Os elementos terras raras na indústria de fertilizantes fosfatados do complexo carbonatítico Catalão I - GO: potencialidades de recuperação
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Data
2019-07-05
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Universidade Federal de Goiás
Resumo
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.
Descrição
Palavras-chave
Elementos de terras raras, Meio ambiente, Lixiviação ácida, Caracterização tecnológica, Extração por solventes, Rare earth elements, Environment, Acid leaching, Technological characterization, Solvent extraction
Citação
FRANZOI, Isthar Sofia. Os elementos terras raras na indústria de fertilizantes fosfatados do complexo carbonatítico Catalão I - GO: potencialidades de recuperação. 2019. 116 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2019.