Steel, the recycling world champion.
Steel is one of the most recycled materials in the world. More than half of it is used again and again, more than plastic, glass or copper. Every day, hundreds of thousands of tonnes of scrap are melted down, from cars, fridges, washing machines, demolished buildings and even old mattress springs.
Sustainability and efficiency: the benefits of recycling steel
Recycled steel is cleaner than new steel, because no new iron has to be mined for it. And special furnaces use considerably less energy than the furnaces in which new steel is made.
The balance between scrap and iron ore
About a third of the steel produced worldwide each year comes from scrap. Almost all of the rest is new steel made from iron ore. Recycling is better for the planet and usually cheaper too, so why do we still produce so much new steel? Because the world needs more steel than scrap can supply. The enormous demand for steel shows that we will have to keep mining iron ore.
Long service life and rising demand
The industry produces almost 2 billion tonnes of steel worldwide every year, about half of which goes into buildings and bridges that will not be scrapped for a very long time. With demand for steel rising, it is estimated that at least half of it will still have to be made from iron ore in the coming decades.
Pioneering solutions for climate-neutral steel production
At the moment, making new steel from iron uses roughly 20 times more coke than recycled steel. With the help of renewable energy, the next step towards climate-neutral steel production is now being taken. As the blast furnace route is phased out because of its high CO₂ emissions, steel is to be produced mainly in electric arc furnaces powered by electricity from renewable sources.
More scrap: strategies for a sustainable future
To make climate-neutral steel production possible, the amount of scrap used in Austria has to double to two million tonnes within the next five to seven years. By 2030, the share of scrap in Europe is to rise to over 60 percent, and by 2050 to as much as 75 percent, to enable a climate-neutral steel industry.
The challenge of tramp elements
Tramp elements in scrap, such as copper, molybdenum, chromium, tin, nickel or arsenic, can cause quality problems because they can harden steel and make it brittle. When electric cars are recycled in particular, more copper wiring from the drive units can end up in steel scrap, which can lead to cracks during rolling. The challenge: copper and other elements are difficult or impossible to remove from steel in the melting process. But a great deal of effort is going into improving quality.
Research for future solutions
The new Christian Doppler Laboratory for “Knowledge-based Design of Advanced Steels” at Montanuniversität Leoben studies how accompanying elements in scrap affect the properties of steel. AI-assisted simulations and micromechanical tests are to set limits for unwanted impurities in order to improve the quality of recycled steel. On this basis, new steel grades have been developed in recent decades that offer greater crash safety and guaranteed quality standards in lightweight construction despite their scrap content.
Our conclusion: using scrap in steel production is becoming ever more important. Optimising recycling processes is a decisive step towards climate-neutral steel production. However, it raises technical challenges that have to be overcome through continuous research and innovation.