Metal manipulation

Written by: Justin Cunningham | Published:

As aluminium becomes the lightweight material of choice for many, we look at one project that aims to secure supply, reduce production emissions and keep value in scrap. Justin Cunningham finds out more about the REALCAR project.

Cars, aircraft and trains are increasingly demanding high quality aluminium to bring down in-use emissions. However, with China being the world’s biggest primary aluminium producer, coal-fired power plants have increasingly been used to provide the intensive energy required for smelting. It means aluminium’s green credentials in the West come with a dirty Eastern twist, which is taking a larger slice of the lifecycle emissions pie chart.

Consumption of aluminium has spiked since the millennium from just under 40 million tonnes a year, to an expected 100 million tonnes or more annually by 2020.

While talk at a Jaguar Land Rover REALCAR event held last month was almost exclusively about the circular economy (i.e. one that produces less waste by design), it was really about making cleaner aluminium, and securing supply for the future. The project demonstrates how to turn high quality aluminium scrap back into high quality consolidated aluminium sheets. While it sounds simple enough, it hasn’t been as straightforward as introducing separate bins and telling staff to be extra vigilant when sorting scrap.

Cross contamination

The problem is that aluminium is extremely sensitive to cross contamination, meaning that when you mix different alloys, you end up with a metallic jambalaya, something in-between the lowest quality and highest quality material. And then there is steel and other metals, which change the material’s composition considerably and makes end properties difficult to control. Once impurities get into the mix, some are very difficult to get out. It all devalues the waste stream and makes it hard to use recycled aluminium for high quality transport projects.

Control has been needed to turn high quality scrap back into predictable, homogeneous and again high quality aluminium ingots. JLR has done this by introducing a closed loop production system at its three press shops and eight partner shops. From here scrap is collected and re-melted into high quality aluminium ingots, but to do this, metallurgists had to develop an entirely new alloy that’s less sensitive to recycled contaminants.

“We’ve optimised an aluminium sheet to make it more tolerant to recycling,” said Adrian Tautscher, head of JLR's sustainable aluminium strategies team. “The grade of alloy we have developed is RC5754, and it is a mix of processed scrap, prime metal and third party scrap that our partners source. It gives us the same performance as an alloy that relies on much higher prime content.

“It means we don’t have to make a distinction about putting virgin or recycled materials in crash structures or other areas. It is about qualifying the material based on what it will be used for.”

Bringing people together

In collaboration with aluminium recycler Novelis and Innovate UK, the project brought together metallurgists, recyclers, rolling mills, and other key stake holders.

More than £7million has been invested across Jaguar Land Rover’s Halewood, Castle Bromwich and Solihull press shops to install the intricate segregation systems needed to capture the aluminium scrap. The press shops process thousands of tonnes of material, employ hundreds of staff and create mountains of scrap – it’s the scale that’s been the real technical issue.

“The target for cross contamination is zero but these are real processes and mixed metal lines so you will get some crossover,” said Andy Doran, Novelis Europe sustainability and recycling development manager. “We are talking tiny proportions. That is part of the chemistry refinement we have done on the metallurgy side, to allow for any residual crossover – but it is all about minimising it.”

To date around 50,000 tonnes of RC5754 has come back into vehicles which is designed to contain up to 75% of recycled content, material already introduced to Jaguar’s XE and XF lines.

Design light

Like all automotive firms, weight has become the enemy. This is particularly the case for JLR, whose heavier luxury cars struggle more than most to reduce tailpipe emissions. Its move to aluminium has been industry leading, with Ford closely eyeing progress. The amount of CO2 equivalent generated from a JLR vehicle is dramatically lower than a decade ago, but Tautscher told the audience that, “as we lightweight more intensely, the materials production phase has grown from 20% to 27%.”

Lifecycle analysis (LCA) points to a dramatic CO2 reduction as more secondary aluminium is used – the recycled material requires just 5% of the energy needed to smelt primary material. But, it also benefits JLR in other ways.

“This is being used for strategic engineering purposes,” added Tautscher. “This is not just an LCA or CSR activity.”

There are very real concerns across the industry about security of supply. JLR is the UK’s largest automotive manufacturer and produces in excess of 500,000 vehicles a year. As volumes continue to rise and new models are introduced, forming a business strategy with aluminium at its heart must address these concerns, and to a large degree this is what the REALCAR project is about.

Rocketing demand coming from the building and construction sectors – particularly in Asia – as well as booming global demand for efficient transport means aluminium is the lightweight material of choice for many as it occupies the Goldilocks territory between steels’ ease of manufacture and carbon fibre’s lighter weight.

Conservative estimates predict that much of the global demand for aluminium is going to be met by primary sources. The worry, however, is that supply is going to come under increasing pressure and the markets renowned price volatility – already considered a headache by purchasing managers – will only get worse.

End of life?

Despite the accolades from industry supporters, from a commentator's point of view you might have expected more. Taking clean scrap, melting it down, and reforming it to be used again as principally the same material, should surely be something the company, and industry, is doing anyway. The question on everyone’s lips was, ‘what about end of life vehicles?’ Surely, this is where the loop needs to be closed if we are really to achieve a circular economy?

“It was challenging enough to do what we did,” explained Tautscher. “The even bigger challenge now is to look at [end of life] and longer term - that is where we want to get to. That’s the only way we are going to achieve higher recycling rates, by looking at these post-consumer sources.”

For many though this is going to require a fundamental shift by the global aluminium industry. Instead of the thousands of different compositions that are currently available, a more limited selection of alloys is surely advantageous to avoid troublesome impurities seeping in, and devaluing the recycled materials.

REALCAR does set a promising foundation, however, and there are more projects to build upon this work with end of life remaining the ultimate destination. For now, though, REALCAR is less of a breakthrough, and more of a milestone. ‘Real develop’ remains some way off.

Fact file: The problem with aluminium

Global recovery of the material is estimated to be 90%, only exceeded by glass at 94%. It’s claimed three quarters of the aluminium ever produced is still in productive use. As long as the material is kept clean and segregated, it is in theory infinitely recyclable. The key thing is eliminating contaminants at source, so they don’t reduce the recycled materials’ quality and make it unusable for industries that require a high level of material quality. While poorer recycled materials can be diluted with more prime material to improve and hone properties, it defeats the point of trying to move away from prime material in the first place. And, for some contaminants like zinc, once they are in to a batch of aluminium, they are almost impossible to remove.

- Justin Cunningham is the technical editor at Eureka (www.eurekamagazine.co.uk) and editor of Engineering Materials (www.materialsforengineering.co.uk)


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