Removal of calcium and magnesium from LiHCO3 solutions for preparation of high-purity Li2CO3 by ion-exchange resin

This paper describes the results from an experimental study of the purification of LiHCO3 solution which is used to produce high-purity Li2CO3 by ion exchange. Generally, there are some amounts of Ca2+ and Mg2+ in the LiHCO3 solution whose contents exceed the requirements to produce qualified high-purity Li2CO3, so they need to be removed from the solution. There are many methods available to remove divalent metal ions from solutions, among which the ion exchange is the most simple and efficient one. Investigations of the performance of the chelating resin Amberlite IRC747 for its adsorption for Ca2+ and Mg2+ in LiHCO3 solutions were conducted. Batch studies showed that the SDM-A model could describe the adsorption isotherm data well, and the Kannan particle diffusion model could describe the exchange kinetics properly. The study for column operation showed that breakthrough points of Ca2+ and Mg2+ both advanced with increasing the feed flow rate, and the penetration function model could describe the effluent curves adequately. HCl and LiOH of 1 mol·L− 1 respectively were used to regenerate resins with good effect. This study will provide the basic reference for process operation and the reactor design to purify the LiHCO3 solution by ion exchange.