Decarbonizing steel: The new direct reduction plant from thyssenkrupp Steel

How does a direct reduction plant work?

The blast furnaces needed to melt iron have long been a symbol of the steel industry. Traditionally, iron ore is melted in them using coke and hot air. However, this process emits a lot of CO₂ due to the use of coal. The direct reduction plant being built in Duisburg-Walsum heralds a new, greener age of steel production with the use of hydrogen. This is because the new process can save up to 3.5 million tons of CO₂ in the future. But how exactly does it work?

The DR plant is supplied with iron ore in the form of iron ore pellets or lump ore, which is first stored temporarily. The iron ore is then transported to the 40-meter-high DR tower. The reformer is located next to the tower. This is where the necessary reduction gas is produced – a mixture of hydrogen, natural gas and recycled process gases. The reduction gas is fed into the gas flow of the DR tower to extract oxygen from the iron ore. This process is much less sustainable in conventional blast furnaces, where coke is burned to produce carbon monoxide. The carbon monoxide then extracts the oxygen from the iron and helps to liquefy it. In contrast, hydrogen is used in the DR tower to extract the oxygen. This produces iron. However, very high temperatures must also be reached in the DR tower. Between 700 and 900 degrees are required to extract solid sponge iron from the iron oxide. This also produces gases. To make production more sustainable, these gases are fed back into the gas cycle. This way, the recycled process gas is returned to the reformer and can be reused together with hydrogen and natural gas.

The product is solid sponge iron, also known as direct reduced iron (DRI). The sponge iron can then be transported to the smelters – electrically operated furnaces that liquefy it. A continuous melting process takes place there – in future with electricity from renewable energies. This also saves CO₂. As with conventional iron processing, there are separate tapping holes for pig iron and slag tapping after melting. The liquid slag is transported to slag granulation. Slag granulate is required and reused in the cement industry, for example. The pig iron, on the other hand, is poured into torpedo ladles and transported on to the steelworks. The innovative concept of the DR plant thus fits into the existing steel production process and enables high-quality yet more sustainable steel production.

Teamwork for a more sustainable industry

Nevertheless, such a transformation is not possible overnight: coordinating the construction of plants and buildings and planning the supply of energy and materials requires experts from a wide range of fields. For example, thyssenkrupp Steel Europe not only has teams from the fields of metallurgy and mechanical engineering working together, but also from the fields of chemistry, process engineering and electrical engineering. As the DR plant is the first of its size to be operated with hydrogen, a great deal of expertise is required. And precision and teamwork are particularly important in order to integrate the new plant seamlessly into steel production.

Hydrogen as the key to climate neutrality

thyssenkrupp Steel's future DR plant is one of the world's largest industrial decarbonization projects. We are thus driving forward the green transformation of an entire industry. In the future, the plant will be operated with green hydrogen. In other words, hydrogen that is produced using wind and solar power. And a DR plant needs a lot of hydrogen: up to 143,000 tons per year. The Rhine-Ruhr site is ideal for this. It is located along the German hydrogen core network. This means that green hydrogen can be supplied by pipeline – and steel can be produced more sustainably. As a result, around 5% of emissions in the Ruhr region are saved in hydrogen operation. thyssenkrupp Steel is therefore not only the largest German hydrogen consumer, but also an important part of the hydrogen economy and, not least, decarbonization. In the long term, we are also aiming to decarbonize the downstream process of crude steel production. A more sustainable industry for the future – that is what drives us.