Review: The formation, characteristics, and resource utilization of lithium slag

The rapid growth of the electric vehicle industry is driving the global lithium industry to further improve. It is expected that mining and smelting of lithium resources will continue to increase in the near future. Therefore, we need to pay attention to the formation, physicochemical characteristics, and resource utilization of lithium slag, considering the mining demand, environmental supervision, and proper treatment of solid waste. In this review, we will examine the distribution of lithium ore, flotation and extraction technologies for obtaining lithium, and the utilization of lithium slag. We will also discuss the evolution of mineral structure and chemical composition during the smelting process of spodumene. Additionally, we will review the usage of lithium slag in cement production, geopolymer material design, and concrete preparation. Lastly, we will discuss the potential applications of lithium slag in low-carbon cementitious materials and glass-ceramics preparation. While lithium slag has been used as an auxiliary gelling material in cement-based products, the presence of sulfate residue greatly hinders its utilization. Moreover, the sulfate residue poses a significant risk of soil and water pollution during the stacking process. Considering the recovery rate of lithium and the environmental impact of lithium slag, pressure leaching with nitric acid proves more advantageous than roasting with sulfuric acid. Compared to the sulfuric acid roasting method, nitric acid pressure leaching method can efficiently extract lithium from low-grade spodumene ore, thus greatly improving its resource utilization rate. The low residual nitrate content in lithium residue due to its good solubility makes the resource utilization of lithium salt solid waste through nitric acid pressure leaching more environmentally friendly. Therefore, this method deserves more attention.