This presented work will introduce a new method for efficiently and selectively extracting pure RbCl_(s) from Na⁺ and K⁺ enriched brines emanating from the phosphoric acid production industry. Utilizing the ion exchange properties of self-synthesized PES coated Zn-Hexa-Cyanoferrate (PES-Zn-HCF) material, the approach enables effective Rb⁺ adsorption followed by stepwise, selective desorption. The process involves passing Rb⁺-containing brines through a column filled with PES-Zn-HCF beads, followed by chromatography-based separation between Rb⁺ and Na⁺/K⁺ using a second column pre-adsorbed with NH₄⁺. A 0.05M NH₄⁺-solution is initially used to extract Na⁺ and K⁺ from the first column, retaining a small Rb⁺ mass, partly re-adsorbed in the second column. After ensuring that the eluent solution flowing out of the column is devoid of Na⁺ and K⁺, the 0.05 M NH4Cl passage is ceased and a 1 M NH₄⁺-solution is now pumped in to extract the remaining Rb⁺. This solution undergoes water evaporation followed by NH₃/HCl sublimation/deposition, resulting in the production of a pure RbCl_(s) product and in the parallel recycling of the NH₄Cl salt that is used as eluent. The study employs theoretical simulations validated by empirical results to demonstrate the method's feasibility as well as a detailed cost assessment, showing the concept to be highly cost effective.