SPP 2315: Customized artificial minerals (EnAM) - a geometallurgical tool for recycling critical elements from waste streams

Today's megatrends can be summarized under the catchphrase: "How can we as a society become more efficient and use natural resources sustainably?" This question encompasses both the_CO2/energy challenge and the raw materials/recycling challenge. Today, recycling technology is at a crossroads. In industrialized countries, approaches have been established to recover the elements and materials that make up the bulk of waste. However, we lack technologies to address the essential, rare elements of a modern society that are lost in waste streams. Such elements give a product its particular functionality and are contained in batteries, capacitors, magnets, electronic circuits, sensors or functional composite structures. Pyrometallurgical processes are a significant sink for many of these elements, as these processes traditionally focus on the quality, yield and economic importance of the main metal phase. All non-functional elements that influence the material quality migrate to the second liquid phase, the slag. The latter consists of oxides, phosphates, carbonates or sulphides of metals. The slag thus becomes the carrier of a large number of valuable elements. As their concentration is low, these elements are dissipated after solidification and integrated into the inorganic matrix. A frequent application of slag, which formally contributes to the recycling rate, is as a filler, binder or geopolymer in the construction industry, whereby the critical elements contained are completely removed from the material cycle. The SPP 2315 EnAM addresses the slag phase as an important source of critical technology elements. When the slag solidifies, it can form an amorphous structure or it can produce crystals. These can be regarded as artificial minerals or ores. Thus, targeted crystallization of defined minerals is potentially capable of concentrating dilute elements by orders of magnitude. It may be necessary to add further species to form defined minerals, which in turn depends on the thermodynamics of the complex multi-component slag system. The identification of an EnAM crystal is the first step in processing. It must be crystallized to a sufficient size (e.g. < 10 µm) and freed from the remaining, partially amorphous solid matrix. The mechanical separation of the EnAM particles ultimately results in a new artificial ore concentrate. Slag processing has been little studied and there is therefore a lack of process laws, e.g. fracture laws or flotation strategies for quantitative description and modeling. In summary, SPP 2315 is working on holistic separation and concentration concepts that will make it possible to keep more elements in the material cycle in the future.

Projects:

Investigation of phase formation and phase constitution in the Li-Mg-Al-O and Li-Al-Mn-O systems with special consideration of spinel solid solutions (Applicant Ludwig, Alfred ; Schirmer, Thomas )

Formation of critical compounds in recycling slags - a study of the chemistry of the melt with MD simulation and the solid products in a micropraeparative approach (Applicants Fittschen, Ursula ; Merkert, Nina ; Schirmer, Thomas )

Publications:
Schnickmann, A.; De Abreu, D.A.; Fabrichnaya, O.; Schirmer, T. Stabilization of ^Mn4+ in Synthetic Slags and
Identification of Important Slag Forming Phases. 2024, Preprint: arxiv.org/abs/2402.07702.

Schnickmann, A.; Hampel, S.; Schirmer, T.; Fittschen, U.E.A. Formation of Lithium Manganates in a Complex
Slag System Consisting of _{Li2O-MgO-Al2O3-SiO2-CaO-MnO-A} First Survey.Metals 2023, 13, 2006,
doi:10.3390/met13122006.

Lourens, F.; Suhr, E.; Schnickmann, A.; Schirmer, T.; Ludwig, A.High-Throughput Study of the Phase
Constitution of the Thin Film System Mg-Mn-Al-O in Relation to Li Recovery from Slags.2023, Prprint:
doi:10.48550/ARXIV.2312.04146.

Lourens, F.; Rogalla, D.; Suhr, E.; Ludwig, A. On the Influence of Annealing on the Compositional and
Crystallographic Properties of Sputtered Li-Al-O Thin Films. 2024, Preprint: doi:10.48550/ARXIV.2402.06553.

Schirmer, T.; Hiller, J.; Weiss, J.; Munchen, D.; Lucas, H.; Fittschen, U.E.A.; Friedrich, B. Behavior of Tantalum
in a Fe-Dominated Synthetic Fayalitic Slag System - Phase Analysis and Incorporation. Preprints 2024,
www.preprints.org/manuscript/202402.0695/v1. doi: 10.20944/preprints202402.0695.v

Schnickmann, A.; Hampel, S.; Schirmer, T.; Fittschen, U.E.A.Application of Spray Synthesis and Sol-Gel
Combustion for the Preparation of Precursors for Slag Reference Materials. 2023. Conference paper DXC,
submitted.

Schirmer, T. STOICHIOMETRIC CALCULATION OF LITHIUM-CONTAINING PHASES BASED ON SPATIALLY
RESOLVED X-RAY ANALYSIS AND VIRTUAL COMPOUNDS. Advances in X-ray Analysis. 2022, 65.