Niobium and tantalum recovery from the primary source and from tin slag, an industrial challenge: A review

Oliveira, Juliana Mendes de; Anes, Iara Alves; Coleti, Jorge Luís; Crocce, Denise; Espinosa, Romano; Carvalho, None Marcelo Siqueira de; Tenório, Jorge Alberto Soares

doi:10.1002/cjce.24621

Cited by 9 publications

(6 citation statements)

References 59 publications

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“…A third source of Ta is residual products (slag) mainly from the processing of cassiterite (SnO 2 ) ore [43]. In these slags, Ta is present together with Nb as pentoxide or (Ta,Nb) 2 O 5 ([44].…”

Section: Background 21 Recovery Routes For Tamentioning

confidence: 99%

Behavior of Tantalum in a Fe-Dominated Synthetic Fayalitic Slag System—Phase Analysis and Incorporation

Schirmer,

Hiller,

Weiss

et al. 2024

Minerals

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Pyrometallurgical processes produce slags that may contain valuable elements because of their high oxygen affinity. However, the concentration is extremely low, which causes losses. In fact, these elements, for example, tantalum and rare earth elements, are less than 1% recycled. To return such technologically important elements to the material cycle, pyrometallurgically is used to enrich them in the simplest possible compounds within the slag, which have favorable properties for recovery (morphology, crystal size, magnetic properties), allowing further mechanical separation. The purpose of modification of the slag system is to obtain engineered artificial minerals” (EnAM), a process in which targeted minerals with high element concentration are formed. In this article, this approach is investigated using tantalum-rich fayalitic slag, since this slag is commonly found in the industry for the pyrometallurgical treatment of waste electric and electronic equipment. Synthetic fayalitic slags in reducing environment under different cooling rates were produced with Ta addition. The characterization of the produced samples was carried out using powder X-ray diffraction (PXRD) and electron probe microanalysis (EPMA). Additionally, the speciation of Fe and Ta was accessible through X-ray absorption near-edge structure (XANES) spectroscopy. EPMA also provided a semiquantitative assessment of the Ta distribution in these individual compounds. In these slags, tantalum accumulated in perovskite-like oxidic and silicate compounds as well as in magnetic iron oxides. The enrichment factor is highest in tantalite/perovskite-type oxides (FexTayO6, CaxFeyTazO3) with up to 60 wt.% Ta and ‘tantalomagnetite’ (FeII(FeIII(2−5/3xTax)O4) with a maximum of ~30 wt.% Ta (only fast cooling). This is followed by a perovskite-like silicon containing oxide (XYO3) with 12–15 wt.% Ta (only slow cooling), and a hedenbergite-like compound (XYZ2O6) with a varying content of 0.3–7 wt.%. The Ta concentration in pure Fe, Fe(1-x)O, hercynitic spinel and hematite is negligible. Despite the very low phase fraction, the most promising EnAM compound is nevertheless perovskite-like tantalum oxide, as the highest enrichment factor was obtained. Tantalum-rich magnetite-like oxides also could be promising.

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Section: Background 21 Recovery Routes For Tamentioning

confidence: 99%

Behavior of Tantalum in a Fe-Dominated Synthetic Fayalitic Slag System—Phase Analysis and Incorporation

Schirmer,

Hiller,

Weiss

et al. 2024

Minerals

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“…This work comes as a tool to guide the development of new methods to recover Nb and Ta from low‐grade sources such as tin slag (as shown in Figure 3). [ 2 ]…”

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confidence: 99%

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2023

Can J Chem Eng

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“…[16] Hydrofluoric, hydrochloric, sulphuric, and nitric dissolutions have been performed in order to extract Nb from tin slags. [12,[17][18][19][20][21][22] The slag from tin ores processing is further present in its high proportion of composition silicon, which can likely make the dissolution of Nb and Ta using hydrofluoric acid (HF) economically inviable once this acid reacts with silicates, needing a more significant quantity to react with the metals. [10] It is known that HF has several issues regarding its use, such as the notorious harmful and toxic aspect due to gas emissions resulting from its use.…”

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confidence: 99%

Extraction of niobium in one step from tin slag by NH₄F‐HCl leaching process

et al. 2023

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Niobium and tantalum are generally found together in nature in ores such as columbite, tantalite, and pyrochlore. These ores can occasionally associate with cassiterite, the tin ore. The pyrometallurgical processes of cassiterite produces a slag that can contain Nb and Ta from the associated ores. Cassiterite processing for tin extraction has generated a considerable quantity of residue. This work aims to study the extraction of Nb from tin slag while leaving the Ta solid. The process of separation consists in one step by leaching using a combined solution of HCl‐NH4F. The slag was characterized by X‐ray fluorescence (EDXRF), atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectrometry (ICP‐OES), X‐ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and granulometric analysis. The effect of parameters of the leaching processes was investigated, such as the time of the process, HCl concentration, liquid‐to‐solid ratio, temperature, and salt‐to‐slag ratio. It was possible to recover 100% of Nb and 5% of Ta in liquor of leaching within 4 h, at 85°C, using an L:S ratio of 20:1, NH4F:slag ratio of 0.12 g, and HCl concentration equal to 9.79 mol/L.

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Niobium and tantalum recovery from the primary source and from tin slag, an industrial challenge: A review

Cited by 9 publications

References 59 publications

Behavior of Tantalum in a Fe-Dominated Synthetic Fayalitic Slag System—Phase Analysis and Incorporation

Behavior of Tantalum in a Fe-Dominated Synthetic Fayalitic Slag System—Phase Analysis and Incorporation

Issue Highlights

Extraction of niobium in one step from tin slag by NH₄F‐HCl leaching process

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Niobium and tantalum recovery from the primary source and from tin slag, an industrial challenge: A review

Cited by 9 publications

References 59 publications

Behavior of Tantalum in a Fe-Dominated Synthetic Fayalitic Slag System—Phase Analysis and Incorporation

Behavior of Tantalum in a Fe-Dominated Synthetic Fayalitic Slag System—Phase Analysis and Incorporation

Issue Highlights

Extraction of niobium in one step from tin slag by NH4F‐HCl leaching process

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Extraction of niobium in one step from tin slag by NH₄F‐HCl leaching process