Mestrado em Química - PPGQ

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Navegando Mestrado em Química - PPGQ por Assunto "Acid leaching"

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    Os elementos terras raras na indústria de fertilizantes fosfatados do complexo carbonatítico Catalão I - GO: potencialidades de recuperação
    (Universidade Federal de Goiás, 2019-07-05) Franzoi, Isthar Sofia; Zamunér Filho, Antonio Nilson; http://lattes.cnpq.br/4703139616158480; Romualdo, Lincoln Lucíolo; http://lattes.cnpq.br/4703139616158480; Figueiredo, Alberthmeiry Teixeira de; Sousa, Marcelo Henrique
    Phosphatic rocks are the greatest phosphorus source in agriculture. Due to the geologic origin of some of them, they are known for having Rare Earth Elements (REE). The goals of this study were: to quatify the REE in the local phosphate fertilizers production chain; to select targets that enables the REE recovery; to perform the physicochemical characterization of chosen samples and to try out rare earth recovery approaches. Sampling was carried out in the industrial facities from Ouvidor and Catalão. In total, 19 samples were collected in several processing stages and the numerical results pointed out the presence of REE both in the raw material and in the end product, even as all points. The most plentiful metal was Cerium (2.149,3 – 9.964,0 mg L-1), followed by Lanthanum, Neodymium and Praseodymium. The granulometric distribution proved the relation between the REE preconcentration in the productive process and fines percentage in the sample. Four samples were selected for a physicochemical characterization. Tests of leaching and solvente extraction were held in a tailing and in a concentrate. The tailings leaching tests have reached light REE extractions in the order of 79% in chloride environment and 69% in sulphuric environment. Afterwards in the extraction by solvente using tributil phosphate (TBP), iron has been successfully removed from liquor in chloride environment while in sulphuric environment there was not significant separation. In the concentrate sample, the leaching was carried out according to the prodution model of phosphoric acid, therefore, two routes were considered, the hydrochloric and sulphuric one. When it comes to P2O5 solubilization both have been sucessful reaching about 90%. The sulphuric route has showed the advantage of an acid liquor with a low calcium concentration by the phosphogypsum precipitation. Although it ocurred the partitioning of the REE between phosphogypsum and acid solution that after makes the rare earths recovery more dificult. The shown disadvantage by the hydrochloric acid route was the high calcium levels in the acid solution. However, all the solubilized REE have stayed in the solution, which facilitates the subsequent separation steps. Phosphorus extractions with TBP in chloride environment (36-38%) were higher than those achieved in the sulphate environment (8-9%). This job shows options of recovery of high economic and technological use elements, in order to provide advances in the sustainability of the phosphate fertilizer industry processes.