Selective leaching of rare earth elements from bauxite residue (red mud), using a functionalized hydrophobic ionic liquid

Davris, Panagiotis; Balomenos, Efthymios; Panias, Dimitrios; Paspaliaris, Ioannis

doi:10.1016/j.hydromet.2016.06.012

Cited by 181 publications

(97 citation statements)

References 30 publications

(31 reference statements)

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“…A STEM-EDS elemental mapping also showed the presence of REE-containing particles, where cerium and titanium presence were correlated [53]. Based on the observations of bauxite residue leaching behaviour, Bayer process secondary minerals like cancrinite and hydrogarnet have also been proposed as the possible hosts of REEs [54]. Hematite has been proven to be able to incorporate tetravalent cerium into its lattice.…”

Section: Bayer Process and Bauxite Residue Relating To The Reesmentioning

confidence: 97%

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: Bayer Process and Bauxite Residue Relating To The Reesmentioning

confidence: 97%

Rare Earth Element Phases in Bauxite Residue

et al. 2018

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“…Al(OH)4 -+CO2+Na + →NaAlCO3(OH)2+H2O (13) Interaction of waste acid can react with hydroxides and carbonates, even for oxides that may be leached [45,[47][48][49]. Dosing with waste acids is effective to lower pH and reduce alkaline substances, but nevertheless, the acid transformation of bauxite residue is controlled by a complicated set of chemistry reactions that depend upon the interaction between the solution phase and multiple solids [15,29,50].…”

Section: Introductionmentioning

confidence: 99%

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

Kong

Xue

et al. 2017

Journal of Hazardous Materials

141

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Graphical abstractHighlights  Speciation and transformation of solid and soluble alkalinities were investigated. SEM, NEXAFS, and STXM were used to observe particle morphology and alkaline Na speciation and distribution. Gypsum combination promoted leaching of Na-bearing solids and the replacement of exchangeable Na. The use of organic citric acid to transform bauxite residue alkalinity.ABSTRACT: Bauxite residue (BR) is a highly alkaline solid hazardous waste produced from bauxite processing for alumina production. Alkaline transformation appears to reduce the environmental risk of bauxite residue disposal areas (BRDAs) whilst potentially providing opportunities for the sustainable reuse and on-going management of BR. Mineral acids, a novel citric acid and a hybrid combination of acid-gypsum treatments were investigated for their potential to reduce residue pH and total alkalinity and transform the alkaline mineral phase. XRD results revealed that with the exception of andradite, the primary alkaline solid phases of cancrinite, grossular and calcite were transformed into discriminative products based on the transformation used. Supernatants separated from BR and transformed bauxite residue (TBR) displayed distinct changes in soluble Na, Ca and Al, and a reduction in pH and total alkalinity. SEM images suggest that mineral acid transformations promote macro-aggregate formation, and the positive promotion of citric acid, confirming the removal or reduction in soluble and exchangeable Na. NEXAFS analysis of Na K-edge revealed that the chemical speciation of Na in TBRs was consistent with BR.Three acid treatments and gypsum combination had no effect on Na speciation, which affects the distribution of Na revealed by sodium STXM imaging.

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“…The alumina industry is particularly interested in the bauxite trace elements for the following reasons: (1) some of them (such as vanadium-V) are undesired impurities that might end up in the product and, therefore, their fractionation through the process must be controlled [10]; (2) some of them (such as gallium-Ga-and in some cases scandium-Sc) can be extracted mainly as a by-product of the primary alumina industry [6,[11][12][13]; (3) some of them (such as beryllium-Be) are considered hazardous from environmental and occupational health points of view [14]. Therefore, keeping track on the fate of trace elements within the Bayer process is very important for the best plant performance and the desired purity of products.…”

Section: Introductionmentioning

confidence: 99%

“…It is well-known that Ga is worldwide mainly produced as a by-product of Bayer process [8,15] and V can also be recovered as vanadium sludge during the production of alumina [7,16]. There exists a growing interest in the extraction of the relatively valuable REEs and Sc from bauxite residue by exploiting various hydrometallurgical or combined pyro-and hydrometallurgical routes [5][6][7]11,17,18]. In addition, the demand for these metals has been increasing steadily and further increase is projected in the future [1,3,15].…”

Section: Introductionmentioning

confidence: 99%

Distribution of Selected Trace Elements in the Bayer Process

Vind

Alexandri

Vassiliadou³

et al. 2018

Metals

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Abstract:The aim of this work was to achieve an understanding of the distribution of selected bauxite trace elements (gallium (Ga), vanadium (V), arsenic (As), chromium (Cr), rare earth elements (REEs), scandium (Sc)) in the Bayer process. The assessment was designed as a case study in an alumina plant in operation to provide an overview of the trace elements behaviour in an actual industrial setup. A combination of analytical techniques was used, mainly inductively coupled plasma mass spectrometry and optical emission spectroscopy as well as instrumental neutron activation analysis. It was found that Ga, V and As as well as, to a minor extent, Cr are principally accumulated in Bayer process liquors. In addition, Ga is also fractionated to alumina at the end of the Bayer processing cycle. The rest of these elements pass to bauxite residue. REEs and Sc have the tendency to remain practically unaffected in the solid phases of the Bayer process and, therefore, at least 98% of their mass is transferred to bauxite residue. The interest in such a study originates from the fact that many of these trace constituents of bauxite ore could potentially become valuable by-products of the Bayer process; therefore, the understanding of their behaviour needs to be expanded. In fact, Ga and V are already by-products of the Bayer process, but their distribution patterns have not been provided in the existing open literature.

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Selective leaching of rare earth elements from bauxite residue (red mud), using a functionalized hydrophobic ionic liquid

Cited by 181 publications

References 30 publications

Rare Earth Element Phases in Bauxite Residue

Rare Earth Element Phases in Bauxite Residue

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

Distribution of Selected Trace Elements in the Bayer Process

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