Scrap: Our Greatest Resource?
Scrap: Our Greatest Resource?
Steel is one of the world’s most recycled materials, with nearly 40% of steel products on the market containing recycled material and 75% of steel products ever made still in use today.
Although producing one tonne of steel today requires just 40% of the energy it did in 1960, the industry must adapt and look at alternative ways to reduce its energy consumption and carbon emissions. To implement greener solutions, and further our thinking towards the circular economy, it is essential every aspect of the supply chain is regarded with equal value. Metal recycling can help lower production costs and CO2 emissions; it can also be recycled again at end of life, meaning steel is the perfect candidate for integration into a circular business model.
In terms of availability in the UK, there is an abundance of potential to better utilise existing resources. There are over 1500 scrap yards in the UK, recycling products at end of life from cars to household goods. In 2018 the UK exported over 8.7 million tonnes of scrap metal for processing in other countries, of which around 7 million tonnes is believed to have been steel. In 2019, the UK produced just over 7.2 million tonnes of steel, showing demand in the UK could potentially be met through better resource management, and lead to a reduction in the need to process virgin iron ore. On average, recycling one tonne of steel saves 1,400 kg of iron ore, 740 kg of coal and 120 kg of limestone, as well as the associated emissions from mining, transporting and refining these raw materials. In terms of associated processing energy, recycling a single steel can save the equivalent amount consumed by running 1 load of laundry, watching TV for 1 hour or running at 10 watt LED bulb for 24 hours.
Information source: https://circulareconomy.worldsteel.org/
One of the main issues currently surrounding the use of scrap is the high level of impurities present from alloying, plating and joining to other materials, which may not be easily separated for recycling. When manufacturing steel for specific applications, the presence of “tramp” elements such as copper and tin can adversely impact the mechanical and corrosion properties of the new product, so it is essential any scrap charged into the melt has the highest Fe content possible, reducing the potential for undesirable elements to be incorporated. Often a melt containing impurities will be diluted with a source of reduced iron, to lessen the potential for any detrimental effects.
There are also issues surrounding the variable price and quality of scrap metal. Scrap is normally bought and sold by weight, where cheaper loads are lower density, tend to contain more non-metal and undesirable elements, meaning it requires further processing before entering the plant. More expensive loads will generally be higher density, contain more iron and less non-ferrous materials, having undergone more rigorous sorting processes. Despite the additional expense, this scrap can provide better value for money as less time and effort is required to prepare the material for use and less waste material is produced through the steelmaking process; waste that will ultimately become an additional landfill cost. Marketing scrap on a Fe unit scale, rather than per tonne may encourage better sorting of recycled materials and lower level of containments.
It is clear there are opportunities to make better use of the scrap steel available in the UK. The basic oxygen process (BOP) can utilise up to around 30% scrap (but averages half that), whilst electric arc furnaces (EAF) can run on up to 100% scrap material. Integrated plants produce a number of high-value steel products, including components for the packaging, automotive and construction industries. Properties such as high ductility and deformability are key to the value of these products which are grossly affected by even a small level of contamination by elements other than iron. Currently, many of these cannot be produced to the required quality using EAF due to high levels of nitrogen in the melt and the potential for unwanted impurities from the scrap steel. Similarly, high value steels produced through the EAF routes, which are typically highly alloyed and can tolerate low to moderate levels of contamination, need tight control of other elements such as copper and tin to ensure high production yield and suitable product performance. Investigations into these issues is essential if the UK is to continue to be self sufficient in steel production and lower emissions from its production.
Information source: https://www.recyclemetals.org/about-metal-recycling/cool-facts.html
Last month, we were delighted to host experts from the scrap industry to facilitate initial internal discussions around the state of scrap in the UK, and how we can make the most from this important resource. We hope to be able to run further workshops in the future to highlight the importance of this resource for the future of the UK steel industry.
If you’d like to read more about the different processes used to manufacture steel and how scrap can play a significant role in the future of the UK steel industry check out the essay “A steely solution?” by SUSTAIN Programme Manager Dr Richard Curry and TWI’s Gareth Fletcher.
