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12 pages, 1497 KiB

Open AccessArticle

Selective Scandium Elution from D₂EHPA-Impregnated Ion-Exchange Resin After Metal Loading from Acidic Chloride Solutions

by Eleni Mikeli, Danai Marinos, Efthymios Balomenos and Dimitrios Panias

Materials 2024, 17(24), 6089; https://doi.org/10.3390/ma17246089 - 13 Dec 2024

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Abstract

This paper investigates the elution behavior of scandium from D₂EHPA (Di-(2-ethylhexyl) phosphoric acid)-impregnated resins that proceed with metal loading from acidic chloride solutions. D₂EHPA resins stem from their recognized selectivity for Sc extraction from acidic solutions. This study focuses on the elution process after ion-exchange extraction and examines various elution systems to achieve selective Sc recovery. Among the tested elution media, fluoride-based systems were proven effective for Sc desorption. The elution of the resins was demonstrated in a column set-up, where complete and selective elution of Sc was achieved. Τhis study contributes to the advancement of Sc extraction methods from chloride solutions, offering valuable insights for industrial applications, especially emphasizing the importance of optimizing the elution step for achieving efficient recovery of Sc. Full article

(This article belongs to the Special Issue Advanced Functional Materials for Hydrometallurgical and Environmental Applications)

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25 pages, 8271 KiB

Open AccessArticle

Recovery of Scandium, Aluminum, Titanium, and Silicon from Iron-Depleted Bauxite Residue into Valuable Products: A Case Study

by Pavel Grudinsky, Liliya Pasechnik, Anfisa Yurtaeva, Valery Dyubanov and Dmitry Zinoveev

Crystals 2022, 12(11), 1578; https://doi.org/10.3390/cryst12111578 - 5 Nov 2022

Cited by 10 | Viewed by 3035

Abstract

Bauxite residue is a high-iron waste of the alumina industry with significant contents of scandium, aluminum, and titanium. This study focuses on the recovery of Sc, Al, Ti, and Si from iron-depleted bauxite residue (IDBR) into valuable products. Iron depletion was carried out using reduction roasting followed by low-intensity magnetic separation to enrich bauxite residue in Al, Ti, and Sc and reduce an adverse effect of iron on scandium extraction. Hydrochloric high-pressure acid leaching, aluminum precipitation by saturation of the acid leachate, solvent extraction of scandium using di(2-ethylhexyl) phosphoric acid (HDEHP) and tributyl phosphate (TBP), alkaline leaching of the acid residue with subsequent silica precipitation were used to obtain appropriate selective concentrates. As a result, scandium concentrate of 94% Sc₂O₃, crude alumina of 93% Al₂O₃, titanium concentrate of 41.5% TiO₂, and white carbon of 77% SiO₂ were prepared and characterized. Based on the characterization of the treatment stages and the obtained valuable products, the prospect for the application of the suggested flowsheet was discussed. Full article

(This article belongs to the Special Issue Extractive Metallurgy and Chemistry)

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13 pages, 2941 KiB

Open AccessArticle

Use of Ion-Exchange Resins to Adsorb Scandium from Titanium Industry’s Chloride Acidic Solution at Ambient Temperature

by Eleni Mikeli, Danai Marinos, Aikaterini Toli, Anastasia Pilichou, Efthymios Balomenos and Dimitrios Panias

Metals 2022, 12(5), 864; https://doi.org/10.3390/met12050864 - 18 May 2022

Cited by 8 | Viewed by 3567

Abstract

Scandium metal has generated a lot of interest during the past years. This is due to the various crucial applications it has found ground in and the lack of production in countries outside China and Russia. Apart from rare earth ores, scandium is present in a variety of wastes and by-products originating from metallurgical processes and is not currently being sufficiently valorised. One of these processes is the production of titanium dioxide, which leaves an acidic iron chloride solution with a considerably high concentration of scandium (10–140 ppm) and is currently sold as a by-product. This research aims to recover scandium without affecting the solution greatly so that it can still be resold as a by-product after the treatment. To achieve this, two commercial ion-exchange resins, VP OC 1026 and TP 260, are used in the column setup. Their breakthrough curves are plotted with mathematical modelling and compared. Results indicate that VP OC 1026 resin is the most promising for Sc extraction with a column capacity of 1.46 mg/mL, but Zr, Ti, and V coextract have high capacities, while Fe does not interfere with the adsorption. Full article

(This article belongs to the Special Issue Advanced Sorbents for Separation of Metal Ions)

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9 pages, 1425 KiB

Open AccessProceeding Paper

Sustainable Supply of Scandium for the EU Industries from Liquid Iron Chloride Based TiO₂ Plants

by Bengi Yagmurlu, Beate Orberger, Carsten Dittrich, Georges Croisé, Robin Scharfenberg, Efthymios Balomenos, Dimitrios Panias, Eleni Mikeli, Carolin Maier, Richard Schneider, Bernd Friedrich, Philipp Dräger, Frank Baumgärtner, Martin Schmitz, Peter Letmathe, Konstantinos Sakkas, Christos Georgopoulos and Henk van den Laan

Mater. Proc. 2021, 5(1), 86; https://doi.org/10.3390/materproc2021005086 - 25 Dec 2021

Cited by 3 | Viewed by 3476

Abstract

Scandium (Sc) applications in solid oxygen fuel cells, aeronautics and heat exchange systems are forecasted to increase significantly without a sufficient continuous Sc supply for Europe. ScaVanger is an EU project for upscaling Sc extraction and purification technologies from various TiO₂ pigment production residues. High purity Sc₂O₃ and ScF₃ will be produced at competitive prices for the EU market. The ScaVanger process is expected to result in a 10% higher production rate and higher product purity as processing starts with a unique cleaning process of actinides. The first plant at a major European TiO₂ pigment production site will be supplying about 30 t/a of Sc₂O₃. Full article

(This article belongs to the Proceedings of International Conference on Raw Materials and Circular Economy)

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13 pages, 2013 KiB

Open AccessArticle

Preparing High-Purity Anhydrous ScCl₃ Molten Salt Using One-Step Rapid Heating Process

by Junhui Xiao, Chao Chen, Wei Ding, Yang Peng, Kai Zou, Tao Chen and Zhiwei Zou

Appl. Sci. 2020, 10(15), 5174; https://doi.org/10.3390/app10155174 - 28 Jul 2020

Cited by 4 | Viewed by 4393

Abstract

In this study, a one-step rapid heating novel process was used to prepare high-purity anhydrous scandium chloride molten salt with low-purity scandium oxide. High-purity anhydrous ScCl₃ molten salt was used as the Sc-bearing raw material for preparing the Sc-bearing master alloy. Inert gas was used to enhance the purity of anhydrous scandium chloride and reduce the hydrolysis rate of scandium. The results show that high-purity scandium chloride (purity, 99.69%) with the scandium content of 29.61%, was obtained, and the hydrolysis rate of scandium was 1.19% under the conditions used: removing ammonium chloride; residual crystal water temperature of 400 °C; m(Sc₂O₃):m(NH₄Cl) = 1:2.5; holding-time of 90 min; heating-rate of 12 °C/min; and argon flow of 7.5 L/min. XRD, SEM, and EPMA analyses further verified that anhydrous scandium chloride crystallization condition was relatively good and the purity of high-purity anhydrous scandium chloride approached the theory purity of anhydrous scandium chloride. Full article

(This article belongs to the Special Issue Recent Advances in the Development and Application of Green Extraction Techniques)

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14 pages, 1481 KiB

Open AccessArticle

Preparing Sc-Bearing Master Alloy Using Aluminum–Magnesium Thermoreduction Method

by Junhui Xiao, Wei Ding, Yang Peng, Tao Chen and Kai Zou

Metals 2020, 10(7), 960; https://doi.org/10.3390/met10070960 - 16 Jul 2020

Cited by 8 | Viewed by 4027

Abstract

In this study, preparation of Al–Mg–Sc master alloy tests were carried out by Al–Mg thermoreduction method. Stirring by blowing argon and pressing with molten salt jar were adopted to reduce scandium segregation and upgrading scandium recovery of scandium-bearing master alloy. The results show that the Al–Mg–Sc master alloy ingot contained 2.90% Sc, 5.73% Mg, 0.0058% Cu, 0.29%, 0.029% Ti, 0.13% Fe, 0.075% Zn, 0.025% Na, and 96.72% recovered scandium obtained under the comprehensive conditions used: m(Al): m(Mg): m(ScCl₃) = 10:1:1.5, stirring speed of eight rpm, reduction temperature of 1223 K, reduction time of 40 min. The experimental results are in agreement with the thermodynamic predictions, and Al–Mg–Sc master alloy indicator was ideal. Full article

(This article belongs to the Special Issue Aluminum Alloys and Aluminum Matrix Composites)

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10 pages, 18410 KiB

Open AccessArticle

Sc₂[Se₂O₅]₃: The First Rare-Earth Metal Oxoselenate(IV) with Exclusively [Se₂O₅]²⁻ Anions

by Stefan Greiner and Thomas Schleid

Crystals 2018, 8(5), 187; https://doi.org/10.3390/cryst8050187 - 26 Apr 2018

Cited by 4 | Viewed by 4191

Abstract

The scandium oxodiselenate(IV) Sc₂[Se₂O₅]₃ was synthesized via solid-state reactions between scandium sesquioxide (Sc₂O₃) and selenium dioxide (SeO₂) with thallium(I) chloride (TlCl) as fluxing agent in molar ratios of 1:4:2. Evacuated fused silica ampoules were used as reactions vessels for annealing the mixtures for five days at 800 °C. The new scandium compound crystallizes in the triclinic space group P

\bar{1}

with the lattice parameters a = 663.71(5) pm, b = 1024.32(7) pm, c = 1057.49(8) pm, α = 81.034(2)°, β = 87.468(2)°, γ = 89.237(2)° and Z = 2. There are two distinct Sc³⁺ positions, which show six-fold coordination by oxygen atoms as [ScO₆]⁹⁻ octahedra (d(Sc–O) = 205–212 pm). Three different [Se₂O₅]²⁻ anions provide these oxygen atoms with their terminal ligands (O^t). Each of the six selenium(IV) central atoms exhibit a stereochemically active lone pair of electrons, so that all [Se₂O₅]²⁻ anions consist of two ψ¹-tetrahedral [SeO₃]²⁻ subunits (d(Se–O^t) = 164–167 pm, d(Se–O^b) = 176–185 pm, ∢(O–Se–O) = 93–104°) sharing one bridging oxygen atom (O^b) with ∢(Se–O^b–Se) = 121–128°. The vibrational modes of the complex anionic [Se₂O₅]²⁻ entities were characterized via single-crystal Raman spectroscopy. Full article

(This article belongs to the Special Issue Crystal Structures of Compounds Containing Ions Selenite)

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