Minero-metallurgical processes for lithium recovery from pegmatitic ores = Processos minero-metalúrgicos para a recuperação de lítio de minérios pegmatíticos

ABSTRACT: With the expected increase of lithium demand in the forthcoming years, an efficient management of all the available resources is necessary. Rock minerals like pegmatites are important primary sources of lithium that shall be valorized. Minero-metallurgical processes have been developed for lithium recovery from pegmatitic ore deposits, involving physical concentration, thermal treatment, digestion and/or leaching in order to obtain a lithium soluble species adequate to produce lithium carbonate by precipitation. Physical concentration by froth flotation or by optical sorting are the two main alternative operations to produce a Li concentrate. Metallurgical treatment starts by calcination where the silicate structure is transformed to a more reactive solid phase (ß-spodumene). Afterwards digestion with sulfuric acid and water leaching allows the dissolution of lithium sulfate. Carbonate pressure leaching is an alternative technology for treating pegmatites and production of lithium carbonate. Energy and chemicals savings is crucial in order to reduce the high costs associated with metallurgical processing of Li rock minerals.  RESUMO: Com o aumento na procura de lítio nos próximos anos, torna-se necessária uma gestão eficiente de todos os recursos disponíveis. Os minérios pegmatíticos são fontes primárias importantes deste metal que devem ser valorizadas. Neste contexto, têm sido desenvolvidos processos minero-metalúrgicos para a recuperação de lítio, que envolvem a concentração física, o tratamento térmico, a digestão e/ou lixiviação, de forma a obter o lítio em formas solúveis que permitam a posterior produção de carbonato de lítio por precipitação. Na concentração física, as duas principais operações para produzir um concentrado de Li são a flutuação por espumas ou a triagem por processos ópticos. O tratamento metalúrgico começa por uma etapa de calcinação, onde a estrutura original do silicato é transformada numa fase sólida mais reactiva (ß-espodumena). Em seguida, a digestão com ácido sulfúrico e lixiviação com água permite a dissolução do sulfato de lítio. A lixiviação sob pressão usando carbonatos é uma tecnologia alternativa para o tratamento de pegmatitos e produção de carbonato de lítio. A gestão eficiente da energia e do consumo de produtos químicos é crucial para reduzir os elevados custos associados ao processamento metalúrgico de minerais de lítio

Comparison of processes for lithium recovery from lepidolite by H2SO4 digestion or HCl leaching

Lithium is becoming a strategic metal due to its important applications in secondary battery electrodes used in electronic appliances and also in electric traction vehicles. Lithium primary resources are brines and rock minerals, the former being nowadays almost exclusively used in the production of lithium commodities. With the expected increase in lithium demand, the development of competitive technologies for recovery lithium from ores like pegmatites is getting imperative. The high energy and reagents consumption in processing minerals is an issue that should be considered. This paper presents some results on the comparison of two acid treatment routes for lepidolite, the H2SO4 digestion and HCl leaching. Before both chemical treatments, lepidolite was calcined at 800oC and was transformed in a more reactive species, ƒÀ-spodumene. The H2SO4 digestion at 175oC (followed by water leaching) allowed 88% Li recovery into the solution in 30 min. By the contrary, the HCl leaching process carried out at 90oC also achieved similar yields but only after 4 h of reaction. In both cases, an acid excess was used, but clearly higher for the essays with HCl. The H2SO4 digestion process was also advantageous in what concerns to selectivity over other contained metals. Al, Mn and Fe concentrations in solutions were substantially higher in the hydrochloric acid leaching. These results showed that the digestion with sulphuric acid can be a more efficient and competitive process

Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolite

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.info:eu-repo/semantics/publishedVersio

Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with sodium metabisulphite

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.info:eu-repo/semantics/publishedVersio

Recovery of lithium carbonate by acid digestion and hydrometallurgical processing from mechanically activated lepidolite

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.info:eu-repo/semantics/publishedVersio

Optimization of metals extraction from spent lithium-ion batteries by sulphuric acid and sodium metabisulphite through a techno-economic evaluation

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.info:eu-repo/semantics/publishedVersio

A model of brand salience

Abstract not available

Primacy and recency effects for the recall of brands across three product categories

The effect of the first brand recalled compared to later brand name recall has been explored in this research. In category cued recall events, the first brand recalled has greater linkages to associations in memory, and is a brand to which consumers are disposed more positively. In addition, the first brand recalled does not inhibit recall of competing brands, but has a facilitating effect on the number, positiveness and uniqueness of associations to the brand name. This concept was explored across three product categories: that of a fast-moving consumer good, a service and a durable. In addition, the first brand recalled was related to the last brand purchased for the services category.<br /