SPP 2315:  Engineered Artificial Minerals (EnAM) – a geo-metallurgical tool to recycle critical elements from waste streams

• Subject Area: Thermal Engineering/Process Engineering ; Materials Science and Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441888760

Nowadays, recycling technology is at the crossroads. In developed countries, recycling technologies have been implemented to recover those elements and materials, which represent the main mass of waste and have a business model. However, we are lacking technologies to address the essential and often rare elements of a modern society, which still become dissipated in the waste streams. Such rare elements typically provide a special functionality to a product; they are contained in batteries, capacitors, magnets, electronic circuits, sensors and functional composite structures in general. Pyrometallurgical processes for the recovery of metals are a significant sink for a large number of these elements. Since these processes traditionally aim at the quality, yield and economic importance of the main metal phase, all non-functional elements and those which effect the material quality are forced to migrate to the slag phase. The latter consists of oxides, phosphates, carbonates and sulphides of metals and metalloids. Thus, the slag becomes the carrier of a broad number of valuable elements. The concentration of these elements is low and therefore they are dissipated and integrated into the inorganic matrix after solidification. A common application of a slag, which contributes formally to a recycling rate, is as a filler, binder or geopolymer in construction, removing the contained critical elements entirely from any material cycle. SPP 2315 EnAM addresses the slag phase as an important source for critical technology elements. When the slag solidifies, it either forms a homogeneous amorphous structure or generates crystals. These crystals are be seen as artificial minerals (EnAM), ores respectively and their generation is investigated to concentrate diluted elements by orders of magnitude. SPP 2315 looks at Li, Ta or Cr containing slag systems. The formation of EnAM itself depends on the thermodynamics of the complex multi-component slag system and the processing conditions of the melt, e.g., the temperature profile and gradient during solidification. Identifying and characterising an EnAM system is only the first step in the processing route in SPP 2315. The EnAM crystal has to be crystallised to a sufficient size and purity and then mechanically liberated from the remaining, sometimes partially amorphous, solid matrix. Finally, mechanical separation of the EnAM particles results in a new artificial ore concentrate. As slag processing has so far been a waste treatment process, there is a lack of strategies and process laws. SPP 2315 is therefore dedicated to the development of appropriate comminution laws and flotation strategies for EnAM. In summary, the SPP 2315 works on holistic separation and concentration concepts, which will allow to keep more elements in the material circle in the future.

• DFG Programme: Priority Programmes
• International Connection: Austria

Projects

• Accelerated discovery of artificial minerals from machine-supported slag admixture and liquid-state processing (Applicants Fuhrmann, Sindy ;  Wondraczek, Lothar )
• Central project - Slag synthesis, design and characterization (Applicants Friedrich, Bernd ;  Peuker, Urs )
• Charge-induced dry concentration of lithium-containing components in fine slag powders (Applicant Weber, Alfred )
• Coordination Funds (Applicant Peuker, Urs )
• Development of a continuous process chain for mechanical separation of EnAM from solidified metal slags (Applicant Gleiß, Marco )
• Efficient Flotation of Engineered Artificial Minerals from Metallurgical Slags by Exploiting Interaction Scanning (FlotEnAMIS) (Applicant Rudolph, Martin )
• Engineering Ta-rich mineral phases based on WEEE recycling slags through fluxes modification, controlled cooling and segregation (Applicant Friedrich, Bernd )
• Exploration of the compositional phase space of metallurgical slag models for a rational design of processes of refractory metal recovery through smelting and recrystallization (Applicants Colombi Ciacchi, Lucio ;  Mädler, Lutz )
• Formation of critical compounds in recycling slags - a study of the melt chemistry with MD simulations and of the solidified compounds in a micro preparation approach (Applicants Fittschen, Ursula ;  Merkert, Nina ;  Schirmer, Thomas )
• Fracture mechanism in heterogenous structures – combining microstructure of EnAM and fracture/ liberation behavior (Applicant Peuker, Urs )
• Investigation of phase formation and phase constitution in the systems Li-Mg-Al-O and Li-Al-Mn-O with special focus on spinel solid solutions (Applicants Ludwig, Alfred ;  Schirmer, Thomas )
• MEPP based modelling and simulation of phase transformation and phase formation in the LAS system by considering mixed kinetic phenomena during solidification (Applicant Fischlschweiger, Michael )
• Multidimensional probabilistic characterization of slag materials for the optimization of cooling, comminution and separation processes, using statistical image analysis supported by machine learning (Applicant Schmidt, Volker )
• Numerical investigation of the liberation of critical raw materials in the form of Engineered Artificial Minerals (EnAMs) from tailored solidified slag phases by DEM-based comminution (Applicant Kruggel-Emden, Harald )
• Selective Agglomeration of Engineered Artificial Minerals (EnAM) in a Suspension of Comminuted Slag (Applicant Bröckel, Ulrich )
• Semi-Mechanistic Modelling of Fracture Mechanisms of Engineered Artificial Minerals (Applicant Schilde, Carsten )
• Single particle analysis for predictive EnAM processing (Applicant Leißner, Thomas )
• Switchable selective collectors for flotation of engineered artificial minerals (Applicant Schmidt, Andreas )
• The Interaction of Stress conditions, Engineered Artificial Minerals Structure and Formulation in Wet Comminution and Separation (Applicant Breitung-Faes, Sandra )
• Thermodynamic database development for the Li2O-Al2O3-SiO2-MnOx system: application for Li recycling (Applicant Fabrichnaya, Ph.D., Olga )

• Spokesperson: Professor Dr.-Ing. Urs Peuker