Fuel for the circular economy – Versatile slag

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Fuel for the circular economy

Fuel for the circular economy

Value depends on one’s perspective. Where others merely see waste to be disposed of, thyssenkrupp MillServices & Systems sees a resource-saving construction material. Or an effective fertilizer. Or a primary material for steel production. The material in question here is slag, which arises as a by-product in the desulfurization of pig iron – and which in processed form creates the basis for a functioning circular economy. 

The most ambitious targets are often expressed not in extremely high numbers, but in extremely low ones. In certain spheres – notably industry, advertising, science, and research – high importance is accorded in particular to the value 0. Zero sugar (and full flavor), zero emissions (and full performance), zero waste (and full utilization). The latter plays a major role at thyssenkrupp MillServices & Systems. Up to now, much of the slag generated in the desulfurization of pig iron has ended up in landfills – where it takes up space urgently needed for the disposal of nonreusable materials.

Alliance of science, research, and industry

This is set to change, thanks to a joint research project of thyssenkrupp MillServices & Systems, two Fraunhofer institutes, the Weihenstephan-Triesdorf University of Applied Sciences, and further participants from industry. The project is driven by the understanding that resources can be spared and, at the same time, CO2e emissions reduced through the reutilization of materials – in this case, slag, which in the past has been greatly undervalued. And, as already mentioned, zero plays an important role here. 

We follow a zero-waste approach. Our goal is the comprehensive reutilization of the slag produced in the desulfurization of pig iron.

Dr. Michael Dohlen
Head of Research & Development at thyssenkrupp MillServices & Systems

As a result, large volumes of slag waste stand to be eliminated annually in Germany and, at the same time, the amount of ore needed for iron smelting in the blast furnace reduced (less ore mined and less CO2 emitted!). No natural resources will have to be mined to manufacture cement, and it will be possible to produce fertilizers from the slag. The key to all of this is electrodynamic fragmentation. By means of technology from the Fraunhofer Institute for Building Physics (IBP) in which the material is subjected to electrical discharges, valuable components can be extracted from the slag. Foremost among these is iron, which can then be put to use in steel production. Others include calcium- and silicium-containing minerals that are used in the cement industry, and sulfur, a sought-after agricultural fertilizer. 

Slag waste as a raw material for industry

Fuel for the circular economy

Through treating and utilizing the slag, natural resources like limestone and sand are spared – and CO2e emissions in the industrial sectors reduced. The research project is providing important impulses for a comprehensive circular economy by bringing together major stakeholders. Michael Dohlen continues: “The true strength of our project is that the processes are illustrated through the different partners – from the generation of the slag, to its treatment, to its use. That makes new collaborations possible between various industries and gives impetus for a functioning circular economy.”

Information on the project and the role of thyssenkrupp Materials Services  

The joint project – “Reduced process emissions in steel and cement production – treatment and use of hot metal desulfurization slag (RESycling)” – is running over a period of four years. It receives support from Germany’s Federal Ministry of Education and Research through the funding measure “Prevention of climate-relevant process emissions in industry (KlimPro-Industrie).” thyssenkrupp MillServices & Systems is a leading provider of systematic industrial services and the largest slag processor in Germany. As a thyssenkrupp Materials Services company, it is contributing to our sustainability goals with the research project.