Separation of niobium and tantalum from Mozambican tantalite by ammonium bifluoride digestion and octanol solvent extraction

Kabangu, M. J.; Crouse, Philip

doi:10.1016/j.hydromet.2012.06.008

Cited by 54 publications

(27 citation statements)

References 9 publications

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“…The status of tantalum as a metal derived from a conflict mineral [7], combined with its low abundance in the earth's upper crust means there is a need to design a sustainable closed-loop process to recycle tantalum from waste capacitors. Due to its very low solubility in typical mineral acids such as HCl, H 2 SO 4 , and HNO 3 compared with other d-block elements, current hydrometallurgical processes for tantalum involve the use of highly corrosive and toxic solutions of concentrated HF, combined with H 2 SO 4 [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

Kinsman

Crevecoeur

Singh-Morgan

et al. 2020

Metals

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The recycling of tantalum (Ta) is becoming increasingly important due to the criticality of its supply from a conflict mineral. It is used extensively in modern electronics, such as in capacitors, and so electronic waste is a potentially valuable secondary source of this metal. However, the recycling of Ta is difficult, not least because of the challenges of its leaching and subsequent separation from other metals. In this work, we show that Ta(V) halides, such as TaCl5 and TaF5, which can potentially be accessed from Ta metal upon acid halide leaching, can be recovered by solvent extraction using a simple primary amide reagent. The need for high halide concentrations in the aqueous phase implies the formation of the hexahalide salts [TaX6]− (X = F, Cl) and that an anion-swing mechanism operates. While extraction of the fluorides is poor (up to 45%), excellent extraction under chloride conditions is found (>99%) and presents an alternative route to Ta recycling.

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Section: Introductionmentioning

confidence: 99%

“…Subsequent back extraction (stripping) of the metalate into a fresh aqueous phase is possible with water or dilute HCl. [8][9][10][11]. As such, it is evident that there is a need to develop more sustainable processes which can not only efficiently recycle tantalum from secondary sources but do so using milder reagents [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

Kinsman

Crevecoeur

Singh-Morgan

et al. 2020

Metals

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“…Currently, all the commercialized solvent extraction processes for the Nb-Ta separation are operated in fluoride media and an intensive effort is still being made to improve the Nb-Ta separation by liquid-liquid extraction in such media. These processes typically require an aqueous phase composed of a mixture of HF or NH 4 F and a mineral acid such as H 2 SO 4 or HCl in the range of 1 to 10 mol.L -1 [9,10,[12][13][14][15][16][17][18]. Moreover, the fluoride processes are only appropriate for high-grade Nb-Ta concentrates [19].…”

Section: Introductionmentioning

confidence: 99%

A fluoride-free liquid-liquid extraction process for the recovery and separation of niobium and tantalum from alkaline leach solutions

Deblonde

Bengio²,

Beltrami³

et al. 2019

Separation and Purification Technology

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The production of high purity niobium (Nb) or tantalum (Ta) compounds still relies on processes that require highly acidic conditions and concentrated HF or NH 4 F solutions. Recent progress in the chemistry of group V elements, along with the evolution of the environmental concerns, call for the development of more sustainable industrial processes for these strategic elements. In sharp contrast with the historical fluoride approach chosen by the Nb and Ta refining industry, there has been a recent surge in the literature concerning the chemistry of these elements in diluted alkaline or oxalate media. We here propose an innovative liquid-liquid extraction process that is amenable to separate Nb and Ta from alkaline feed solutions, can be operated at low acidity and that does not require any fluoridebased chemical. The developed strategy is as follows: first, Nb and Ta are co-extracted from their alkaline solution (pH 12) using a quaternary ammonium salt (Aliquat® 336) dissolved in an organic diluent; then, Nb is selectively back-extracted in a mixture of diluted nitric and Page 2/31 oxalic acids; and finally, Ta is stripped in a diluted nitric media. The process also affords purifying Nb from Ti, Fe and Na. Following an optimization at laboratory scale, the full process has been validated during continuous running tests (160 h at 1.4 L.h-1) using industrial Nb-Ta caustic solutions coming from the development of the so-called Maboumine process. The developed process works at room temperature, low acidity ([H + ] < 1 M), exhibits high recovery yields, and allows producing Nb 2 O 5 •nH 2 O with purity higher than 99.5 %. The process also yields a tantalum product (Ta 2 O 5 •nH 2 O with >20 wt% Ta) even when starting from a diluted feed (39 ppm Ta). The proposed strategy paves the way for new Nb and Ta hydrometallurgical processes operating under mild chemical environments and represents a concrete alternative to the current fluoride-intensive industrial methods. Highlights A new process for separating Nb and Ta in fluoride-free media is proposed High-purity Nb oxide (99.5 %) can be produced Nb and Ta can be recovered and separated starting from an alkaline feed solution The process works at room temperature and under mild chemical conditions

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“…Both metals are found in the same natural source and, because of their almost identical physicochemical features, their separation is challenging and is the subject of many on-going research projects. Multiple techniques, such as High Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance, Raman Spectroscopy, Inductively Coupled Plasma (ICP), and potentiometry were used as analytical tools for these elements [1][2][3][4]. Earlier research on their production processes mainly focused on complexation of both compounds in acidic fluoride-based media [5].…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of niobium and tantalum hexameric forms and their substituted ions by capillary electrophoresis in alkaline medium

Cock

Delaunay

Deblonde

et al. 2017

Talanta

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In this work a capillary electrophoretic (CE) method is used for the kinetic study of the intermetallic substitutions in hexameric ions of two strategic metals, tantalum and niobium in an alkaline medium. Recently proposed processes for the production and analytical separation of tantalum and niobium that are faster, more economical and environmental friendly are based on the use of highly alkaline media. It was previously established that in these media, tantalum and niobium exist as hexameric species, HTaO (Ta) and HNb0 (Nb), which can be analysed with a CE method using an alkaline electrolyte and UV detection. However, when using the above method on an industrial sample a minor species that should correspond to the substituted TaNb form was observed. The purpose of the present study is to probe, by means of CE, the kinetic of the formation of substituted niobate-tantalate ions, TaNb (1 ≤ x ≤ 5), starting from mixtures of pure hexaniobate and hexatantalate ions. This study required the development of a new CE method allowing the separation of all the five substituted ions and their two non-substituted hexameric parent ions in less than seven minutes. In details, a previously developed separation method was transferred to a Beckman instrument and the separation improved by adjusting the total length, the applied voltage, the injection volume, the rinsing steps and the internal standard. The kinetic study shows that samples initially containing non-substituted hexameric forms of tantalum and niobium in a 1:1M ratio naturally form the five possible substituted species TaNb (1 ≤ x ≤ 5) after only a few hours which may represent an issue for future Nb-Ta separation processes operated in alkaline media. The developed method was also transferred to an Agilent instrument and the kinetic study repeated. Results obtained with the Agilent instrument corroborate those obtained with the Beckman instrument. The proposed electrophoretic separation method lays the ground for new analytical techniques that could help assessing the presence of substituted species that can be deleterious for Nb-Ta purification processes.

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Separation of niobium and tantalum from Mozambican tantalite by ammonium bifluoride digestion and octanol solvent extraction

Cited by 54 publications

References 9 publications

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

A fluoride-free liquid-liquid extraction process for the recovery and separation of niobium and tantalum from alkaline leach solutions

Kinetic study of niobium and tantalum hexameric forms and their substituted ions by capillary electrophoresis in alkaline medium

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