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Metal Recovery Processes
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2017
Lithium carbonate is chosen for precipitation because among the alkali-metal carbonates, it exhibits at room temperature the lowest solubility, 13.3 g/1, which decreases further to 7.2 g/l at a higher temperature of 100°C. If the concentrations of Mg and Ca are relatively high in the brine, the method must be modified. The most notable development in this area has been the full-scale production of Li2CO3 and K2SO4 salts in 1985 from the brines found in Salar de Atacama, Chile.46 In the classical method47–49 of recovering lithium from the spodumine ore (Figure 19), the naturally occurring α-form is first subjected to thermal treatment at 1100°C to convert it into the reactive β-form. The heat-treated material is subsequently baked with H2SO4 at 250°C to produce lithium sulfate. The baked product is leached with water to solubilize Li2SO4. The leach liquor is made free of impurities like Fe and Al before precipitating Li2CO3 at elevated temperatures by adding Na2CO3.
Beneficiation of a Nigerian lepidolite ore by sulfuric acid leaching
Published in Mineral Processing and Extractive Metallurgy, 2023
Daud T. Olaoluwa, Alafara A. Baba, Aboyeji L. Oyewole
Some of the techniques aiming at obtaining high-grade lithium/lithium compounds have not been reported on Nigerian-sourced lithium ore varieties. The present study, therefore, aimed to investigate the direct leaching of a Nigerian lepidolite ore by sulphuric acid to remove impurity elements and leave behind a pure form of lepidolite which could be further processed to obtain lithium sulphate. The obtained lithium sulphate could find application as a potential component of ion conducting glasses used in solar panels, batteries, curing agents in cement, as well as treatment of bipolar disorder. However, a physiological study of the lithium sulphate crystals was carried out using an animal model and will be discussed in a subsequent publication.