Efficient and Selective Recovery of Trace Scandium by Inorganic Titanium Phosphate Ion-Exchangers from Leachates of Waste Bauxite Residue

Zhang, Wenzhong; Koivula, Risto; Wiikinkoski, Elmo Werneri; Xu, Jü; Hietala, Sami; Lehto, Jukka; Harjula, Risto

doi:10.1021/acssuschemeng.6b02870

Cited by 69 publications

(55 citation statements)

References 60 publications

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“…Selectivity of the SILP for Sc(III) over other REEs was therefore not superior to previously reported metal phosphate ion-exchangers applied for Sc(III) recovery from bauxite residue. 75,76 However, results imply that the SILP could be used for adsorption of REEs from acidic media and then Sc(III) could be further separated from other elements in a chromatography column (aer optimizing chromatographic conditions such as proper eluent, ow rate etc. ).…”

Section: Effect Of Interfering Ionsmentioning

confidence: 99%

Recovery of scandium(iii) from diluted aqueous solutions by a supported ionic liquid phase (SILP)

2017

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The adsorption of scandium from diluted, acidic solutions by a supported ionic liquid phase (SILP) was investigated, as part of a process for recovery of scandium from bauxite residue (red mud). Both dry impregnation and covalent linking were studied for the SILP preparation. The SILP betainium sulfonyl(trifluoromethanesulfonylimide) poly(styrene-co-divinylbenzene) [Hbet-STFSI-PS-DVB] was prepared by covalent linking of the ionic liquid to the resin and this resulted in an adsorbent suitable for scandium recovery. For a chloride feed solution, the effects of pH, contact time, adsorption capacity, desorption, reusability of adsorbent and the influence of Fe(III), Al(III) and Ca(II) on the Sc(III) adsorption were studied. The adsorption of Sc(III) from nitrate and sulfate feed solution under optimal conditions was studied as well. The adsorption kinetics followed a pseudo-second order kinetic model. Equilibrium studies at room temperature showed that the experimental data could be well fitted by the Langmuir isotherm model. The stripping of Sc(III) from the loaded SILP was achieved with 1 M sulfuric acid. The SILP was stable and could be reused for seven adsorption/desorption cycles without significant losses in its adsorption efficiency for Sc(III). IntroductionScandium belongs to the group of rare-earth elements (REEs) and nds applications in aluminum alloys, halide lamps and fuel cells.1 However, it is an expensive metal with small global production volumes. Although scandium is relatively abundant in the Earth's crust (22 ppm), there are few scandium minerals and it rarely occurs in rich ore deposits. It is mainly recovered as by-product from the production of other metals (REEs, U, Ti, W, Al, Ni, Ta and Nb).2-4 Bauxite residue (red mud), the waste industrial product of the Bayer process for alumina production from bauxite ore, can contain up to 130 ppm of scandium and it is potentially a valuable scandium resource.5,6 Scandium can partially be recovered from bauxite residue by acid leaching. Typically, in this way many metal impurities go into the leachate as well and in concentrations much higher than that of scandium. 1,7,8 Liquid-liquid extraction is used for the recovery of Sc(III), 9 but it requires much higher initial concentrations of Sc(III) than the ones that can be found in the pregnant leach solutions.1 Nevertheless, for recovery of low concentrations of Sc(III) its enrichment with a selective adsorbent in high capacity ion exchange columns could be an efficient technique. Much of the research work on Sc(III) recovery by adsorption and extraction has been performed with resins, View Article OnlineView Journal | View Issue components can contaminate the aqueous effluents. 37 In the second class of SILPs there is no discrete IL phase in the structure of the solid support. Instead, the IL can be considered as a covalently anchored ligand. Covalent linking ensures that the IL will not be leached from the support. 32,40The objective of this work is to develop a stable SILP for the adsorption of Sc(III...

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Section: Effect Of Interfering Ionsmentioning

confidence: 99%

Recovery of scandium(iii) from diluted aqueous solutions by a supported ionic liquid phase (SILP)

2017

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“…Previously, complete or partial recovery of Sc from bauxite residues was reported to be achieved mainly by solvent extraction, ion exchange, or the combination of these two techniques, as a result of its low concentration in the leachates [14][15][16][17][18][19][20]. Zhang et al recovered 91% of Sc from bauxite residue leachates by inorganic metal(IV)-phosphate ion exchangers, although Fe(III) was found to be an interfering ion in this process [20].…”

Section: Introductionmentioning

confidence: 99%

“…Zhang et al recovered 91% of Sc from bauxite residue leachates by inorganic metal(IV)-phosphate ion exchangers, although Fe(III) was found to be an interfering ion in this process [20]. In another study, a newly developed supported ionic liquid phase (SILP) achieved almost complete Sc extraction, while showing a decreased efficiency in the presence of Fe(III) [14].…”

Section: Introductionmentioning

confidence: 99%

Effect of Aqueous Media on the Recovery of Scandium by Selective Precipitation

Yagmurlu

Dittrich²,

Friedrich

2018

Metals

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This research presents a novel precipitation method for scandium (Sc) concentrate refining from bauxite residue leachates and the effect of aqueous media on this triple-stage successive precipitation process. The precipitation pattern and the precipitation behavior of the constituent elements was investigated using different precipitation agents in three major mineral acid media, namely, H 2 SO 4 , HNO 3 , and HCl in a comparative manner. Experimental investigations showed behavioral similarities between HNO 3 and HCl media, while H 2 SO 4 media was different from them because of the nature of the formed complexes. NH 4 OH was found to be the best precipitation agent in every leaching media to remove Fe(III) with low Sc co-precipitation. To limit Sc loss from the system, Fe(III) removal was divided into two steps, leading to more than 90% of Fe(III) removal at the end of the process. Phosphate concentrates were produced in the final step of the precipitation process with dibasic phosphates which have a strong affinity towards Sc. Concentrates containing more than 50% of ScPO 4 were produced in each case from the solutions after Fe(III) removal, as described. A flow diagram of the selective precipitation process is proposed for these three mineral acid media with their characteristic parameters.

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“…Following on from leaching, the dissolved metals must be selectively separated and recovered, most commonly in the form of oxides. In the REDMUD project, this is being undertaken using selective precipitation and solvent extraction [28,32], column separation [33], and supported ionic liquid phases (SILPs) [34,35].…”

Section: Minor Metals: Titanium Scandium and Reesmentioning

confidence: 99%

Using Life Cycle Thinking to Assess the Sustainability Benefits of Complex Valorization Pathways for Bauxite Residue

Joyce

Björklund

2019

J. Sustain. Metall.

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Bauxite residue, the main waste product of alumina production, is a potentially valuable secondary resource. The MSCA-ETN REDMUD project aims to develop environmentally friendly technologies to realize this value, by extracting valuable metals (aluminium, iron, titanium, scandium, rare-earth elements) or utilizing it in construction applications. Simply utilizing a waste product as an input is not, however, sufficient to claim that a process is environmentally friendly; the processes developed must be demonstrably better for the environment, from a life cycle perspective, than business as usual. The earlier in the research and development process that environmental information can be taken into account, the more impact it can have on decision-making. In this study we demonstrate that Life Cycle Thinking approaches can provide actionable environmental information at an early stage in the research process, and that in doing so it can help steer early stage technology development towards overall improved industry environmental performance. Knowledge of the potential environmental benefit from displacing different materials can help identify primary or additional targets, for example the use of metal extraction residues for construction materials. A high-level 'red flags' assessment of the relative environmental impact of inputs to valorization processes and the products they displace can be used to identify problematic inputs and processes in the absence of quantitative details. Finally, once preliminary quantitative data are available for a process, streamlined Life Cycle Assessment can be used to calculate the environmental balance of a process, and identify specific hotspots of environmental impact.

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Efficient and Selective Recovery of Trace Scandium by Inorganic Titanium Phosphate Ion-Exchangers from Leachates of Waste Bauxite Residue

Cited by 69 publications

References 60 publications

Recovery of scandium(iii) from diluted aqueous solutions by a supported ionic liquid phase (SILP)

Recovery of scandium(iii) from diluted aqueous solutions by a supported ionic liquid phase (SILP)

Effect of Aqueous Media on the Recovery of Scandium by Selective Precipitation

Using Life Cycle Thinking to Assess the Sustainability Benefits of Complex Valorization Pathways for Bauxite Residue

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