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Minerals of base metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
The large-scale production of lithium is from spodumene ores. Separation of lithium minerals can be efficiently achieved by taking advantage of their physical, electrical and magnetic properties. Physical separations are performed by wet and dry screening, tabling and magnetic, electromagnetic, electrostatic, magnetohydrostatic bullet and heavy media separation. Gravity separation is feasible only if the spodumene is coarsely grained. High grade spodumene concentrate (75–85%) suitable for lithium extraction can be generated by flotation which can be further processed pyrometallurgically or hydrometallurgically to produce lithium carbonate or other desirable lithium compounds. Roasting is performed at about 1050° C during which spodumene goes through a phase transformation from α-spodumene to ß-spodumene. While α-spodumene is resistant to hot acid attack the ß-spodumene is amenable to hot sulphuric leaching. The phase transformation brought about by roasting results in the spodumene crystal structure expansion of 30%. After cooling the roasted material is mixed with sulphuric acid and roasted again at 200° C in the course of which an exothermic reaction ensues starting at 170° C. Lithium is extracted from ß-spodumene forming a water-soluble lithium sulphate.
Lithium recovery from mechanically activated mixtures of lepidolite and sodium sulfate
Published in Mineral Processing and Extractive Metallurgy, 2021
Nader Setoudeh, Ataollah Nosrati, Nicholas J. Welham
The demand for lithium is forecast to increase significantly in the next decade. The annual global consumption of lithium, commonly measured in tonnes of lithium carbonate equivalent (LCE), is predicted to increase from 190,000 t/year by 2015 to 280,000 t/year by 2020 (Kuang et al. 2015). In the past few years, the demand for lithium has substantially increased due to the prevalence of small electronic devices requiring batteries which are both lightweight and high capacity. The forecast global demand for lithium carbonate shows doubling requirements between 2015 and 2025 (Welham et al. 2017) primarily due to the anticipated increase in uptake of electric vehicles. Therefore, the rising demand for lithium and lithium compounds in the future increases the need to develop processes for all viable lithium bearing resources. Historically, more than 80% of lithium produced in the world came from brines, however the recent expansion of production has been largely due to new production from hard rock pegmatite resources coming on stream (Luong et al. 2013; Kuang et al. 2015).