Efficient Extraction of Lithium and Rubidium from Polylithionite via Alkaline Leaching Combined with Solvent Extraction and Precipitation

Lithium and rubidium, as important alkali metals, have a wide range of applications in many fields because of their unique physical and chemical properties. This paper proposes a novel method for the extraction of lithium and rubidium from polylithionite. The process primarily involves alkaline leaching, solvent extraction of rubidium, lithium phosphate precipitation, and zeolite synthesis. Results of alkaline leaching experiments show that the leaching rates of lithium and rubidium are 96.43 and 97.50%, respectively, under a leaching temperature of 250 °C, an NaOH concentration of 600 g/L, a leaching duration of 3 h, and a liquid–solid ratio of 7:1 mL/g. Through solvent extraction, the extraction rate of rubidium can reach 99.5%. More than 93.96% of lithium can be recycled by adding phosphoric acid to prepare lithium phosphate. The obtained basic leaching residue is pretreated to synthesize zeolite, achieving reasonable utilization of the waste residue. The rational use of waste residue has added value to the process and promoted the sustainable use of resources.