A comminution chain for lithium-bearing slags as artificial minerals using roller mills

Efficient recovery of lithium from secondary sources, such as pyrometallurgical battery slags, remains a major challenge with significant environmental and resource implications. This study develops and evaluates a scalable comminution process chain for engineered lithium-rich slags, emphasizing energy-efficient grinding toward a flotation-ready product (<100 µm). Impact- and compression-based mills were compared with respect to breakage mechanisms, particle-size evolution, and specific energy demand for crushing. Fine grinding was subsequently conducted in a rigidly mounted roller mill, where roller-gap variation was systematically analyzed to optimize particle-size distribution and energy consumption. Energy efficiency was quantified using size-specific energy and energy utilization. Compression stressing produced narrower particle-size distributions and higher energy efficiency, with the most energy-effective performance observed at moderate gap ratios of 40% of the median size of feed. In contrast, impact stressing generated broader distributions dominated by shattering but facilitated early liberation of metallic droplets from the slag matrix. Continuous grinding experiments in series and circuit modes demonstrated that circuit operations achieved up to 20% lower energy demand by preventing redundant stressing of fines, whereas series milling achieved higher mass yield for the same throughput and number of stress events. The proposed hybrid process chain, combining impact pre-crushing with staged roller milling, provides a mechanistic framework for designing energy-efficient dry-grinding circuits and supports scalable lithium recovery from complex slags.