Known unknowns

Materials World magazine
,
31 Mar 2017

Robert Fell argues against the misconceptions over metal recycling in the UK and explains why stainless steel is leading the charge in the recycling sector.

There are some in the wider metals industry who are absolutely sure of four things – you can’t get clean metal from a scrap yard, recycling scrap metals is down-cycling, electric arc furnances (EAFs) make copper-laden steel and regardless, everything can be reused in some way. The trouble is, none of these statements are really true.

The first two misconceptions exist because metal recyclers are seen as low-tech ‘chop-shops’ simply gathering and processing scrap metal. This preconception is both old-fashioned and far from the truth. At the higher levels of the supply chain, and particularly those which supply the furnaces directly, recyclers have long since embraced high-tech equipment that can process scrap metal to any given specification. The British Metals Recycling Association (BMRA), the Cast Metals Federation and UK Steel have an agreed set of UK specifications for ferrous raw materials. These include Grade 3A, which is fragmentised old light steel arisings free from direct and non-ferrous materials in pieces of no more than 150mm in any direction and 4G, which is baled new production compressed detinned steel sheet no more than 0.25mm thick.  

Metal recyclers are deploying high-powered fragmentisers or shredders combined with downstream separation equipment that use technologies such as eddy currents, air jets and lasers to separate as many fractions as possible from the resulting shredder outputs. With little value in the larger ferrous fraction, recyclers need to collect as much of the more valuable fractions such as copper and aluminium as they can. Plastics, aggregates, glass and textiles are also removed for further processing and recycling.

As a result of more precise technology, the industry can deliver material to steelworks processed to the nth degree as long as the customer is willing to pay for it – although, at the moment, they are not. Recyclers can deliver high-grade, furnace-ready material with few or no impurities. They can deliver materials in the required dimensions that will enable foundries to ensure compact charging of their furnaces, thereby avoiding the risk of air spaces that could be created by using larger pieces of scrap metal. In short, recyclers can provide almost any specification, as long as the economics are there.

Testing and safety standards 

Nowhere is this more apparent than in the stainless steel market. There are specialist recycling companies delivering pre-sorted loads to precise and exacting specifications, often working to three decimal points on elements such as lead and tin. The buyer or mill will normally reserve the right to reject material that fails to conform to the specification and could even apply a reloading charge. Materials that result in a ‘burst cast’ could cost as much as £30,000, so the need for precision is necessary.

Careful sorting begins the moment a delivery arrives at the yard when the load’s specifications are noted using a highly sophisticated computing system. Having been unloaded, each pile is tested using a hand-held device such as an XRF analyser and representative samples are taken. These samples are then cast into homogenous test pieces in the on-site foundry and each sample is analysed further, using an optical emission spectrometer or bench-based acid tests. Using this data, and where required adding the requisite amounts of pure alloys such as nickel, the recyclers can deliver a batch to the exact specifications set out by the individual mill. 

But before products even get to be recycled, there is an ongoing argument that they should be reused. This is absolutely correct but only up to a point. While items such as electrical goods can more easily be checked for safety and potentially sold on with a warranty, other products cannot. 

Girders and plumbing components such as 19mm compression joints present more problems when it comes to safety. 

It is hard to assess what stresses and strains have been placed on girders during their working lives, so it is very unlikely that they could be provided with any warranty. Without proof that they are safe, they certainly would not be reused in construction. Similarly, if the nut of a compression joint has been over-tightened when first used, there is a risk it could fail when it is reused and cause significant damage.

Seeking solutions

The next misconception is that you can only ever down-cycle material. In fact, metal recyclers working in the stainless steel sector are supplying materials to companies who are producing parts for the aerospace sector. Given that the aerospace industry operates within safe-life design parameters, it would not be using parts made from recycled metal if that metal did not meet precise and exacting standards. 

Similarly, there are companies in the automotive sector that have embraced the closed-loop manufacturing process and are now using recycled aluminium in their car bodies. While the aim may be to become self-sufficient in terms of scrap supply, they still have to supplement their infeed. Of all the metals doomed to be labelled by some as down-cycled, it seems to be recycled steel that is held up as the worst offender when it comes to quality, making it fit for little more than rebar in the end. Even if that was completely correct, it could be argued that we will always need rebar. Why would anyone use primary materials to make this when there is scrap metal ready and available?

The belief that, due to tramp materials and in particular copper, that is all recycled iron is fit for is rebar is wrong. Put simply, if you don’t put copper in the furnace, you won’t get it out. While it is undeniable that there may currently be some levels of copper and other tramp materials in some iron feedstock, this is mostly due to a conflux of historic factors, such as a lack of processing capability and a lack of will to spend on fraction separation. Were there an economic incentive to use the same technology used to analyse other materials, the levels of tramp materials would drop. 

Nevertheless, there remains a risk that due to the potential for iron to have been recycled many times we may ultimately see tramp material levels climb to unacceptable amounts. To avoid this, the entire sector needs to begin investigating innovative new ways to strip out the tramp materials. Given the current European-led drive for establishing a truly circular economy, leaving the lack of pull-mechanisms aside, perhaps we should also be looking for governmental support as well.

The environmental benefits alone should drive industry and government to work together to seek solutions to the problems we have when recycling metals, from tramp materials to nitrogen levels. Every tonne of recycled steel saves:

  • 1.5 tonnes of iron ore
  • 0.5 tonnes of coal
  • 70% of energy
  • 40% of water
  • 75% of CO2 emissions 
  • 0.97 tonnes of CO2

However, we exported eight million tonnes of scrap last year to countries including Turkey, Spain, Indonesia and India. The scrap is shipped either in containers or loose loaded in the hold. Some is even sent by road. Not great on an environmental level, but there is currently no demand domestically either because there are few furnaces or because there is still a preference for primary raw materials. 

Yet, by harnessing the knowledge across the whole supply chain, we could reduce our reliance on primary raw materials and ensure that they can then be destined for the production of specific, high-tech products where, due to safety parameters or production techniques, only metal from ore can be used. As possessing technology improves, this list of products should slowly decrease, making us more or less self-reliant but also more protective of the environment. The stainless steel recycling sector has led by example – now we just have to follow.

Robert Fell FIMMM is CEO of the British Metals Recycling Assocation and has worked in the wider metals industry for more than 30 years, having begun his career at Metal Box, UK. He joined the Ardagh Group in 2006 to take on a senior role in R&D. While at Ardagh, he also took on active roles in both the Metals Packaging Manufacturing Association and British Aerosols Manufacturers Association.