Extraction of lithium from lepidolite via iron sulphide roasting and water leaching

In this study, lithium was recovered from lepidolite via iron sulphide (FeS)-CaO roasting and water leaching. The thermodynamics taking place during the roasting of lepidolite and the additives was simulated by using the HSC programme. The simulation indicates that SO2/SO3 formed from the oxidation of FeS plays an important role in extracting lithium from lepidolite. Roasting at 750 degrees C using FeS/Li and Ca/F molar ratios of 5:1 and 1:1, respectively, followed by leaching at 50 degrees C using water/calcine mass ratios of >5:1 could yield a maximum of 81% Li recovery (at <1 g/L Li concentration). It was found that 71.5% of S was liberated into the atmosphere, resulting in lower extraction of Li and more diluted leach liquors compared to those obtained during closed-system roasting of lepidolite and Fe sulphate mixes. (C) 2015 Elsevier B.V. All rights reserved.