Adsorption of rare earth elements in regolith-hosted clay deposits

Borst, A.; Smith, Martin; Finch, Adrian A.; Estrade, Guillaume; Villanova-de-Benavent, Cristina; Nason, Peter; Marquis, Eva; Horsburgh, Nicola J.; Goodenough, Kathryn; Xu, Cheng; Kynický, Jindřích; Geraki, Kalotina

doi:10.1038/s41467-020-17801-5

Cited by 211 publications

(122 citation statements)

References 69 publications

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“…Thus, we suggest that Ca and S are incorporated into the crystal structure according to the isomorphism scheme (Y+REEs) 3+ + (PO 4 ) 3− ↔ (Ca+Sr) 2+ + (SO 4 ) 2− . Some attempts have been made to synthesize the Cadoped REE monazite-like phosphates (Gallini et al, 2005a, b;Sivakumar and Varadaraju, 2005), and they were successful if Ca 2+ was coupled with U 4+ or Th 4+ (Bregiroux et al, 2007). The full substitution leads to the formation of minerals of the cheralite family with a monazite-like structure (Hugues et al, 1995;Clavier et al, 2011).…”

Section: Influence Of Composition On Structure Of Rhabdophane and Possible Isomorphism Schemesmentioning

confidence: 99%

Authigenic rhabdophane from brown iron ore of the oxidation zone of the Babaryk massive sulfide occurrence (South Urals): scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) study

et al. 2021

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Abstract. Rhabdophane (Ce0.34−0.43Nd0.13−0.14Ca0.06−0.29La0.08−0.11Y0.05−0.12Pr0.03−0.05Sm0.02−0.05Gd0.02−0.05Fe0−0.04Dy0.00-0.01)0.97-1.01((P0.69−0.96S0.04−0.31)1.00O4)⚫H2O is found in a Fe3+-oxyhydroxide nodule (brown iron ore) collected from the upper part of the oxidation profile of the Babaryk massive sulfide occurrence (South Urals, Russia) at a 1.6 m depth. The structural and microtextural features of rhabdophane are revealed by electron backscattered diffraction (EBSD); the chemical composition and distribution of the main components are determined on a scanning electron microscope (SEM) equipped with an energy-dispersive analyzer (EDA); the bulk contents of rare earth elements (REEs) and other elements in rock samples are analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Rhabdophane forms spherulitic aggregates up to 35 µm in size with a fine-grained core and radial radiant rims composed of prismatic crystals. The chaotically oriented aggregates of its particles of various sizes including prismatic crystals and spherulitic intergrowths also fill fractures up to 200 µm long and 20–30 µm thick in goethite. The zonal radial radiant structure of the rhabdophane aggregates and their occurrence in fractures of goethite unambiguously indicate the authigenic origin of rhabdophane. The chemically heterogeneous rhabdophane grains always contain Y, Ca and S and rarely Fe and Sr and are Th- or U-free. Contrasting zonation of Ca, S and Y contents is characteristic of spherulites. The band contrast of the EBSD patterns shows a good crystallinity of prismatic crystals regardless of the chemical composition even for Ca–S-rich zones. On the other hand, the Ca- and S-rich fine-grained centers of the spherulites do not yield any distinguishable diffraction patterns. There is a strong negative correlation in pairs (Ca+Sr)–P and (REEs+Y)–S and a positive correlation in pairs (Ca+Sr)–S and (REEs+Y)–P, which indicates the isomorphism according to the scheme (REEs+Y)3+ + (PO4)3− ↔ (Ca+Sr)2+ + (SO4)2−. Thus, the chemical composition of rhabdophane does not completely correspond to the rhabdophane–tristramite/brockite series because of the absence of tetravalent U or Th. In contrast to similar samples from the deeper part of the oxidation zone, the brown iron ore with rhabdophane is enriched in light rare earth elements (LREEs) and P. The REEs were probably sourced from ore-bearing volcanomictic rocks, while P could also have been derived from the soil. The enrichment in REEs and P and the formation of rhabdophane are related to the alternation of dry and wet periods, the P input, and sorption–desorption of REEs from Fe3+ oxyhydroxides and/or clay minerals due to pH changes and variable composition of pore water.

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Section: Influence Of Composition On Structure Of Rhabdophane and Possible Isomorphism Schemesmentioning

confidence: 99%

Authigenic rhabdophane from brown iron ore of the oxidation zone of the Babaryk massive sulfide occurrence (South Urals): scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) study

et al. 2021

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“…Ion-adsorption clay deposits have been discovered outside of China, such as in Serra Nevada in Brazil. Madagascar is one of the African countries, which has shown REE potentials (Harmer and Nex 2016;Hoshino et al 2016;Borst et al 2020). Further explorations should focus on kaolinite in other places of the world which have shown prospective interests for this kind of deposits (Borst et al 2020).…”

Section: Ion Adsorption Clay Depositsmentioning

confidence: 99%

Global Deposits of Rare Earth Elements and Prospects in the Democratic Republic of Congo

Kasay¹,

Bolarinwa²,

Aromolaran³

et al. 2021

Preprint

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Rare earth elements (REE) are not as rare as their name indicate, but the deposits in which they are found at an economic interest are not very common. They are enriched in carbonatites, pegmatites, alkaline and per-alkaline igneous rocks, placers, laterites, veins, bauxites and iron adsorption clays. Economic deposits of REE are mined from 3 main minerals, which are bastnaesite, monazite and xenotime. REE have been widely used in many high-tech and green technology gadgets, including batteries, computer memories, permanent magnets, smartphones, solar panels, wind turbines, speakers, air conditioners and many other applications. Due to these applications, REE are sought after by many developed and developing economies. The Democratic Republic of Congo (DRC) is endowed with mineral potentials. Studies have speculated REE concentration in areas with carbonatite complexes such as Lueshe, Bingo and Kirumba. Other regions with REE potentials include pegmatites. A high weathering rate contributes to metals and REE deposition in lateritic profiles of pegmatites and other alkaline rocks. Additionally, there are placers in many locations of riverbanks. For example, the alluvial placers of Kabengelwa, Mashabuto and Obaye are enriched in monazite and contain significant quantities of rare earth oxides. We believe that, with more research and explorations, the DRC could be a potential target for future REE projects.

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“…In recent years their importance in a variety of 'green' technologies coupled with the current supply monopoly held by China (∼80% of all mine production in 2016, Schulz et al, 2017) has encouraged numerous efforts in other countries to identify their own REE reserves (Hatch, 2012). Weathering processes can serve to increase the grades of primary ores thereby forming supergene deposits; such processes are responsible for the development/enrichment of REE ore deposits such as Mt Weld, Western Australia (Lottermoser, 1990); Bear Lodge, Wyoming, USA (Andersen et al, 2017); and the ion-adsorption clays of southern China and Madagascar (Kynicky et al, 2012;Ram et al, 2019;Borst et al, 2020). A range of factors and processes control REE distribution in weathering profiles.…”

Section: Introductionmentioning

confidence: 99%

An in situ, micro-scale investigation of inorganically and organically driven rare-earth remobilisation during weathering

Kalintsev

Brugger

Ram

2021

MinMag

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At present, a significant portion of rare-earth elements (REEs) are sourced from weathering profiles. The mineralogy of the protolith plays an important role in controlling the fate of REEs during weathering, as accessory minerals contain the bulk the REE budget in most rocks, and different minerals vary in their susceptibilities to weathering processes. REE supergene deposits (‘adsorption clay deposits’) are associated with deep weathering in tropical environments, which often precludes characterisation of the incipient steps in REE liberation from their host minerals in the protolith. Here we have targeted a weathered REE-enriched lithology from a sub-arid environment undergoing relatively rapid uplift, namely the Yerila Gneiss from the Northern Flinders Ranges, Australia, where regolith was shallow or absent and parent rock material had yet to completely break down. Results from X-ray fluorescence mapping, scanning electron microscopy (SEM), SEM-focussed ion beam milling (FIB-SEM), inductively-coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS highlight the migration pathways of REEs and associated U and Th from allanite-(Ce) grains that are the main REE host within Yerila Gneiss material. Migration of light REEs and Th away from the allanite-(Ce) grains via radial cracks resulting from allanite-(Ce) metamictisation was interpreted to result from weathering, as Ce is partially present in its tetravalent oxidation state and Th mobility is most easily explained by the involvement of organic ligands. FIB-SEM provides further evidence for the importance of biogenic processes in REE+U/Th mobility and fractionation in uranothorite-associated spheroidal structures associated with the weathering of allanite-(Ce). Organic carbon was also found in association with a xenotime-(Y) grain; in this case, REE liberation is most likely a by-product of biogenic phosphate utilisation. These results highlight that local controls (at mineral interfaces) mediated by biota and/or biogenic organic matter can control the initiation of REE (+Th,U) mobilisation during weathering.

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Adsorption of rare earth elements in regolith-hosted clay deposits

Cited by 211 publications

References 69 publications

Authigenic rhabdophane from brown iron ore of the oxidation zone of the Babaryk massive sulfide occurrence (South Urals): scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) study

Authigenic rhabdophane from brown iron ore of the oxidation zone of the Babaryk massive sulfide occurrence (South Urals): scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) study

Global Deposits of Rare Earth Elements and Prospects in the Democratic Republic of Congo

An in situ, micro-scale investigation of inorganically and organically driven rare-earth remobilisation during weathering

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