Comparative Study of Organic and Inorganic Leaching Agents for Lithium Recovery from Lepidolite and Spodumene

This study evaluated the characterization and comparative leaching of lithium from pegmatitic minerals lepidolite and spodumene. Structural analyses by X-ray diffraction (XRD) confirmed lepidolite as the primary lithium-bearing phase, associated with muscovite and andradite, while spodumene was identified along with traces of B₂O₃ and MgO. Digital morphological and elemental analyses corroborated these identifications, revealing lamellar surfaces in lepidolite and granular to prismatic crystals in spodumene. Leaching experiments were conducted under controlled laboratory conditions (30 °C, 800 rpm, 37 µm, pulp density 1 g·L⁻¹), employing mineral acids, organic acids, amino acids, and salts. In lepidolite, sulfuric acid achieved lithium recoveries above 80%, followed by oxalic acid (~70%), confirming the effectiveness of acidic media in disrupting its silicate framework. In contrast, α-spodumene exhibited limited reactivity, with maximum recoveries of ~ 30% under malic acid, underscoring the need for prior activation stages (thermal conversion or alternative treatments). The results highlight the decisive influence of mineralogy and leaching agents on lithium extraction efficiency, emphasizing that lepidolite is more amenable to direct hydrometallurgical processing, whereas spodumene requires innovative strategies to enable its industrial utilization.