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Dynamique du nickel et d'autres éléments en traces métalliques (Co, Cr, Cu et Mn) dans des matériaux miniers ultramafiques

Abstract : A way to ensure physical and chemical stability of mining spoils heaps from nickeliferous laterites is to revegetate them using the native vegetation of the ultramafic soils. The aim of this work was to study the geochemical reactivity of nickeliferous mining spoils of Niquelândia and Barro Alto complexes (Goiás) for the further application of such a revegetation process. Mineralogy and reactivity of TME bearing phases in the spoils were determined. The influence of transport and percolating solution composition on the Ni mobilisation were then studied using saturated and unsaturated column experiments. Finally, the comparison of the composition of solution circulating in natural ultramafic soils with those circulating in experimental plots composed of typical mining ores allowed us to have a first evaluation of the adaptability of natural vegetation to spoils. Two main phases are present in the spoils: a garnieritic spoil, mainly composed of ferruginous smectites enriched in exchangeable Ni (1230 mg kg-1); and a limonitic spoil, mainly composed of goethite with little mobile Ni but very high exchangeable Cr(VI) contents (980 mg kg-1) located as outer sphere complexes at the goethite surface. Synthetic goethite and purified smectite served as model phases to refine the characterisation of main reactive mechanisms implied in Ni mobilisation (PHREEQC modelling). Besides outer (smectite, garnierite) and inner (goethite, limonite) sphere complexation reactions, we showed that the dissolution of mineral phases (phylosilicates, goethite and manganese oxides) and the adsorption of metal-citrate or metal-EDTA complexes do have an important role in the composition of the solution circulating in the spoils
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Submitted on : Thursday, March 29, 2018 - 11:52:58 AM
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  • HAL Id : tel-01748919, version 1
  • PRODINRA : 345685


Sophie Raous. Dynamique du nickel et d'autres éléments en traces métalliques (Co, Cr, Cu et Mn) dans des matériaux miniers ultramafiques. Sciences agricoles. Institut National Polytechnique de Lorraine, 2011. Français. ⟨NNT : 2011INPL004N⟩. ⟨tel-01748919⟩



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