Recovery Of Scandium Research Articles

Ionic Liquid-Based Extraction Strategy for the Efficient and Selective Recovery of Scandium.

The recovery of scandium (Sc) from highly acidic industrial effluents is currently hindered by the use of large quantities of flammable and toxic organic solvents. This study developed an extraction system using ionic liquids (ILs) and phenylphosphinic acid (PPAH) as diluents and an extractant, respectively, to selectively recover Sc from the aqueous phase. The effect of IL chemical structure, aqueous pH and temperature on the extraction of Sc was systematically investigated and the findings revealed that ILs with longer alkyl side chains had reduced Sc extraction ability due to the presence of continuous nonpolar domains formed by the self-aggregation of the IL alkyl side chain. The IL/PPAH system maintained high extraction ability toward Sc across a wide temperature range (288 K to 318 K) and the extraction efficiency of Sc could be improved significantly by increasing the aqueous pH. The extraction process involved proton exchange, resulting in the formation of a metal-ligand complex (Sc(PPA)3).

Research and Development of Obtaining Scandium from Waste Cake by Aluminothermal Method

To study and obtain scandium, we used technogenic waste (waste cake) from the Kadamzhai antimony plant. For the experiment, we took 0.05 μm enriched fine fraction of the cake. To carry out the aluminothermic reaction, we weighed 90 g of enriched cake and 10 g of aluminum powder on technical scales. To obtain scandium, we used a quartz crucible as a reactor, since the reaction in it does not pollute the obtained product, the reaction will begin at 810° C. Complete recovery of scandium occurs at 935° C, in 7-8 minutes. For the aluminothermic reaction, we used enriched cake from the Kadamzhai antimony plant.

Study on adsorption of scandium by iminodiacetic acid resin TP207

Abstract Scandium (Sc) is a rare transition metal applied in unique electronic/alloy materials such as magnesium scandium alloy, aluminum scandium alloy, laser glass, superconductors, and electronic components. However, scandium is extremely hard to obtain. In this paper, the iminodiacetic acid resin TP207 was first applied for the recovery of scandium from a hydrochloric acid solution. The adsorption of Sc3+ by TP207 resin was analyzed by SEM-EDS, FT-IR, and XPS. It was found that the best adsorption time was 2 hours with the equilibrium adsorption rate reaching 99%. The saturated adsorption amount of resin was 0.05g/ml. This process involves the ion exchange of scandium ions with sodium ions on the resin and the chemisorption of scandium with the -COO- group. Furthermore, the TP207 resin exhibited a quasi-second-order kinetic mechanism towards Sc3+, which was the rate of adsorption is proportional to the concentration of the reactants. In addition, the adsorption of resin for Sc3+ is an endothermic reaction by calculating the thermodynamic parameters, and there is a 3.6% difference in adsorption efficiency between the two cycle experiments. In a word, the TP207 resin is a very promising adsorbent for Sc beneficiation from the HCl system.

Selective biosorption and recovery of scandium using the alga Fucus vesiculosus

The goal of this work was to study the viability of the application of biosorption using the brown alga Fucus vesiculosus in the recovery of scandium from red mud. The highest affinity of the biosorbent for scandium and aluminium was at pH 3. Sorption isotherms fitted to the Langmuir model for scandium and aluminium with adsorption capacities as high as 1.04 mmol·g−1 for both metals but with higher affinity for scandium than for aluminium. The performance of the biomass in fixed-bed columns was evaluated in different experimental conditions (flow rate, bed height and inlet metal concentration). Metal desorption was achieved with different inorganic and organic acids. After three consecutive sorption–desorption cycles using 0.1 N citric acid and deionized water during the regeneration step, the brown alga showed a progressive increase in scandium uptake due to the cross-linking citric acid and the alginate chains. The biomass was characterized before and after biosorption using Fourier transforms infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) coupled with an energy dispersive elemental analyser (EDS). The sorption involves different functional groups, such carboxylate and sulphonic groups by chelation and electrostatic interactions.

Bio-inspired metal extraction: Tailoring peptides for highly selective scandium recovery

Scandium, a pivotal metal with widespread applications, faces challenges in recovery due to its highly dispersed distribution. Biological molecules such as proteins and peptides have shown great potential in the field of metal recovery due to their unparalleled affinity and remarkable selectivity. This research aims to design a scandium-binding peptide by mutating the amino acids and optimizing the structure of the EF-hand peptide derived from lanmodulin, a naturally lanthanides-binding protein. Utilizing computer-aided techniques, three peptides-P1 and its two variants (P2 and P3), were screened and synthesized to characterize their interaction with scandium and other competing metals through circular dichroism (CD), atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR) as well as column adsorption experiments. Results showed that the peptide P2 and P3 exhibited higher affinity to scandium than P1, as a result of the more binding sites and the existence of hydrogen bonds in the peptides. Moreover, scandium could induce the significant change in backbone structure of these peptides, and coordinated with carboxyl groups of aspartic acid and glutamic acid. The column adsorption experiments with immobilized peptide P3 on microbeads revealed that a final scandium purity of 96.71 % was achieved and a enrichment coefficient of > 103 was obtained. This study offers a transformative strategy for selective scandium extraction from complex industrial matrices and lays the foundation for future innovations in green extraction technologies.

The stepwise extraction strategy for selective recovery of scandium from hydrochloric acid leachate of bauxite residue based on reactivity of metal ions

The recovery of Sc from secondary resources such as bauxite residue has received considerable interest. As the main elements in bauxite residue, Fe and Al exhibit significant interference in the selective separation of Sc. Herein this work, a stepwise extraction strategy of Sc from the hydrochloric acid leachate of bauxite residue was proposed based on the differences in reactivity of metal ions. The results show that Fe(III) and Sc(III) can be extracted sequentially with Aliquat 336 and Cyanex 272 from hydrochloric leachate. The separation factors of Fe/Sc, Fe/Al and Sc/Al were up to 4.3 × 104, 4.1 × 104 and 2.6 × 103, respectively. The results of spectroscopic characterization indicate that a cation exchange and coordination occur during the extraction of Sc(III) with Cyanex 272. The Sc(III) complex with Cyanex 272 (H2A2) is presented as ScClA2(HA)2¯. The loaded Aliquat 336 and Cyanex 272 can be stripped with acidified sodium sulfite and oxalic acid, respectively. The extraction-stripping performance of the stepwise separation route was investigated and the extraction efficiency of Fe(III) and Sc(III) can be remained above 97 % after 5 cycles. The proposed strategy has the potential to be considered industrially for the recovery of Sc from bauxite residue and other secondary resources.

Recovery of scandium from Sc-bearing aegirine by Na2CO3 roasting-water washing-H2SO4 leaching process

As one of the most valuable rare earth elements in Bayan Obo tailings, scandium is a vital material broadly used in the fields of aerospace, glass ceramics, petrochemical, and agriculture. As scandium was found primarily in silicate minerals such as aegirine and amphibole in the Bayan Obo rare earth deposit, in order to utilize scandium in aegirine mine, a novel Na2CO3 roasting-water washing-H2SO4 leaching process (NRWHLP) was proposed. This process was found to be feasible based on the results. During the roasting process, scandium entered the NaFeO2 phase which is easily hydrolyzed to a reactive ferric hydroxide phase. In the optimal reaction conditions: roasting with a Na2CO3-to-aegirine molar ratio of 3.2:1 for 150 min at 750 °C, washing twice at 80 °C, leaching with a L/s = 4 and 8 mol/L H2SO4 for 30 min at 80 °C, scandium leaching efficiency can be above 97 %. This study will provide a novel process for the exploitation of scandium and a theoretical basis for future industrial applications of the Bayan Obo rare earth tailings.

Adsorption of Scandium Ions by Amberlite XAD7HP Polymeric Adsorbent Loaded with Tri-n-Octylphosphine Oxide.

In an actual economic context, the demand for scandium has grown due to its applications in top technologies. However, further development of new technologies will lead to an increase in the market for Sc related to such technologies. The present study aims to improve and upgrade existing technology in terms of efficient scandium recovery, proposing a new material with selective adsorptive properties for scandium recovery. To highlight the impregnation of Amberlite XAD7HP resin with tri-n-octylphosphine oxide extractant by the solvent-impregnated resin method, the obtained adsorbent material was characterized by physico-chemical techniques. Further, the specific surface of the adsorbent and the zero-point charge of the adsorbent surface have been determined. Different parameters, such as initial concentration, adsorbent amount, contact time, or temperature, have been studied. The initial pH effect was investigated when a maximum adsorption capacity of 31.84 mg g-1 was obtained at pH > 3, using 0.1 g of adsorbent and a contact time of 90 min and 298 K. An attempt was made to discuss and provide a clear representation of the studied adsorption process, proposing a specific mechanism for Sc(III) recovery from aqueous solutions through kinetic, thermodynamic, and equilibrium studies. Adsorption/desorption studies reveal that the prepared adsorbent material can be reused five times.

Selective Recovery of Scandium (Sc) from Sulfate Solution of Bauxite Residue Leaching Using Puromet MTS9580 Ion-Exchange Sorption

Rare earth elements (REEs) and Sc are concentrated in aluminum production byproducts. The novel REEs recovery approach, which involves leaching with acid at a pH > 3 in the presence of MgSO4, results in the formation of a pregnant leach solution (PLS) with a low concentration of iron (Fe) and titanium (Ti) and a large number of valuable elements. This work studies the application of chelating resin Puromet MTS9580 in the sorption recovery of Sc from sulfate solutions. To analyze the static Sc sorption data, Langmuir, Freundlich, and Temkin isotherm models were used. The Langmuir isotherm model was the best fitted to the experimental data, with a coefficient of determination (R2) of 0.983. The dynamic adsorption experiment was conducted using a PLS and a simulated solution without contaminants. Adsorption of Sc from the simulated solution was better fitted to the Thomas model with a Sc capacity greater than 6.4 mg mL−1. Because Ti had a gradual decrease in C/C0, which the Thomas model was unable to simulate, the modified dose-response (MDR) model fitted better with PLS with a Sc capacity greater than 3.8 mg mL−1. The NaHCO3 solution (200 g L−1) effectively desorbed Sc (>98%) from simulated and PLS solutions after 1.5 h of stirring in a batch mode. After 1.5 h of desorption, the concentration of Sc in the desorption solution was 461.5 mg L−1, while the concentration of Mg and Ti was lower than 200 mg L−1 and 50 mg L−1, respectively.

New insights on scandium separation from scandium concentrate with titanium dioxide wastewater.

In this study, a scandium concentrate with Sc2O3 content of 66.24g/t was obtained from V-Ti magnetite tailings by physical concentration, and the main Sc-bearing minerals were augite and hornblende. A novel process of roasting and leaching was proposed to extract scandium from scandium concentrate with titanium dioxide wastewater. Scandium concentrate was pretreated by roasting, and titanium dioxide wastewater was used to directly leach scandium from the roasted ore. The effects of roasting and leaching parameters such as roasting temperature, roasting time, roasting agents, leaching temperature, leaching time, liquid-to-solid ratio, and leaching agents on scandium separation were thoroughly researched in the experimental procedure. The results show that a scandium leaching efficiency of 85.89% was obtained, and the scandium content of leaching residue decreased to 9.31g/t under the optimal conditions: a roasting temperature of 1123K, a roasting time of 120min, a leaching temperature of 343K, a leaching time of 120min, and a m (titanium dioxide wastewater)∶m (roasted ore)∶m (ammonium fluoride) ratio of 8∶1∶0.09. The main findings of the scandium separation mechanism show that Sc-bearing minerals can effectively decompose and release scandium element after roasting, and created favorable conditions for scandium leaching with titanium dioxide wastewater to achieve the purpose of scandium recovery.

Overview of Technologies Used to Extract Scandium from Secondary Raw Materials

The exceptional mechanical and chemical properties exhibited by scandium, characterized by its low density, high strength, and remarkable resistance to corrosion, have positioned it as a sought-after metal in diverse industrial applications. Consequently, a surge in market demand for scandium has been observed, highlighting its unique attributes compared to other metals. The Republic of Kazakhstan has identified potential sources of scandium in the waste generated by the titanium, uranium, and aluminum industries. By implementing efficient processing techniques for these production wastes, the country can effectively address the deficit of scandium while also mitigating man-made emissions, thus significantly improving the environmental landscape. This article aims to explore and evaluate contemporary methodologies that have been employed for the recovery of scandium from the aforementioned secondary sources. By examining and analyzing these techniques, we can gain insights into the most effective and sustainable approaches to harnessing scandium from waste materials in Kazakhstan. This research not only contributes to meeting market demands but also ensures the responsible utilization of scandium, benefiting not just the country's economy but also its environmental sustainability.

Life cycle assessment of a novel production route for scandium recovery from bauxite residues

Scandium (Sc) has various technological applications, but the concentrations of Sc in ores are low. Both, the mining of low concentrated Sc and the production of industrial-grade Sc are a heavy burden on the environment. Bauxite residue (BR) from alumina production represents one of the major sources of Sc in Europe (Ochsenkühn-Petropulu et al., 1994). The goal of this study is to assess the environmental impacts from cradle to gate of a novel production route developed in the Scandium Aluminium Europe project (SCALE) to extract Sc at concentrations <100 ppm from BR, to concentrate and upgrade it to pure ScF3 and Sc2O3 and ultimately to refine it to an aluminium scandium master alloy with 2 % Sc mass fraction (AlSc2 %). Results show that the global warming potential (GWP), measured in CO2-eq per kg Sc2O3, generated with the novel route is about half the GWP of the state-of-the-art Sc2O3 production from rare earth tailings when applying equal allocation principles. The initial process step to dissolve BR and extract Sc consumes elevated amounts of acid and energy and is responsible for at least 80 % of the route’s total environmental impact. The amount of the generated filter cake (FC) is equal to the amount of the BR input and is a potential resource for cement clinker production. The ecotoxicological study indicates that both FC and BR are slightly ecotoxic.

Recovery of Scandium, Nickel and Cobalt from Hydrometallurgical Waste of Laterite

Recovery of new-energy critical metals including scandium, nickel and cobalt as well as copper and zinc from a neutralization residue produced in laterite hydrometallurgical process has been studied. Effect of leaching parameters such as acid consumption, solution pH and temperature has been investigated. It was found that scandium, nickel, cobalt and copper could be recovered at high efficiencies from the residues by selective leaching using sulphuric acid solutions under ambient conditions, while the co-leaching of impurities including iron, aluminium and silicon was low under the optimal conditions. The nickel, cobalt, copper and zinc in the leaching solution could be further concentrated into mixed sulphides and separated from impurities by sulphide precipitation.

A green extraction process for the selective recovery of Sc(iii) based on hydrophobic betaine derivative ionic liquids.

The efficient extraction recovery of scandium (Sc(iii)) is crucial for its application in high-end technology. Two novel hydrophobic carboxylic acid ionic liquids (ILs), namely, [lauryl betaine][bis(trifluoromethanesulphonyl)imide] ([Laur][Tf2N]) and [cocamidopropyl betaine][bis(trifluoromethanesulphonyl)imide] ([Coca][Tf2N]), were synthesized using two inexpensive amphoteric surfactants as cation sources. [Laur][Tf2N] (257 °C) and [Coca][Tf2N] (251 °C) exhibited good thermal stability and strong hydrophobicity. The viscosity of [Coca][Tf2N] (4.29 × 103 mP s) was higher than that of [Laur][Tf2N] (2.55 × 103 mPa s) at 25 °C. The optimal extraction conditions were an extraction equilibrium time of 40 min, an initial Sc(iii) concentration of 0.001 mol L-1, a sodium nitrate concentration of 0.5 mol L-1, and a pH of 3. The extraction efficiency of [Laur][Tf2N] and [Coca][Tf2N] could even exceed 98.7% and 96.0%, respectively. The cation exchange extraction mechanism was studied by slope analysis, IR spectroscopy and 13C NMR spectroscopy. Sc(iii) extracted using [Laur][Tf2N] and [Coca][Tf2N] could be completely stripped with 0.1 mol L-1 and 0.2 mol L-1 HNO3 once, respectively. The structure of the ILs was not broken after stripping, and the extraction efficiency of the ILs remained almost unchanged after five cycles. In addition, the extraction differences at different pH levels made it possible to separate Sc(iii) from other rare earths using ionic liquids [Laur][Tf2N] and [Coca][Tf2N].

Solvent extraction of scandium from leaching solution of red mud roasted with ammonium sulfate using D2EHPA/TBP

Red mud is an important secondary resource for scandium production. The red mud leaching solution containing scandium in this study was derived from environmentally friendly ammonium sulfate roasting and water leaching process. A synergistic extraction with a mixture of di(2-ethylhexyl) phosphate acid (D2EHPA) and tributyl phosphate (TBP) for recovery of scandium from red mud leaching solution is proposed. The effects of D2EHPA concentration, H2SO4 concentration, rare earth elements, dosage of TBP, phase ratio (A/O), contact time and H2O2 concentration on scandium extraction were investigated. The results show that more than 99% scandium is extracted under the optimal conditions while Fe, Al, Ti, Ca and rare earth elements (Ce, Y, La, Nd, Er, etc.) are hardly extracted. The stripping efficiency of Sc reaches above 92.37% under the optimal stripping conditions of 5 mol/L NaOH with an A/O of 1 at 90 °C for 30 min. The proposed technology could provide an effective method for extraction of scandium from red mud leaching solution.

Highly selective extraction of scandium(III) from rare earth elements using quaternary ammonium based ionic liquids: Experimental and DFT studies

Global demand for rare earth elements (REEs) is steadily increasing, emphasizing the necessity of effective extraction and recovery methods. Although REEs recovery from electronic waste using ionic liquid (IL) extractants offers an alternative solution to avoid potential adverse environmental impacts during traditional mining and processing, highly efficient and selective extraction is still essential. Especially, due to similarities with other REEs, recovery of scandium (Sc(III)) is confronting grand challenges. Herein, quaternary ammonium based ILs (QA-ILs), i.e., [N333 MeOAc][Tf2N] and [N444 MeOAc][Tf2N], have been successfully synthesized for selective Sc(III) extraction from other REEs under various conditions, e.g., initial acidity and IL concentration. Both ILs demonstrate superior selectivity for Sc(III) extraction from other REEs. Specifically, at pH 4.5 and 5, the extraction efficiency of Sc(III) using [N333 MeOAc][Tf2N] was 73.6 % and 83.4 %, respectively, while it was high up to 90.5 % and 95.9 %, respectively, using [N444 MeOAc][Tf2N]. Because of stronger hydrophobicity, [N444 MeOAc][Tf2N] exhibited a higher extraction efficiency. Furthermore, [N444 MeOAc][Tf2N] demonstrated a higher selectivity for Sc(III) as compared to other REEs, with high separation factor of 17 for Sc(III)/Lu(III) and Sc(III)/Yb(III). Additionally, the ILs can be recycled with a high stripping efficiency up to 86 % using 4 mol·L−1 H2SO4 solution. Density functional theory calculations further validated neutral exchange of Sc(III) in the neutral IL extraction process. This study presents a feasible solvent extraction system using novel QA-ILs for highly effective and selective Sc(III) extraction from waste streams.

Sustainability analysis for scandium recovery from secondary sources

Primary aluminium industry is one of the largest industries associated with high greenhouse gas emissions. It is reported that in 2022, the aluminium production emitted nearly 270 Mt of direct CO2 in the atmosphere. To achieve the European goals of zero emissions by 2050, a reduction of 4% annually is essential. Τhe industry needs to take a turn towards less impactful production practices, focusing on the valorisation of residues for promoting sustainability. Bauxite residue from alumina production represents a remarkable source of Rare Earth Elements (REEs). This study offers valuable insights into the environmental and economic aspects of processes related to resource Scandium (Sc) extraction and processing in Greece, Romania and Turkey. In this frame, a comparative analysis of the environmental impact of the extraction process of REEs from Bauxite Residues (BR) in the regions mentioned above is presented. The results show that an up to 23% greenhouse gas emissions reduction can be achieved, while the environmental categories of human health risks, aquatic toxicity potential, and terrestrial ecotoxicity potential are improved by applying hydrothermal processes and direct leaching to BR. While the stages of Sc extraction remain consistent, variations in the chemical compositions of BR underscore the influence of local factors. The findings also emphasize the importance of tailoring extraction processes to local conditions and compositions for scandium extraction. These insights can guide industry decisions and contribute to responsible resource management in the future.

Assessing the Efficiency of Ion Exchange Resins for the Recovery of Scandium from Sulfuric Acid Leaching Solutions

Scandium, a valuable element with restricted production sources mainly situated in China and Russia, is typically obtained as a by-product during the production of various materials. As the demand for scandium grows in the expanding aluminum and fuel cell industries, and with significant investments in rare earth mining in the USA and Australia, there is a need to explore alternative recovery sources. This research investigates the recovery of scandium from an acid pregnant leaching solution using ion exchange resins. The pregnant leaching solution was obtained after the leaching of bauxite residue with sulfuric acid. Commercial resins with different functional groups were tested for their performance in scandium extraction. In addition, the co-adsorption of impurities, such as iron and titanium, was studied. The feed solution consisted of 12.7 mg/L Sc and main impurities of 272 mg/L Fe and 33.6 mg/L Ti and was pretreated before the ion exchange process by acidification with sulfuric acid and iron powder addition to suppress silica gel formation and minimize the Fe(III) content in the solution accordingly. Among the tested resins, a D2EHPA-impregnated resin had high selectivity for Sc towards Ti, while a monophosphonic resin was also a promising option since it had a higher capacity for Sc but co-extracted Ti. These findings offer promising opportunities for the recovery of scandium from acid leaching solutions and could contribute to addressing the growing demand for this valuable element.

Separation and recovery of titanium and scandium from the red mud

In this study, a full process in recovery of titanium and rare earth elements (REEs) from the red mud was developed. The suggested route consists of four main stages in the process flow diagram: sample preparation, leaching, hydrolysis, and solvent extraction. Sample preparation is proposed using a two-stage water washing followed by calcination to remove the acid-consuming components of the red mud. Dissolution of the Ti and REEs (with a focus on Sc) was developed using sulfuric acid followed by a hydrolysis process for the titanium precipitation. Concentration of the REEs in the solution was performed using a solvent extraction process. The dissolution efficiency of Ti and Sc were found 91 % and 93 %, respectively. Ti precipitation efficiency was about 86 %, and the final TiO2 product had a purity of 92 %, with the main impurities of a mixed iron and titanium oxide. After recovering Ti, Sc concentration using solvent extraction was studied. Using D2EHPA and alkaline stripping, Sc was concentrated from 69 ppm in the red mud to 1125 ppm in the obtained precipitate. The proposed process has the potential to be considered industrially due to its relative simplicity, high recovery yield, integrity, and utilization of low-cost reagents.

Ecotoxicity attenuation by acid-resistant nanofiltration in scandium recovery from TiO2 production waste

The lack of high-grade scandium (Sc) ores and recovery strategies has stimulated research on the exploitation of non-ore-related secondary sources that have great potential to safeguard the critical raw materials supply of the EU's economy. Waste materials may satisfy the growing global Sc demand, specifically residues from titanium dioxide (TiO2) production. New technologies are being developed for the recovery of Sc from such residues; however, the possible environmental impacts of intermediary products and residues are usually not considered. In order to provide a comprehensive ecotoxicity characterisation of the wastes and intermediate residues resulting from one promising new technology, acid-resistant nanofiltration (arNF), a waste-specific ecotoxicity toolkit was established. Three ecotoxicity assays were selected with specific test parameters providing the most diverse outcome for toxicity characterisation at different trophic levels: Aliivibrio fischeri (bacteria) bioluminescence inhibition (30 min exposure), Daphnia magna (crustacean) lethality and immobilisation (24 h exposure) and Lemna minor (plant) growth inhibition with determination of the frond number (7 d exposure). According to our results, the environmental impact of the generated intermediate and final residues on the aquatic ecosystem was mitigated by the consecutive steps of the filtration methods applied. High and statistically significant toxicity attenuation was achieved according to each test organism: toxicity was lowered based on EC20 values, according to the A. fischeri bioluminescence inhibition assay (by 97%), D. magna lethality (by 99%) and L. minor frond number (by 100%), respectively, after the final filtration step, nanofiltration, in comparison to the original waste. Our results underline the importance of assessing chemical technologies' ecotoxicological and environmental impacts with easy-to-apply and cost-effective test methods to showcase the best available technologies.