Felipe Maciel
Manager, Environment and Climate Change
18 November 2024
Steel scrap is a vital part of the whole steel industry and its importance in reducing CO2 emissions, conserving resources, and driving the economics of the industry is only growing, but the difficulties in each of the stages of scrap processing pose challenges to steelmakers.
The pressure on the industry to meet these challenges will only increase as governments around the world strive to meet their countries’ net-zero commitments and introduce stricter recycling regulations.
As our #steelFacts publication details, steel is one of the most widely used materials in the world, found in everything from buildings and bridges to cars and household appliances.
But what happens when steel products reach the end of their life cycle in all these applications? Actually, it’s not the end. Indeed, for steel there is no end, as steel is 100% and infinitely recyclable without any loss of quality. The steel in end-of-life products can be melted down to be reused in the production of new steel.
This involves several stages:
A significant amount of scrap currently used in steelmaking processes is acquired before it reaches the marketplace. Known as prompt scrap, these are residuals of large-scale industrial manufacturing processes — leftovers from the production of household appliances, automobiles, and electronics, among others. The concentrated volume generated in one location with low levels of contamination by other materials makes this type of scrap more valuable and widely used to its full extent.
End-of-life (or obsolete) scrap, however, is what we as consumers most likely think of when we think of steel scrap. This is from home goods and other products that have fulfilled their use purposes and have found their way to a recycling collection point. This category also includes collecting scrap from sources not often thought of, such as dismantled ships and obsolete industrial installations. Due to the sheer variety of sources and potential contaminants, there are significant challenges to collecting and transporting end-of-life scrap to steel facilities in an environmental and safe manner.
Scrap needs to be sorted and separated based on type and quality. As steel is made from a mix of various alloys and materials, such as carbon, chromium, manganese, nickel, and others, you need to match the steel grade you want to produce with scrap that matches its properties. It is not only the number of alloys that complicate the process, but the quantities of each of the alloys in the scrap. Different carbon content levels in steel can very significantly affect that hardness, strength, or weldability of the final product, so this needs to be taken into consideration.
There is of course also the problem of many totally unwanted elements in the scrap mix, many of which, like copper, are extremely difficult to separate from the iron in the steel. The methods used for sorting scrap can vary widely, from using magnets to separate the scrap from non-ferrous metals, to using a variety of specially developed high-precision sorting equipment, sometimes developed and patented by a recycling company or steel companies themselves. The initial costs and maintenance requirements of such equipment can be quite considerable, and companies are always looking for opportunities to improve their efficiency.
There are also costs and risks associated with the storage and destination of the unwanted elements that need to be managed safely and in an environmentally appropriate way.
Once sorted, large scrap metal pieces are fed into industrial shredders, which break them into smaller pieces. This makes the material easier to transport and process.
The shredded scrap steel is then placed into furnaces and melted down at temperatures that can exceed 1,600°C (2,900°F), turning the steel into molten metal. The molten steel is refined by the addition of fluxes such as lime to remove any lingering impurities.
The refined steel is then poured into moulds, cooled, and rolled into new steel products, such as sheets, bars, or beams, ready to be used as they are or to be further processed into other products.
Although basic oxygen furnaces (BOFs) can also be loaded with up to around 30% scrap, scrap is most commonly melted down in electric arc furnaces (EAFs), which can be loaded with 100% scrap.
CO2 emissions
As our Sustainability Indicators show, the average CO2 emissions from producing steel via the EAF route are significantly lower than the more established blast furnace route. The energy required is also much lower.
worldsteel estimates that around 650 Mt of end-of-life scrap is generated per year, which avoids the emissions of approximately 975 Mt of CO2 annually and significantly reduces the use, and associated emissions of producing, other natural resources such as iron ore, coal and limestone.
This often leads people to ask why the entire steel industry cannot operate in this way. At the moment there is simply not enough scrap to meet the demand for steel. As the average life of steel products ranges from a few weeks for steel packaging to up to 100 years for buildings and infrastructure, we estimate that the average lifespan of a steel product is 40 years, which means that there is a significant delay between the production of steel and its scrap being available for recycling.
There are also challenges in producing certain types of steel grades via the scrap route, although significant progress has been made in this field in recent years.
We estimate that the amount of scrap available for recycling will increase to around 900Mt by 2050, driven mainly by the steel used in the rapid industrialisation of China in the first decade of the 21st century becoming available. However, with steel demand currently at 1.75 billion tonnes, even 900 Mt is nowhere near sufficient.
worldsteel member workshop
This in-person event, which was to be held in January 2025, is cancelled. The Environmental Committee will work on a new proposed format to address the topic.
Should you have any comments/suggestions, please contact us at environment@worldsteel.org.
