Study on Impurity Removal from Lepidolite Leaching Solution and the Extraction Process of Rubidium

Efficient removal of iron and aluminum impurities is critical for the extraction of lithium and rubidium from zinnwaldite, a lithium-bearing mineral. In this study, solvent extraction using P507 was employed to remove iron and aluminum from zinnwaldite leaching solutions. However, stripping iron from the organic phase proved challenging due to the strong interaction between iron ions and the extractant. To address this, a novel reduction stripping method was developed using ascorbic acid (AA) as a reductant. This method exploits the reduction of Fe3+ to Fe2+ in the aqueous phase, weakening the binding between iron ions and the organic phase, thus enabling efficient stripping. The optimized process achieved over 99.99% removal of iron and aluminum impurities. Subsequently, rubidium was selectively extracted using t-BAMBP, with a total recovery rate of 88.53%. Scaling-up experiments confirmed the feasibility of the process for industrial applications, demonstrating high efficiency and reagent recyclability. This study offers a promising approach for the efficient extraction and separation of valuable metals from zinnwaldite, with potential for broader applications in metal processing.