Preferential extraction of rubidium from high concentration impurity solution by solvent extraction and preparation of high-purity rubidium salts

Rubidium has a wide range of application prospects in high-tech fields, which makes the extraction of rubidium resources of great significance. However, the similar properties among alkali metals render their separation from each other a considerable challenge. This study aims to recover rubidium from high concentration impurity solution via solvent extraction, and further purify and refine rubidium salt products. The organic phase consisted of the acidic extractant [4-tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP)] and xylene. The affecting parameters, such as contact time, extractant concentration, alkalinity, and phase ratio (O/A) were thoroughly investigated during the separation process. Rubidium could be completely extracted after the four-stage countercurrent extraction, accompanied by 18.84 % of K+ also entered the organic phase. Furthermore, deionized water was employed to remove impurity elements, such as contaminant potassium in the loaded organic phase. The scrubbing findings revealed that the scrubbing rate of K+ reached 99.03 % after five-stage countercurrent scrubbing at a phase ratio of 5:1. Most importantly, rubidium chloride solution was obtained after HCl stripping, which was further used to prepare high-purity rubidium chloride and rubidium carbonate products with a purity of 99.5 %. Eventually, this work provides a complete process for rubidium extraction and product preparation.