A study on the coupling of Li+ and H3BO3 extraction and their mutual promotion mechanism

Efficient extraction of lithium and boron resources from salt-lakes is a prominent topic of research among scholars. In this study, a process route for the simultaneous extraction of lithium and boric acid was employed, followed by their separation through stepwise stripping. During the experiments, a coupling effect in the extraction of Li⁺ and H₃BO₃ was found, leading to an in-depth investigation of their mutual promotion mechanisms. Three significant patterns have been clearly verified through experiments, molecular dynamics simulations and quantum chemical calculations: First, the acidic extractant N221 can not only extract Li⁺, but also enhance the extraction of H₃BO₃; Second, mono-fatty alcohol R-OH as dilute can effectively extract H₃BO₃ while also promoting the extraction of Li⁺. Lastly, Li⁺ and H₃BO₃ can mutually promote each other's extraction. Using the Qinghai old brine, N221 system achieved a 99 % extraction efficiency for H₃BO₃, with an initial lithium extraction of 97 %, around 80 % in subsequent rounds. This paper proposes an effective method for the extraction of Li⁺ and boric acid, and thoroughly studied the mechanism of their mutual promotion of extraction. This research offers new insights into the comprehensive utilization of salt-lake resources.