Este trabalho apresenta o estudo de recuperação de índio (In) e zinco (Zn) presentes em telas de monitores de computadores sucateados, por meio de técnicas hidrometalúrgicas. O trabalho foi subdividido em duas partes distintas: dissolução dos metais In e Zn mediante digestão ácida do pó de revestimento da tela de monitores e separação dos metais pela técnica de extração por solventes.
Na etapa de dissolução dos metais, investigou-se a influência das seguintes variáveis de processo: tipo de reagente, relação ácido/amostra, tempo de reação e temperatura. Após a otimização dos parâmetros do processo, obteve-se uma dissolução de índio superior a 95% e de Zn superior a 99,5%. Foi obtido um licor contendo 9,8 g/L de zinco, 1,49 g/L de índio e 102 g/L de sulfato, contendo como impureza 0,016 g/L de ferro, e acidez de 2,2 mol/L (pH = 0,34).
Após a definição das melhores condições de abertura química, a amostra foi processada para a obtenção do licor para a realização dos experimentos de extração por solventes. Foram realizados experimentos descontínuos de extração por solventes para a verificação da viabilidade técnica e melhores condições de separação dos metais, e um experimento contínuo para o carregamento do solvente. Na etapa de extração, as variáveis de processo investigadas foram: tipo de extratante, pH do licor e tempo de reação.
Os experimentos foram realizados na relação volumétrica aquoso/orgânico (A/O) igual a 1 e concentração de extratante de 1,0 mol/L. Os extratantes investigados foram: DEHPA, IONQUEST 801 e CYANEX 272. O estudo das variáveis foi realizado apenas com os dois primeiros extratantes. Os experimentos de reextração foram realizados com HCl e H2SO4, na relação volumétrica de 1:1 e em diferentes concentrações dos ácidos. Os experimentos de bancada indicaram que a separação dos metais pode ser realizada usando DEHPA 1,0 mol/L como extratante, o H2SO4 1,0 mol/L como agente de lavagem, para a reextração dos elementos coextraídos com o índio (principalmente Zn), e HCl 3,0 mol/L para a reextração do In do orgânico carregado. / This work presents the study of recovery of indium (In) and zinc (Zn) present in computer monitor screens by means of hydrometallurgical techniques. This work was divided into two distinct parts: one is the dissolution of the metals In and Zn through acid digestion of the sample and the separation of the metals through solvent extraction technique.
In the acid dissolution, the influence of the following process variables was investigated: type of reagent, acid/sample ratio, time of reaction and temperature. Following the optimisation of the parameters of the process, dissolution of indium above 98% and of Zinc over 99.5% was achieved. A liquor containing 9.8 g/L of zinc, 1.49 g/L of indium and 102 g/L of sulphate having as impurity 0.016 g/L of iron, and acidity of 2.2 mol/L (pH = 0.34) was obtained.
After the optimization of the chemical opening conditions, the sample were processed in order to obtain the liquor for the solvent extraction experiments. Batch experiments of solvent extraction aiming at verifying the technical viability and best conditions for the separation of the metals and a continuous experiment to load the solvent were carried out. In the extraction phase, the process variables investigated were: type of extractant, pH of the liquor, and reaction time. The experiments were carried out at an aqueous/organic (A/O) volumetric ratio equal 1:1 and concentration of extractant 1.0 mol/L. The extractants investigated were DEHPA, IONQUEST 801 and CYANEX 272. The study of the variables was carried out with DEHPA and IONQUEST 801. The stripping experiments were carried out with HCl and H2SO4, at a volumetric ratio 1 with different acids concentrations. The batch experiments indicated that the separation of the metals In and Zn can be done using DEHPA 1 mol/L as extractant, H2SO4 1 mol/L as scrubbing agent and HCl 3 mol/L as stripping agent.
After defining the best conditions for the extraction, scrubbing and stripping steps a continuous experiment was programmed. The McCabe-Thiele diagrams indicated that 3 extractions stages and 7 stripping stages was enough to extract and strip the In from the liquor and the loaded organic respectively. Due to the small amount of the liquor, the continuous experiment contemplate only the extraction and scrubbing steps. The experiment was done in mixer-settler cells, with capacity of 70 mL in the mixer and 250 mL in the settler, in a counter current system. The stripping step was carried out in batches simulating the counter current system. The continuous experiment (extraction and scrubbing steps) were carried out with the use of DEHPA 1.0 mol/L as the extractant agent and a solution of H2SO4 1.0 mol/L as the scrubbing agent in order to remove the impurities extracted. Four extraction stages and 4 stages were employed in each step, using a volumetric ratio A/O equal 5:1 in the extraction and a volumetric ration O/A equal 4:1 in the scrubbing step.
A loaded organic containing 7.5 g/L of In and 0.003 g/L of Zn and a raffinad containing 9.4 g/L Zn and less than 0.001 g/L of In were obtained from a liquor containing 9.8 g/L and 1.49 g/L. The content of the metals in the stripped solution were 26.7 g/L de In e 0.001 g/L de Zn.
| Identifer | oai:union.ndltd.org:IBICT/oai:bdtd.cdtn.br:168 |
| Date | 08 March 2013 |
| Creators | Ana Cristina Vieira Zuccheratte |
| Contributors | Carlos Antônio de Morais, Rubens Martins Moreira |
| Publisher | CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, CTMI - Programa de Pós-Graduação em Ciência e Tecnologia das Radiações, Minerais e Materiais, CDTN, BR |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações do CDTN, instname:Centro de Desenvolvimento da Tecnologia Nuclear, instacron:CDTN |
| Rights | info:eu-repo/semantics/openAccess |
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