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

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Our research's long-term goal in this project is to understand the solidification of slag melts. This will help an efficient recovery of critical elements from pyro-metallurgical slags in the form of engineered artificial minerals (EnAM). LiAlO2 has been identified as a promising EnAM to recover Li from Li-ion battery recycling slags. The addition of Al supports its formation as the major Li bearing phase. However, if Mn is present in the melt, its formation is nearly wholly suppressed. Instead of the LiAlO2, a primary Li-Mn spinel solid solution is formed and, later on, several other Li bearing phases. Our objective in this project is to understand the solidifying processes of spinel solid solution in the system Al2O3, MgO, CaO, Li2O, SiO2 in the presence of Mn on a molecular level. Our approach will include a) MD simulation of the most important ions to identify the precursor polytopes and viscosity of the melt and b) and the preparation and characterization of a matrix of inkjet-printed micro-specimens, as well as of a smaller number of small scale and large scale smelted synthetic slags. These will elucidate the microstructure and composition of the actual solidified compounds. Once the primary solidification is understood, the knowledge will be fundamental to enforce the formation of the desired EnAM LiAlO2. The procedures we develop can be adopted to other systems and EnAMs.