Navegando por Autor "Santos, Leonardo Leandro dos"
Agora exibindo 1 - 3 de 3
- Resultados por página
- Opções de Ordenação
Artigo Beta-spodumene:Na2CO3:NaCl system calcination: a kinetic study of the conversion to lithium salt(Elsevier, 2019-07) Nascimento, Rubens Maribondo do; Santos, Leonardo Leandro dos; Pergher, Sibele Berenice CastellãThe basic objective of the work was to evaluate the calcination step in the lithium extraction process and to obtain a kinetic model that would adjust the experimental data for the reaction of the carbonate recovery during the processing of beta-spodumene, activated by melting with sodium carbonate/sodium chloride. In this work there were obtained activation energy values using experimental data obtained from the treatment of complex systems such as minerals. This is of interest because of the contribution it makes to the field of physical chemistry. Some of the main results indicated that the best molar ratio was 3Li2O:1Na2CO3 + 5% w/w NaCl in the conversion to Li2CO3 with approximate 70% Li yield, using a 823–923 K range with a calcination cycle of 120min. The kinetic results indicated that the pseudo-second-order kinetic modeling fits the equilibrium data well under employed temperature conditions on literature, based on second stage of reaction mechanism (chemoselective exchange reaction)Tese Extraction of lithium from beta-spodumene using routes with simultaneous acquisition of zeolitic structures(2018-07-25) Santos, Leonardo Leandro dos; Pergher, Sibele Berenice Castella; Nascimento, Rubens Maribondo do; ; ; ; Braga, Tiago Pinheiro; ; Bieseki, Lindiane; ; Sapag, Manuel Karim;The expected increase in demand for lithium salts raises a growing concern regarding this metal scarcity and environmental issues in the national industry of lithium extraction in tilled reserves. The methodologies applied in lithium extraction are associated with the use of sulfates, organic and actinide-based solvents that leads to the formation of sulfated silico-aluminum by-products and radioactive waste. Therefore, this study aimed to develop and to design environmentally efficient routes in order to extract lithium in salt form from beta-spodumene (β-LiAlSi2O6) and technologically feasible routes to simultaneously obtain zeolites as a by-product. A literature review describes techniques to extract lithium using sulfated additives with by-product recovery after the synthesis process, which indicates that this research is considered unprecedented for having obtained zeolitic crystalline structures formed in the lithium extraction route. In order to elaborate efficient and economically feasible extraction routes, a prior understanding of the attributes of molecular sieves was necessary, in particular, the zeolite types. Thus, the efficiency of lithium extraction using Na2CO3, NaOH e NaCl additives was evaluated through the measurement of atomic absorption in the supernatant, based on chemoselective ion exchange between Li+ from β-LiAlSi2O6 and Na+ from Na2CO3 and NaCl, resulting in up to 85% of extracted lithium. The addition of NaOH promoted the mineralization for the dissolution of β-LiAlSi2O6, enabling the recovery of Li and the availability of Si and Al for the nucleation and the development of zeolite structures. As a result, two routes were developed operating in the closed and continuous circuit (HTS: high-throughput screening). Each route consisted of different stages such as calcination, hydrothermal treatment, and the use of bicarbonate for the dissolution and precipitation of the associated lithium salt, besides the recovery of new materials like as by-products of cage (LTA and FAU) or channel (LTT, MOR, and MFI) zeolitic topology. At last, in order to validate the strategies used, the materials were categorized applying techniques such as XRD, XRF, TGA, ICP, N2 adsorption isotherms, SEM, TEM and FT-IR with adsorbed pyridine.Livro Valorização da cadeia produtiva do lítio: alternativas sustentáveis para extração de lítio do espodumênio(EDUFRN, 2020-05-11) Santos, Leonardo Leandro dos; Bieseki, Lindiane; Bertolino, Luiz Carlos; Oliveira, Manuela Silva Martins de; Nascimento, Rubens Maribondo do,; Pergher, Sibele Berenice Castellã; Campos, Victor Matheus Joaquim Salgado; Santos, Werlem Holanda dosNo que diz respeito a este livro, ele revisa a geologia, a mineração, o processamento, os usos, as estatísticas do mercado nacional e internacional, os dados químicos e as propriedades físicas que envolvem o lítio. Foi elaborado a partir da pesquisa para o desenvolvimento e a inovação em tecnologias aplicadas ao beneficiamento e à recuperação de minerais litiníferos brasileiro, incluindo prospecção e pesquisa mineral, lavra, beneficiamento e aproveitamento de rejeitos com foco na produção de compostos de lítio de alta pureza, especialmente carbonato de lítio. O principal objetivo é apresentar possibilidades e alternativas de mecanismos para extração de lítio a partir do espodumênio, desde o reaproveitamento do resíduo formado, em especial na transformação em peneiras moleculares, até o desenvolvimento de rotas ambientalmente amigáveis, que possibilitem a formação de coprodutos de topologias e propriedades zeolíticas, por meio de novas práticas, tendências tecnológicas e desafios em pesquisas nos campos da ciência e engenharia. Se hoje conseguimos carregar nossos portáteis em poucas horas e os usar ao longo de todo o dia, é por causa das baterias de íons de lítio: é difícil lembrar de como era a vida sem elas. É por isso que o Nobel de Química de 2019 foi dado aos três cientistas que ajudaram a desenvolvê-las, a saber: S. Whittingham, A. Yoshino e J. Goodenough.