Separation of sodium and potassium using adsorption – elution/crystallization scheme from bittern

A process scheme has been developed for the selective separation of sodium (Na) and potassium (K) from the bittern using a combination of adsorption – elution / evaporation / crystallization units. Adsorption – elution stages have been adopted for K enrichment from bittern using clinoptilolite as absorbent material and sodium nitrate as the subsequent eluent for the glass column. Then evaporation and cooling crystallization are appended to separate the sodium nitrate and potassium nitrate from the potassium-enriched solution. Afterwards, the mother liquor was completely recycled, and ten cycle experiments were carried out to determine that the purity of potassium nitrate, which exceeded 99%. Lastly, the endothermic process of preparing eluent and the exothermic process of potassium nitrate crystallization, can be capitalized by implementing a heat exchanger between the two processes and reduce the overall energy consumption. Thus, a heat flow simulation was carried out using Aspen plus software, and a temperature convergence was computed.