Simultaneous leaching of Li, Rb, Cs from lepidolite via external electric field enhanced alkali leaching

Lepidolite, a critical mineral resource, contains lithium (Li), rubidium (Rb), and cesium (Cs) — indispensable core elements for modern industrial development. This study proposes a novel “calcining-electric field enhanced alkaline leaching” process for the simultaneous extraction of Li, Rb, and Cs from lepidolite. Under the calcination conditions (850 °C, 120 min) and optimal alkaline leaching parameters (70 wt% NaOH initial concentration, 4:1 liquid–solid ratio, 180 °C, 6 h, 100 r/min stirring speed, and 1.1 A/cm 2 current density), the leaching efficiencies of Li, Rb, and Cs reach 94.3%, 95.2%, and 92.6%, respectively. Compared with the traditional alkaline leaching without an electric field, the proposed method improves the leaching rates of Li, Rb, and Cs by 5.2%, 1.0%, and 11.3%, respectively, under the combined effects of external electric field and alkaline medium. Combined with phase analysis, micro-morphology characterization, surface element content determination, and reactive oxygen species (ROS) quantitative analysis via XRD, SEM, EDS, and UV–Vis characterizations, the core mechanism is revealed: the external electric field induces in-situ formation of stable ROS in the alkaline medium, which effectively destroys the surface and layered structure of calcined lepidolite concentrate, accelerates the oxidative decomposition of ionic bonds in polymetallic silicates and uniform substitution on the mineral surface, exacerbates lattice distortion and internal structure damage, promotes phase transformation of polymetallic silicates, and enhances the conversion of Li, Rb, and Cs to soluble hydroxides, ultimately realizing the directional phase reconstruction of lepidolite concentrate from primary aluminosilicate to soluble hydroxide phases.