Project Details
Projekt
Engineering Ta-rich mineral phases based on WEEE recycling slags through fluxes modification, controlled cooling and segregation
Applicant
Professor Dr.-Ing. Bernd Friedrich
Subject Area
Metallurgical, Thermal and Thermomechanical Treatment of Materials
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 470553874
The 1st FP shows that Ta segregation in magnetic mineral phases was low. On the contrary, evidence pointed towards Ta segregation into perovskite-based minerals, Ca-Al-silicates, and Tantalite. For this reason, it was decided that in the 2nd FP the production of EnAM for the selective enrichment of Ta should not be pursued through its integration into inverse spinel phases (Magnetite), but rather through enhanced integration into silica-rich or Ca/Mg-rich phases (Perovskite). Therefore, strategic use of fluxes (CaO, MgO, TiO2) will be sought to improve the selective Ta enrichment as well as the tasks of mineral liberation and 3D characterization. Controlled cooling strategies will be taken further to determine the point at which a 100% crystalline mineral matrix and large, idiomorphic grains will be formed. We will also continue to play with the test's atmospheric conditions to promote Ta's selective precipitation. Magnetic phases will also be an important point of these phases, not for the immobilization of Ta but for the simple mechanical extraction of iron (Fe3O4) from the slag as a potential by-product of the EnAMs produced. The main project objective is: "Understanding formation mechanisms and controlling the crystal growth of artificially formed Ta-rich phases as a tool for selective separation from WEEE scraps". Formation of EnAM with incorporated Ta in the targeted phases allows the upgrading in concentration and, consequently, their respective extraction by mechanical separation and conventional hydrometallurgical processing. This aim is to be achieved through the following specific targets: -Synthesis of geochemically formed low-pressure magnetic phases for the direct valorization of iron; -Synthesis of iron-free mineral phases highly enriched with Ta for an accurate pre-mechanical liberation step; -Determining the required process window, such as oxygen partial pressure, temperature, cooling conditions, and additives; -Influencing phase distribution coefficients and crystal sizes, and if necessary; autogenous decomposition to enable mechanical separation; -Developing accurate thermodynamic models describing the mobility of target metals.
DFG Programme
Priority Programmes
