Applying the Engineered Artificial Mineral (EnAM) Concept from Lab to Pilot Scale: Lithium Aluminate in Lithium-Bearing Slag Systems

The engineered artificial mineral (EnAM) concept aims to concentrate target elements in tailored mineral phases with defined composition, grain size, and shape through controlled slag chemistry and crystallisation. This study evaluates the transfer of LiAlO2 formation as a Li-bearing EnAM from a 5 kg laboratory-scale slag to a 125 kg pilot-scale slag. The pilot-scale slag was produced in a 300 L top-blown rotary converter and subjected to controlled cooling. A multiscale characterisation workflow combining micro-X-ray fluorescence (µXRF), X-ray computed tomography (XCT), SEM-EDX and electron backscatter diffraction (EBSD) was used to investigate EnAM distribution, morphology, intergrowth and grain structure. LiAlO2 was formed at pilot scale, with a phase fraction of 7.5–10.5 wt. % compared with 11.2–14.4 wt. % at laboratory scale. µXRF revealed substantially larger EnAM clusters at pilot scale, whereas EBSD showed that these clusters consist of finer, more irregular LiAlO2 grains. Nevertheless, both scales exhibited a comparable size-shape progression from smaller, compact clusters toward larger, less compact structures. XCT and SEM-EDX further revealed intergrowth of LiAlO2 with Mn-Al spinel. The results demonstrate the feasibility of transferring EnAM formation to pilot scale while showing that scale-up modifies EnAM yield, clustering, intergrowth, and individual grain properties.