ReMin - Collaborative research project: SlagCEM - High-quality cements and pig iron from steelmaking slags

The aim of the project is to research a process for recovering secondary metals and cements from so-called LD slags. The application of this process and the utilization of the resulting secondary raw materials in the steel and cement industries should lead to significant savings in primary raw materials and a reduction in greenhouse gas emissions. LD slags are generated as by-products during steel production. Due to the nature of the process, they contain up to 30 wt.% iron oxide and are used as lump slag in road construction, earthworks and hydraulic engineering, among other applications. A problem is the lack of spatial stability with high proportions of free CaO, which restricts the use of LD slags to a few areas of application. In the SlagCEM project, the targeted reducing post-treatment of molten LD slag is being investigated and a process for its complete utilization in the form of pig iron and high-quality cement clinker is being researched. Investigations are carried out on the optimal adjustment of the composition of the melt with regard to the utilization properties and the technical/economic feasibility. The experimental investigations range from laboratory scale to test campaigns in small-scale electric arc furnaces. On this basis, tests are carried out on a large-scale technical level. The hydration properties of the post-treated LD slag are fundamentally investigated and furthermore tested with standardized methods for various potential applications as a cement clinker substitute. The planning of large-scale implementation at the steel mill site is a core objective of the project. To achieve this goal, material, technical and logistical issues must be answered and solved. The environmental impact of this recycling option for LD slags must be investigated in detail and evaluated by drawing up a life cycle assessment.