Kaolin as a potential lithium source: a preliminary study of the Torniella ceramic raw material deposit (southern Tuscany)

Sara Longo , Pilario Costagliola, Pierfranco Lattanzi, Marta Morana, Guia Morelli, Massimiliano Reginelli, Valentina Rimondi, Simona Raneri

The Torniella ceramic raw material deposit (southern Tuscany) is hosted within highly altered rhyolites of the Tertiary Tuscan magmatic province. Locally, kaolinite-rich veins occur, consisting of more 80% kaolinite, with minor quartz and traces of svanbergite, SrAl3(PO4)(SO4)(OH)6. The bulk vein material shows interesting lithium (Li) contents, ranging from 1600 to 3700 mg/kg, with local enrichment up to 6000 mg/kg. Preliminary experiments to assess the potential for Li extraction resulted in negligible release (0.2-0.4%) at room temperature (reaction with pure water, 1M MgCl2 solution, and 1M HCl solution). Roasting at 600 °C and leaching with oxalic acid resulted in up to 60% Li recovery. Conversely, roasting at 850 °C with sodium sulfate and water leaching yielded a lower Li recovery (～40%). These results suggest that Li can be effectively mobilised only after thermal activation. While the local resource is limited and the deposit itself is unlikely to be economically viable, this study acknowledges the potential of Li recovery as a by-product of kaolin extraction for the ceramic industry.