A green circular economy requires sustainable energy and material flows and decarbonized industrial processes. This is the only way to achieve the goals of the Paris Climate Agreement to reduce greenhouse gas emissions. In the STARS project - solar thermal applications for secondary raw materials from steel production - the four project partners are researching sustainable solutions for future viable energy storage materials. The aim is to use steel mill slag as a secondary raw material for ceramic components and energy carrier material in concentrated solar thermal technology (CST). CST attempts to use mirrors and special substrates to ensure an improved solar-to-heat ratio of solar energy. In addition to energy efficiency, product-related features such as components with consistent quality and a long service life, recyclable components and high-temperature materials are particularly relevant.

Expertise in LCA of slag recycling

This is where the STARS project comes in. The project partners process the steel mill slag into particles for thermal energy storage, ceramic coatings and other components for solar thermal processes. thyssenkrupp MillServices & Systems GmbH prepares the steel mill slag for the corresponding applications. The German Aerospace Center (DLR) and LWK-PlasmaCeramic GmbH process these into innovative products by means of granulation, dripping and sintering or plasma coating. The German Aerospace Center (DLR) evaluates the technical properties of the products, while Fraunhofer UMSICHT assesses the new manufacturing processes and components in their early development stage from an ecological perspective. The existing experience in the evaluation of slag recycling concepts is incorporated here.