a true circular economy for our aluminium products in the UK Construction Industry whilst maintaining value.
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 identified 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 identified grades being removed can be obtained from recyclers to be placed on site for collection of this post-consumer scrap.
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.
More information about CAB’s Closed Loop Recycling Scheme and events is available through the CAB website. Should you wish to learn more about the use of Aluminium used in Construction, please contact CAB, join the Association and be recognised as being involved in supporting your Industry and helping to shape its future.