An acidic mixture of sulfuric and fluosilicic acid (H2SO4+H2SiF6) was employed as lixiviant to enhance leaching of lithium from lepidolite. The H2SiF6 was obtained as a byproduct of anhydrous hydrofluoric acid production, aiming to provide HF molecules. It was found that the HF molecules were the main reaction component and played a key role in strengthening the dissolution of lepidolite. Different factors, including mass ratio of ore/H2SO4/H2SiF6, concentrations of H2SO4 and H2SiF6, leaching temperatures (40-80 ℃) and time (15-75 min), were investigated. Moreover, an efficient tubular reactor was employed to improve this acid leaching system. Under the optimal conditions (ore/H2SO4/H2SiF6 mass ratio of 1:0.8:1.6, 80 wt.％ H2SO4, 15 wt.％ H2SiF6, 80 ℃, 15 min), 97.9％ of Li, 96.4％ of K, 97.6％ of Rb, 96.7％ of Cs and 81.4％ of Al (mass fraction) were leached. Additionally, a two-step thermal process was proposed to remove fluorine of leaching slurry. This acid treatment using an acidic mixture of H2SO4 and H2SiF6 in a continuous tubular reactor shows potential as an alternative process to extract lithium from lepidolite.
lepidolitelithium extractioncontinuous tubular reactorfluosilicic acidfluorine chemical method
郭慧、旷戈、李欢、裴文涛、王海东
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郑州大学 化工学院,郑州 450001
福州大学 石油化工学院 化学工程技术研究所,福州 350108
中南大学 资源加工与生物工程学院,长沙 410083
Western Australian School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, Perth, WA 6102, Australia
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