Advances in the extraction of rubidium from liquid mineral resources

Rubidium, as a strategic critical material, exhibits broad application prospects in many high-tech fields, including aerospace, bioengineering, medicine, energy, and environmental science. At present, rubidium resources mainly occur in solid minerals, such as lepidolite and pollucite, as well as in liquid resources, including salt lake brines, seawater, and mineral leachates. With the gradual depletion of high-grade rubidium-bearing ores and the continuous increase in rubidium prices, the extraction of rubidium from liquid resources with abundant reserves has become a research hotspot. Based on a brief overview of the global status of rubidium resources, this paper systematically reviews the main technologies for extracting rubidium from liquid mineral resources, including fractional crystallization, precipitation, solvent extraction, adsorption, and membrane separation. The processes and underlying mechanisms of each method are summarized in detail. Their applicability and technical bottlenecks are comparatively analyzed. Corresponding improvement strategies are proposed to address these limitations. On this basis, future research should further strengthen fundamental studies on rubidium extraction to provide theoretical guidance for the structural optimization of high-efficiency separation materials and process design. Meanwhile, novel adsorbents, extractants, and membrane materials with high selectivity and stability should be developed, and their performance should be validated in real and complex liquid resource systems. In addition, integrated processes coupling solvent extraction, adsorption, and membrane separation should be promoted to enhance mass transfer efficiency and resource utilization. These efforts aim to provide a reference for the development of clean, efficient, and sustainable technologies for rubidium resource extraction.