Content and mode of occurrences of rare earth elements in the Zagrad karstic bauxite deposit (Nikšić area, Montenegro)

Radusinović, Slobodan; Jelenković, Rade; Pačevski, Aleksandar; Šimić, Vladimir; Božović, Ð.; Holclajtner-Antunović, Ivanka; Životić, Dragana

doi:10.1016/j.oregeorev.2016.05.026

Cited by 49 publications

(32 citation statements)

References 42 publications

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“…Because the formation of metastable Al2O3 with [5] Al may be prevalent at low temperature condition ( ~50 ºC) as shown in the current study, the absorption of metal elements including rare-earth elements (REEs) on bauxite can be controlled by the presence of metastable alumina. It has been reported that the REEs are more enriched in boehmiterich bauxite than in gibbsite-rich bauxite (e.g., Boni et al, 2013;Hanilçi, 2013;Radusinović et al, 2017). While speculative, this difference in REE contents may stem from the presence of [5] Al (and thus its high catalytic activity) in the boehmite-derived metastable alumina at low temperature.…”

Section: Quantification Of Coexisting Phases In the Heat-treated Alummentioning

confidence: 99%

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Kim

Lee

2021

American Mineralogist

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Detailed knowledge of the structural evolution of diverse aluminum (oxy)hydroxides with varying temperatures up to ~300 °C provides insights into the dehydration processes involving transitions among metastable phases in Earth's surface and crust. Here, we report the high-resolution solid-state 27 Al NMR spectra for three different types of aluminum (oxy)hydroxides (i.e., boehmite, bayerite, and gibbsite) with varying annealing temperatures up to 300 °C, revealing the effect of distinct precursor minerals on the stability of metastable alumina. 27 Al MAS NMR results allow us to obtain the quantitative fractions and NMR parameters for each phase during transformation. The results demonstrate that each aluminum (oxy)hydroxide phase follows the unique transformation path to metastable alumina. The 27 Al MAS and 3QMAS NMR spectra of boehmite show that a minor but observable [4] Al signal (~2%) is detected at ~50 °C, and the [4] Al fraction gradually increases up to 300 °C (~16%), indicating that the phase transformation from boehmite to -/-Al 2 O 3 occurs at a temperature as low as ~50 °C, significantly lower than earlier estimations based on XRD. Together with the [4] Al fraction, the [5] Al fraction increases from < 1% at 50 °C to ~2.3% at 300 °C, whereas the NMR results of bayerite and gibbsite do not show the presence of [5] Al. In addition, the 27 Al 3QMAS NMR spectra resolved the [6] Al site in boehmite and that in -/-Al 2 O 3 , which could not be uniquely determined from 1D NMR spectra. The population of bayerite abruptly decreases from 100% (at 150 ºC), through ~47% (at 200 ºC), to 0% (at 250 ºC), indicating that the phase transition from bayerite to boehmite + -/-Al 2 O 3 occurs within a narrow temperature range. As for gibbsite, while [4] Al is not observed in the spectra up to 200 °C, the [4] Al fraction of ~2% is observed in the spectra for gibbsite annealed at 250 °C, and the [4] Al fraction increases rapidly to ~15% as the annealing temperature increases to 300 °C, suggesting that the phase transformation into -/-Al2O3 occurs at ~250 ºC. The results confirm that the phase transformation paths (gradual vs. dramatic) depend on the type of precursor minerals. Particularly, the threshold temperature at which the onset of the phase transformation from boehmite to metastable alumina (~50 ºC) is lower than those from other precursor minerals (>150 ºC). Furthermore, the phase transformation from boehmite to -/-Al 2 O 3 occurs gradually within broad temperature ranges from ~50 °C. This is due to This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Section: Quantification Of Coexisting Phases In the Heat-treated Alummentioning

confidence: 99%

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Kim

Lee

2021

American Mineralogist

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“…Moreover, hydroxylbastnäsite has been highlighted as the most frequently identified REE mineral in karst bauxites [29]. Raman spectroscopy was successfully applied to aid the identification of authigenic monazite-Nd and authigenic xenotime in Zagrad karst bauxite deposit (Montenegro) [16]. Cerium can occur in the oxide form as authigenic cerianite [26].…”

Section: Rees Geochemistry and Phases In Bauxitementioning

confidence: 99%

“…This list of REE minerals in bauxites is not exhaustive as there is a wide variety of REE phases described. An increasing volume of research is being published about the mineralogy of REEs in bauxite deposits worldwide in the recent years [16,[30][31][32]. An overview and a case study of the REEs geochemistry in European bauxite deposits as well as in the derived residues is given by Deady et al [15].…”

Section: Rees Geochemistry and Phases In Bauxitementioning

confidence: 99%

Rare Earth Element Phases in Bauxite Residue

et al. 2018

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Abstract:The purpose of present work was to provide mineralogical insight into the rare earth element (REE) phases in bauxite residue to improve REE recovering technologies. Experimental work was performed by electron probe microanalysis with energy dispersive as well as wavelength dispersive spectroscopy and transmission electron microscopy. REEs are found as discrete mineral particles in bauxite residue. Their sizes range from <1 µm to about 40 µm. In bauxite residue, the most abundant REE bearing phases are light REE (LREE) ferrotitanates that form a solid solution between the phases with major compositions (REE,Ca,Na)(Ti,Fe)O 3 and (Ca,Na)(Ti,Fe)O 3 . These are secondary phases formed during the Bayer process by an in-situ transformation of the precursor bauxite LREE phases. Compared to natural systems, the indicated solid solution resembles loparite-perovskite series. LREE particles often have a calcium ferrotitanate shell surrounding them that probably hinders their solubility. Minor amount of LREE carbonate and phosphate minerals as well as manganese-associated LREE phases are also present in bauxite residue. Heavy REEs occur in the same form as in bauxites, namely as yttrium phosphates. These results show that the Bayer process has an impact on the initial REE mineralogy contained in bauxite. Bauxite residue as well as selected bauxites are potentially good sources of REEs.

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“…During laterization and bauxitization processes, intense weathering and the limited mobility of REE in the weathering profiles cause the enrichment of these elements in residual ores, including bauxite, relative to their parent rocks in the form of: (i) concentration of primary (magmatic) refractory REE phases, (ii) precipitation of secondary authigenic/ diagenetic REE phases, (iii) LREE-actinide oxides sorbed in supergene/ epigenetic Fe-oxides and (iv) ion-adsorption clays [13,15,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Geochemistry and Mineralogy of Rare Earth Elements (REE) in Bauxitic Ores of the Catalan Coastal Range, NE Spain

Reinhardt

Proenza

Villanova-de-Benavent

et al. 2018

Minerals

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Karst bauxite deposits are currently investigated as a new resource for rare earth elements (REE) in order to avoid present and future supply shortfalls of these critical metals. The present work focuses on the geochemistry and mineralogy of the REE in karst bauxite deposits of the Catalan Coastal Range (CCR), NE-Spain. It is revealed that the studied bauxitic ores have a dominant breccia and local ooido-pisoidic and pelitomorphic texture. The bauxitic ores are mostly composed of kaolinite and hematite, as well as of lesser amounts of boehmite, diaspore, rutile and calcite. The mineralogy and major element composition indicate incomplete bauxitization of an argillaceous precursor material possibly derived from the erosion of the Mesozoic Ebro massif paleo-high. The studied bauxites are characterized by ∑REE (including Sc, Y) between 286 and 820 ppm (av. 483 ppm) and light REE to heavy REE (LREE/HREE) ratios up to 10.6. REE are mainly concentrated in phosphate minerals, identified as monazite-(Ce) and xenotime-(Y) of detrital origin and unidentified REE-phosphates of a possible authigenic origin. REE remobilization presumably took place under acidic conditions, whereas REE entrapment in the form of precipitation of authigenic rare earth minerals from percolating solutions was related to neutral to slightly alkaline conditions. During the bauxitization process no significant REE fractionation took place and the REE distribution pattern of the bauxitic ores was governed by the REE budget of the precursor material. Finally, adsorption as a main REE scavenging mechanism in the studied CCR bauxite deposits should not be considered, since the presented data did not reveal significant REE contents in Fe-and Mn-oxyhydroxides and clay minerals.

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Content and mode of occurrences of rare earth elements in the Zagrad karstic bauxite deposit (Nikšić area, Montenegro)

Cited by 49 publications

References 42 publications

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Probing the transformation paths from aluminum (oxy)hydroxides (boehmite, bayerite, and gibbsite) to metastable alumina: A view from high-resolution 27Al MAS NMR

Rare Earth Element Phases in Bauxite Residue

Geochemistry and Mineralogy of Rare Earth Elements (REE) in Bauxitic Ores of the Catalan Coastal Range, NE Spain

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