Clean Process for Selective Recovery of Lithium Carbonate from Waste Lithium-Bearing Aluminum Electrolyte Slag

Abstract

Lithium (Li)-bearing aluminum electrolyte slag is an inevitable byproduct of the aluminum industry, and improper disposal or stacking it may lead to potential environmental hazards. This study employed hydrometallurgical processes to selectively leach lithium from Li-containing aluminum electrolyte slag, using sodium carbonate solution as the leaching agent. A notable leaching efficiency of 99.12% is yielded for lithium, with minimal leaching observed for other elements such as calcium (Ca) and aluminum (Al). In addition, a countercurrent extraction process consisting of five stages conducted at a temperature of 80 °C resulted in a lithium leaching efficiency of 97.12%. The recycling of the leaching agent in conjunction with the production of lithium carbonate and cryolite eliminates the generation of waste liquid or waste slag. The Spearman correlation coefficient analysis demonstrates that temperature and reaction time play more roles in the leaching efficiency of Li compared to the liquid-to-solid ratio and concentrations of the leaching agent. The adoption of this ecologically sustainable approach exhibits potential in promoting the growth of the aluminum industry while simultaneously tackling the resource and environmental issues linked to Li-rich slags.