Preparation and examination of the properties of complex scandium fluorides

Sokolova, Yu. V.; Cherepanin, R. N.

doi:10.1134/s1070427211080040

Cited by 8 publications

(8 citation statements)

References 2 publications

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“…For instance, addition of oxalic acid results in precipitation of scandium oxalate [19], while (NH 4 ) 2 HPO 4 reagent results in ScPO 4 precipitation [25]. Addition of NaF solutions in different concentrations to an NH 4 HF 2 solution containing Sc can result in precipitation of a mixture of salts namely, ScF 3 , Na 3 ScF 6 and Na(NH 4 ) 2 ScF 6 in different proportions [26]. For antisolvent crystallization, the choice of a suitable solvent is dependent on several factors including ionic speciation in the new solvent matrix [27].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the solubilities of ScF 3 and (NH 4 ) 3 ScF 6 have been determined in HF-dosed solutions [30]. Various crystalline phases which include ScF 3 , NH 4 ScF 4 , (NH 4 ) 5 Sc 3 F 14 , NH 4 Sc 3 F 10 , (NH 4 ) 2 Sc 3 F 11 , and the α-and β-polymorphs of (NH 4 ) 3 ScF 6 have been reported for the ScF 3 -NH 4 F system [26,31]. β-(NH 4 ) 3 ScF 6 was identified as the most stable phase in the ScF 3 -NH 4 F system at high fluoride concentrations at temperatures below 90 °C [31,32].…”

Section: Introductionmentioning

confidence: 99%

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Recovery of Scandium by Crystallization Techniques

Peters

Kaya

Dittrich

et al. 2019

J. Sustain. Metall.

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Bauxite residues, i.e., red mud, can be processed to recover various valuable end products, while reducing the environmental impact of the waste. Scandium is one of the valuable elements in bauxite residues. It is possible to extract and enrich scandium from red mud by leaching and solvent extraction. Scandium can then be recovered from the pregnant strip liquor by crystallization. Different crystallization techniques can be used to generate the supersaturation required for scandium to crystallize out as a salt. In the present study, the crystallization of an ammonium scandium fluoride phase by cooling and antisolvent crystallization techniques is presented. Cooling crystallization gave a low yield of ammonium scandium hexafluoride, (NH 4) 3 ScF 6 , below 50% at the lowest temperature of 1 °C investigated. Antisolvent crystallization using ethanol gave almost complete recovery with precipitation efficiency greater than 98% for an ethanol-to-strip liquor volumetric ratio of 0.8. Solubility data of (NH 4) 3 ScF 6 under different temperatures and in different ethanol-strip liquor mixtures is herein presented. The product obtained by antisolvent crystallization had very minute crystals (< 2 µm) due to the high supersaturation generated upon adding ethanol to the strip liquor, while it was easier to obtain larger crystals by cooling crystallization. Fe and Ti impurities were detected in the solid product, and an insight into the mechanism of impurity uptake is discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recovery of Scandium by Crystallization Techniques

Peters

Kaya

Dittrich

et al. 2019

J. Sustain. Metall.

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“…There is information about the crystallization of scandium fluoride phases in literature. Scandium can be precipitated from an ammonium fluoride solution as ScF 3 ·(0-0.25)H 2 O, NH 4 ScF 4 , (NH 4 ) 3 ScF 6 , (NH 4 ) 5 Sc 3 F 14 , NH 4 Sc 3 F 10 or (NH 4 ) 2 Sc 3 F 11 , depending on the composition of the solution and temperature [18][19][20]. Scandium could also be precipitated as sodium or potassium fluoride and ammonium fluoride salts [19].…”

Section: Introduction-previous Studies and State Of The Artmentioning

confidence: 99%

“…Scandium can be precipitated from an ammonium fluoride solution as ScF 3 ·(0-0.25)H 2 O, NH 4 ScF 4 , (NH 4 ) 3 ScF 6 , (NH 4 ) 5 Sc 3 F 14 , NH 4 Sc 3 F 10 or (NH 4 ) 2 Sc 3 F 11 , depending on the composition of the solution and temperature [18][19][20]. Scandium could also be precipitated as sodium or potassium fluoride and ammonium fluoride salts [19]. Scandium has been crystallized as scandium trifluoride on an industrial scale after the stripping of Ti(IV), Th(IV) and Sc(III) from dodecyl phosphoric acid in kerosene using hydrofluoric acid in uranium processing [13].…”

Section: Introduction-previous Studies and State Of The Artmentioning

confidence: 99%

Scandium Recovery from an Ammonium Fluoride Strip Liquor by Anti-Solvent Crystallization

Kaya¹,

Peters²,

Forsberg³

et al. 2018

Metals

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In this study, the crystallization of scandium from ammonium fluoride strip liquor, obtained by solvent extraction, was investigated using an anti-solvent crystallization technique. Acetone, ethanol, methanol and isopropanol were added individually to the strip liquor as the anti-solvent and scandium was precipitated and obtained in the form of (NH 4 ) 3 ScF 6 crystals. The results show that scandium can be effectively crystallized from the strip liquor to obtain an intermediate, marketable scandium product. Yields greater than 98% were obtained using an anti-solvent to strip liquor volumetric ratio of 0.8. Acetone had the least performance at lower anti-solvent to strip liquor volumetric ratios, possibly due to its limited H bonding capability with water molecules when compared to alcohols.

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“…1,2,9 Nevertheless, a relatively high solubility (K sp ¼ 2.55 Â 10 À12 ) was reported for NH 4 ScF 4 . 15 The leakage of Ln 3+ from UC-NPs (for example, in NaYF 4 , CaF 2 , and Gd 2 O 3 matrices) and their (cyto)toxicity was questioned before. 16 A limited number of studies report on the genesis of nephrogenic systemic brosis and calcic uremic arteriolopathy induced by the released Gd 3+ from Gd-based MRI contrasting agents and on the neurotic symptoms caused by La 3+ and Yb 3+ .…”

mentioning

confidence: 99%