Simultaneous Recovery of Lithium and Boron from Brine by the Collaborative Adsorption of Lithium-Ion Sieves and Boron Chelating Resins

In view of the coexistence of lithium and boron in brines, in this article, the novel adsorption technology was developed for the simultaneous recovery of lithium and boron from brines based on the cooperative action of titanium-type lithium-ion sieves and N-methylglucamine boron specific resins. During the collaborative adsorption, lithium-ion sieves adsorbed Li+ ions based on the Li+/H+ ion-exchange mechanism, and the released H+ ions from lithium-ion sieves would be neutralized by the amine functional groups of the N-methylglucamine resins to enhance the Li+/H+ ion exchange. Meanwhile, the adjacent double hydroxyl functional groups of the N-methylglucamine resins formed preferentially the complexation adsorption with borate ions to recover boron from brines. The synergistic adsorption mechanism between lithium-ion sieves (home-made PVB-HTO granules) and N-methylglucamine boron specific resins (commercial D403 resins) was investigated experimentally in batch adsorbers. Furthermore, six groups of experiments were performed in the continuous mode for the simultaneous recovery of lithium and boron from the salt-lake brines with 50∼200 mg/L of Li and B contents and 50–200 of Mg/Li molar ratio, where three-stage continuous stirred–tank adsorbers containing 18 L of brine, 300 mL of PVB-HTO granules, and 600 mL of D403 resins were used for the lithium and boron recovery from brine. Then, the regeneration of the PVB-HTO granule-packed column by 0.3 M HCl solution was carried out to obtain the lithium-rich solution, and the regeneration of the D403 resin-packed column by 0.3 M HCl solution was performed to obtain the boron-rich solution. The feasibility and efficiencies of the adsorption method for the simultaneous recovery of lithium and boron from salt-lake brines will be evaluated.