Easily Leachable Rare Earth Element Phases in the Parnassus-Giona Bauxite Deposits, Greece

Mouchos, Evangelos; Wall, Frances; Williamson, Ben J.; Palumbo-Roe, Barbara

doi:10.12681/bgsg.14245

Cited by 9 publications

(7 citation statements)

References 15 publications

(27 reference statements)

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“…An easily leachable REE occurrence form by ion-adsorption, related possibly to kaolinite, illite or chamosite, has been speculated to exist in Parnassos-Ghiona bauxites [72]. This claim has some support from present investigation (Figure 2).…”

Section: Manganese-associated Cerium Oxide or Oxyhydroxidesupporting

confidence: 79%

“…Thus, the route of recovering REEs from crushed bauxite before Bayer digestion is encouraged to be tested. In support of the latter, Mouchos et al [72] have demonstrated that between 19% and 47% of REEs in bauxite are easily leachable, in fact ion exchangeable, using ammonium sulphate. They also proposed an option to selectively mine the REE-enriched lower parts of bauxite deposits and thus recover REEs prior to Bayer process [72].…”

Section: Considerations For the Recovery Of Rees From Bauxite Residuementioning

confidence: 90%

“…In support of the latter, Mouchos et al [72] have demonstrated that between 19% and 47% of REEs in bauxite are easily leachable, in fact ion exchangeable, using ammonium sulphate. They also proposed an option to selectively mine the REE-enriched lower parts of bauxite deposits and thus recover REEs prior to Bayer process [72]. Our mineralogical assessment supports such an approach, as the REE phases in bauxite are less complex than in bauxite residue.…”

Section: Considerations For the Recovery Of Rees From Bauxite Residuementioning

confidence: 90%

“…Authigenic cerium-predominant REE phases were noted to be associated with fissures filled with aluminosilicate matrix that is likely kaolinite (Figure 2). Kaolinite-associated authigenic REE phases have not been reported before, but their presence has been assumed in Parnassos-Ghiona bauxite due to the easily leachable proportion of REEs [72]. It was noted previously, however, that some detrital florencite crystals were encased within clay fragments [28].…”

Section: Precursor Ree Phases In Aog's Bauxite Feedmentioning

confidence: 99%

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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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Section: Manganese-associated Cerium Oxide or Oxyhydroxidesupporting

confidence: 79%

Section: Considerations For the Recovery Of Rees From Bauxite Residuementioning

confidence: 90%

Section: Considerations For the Recovery Of Rees From Bauxite Residuementioning

confidence: 90%

Section: Precursor Ree Phases In Aog's Bauxite Feedmentioning

confidence: 99%

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Rare Earth Element Phases in Bauxite Residue

et al. 2018

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“…Leaching of the REE is higher when the final pH is lower; however, this trend is not seen in the iron leaching results ( Table 7), indicating that the REE are likely to be associated with pH sensitive minerals other than iron. REE fluorcarbonates were observed in thin section and are a possible source of recoverable REE in these samples and in other karst bauxites [51]. The behaviour of the REE was distinctly different in the clay-rich bauxite.…”

Section: Organic Acid Leachingmentioning

confidence: 69%

Comparison of Three Approaches for Bioleaching of Rare Earth Elements from Bauxite

et al. 2020

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Approximately 300 million tonnes of bauxite are processed annually, primarily to extract alumina, and can contain moderate rare earth element (REE) concentrations, which are critical to a green energy future. Three bioleaching techniques (organic acid, reductive and oxidative) were tested on three karst bauxites using either Aspergillus sp. (organic acid bioleaching) or Acidithiobacillus ferrooxidans (reductive and oxidative bioleaching). Recovery was highest in relation to middle REE (generally Nd to Gd), with maximum recovery of individual REE between 26.2% and 62.8%, depending on the bauxite sample. REE recovery occurred at low pH (generally < 3), as a result of organic acids produced by Aspergillus sp. or sulphuric acid present in A. ferrooxidans growth media. Acid production was seen when A. ferrooxidans was present. However, a clear increase in REE recovery in the presence of A. ferrooxidans (compared to the control) was only seen with one bauxite sample (clay-rich) and only under oxidative conditions. The complex and varied nature of REE-bearing minerals in bauxite provides multiple targets for bioleaching, and although the majority of recoverable REE can be leached by organic and inorganic acids, there is potential for enhanced recovery by bioleaching.

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The Rare Earth Elements Potential of Greek Bauxite Active Mines in the Light of a Sustainable REE Demand

Gamaletsos

Γοδελίτσας²,

Filippidis

et al. 2018

J. Sustain. Metall.

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Easily Leachable Rare Earth Element Phases in the Parnassus-Giona Bauxite Deposits, Greece

Abstract: The Parnassus-Giona karst bauxite deposits contain significant concentrations of rare earth elements (400-500 ppm

Cited by 9 publications

References 15 publications

Rare Earth Element Phases in Bauxite Residue

Rare Earth Element Phases in Bauxite Residue

Comparison of Three Approaches for Bioleaching of Rare Earth Elements from Bauxite

The Rare Earth Elements Potential of Greek Bauxite Active Mines in the Light of a Sustainable REE Demand

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