Recuperação de lantanídeos à partir de resíduos de lâmpadas fluorescentes através de lixiviação química
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Data
2023-08-21
Autores
Mello, Yan Gorski [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As lâmpadas fluorescentes, amplamente aplicadas na iluminação domiciliar e industrial, têm sido aos poucos substituídas por tecnologias de iluminação mais modernas. O descarte das mesmas, entretanto, está longe de ser o ideal. Dentre os materiais que compõem as lâmpadas fluorescentes, as terras raras somam um percentual significativo, mas que não têm sido efetivamente recuperadas. A presença de interferentes, como o cálcio, no material descartado dificulta a extração eficiente do material a ser recuperado e reaplicado em novas tecnologias. Com objetivo de auxiliar na compreensão de uma das rotas mais comuns de recuperação das terras raras, este estudo investigou alguns parâmetros da rota de lixiviação ácida com HCl, buscando entender o efeito na alteração de parâmetros e presença de uma etapa de pré-tratamento (lixiviação branda com HCl diluído). Análises detalhadas de cada etapa do processo foram realizadas à partir de técnicas como a espectroscopia de fotoluminescência e a fluorescência de raios X. O volume de solvente foi variado, analisando o efeito de usar metade do solvente proposto em estudos anteriores, assim como a presença de uma lixiviação branda aplicada como um pré-tratamento. Os resultados analisados indicaram que a presença do pré-tratamento é essencial para a obtenção de um produto final com alta pureza (aproximadamente 99,5%), uma vez que ela é capaz de remover a maior parte do interferente presente na amostra inicial. Já a redução de volume de solvente não apresentou alterações significativas, justificando a redução do mesmo, uma vez que volumes menores de solvente são sempre mais desejáveis de um ponto de vista ambiental. Diante disso, uma etapa de extrema importância em todo o processo e que ainda deve ser otimizada é a precipitação de oxalatos, uma vez que a extração dos materiais se provou efetiva, porém pôde ser percebido que a recuperação desses materiais através da etapa de precipitação ainda possui espaço para otimizações.
Fluorescent lamps, widely used in home and industrial lighting, have gradually been replaced by more modern lighting technologies. However, their disposal is far from ideal. Among the materials that make up fluorescent lamps, rare earth elements account for a significant percentage, but they have not been effectively recovered. The presence of interferents, such as calcium, in the discarded material hinders the efficient extraction of the material to be recovered and reused in new technologies. With the aim of aiding the understanding of one of the most common routes for rare earth recovery, this study investigated certain parameters of the acid leaching process using HCl, seeking to understand the effect of parameter alterations and the inclusion of a pre-treatment step (gentle leaching with diluted HCl). Detailed analyses of each process step were conducted using techniques such as photoluminescence spectroscopy and X-ray fluorescence. The solvent volume was varied, examining the impact of using half the amount proposed in previous studies, as well as the inclusion of a gentle leaching step applied as a pre-treatment. The analyzed results indicated that the presence of pre-treatment is essential to achieve a final product of high purity (approximately 99,5%), as it effectively removes the majority of the interferent present in the initial sample. Conversely, the reduction in solvent volume did not yield significant changes, justifying its reduction, given that smaller solvent volumes are always more environmentally desirable. Given this, a step of utmost importance throughout the process that still needs optimization is the precipitation of oxalates, as material extraction proved effective, yet room for optimization in the recovery of these materials through the precipitation step was observed.
Fluorescent lamps, widely used in home and industrial lighting, have gradually been replaced by more modern lighting technologies. However, their disposal is far from ideal. Among the materials that make up fluorescent lamps, rare earth elements account for a significant percentage, but they have not been effectively recovered. The presence of interferents, such as calcium, in the discarded material hinders the efficient extraction of the material to be recovered and reused in new technologies. With the aim of aiding the understanding of one of the most common routes for rare earth recovery, this study investigated certain parameters of the acid leaching process using HCl, seeking to understand the effect of parameter alterations and the inclusion of a pre-treatment step (gentle leaching with diluted HCl). Detailed analyses of each process step were conducted using techniques such as photoluminescence spectroscopy and X-ray fluorescence. The solvent volume was varied, examining the impact of using half the amount proposed in previous studies, as well as the inclusion of a gentle leaching step applied as a pre-treatment. The analyzed results indicated that the presence of pre-treatment is essential to achieve a final product of high purity (approximately 99,5%), as it effectively removes the majority of the interferent present in the initial sample. Conversely, the reduction in solvent volume did not yield significant changes, justifying its reduction, given that smaller solvent volumes are always more environmentally desirable. Given this, a step of utmost importance throughout the process that still needs optimization is the precipitation of oxalates, as material extraction proved effective, yet room for optimization in the recovery of these materials through the precipitation step was observed.
Descrição
Palavras-chave
Lixiviação, Fluorescência, Terras raras, Economia circular, Lâmpadas fluorescentes