Hydrometallurgical Separation of Niobium and Tantalum: A Fundamental Approach

Nete, M.; Purcell, Walter; Nel, J.T.

doi:10.1007/s11837-015-1711-2

Cited by 28 publications

(25 citation statements)

References 21 publications

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“…The classical route would involve dissolving the slag in HF/H 2 SO 4 , extraction with organic solvents, and re-extraction with ammonium salts (NH 4 F plus NH 3 ). This would allow recovery of salts of the K 2 Ta 2 O 3 F 6 and Nb 2 O 5 ·nH 2 O type, from which the desired Nb and Ta oxides could be obtained [33].…”

Section: Discussionmentioning

confidence: 99%

Recovery and Purification of Tin from Tailings from the Penouta Sn–Ta–Nb Deposit

et al. 2018

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A concentrate obtained from mining tailings containing mainly cassiterite and columbotantalite was reduced for the production of tin metal. The compounds CaCO 3 , Na 2 CO 3 , K 2 CO 3 , and borax were used as fluxes in the pyrometallurgical reduction smelting process, and graphite was employed as the reducing agent. The greatest recovery of Sn (>95%) was obtained when using CaCO 3 as the flux; the purity of Sn was 96%. A slag equivalent to 25% of the mass of the initial concentrate was produced during the recovery of the Sn. This contained 45% Nb 2 O 5 and Ta 2 O 5 , adding extra value to the mine tailings. The tin metal ingot was purified by electrorefining involving a tin and H 2 SO 4 electrolyte solution and a 101.9 A/m 2 current applied for 148 h. Under these conditions, 90 wt % of the Sn in the ingot was recovered at a purity of 99.97%.

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Section: Discussionmentioning

confidence: 99%

Recovery and Purification of Tin from Tailings from the Penouta Sn–Ta–Nb Deposit

et al. 2018

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“…Although the molar mass of Ta 6 is about twice higher that than of Nb 6 , they both exhibit a rather identical hydrated radius. This similar radius also complicated the analytical separation of both compounds in previously tested techniques [1,2,4]. As stated above, the physicochemistry of tantalum and niobium was studied earlier and it was proven that, in addition to their UV absorption, the hexaniobate and hexatantalate ions, which are naturally formed at pH above 9, have readily different electrophoretic mobilities and can thus be separated by means of CE methods [9,15].…”

Section: Introductionmentioning

confidence: 99%

“…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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“…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%

“…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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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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Hydrometallurgical Separation of Niobium and Tantalum: A Fundamental Approach

Cited by 28 publications

References 21 publications

Recovery and Purification of Tin from Tailings from the Penouta Sn–Ta–Nb Deposit

Recovery and Purification of Tin from Tailings from the Penouta Sn–Ta–Nb Deposit

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

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

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