A Strategic Pre-Mechanical Activation Approach for Reducing Acid Consumption and Ion Release on Acid Leaching of Lithium-Bearing Clays

The increasing demand for lithium and the limited availability of high-grade resources have accelerated interest in lithium-bearing clays as a promising alternative, despite their relatively lower lithium content. Lithium extraction from such clay minerals typically requires thermal treatment or acid leaching to disrupt the clay crystal lattice and enhance lithium solubility. The enrichment tailings from the Kırka Boron Processing Plant in Türkiye consist predominantly of dolomite-rich clay minerals and contain approximately 900–1200 ppm Li. Considering the substantial quantities of these tailings currently stored on-site, recovering lithium and converting these materials into a valuable resource would be of significant economic importance. However, due to their mineralogical composition, conventional acid leaching of these tailings demands relatively high sulfuric acid consumption (1.5–2.0 M H2SO4). This leads to excessively low solution pH and the generation of highly acidic waste streams, while also promoting the co-dissolution of iron (Fe) and aluminum (Al) ions at pH levels below 2, which negatively affects lithium recovery and downstream processing. In this study, mechanical activation was applied to the tailings prior to acid leaching. As a result, the acid requirement to achieve lithium extraction efficiencies of 90% and above was successfully reduced from 1.5 M to 1.0 M H2SO4. Moreover, solution pH was maintained near neutral (~7), and the undesirable dissolution of Fe and Al ions was effectively suppressed and kept under control.