The rising demand and price of lithium in recent years have created an economic opportunity for recovering lithium from pyrometallurgical slags. By using thermodynamic models, lithium can be concentrated in phases like lithium aluminate and eucryptite, which are then separated from gangue material through flotation, followed by leaching for lithium recovery. Flotation efficiency is vital for success, and one key factor is optimizing the particle size of the slag material. Furthermore, milling slag particles also plays a crucial role in this process by enabling the liberation of lithium-rich phases, bridging the gap between pyrometallurgical and hydrometallurgical processes.
This study investigates the impact of dry milling and its associated parameters on the flotation efficiency of γ-LiAlO2. A synthetic slag composed primarily of γ-LiAlO2, eucryptite, and melilite is subjected to compressive stress through a double-roll mill. The resulting material is subsequently introduced into flotation cells. The study elucidates the comminution process of the slag, achieving the desired particle size. The specific milling parameters include gap size, rotational speed, and mass flow. The study’s findings show improved flotation by increasing the gap size to 60% in regard to the x50 of the fraction . These gap sizes result in lower specific energy consumption compared to smaller gap sizes. Setting the rotational speed higher than the falling velocity of the particles promotes the formation of a particle bed, positively influencing flotation. Although variations of the mass flow do not directly affect the flotation efficiency, this paramater plays a crucial role in the energy consumption of the mill. Therefore, optimizing milling parameters based on the size, and shape of crystals of lithium rich phases directly enhances the efficiency of comminution and flotation processes, particularly within the 100-30 µm particle size range, where the highest flotation and recovery rates, up to 70%, are observed.