Extraction of lithium from a montebrasite concentrate: Applied mineralogy, pyro- and hydrometallurgy

Lithium is a strategic, future-bearing element due to its high-tech usages, mostly for batteries in electrical vehicles and devices, but is also rated with high supply risk. Due to high market prices, several resources are under (re)evaluation. A concentrate from the Argemela deposit in northern Portugal has an overall grade of 4.5% Li2O, and the carrier is montebrasite. The ore's grade is around 40% of the mineral, and the main gangue phases are quartz (also around 40%) and muscovite. Several other phosphates are associated with montebrasite, mainly planerite and childrenite. This makes the hydrometallurgical extraction of lithium from the concentrate challenging. An initial sulphuric acid roasting step was optimized at 800 °C, based on montebrasite data obtained by TGA, above the temperatures of dehydroxylation of planerite (340 °C) and decomposition of montebrasite (750 °C). Over 95% Li extraction from montebrasite concentrate was achieved by acid roasting and aqueous leaching under the operating conditions obtained, respectively, in laboratory scale: 800 °C and 15 min, 2 h leaching at room temperature (25 °C), which yielded leach liquors containing around 12 g/L Li. The residue, dominated by quartz and berlinite, keeps