Recovery of critical raw materials and CO2 binding
Steelmaking slags, paricularly those from the BOF process, serve as collectors for various metals and other elements from pig iron. Among these are critical raw materials (CRMs) such vanadium and phosphorus, making slags a viable secondary resource. Ensuring a stable supply of these materials is crucial for the EU’s industrial development. In addition, recent studies have highlighted the significant CO2-binding capacity of ground steelmaking slags through carbonate precipitation. The EFRE/JTF-funded project GeoCRM aims at the holistic utilization of steelmaking slags, focusing on the recovery of CRMs and the slags CO2 sequestration potential.
Through detailed geometallurgical characterization, slags are analysed for their mineralogical, chemical, and – most importantly – textural properties. These analyses enable targeted downstream processing via mineral processing and extractive metallurgy. Key parameters such as particle size distribution and elemental deportment are quantified using automated mineralogy tools like μXRF and EDX-SEM platforms (e.g., QEMSCAN and MLA). These datasets inform the development of optimized treatment processes, including comminution, separation, and metallurgical recovery.
The overarching goal is to utilize the entire slag matrix – recovering Fe-oxides, CRMs, and finely ground Ca-silicates – within a zero-waste framework. Even the fine residues are targeted for use as secondary raw materials in CO2 sequestration, potentially replacing olivine-rich ultramafic rocks.
GeoCRM has a duration of three years and is being carried out under the leadership of the VDEh Operations Research Institute by the FEhS Institute for Building Materials Research, the Advanced Mineral Processing Technologies Teaching and Research Unit at RWTH Aachen University, Co-reactive, and tkMSS – thyssenkrupp MillServices & Systems.
