Preparation of High-Purity Lithium Carbonate Using Complexing Ion-Exchange Resins

Sorption of a series of alkaline earth and nonferrous metals (Ca, Mg, Cu, Ni, and Zn) from lithium hydrocarbonate and chloride solutions onto ion-exchange resins of various classes was studied. The highest values of the static exchange capacity were observed in sorption from a LiHCO3 solution onto imino carboxylic ion exchangers Amberlite IRC 748 (Rohm and Haas, the United States), Purolite S930 (Purolite, the United Kingdom), and AXIONIT 3S (AO Aksion RDM, Russia). In sorption from a LiCl solution with pH 1.4, the sorption capacity of all the sorbents tested is 3-7 lower. Sorption treatment of a LiHCO3 solution to remove Na, K, Ca, Mg, Al, Si, Ti, Cr, Mn, Fe, Ni, Cu, and Zn impurities under dynamic conditions using AXIONIT 3S imino carboxylic sorbent was performed. The sorption ensures deep removal of Ca, Cu, and Zn impurities from a LiHCO3 solution. A procedure was suggested for preparing high-purity lithium carbonate by ion-exchange purification of a LiHCO3 solution on an imino carboxylic sorbent, followed by thermal decomposition of the purified solution at the boiling point to obtain a lithium carbonate precipitate. Lithium carbonate with the main substance content of 99.90 +/- 0.05 wt % was obtained.