As a major by-product of our industry, slag has long been sold by steelmakers for use in construction, but its use in agriculture has been less well known. In Ukraine, we have been researching its value to farmers to improve soil properties and crop yield.
One of the main reasons why farmers need fertiliser is to reduce the amount of acidity in the soil.
Read more >
Why this is important for ArcelorMittal
In steelmaking, resource efficiency takes two forms: making the steelmaking process more efficient by re-using its by-products, both solids and waste gases; and utilising more scrap from steel that’s already been used. Both are important factors in making the production that underpins modern living more sustainable.
Making new steel via the blast furnace route means converting iron ore into steel using coking coal and limestone. This results in a number of useful by-products such as slag and oily mill sludge. Finding ways to re-use these by-products is an obvious win-win: if we re-use them within our steelmaking process, we reduce the amount of virgin inputs we need and so cut our raw material costs as well as our environmental impact. And where we sell them for use in other industries, again we create additional value in these ways.
Our blast furnace mills therefore produce far more value than simply steel. They make slag, which can be used as fertilizer by farmers or in cement-making, and greenhouse gases are reduced in both cases. They also provide heating and power for neighbouring communities from their waste gases. And, waste gases can also be used for making chemicals, plastics, fuels and more, and we are currently testing the potential for this. One example is our partnership with LanzaTech.
At the end of its useful life, steel is ideally suited to being recycled, since it doesn’t lose its physical properties in the process, even if alloys are mixed into the scrap. Some scrap is used in the blast furnace process, but scrap is ideally suited to the electric arc furnace route to steelmaking. Here steel can be produced entirely from scrap, without the need for iron ore or coke. Newer steel industries in emerging economies have been built using electrical arc furnaces. Some 30% of the steel we produce globally comes from scrap, and we’re one of the world’s biggest recyclers.
The integration of scrap back into steelmaking supports a circular economy. In fact 87% of the world’s obsolete steel is recycled. But we have to wait for more scrap to become available to meet our needs. At present in Europe, for example, there's only enough scrap to meet half of the region's demand. There’s another resource efficiency challenge in steelmaking: to reduce the off-cuts of steel our customers generate when they manufacture their products – like car doors – from our steel. The potential for our industry to cut carbon emissions by working with our customers to produce less of this ‘pre-consumer scrap’ has been highlighted by Professor Julian Allwood at the University of Cambridge. Just how resources flow from one phase in the steel lifecycle to the next is something we are looking at with a number of leading universities.
This outcome is sponsored at group level by Carl de Mare, vice president of emerging technology development, and he will lead efforts to explore the opportunities to create value from efficient resource use, both within our steelmaking process and in relation to other industries.
Making a tonne of steel from scrap in an electric arc furnace avoids the emission of 1.29 tonnes of CO2, since it removes the use of coke and uses less energy. But availability, quality and price are all issues: scrap is in short supply which puts pressure on the quality and competitiveness of the scrap supply versus iron ore. So at the moment, we need to use scrap where it makes most technical sense – where its impurities from other materials in the recycled scrap are easily accommodated - typically in construction and infrastructure products. In 2015 we used 28.1 million tonnes of scrap, avoiding nearly 37 million tonnes CO2. This represents a slight reduction on previous years, resulting from a drop in our production from electric arc furnaces, which we consider to be caused by the slowdown in the construction industry. Overall, however, some 30% of our crude steel globally is still produced from scrap.
In the longer term, as more steel comes to the end of its useful life and more and more scrap is available, we need to ensure not only that its quality is better, but also that we increase our capacity to recycle scrap in our production processes. We’re working with several customers, industry groups and universities on these issues. For example, we’re helping to create an authoritative source of data on steel stocks, and recovery and recycling rates across the world, and we’re working to improve the quality of the scrap recovered from vehicles by dismantling cars before they are shredded. This work will help us identify where there are obstacles to improving scrap supplies, what these are, and where there is the greatest potential for us to create value.
We re-use the by-products of steel wherever we can in our own processes, and we have a dedicated R&D team that uses a proprietary tool called ROMEO to assess the value of different ways to do this, both in terms of cost savings and environmental impact. Since we launched ROMEO in 2009, it’s been used in about 20 different technical projects, with around $40 million of cost savings. In 2015 it was used at Belval, Luxembourg, to evaluate the re-use of dust and sludges in the electric arc furnace; at Bremen, Germany, for a slag re-use project; and at Fos, France, to consider the value of treating several by-products using rotary hearth furnace technology. There are new projects planned for 2016 at Differdange, Luxembourg, and Dunkerque, France.
If we can’t find a use for them, we sell our by-products to other sectors. Slag has long been used as a component for roadstone, and in the building industry. In agriculture, we know it’s making a significant impact on crop yields and in 2015 we measured this in Ukraine. Although there was a fall in demand for blast-furnace slag from the cement industry in 2015, all in all we ensured nearly 16 million tonnes was re-used and recycled, including 8 million tonnes of it to the cement industry, which avoided 6 million tonnes CO2 alone.
The concept of a circular economy rests on retaining the value of resources in the economy, rather than discarding them. So for us, it’s about finding ways to re-use everything – not just our steel products but also our by-products like waste gases and slag.
During 2015 we set up a working group to look at the circular economy, which will go beyond recycling and re-using by-products to take a wider perspective on the commercial opportunities on offer, and what stakeholders are expecting from us in this area.
We were very pleased to be ranked ninth out of 52 in the league table of companies assessed by the Dutch Association of Investors for Sustainable Development (VBDO) in its 2015 study on the circular economy, Benchmark of Circular Business Practices. They cited our track record on recycling, as well as our investment in lifecycle analysis and our dedicated R&D team working on the re-use of residues from the steelmaking process.
Our partner in the project to convert waste gas into fuels, LanzaTech, won the Circular Economy Entrepreneur award at The Circulars, the world’s leading circular economy awards programme.