Quantum chemical calculation assisted efficient lithium extraction from lithium precipitation mother liquor via solvent extraction

Abstract

Recovering lithium from lithium precipitation mother liquor is a challenge for the lithium salt industry to achieve steady development. In this study, we selectively recovered lithium from the mother liquor using solvent extraction, and screened extractants based on lithium affinity using quantum chemical calculation. A β-diketone-organophosphorus synergistic system was screened for lithium extraction. Through a systematic process involving extraction, scrubbing, and stripping, the maximum lithium recovery rate was achieved. After three stages of countercurrent extraction, the lithium extraction rate reached 99.64 %, with a sodium extraction rate of 2.32 %, leaving a lithium concentration of only 6.85 mg/L in the raffinate, demonstrating selective lithium extraction. The stripped solution, when concentrated, yielded a high-purity lithium chloride product. Slope analysis and DFT calculations indicated that the optimal lithium extraction was achieved when the molar concentrations of the extractant and co-extractant were equal. This work provides insights into the sustainable recovery of lithium from lithium precipitation mother liquor.