Browsing by Author "Pereira, Manuel F. C."
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- Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with sodium metabisulphitePublication . Vieceli, N.; Nogueira, Carlos; Guimarães, C.; Pereira, Manuel F. C.; Durão, F.; Margarido, F.ABSTRACT: The hydrometallurgical extraction of metals from spent lithium-ion batteries (LIBs) was investigated. LIBs were first dismantled and a fraction rich in the active material was obtained by physical separation, containing 95% of the initial electrode, 2% of the initial steel and 22% of plastic materials. Several reducers were tested to improve metals dissolution in the leaching step using sulphuric acid. Sodium metabisulphite led to the best results and was studied in more detail. The best concentration of Na2S2O5 was 0.1 M. The metals dissolution increased with acid concentration, however, concentrations higher than 1.25 M are unnecessary. Best results were reached using a stirring speed of 400 min(-1). The metals leaching efficiency from the active material (Li, Mn, Ni, Co) increased with the temperature and was above 80% for temperatures higher than 60 degrees C. The dissolution of metals also rose with the increase in the liquid/solid ratio (LAS), however, extractions above 85% can be reached at LAS as lower as 4.5 L/kg, which is favourable for further purification and recovery operations. About 90% of metals extraction can be achieved after only 0.5 h of leaching. Sodium metabisulphite can be an alternative reducer to increase the leaching of Li, Mn, Co, and Ni from spent LIBs.
- Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolitePublication . Vieceli, N.; Nogueira, Carlos; Pereira, Manuel F. C.; Durão, F.; Guimarães, C.; Margarido, F.ABSTRACT: The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. Therefore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from lepidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and response-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphization and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.
- Optimization of metals extraction from spent lithium-ion batteries by sulphuric acid and sodium metabisulphite through a techno-economic evaluationPublication . Vieceli, N.; Nogueira, Carlos; Pereira, Manuel F. C.; Durão, F.; Guimarães, C.; Margarido, F.ABSTRACT: The main factors that affect the extraction of metals from spent lithium-ion batteries by acid leaching using H2SO4, and sodium metabisulphite, were evaluated and optimized through a set of experiments, framed by a techno-economic approach. The maximum value of the profit response was obtained with the highest possible values of acid concentration (2.5 M) and time (2 h), a liquid/solid ratio of 5 L/kg, and the lowest possible value of temperature (40 degrees C). After leaching, the electrodes active material contained in the metals decreased, while it was still significant in the graphite, as observed by scanning electron microscopy-energy dispersive spectrometry and x-ray powder diffraction. Even though the performed economic evaluation was a summarized outline it can be considered suitable to compare different leaching conditions and to determine the possible best combinations of factors that can optimize the profit response.
- Recovery of lithium carbonate by acid digestion and hydrometallurgical processing from mechanically activated lepidolitePublication . Vieceli, N.; Nogueira, Carlos; Pereira, Manuel F. C.; Durão, F.; Guimarães, C.; Margarido, F.ABSTRACT: Lithium extraction from hard-rock ores has regained importance due to the increased demand for this metal to supply the growing battery market. Therefore, several studies have been focused on the lithium extraction from ores, however, leaching and purification steps are sparsely studied. Thus, the objective of this study was to evaluate the main factors affecting the water leaching step and the subsequent purification operations for lithium recovery from a lepidolite concentrate, which was processed by mechanical activation and sulphuric acid digestion. In the leaching step, among the variables studied, only one, the leaching temperature, showed a significant effect on the lithium extraction, taking into account the range of values tested. Thus, the recommended operating value for the leaching time and the L/S ratio is the minimum, while for the leaching temperature is 50°C. After optimizing the leaching operation, the purification of the leachate, by neutralization, was thoroughly performed by efficient removal of impurities (Fe, Al, Mn and Ca), allowing to obtain lithium carbonate as final product, as well as other relevant by-products, such as rubidium and potassium alums.