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Roberta L Flemming - One of the best experts on this subject based on the ideXlab platform.
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solubility of wodginite titanowodginite microlite pyrochlore columbite mn and Tantalite mn in flux rich haplogranitic melts between 700 and 850 c and 200 mpa
Lithos, 2020Co-Authors: Alysha G Mcneil, Robert L Linnen, Roberta L FlemmingAbstract:Abstract Ore minerals of niobium and tantalum are typically associated with pegmatites and rare metal granites; these include columbite, Tantalite, wodginite, titanowodginite, microlite and pyrochlore. Solubility and crystallization mechanisms for columbite-(Mn) and Tantalite-(Mn) have been extensively studied in haplogranitic melts, with little research into other ore minerals. In this study the solubilities of wodginite, titanowodginite, microlite and pyrochlore are compared to those for columbite-(Mn) and Tantalite-(Mn) in a flux-rich haplogranitic melt of alumina saturation index (ASI) 1.0 (ASILi of 0.83) at 700–850 °C and 200 MPa. The effect of melt composition on the solubilities of wodginite, titanowodginite, and microlite compared to Tantalite-(Mn) is also investigated in highly fluxed haplogranitic melts of ASI 1.0, 1.10, and 1.24 (ASILi of 0.83, 0.90, 1.02), at 700 °C and 800 °C and 200 MPa. The log solubility product (logKsp) at 750 °C and melt ASI of 1.0 is highest for Tantalite-(Mn) (−2.32 mol2/kg2) followed by columbite-(Mn) (−2.68 mol2/kg2), and pyrochlore (−3.71 mol3/kg3) titanowodginite (−3.73 mol3/kg3), wodginite (−3.77 mol3/kg3), and microlite (−3.78 mol3/kg3), the latter four of which are almost identical within error. However, solubility can also be expressed as a mineral-melt partition coefficient, with higher partition coefficients reflecting lower solubilities. The tantalum mineral-melt partition coefficients of wodginite (27.0), titanowodginite (30.2), and Tantalite-(Mn) (29.6) are identical within error; microlite is higher (80.3, reflected by lower concentrations of tantalum in the melt for stoichiometric saturation) because it contains a major melt cation, sodium. The niobium mineral-melt partition coefficient for columbite-(Mn) (66.1) is higher than for pyrochlore (50.1). Wodginite, titanowodginite, pyrochlore, columbite-(Mn) and Tantalite-(Mn) have similar temperature and melt composition dependences, but conversely, microlite solubility increases with ASI. As all studied minerals have been shown to have similar relative solubilities at stoichiometric saturation, it can be concluded that, in general, the presence of bivalent (Ca, Mn, Fe) and some tetravalent cations (Sn, Ti) control which tantalum and niobium phases crystallize in rare metal deposits.
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hydrothermal synthesis of columbite mn Tantalite mn hafnon and zircon at 800 850 c and 200 mpa
Canadian Mineralogist, 2015Co-Authors: Alysha G Mcneil, Robert L Linnen, Roberta L FlemmingAbstract:Fully ordered columbite-(Mn), Tantalite-(Mn), hafnon, and zircon were successfully synthesized using an acid solution of 6N:1N (N = normal) HF:H 2 SO 4 and stoichiometric oxide mixtures. The mixtures and solutions were sealed and placed in rapid-quench cold-seal pressure vessels (CSPV) at 800–850 °C and 200 MPa. Mineral structures and compositions have been confirmed by scanning electron microscope (SEM), micro X-ray diffraction (μXRD), and electron probe microanalysis (EPMA). The unit cell parameters of the minerals determined by μXRD: Orthorhombic ( Pbcn ) columbite-(Mn) a 14.434(2), b 5.768(1), c 5.084(1) A; orthorhombic ( Pbcn ) Tantalite-(Mn) a 14.457(3), b 5.773(1), c 5.096(1) A; tetragonal hafnon ( I 4 1 /amd ) a 6.582(2), c 5.9702(1) A; and tetragonal zircon ( I 4 1 /amd ) a 6.607(4), c 5.9898(2) A. The chemical formulae as determined by EPMA are very close to stoichiometric: Mn 0.96 Nb 2.02 O 6 , Mn 0.99 Ta 2.01 O 6 , Hf 0.99 Si 1.01 O 4 , and Zr 1.00 Si 1.00 O 4 , respectively.
Rucheng Wang - One of the best experts on this subject based on the ideXlab platform.
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U-Pb isotopic dating of columbite-Tantalite minerals: Development of reference materials and in situ applications by ion microprobe
Chemical Geology, 2019Co-Authors: Hélène Legros, Rolf L Romer, Julien Mercadier, Johan Villeneuve, Etienne Deloule, Marieke Van Lichtervelde, Stijn Dewaele, Philippe Lach, Xudong Che, Rucheng WangAbstract:Columbite-Tantalite group minerals are the most common Nb-Ta minerals. Columbite-Tantalite is particularly suitable for U-Pb dating due to its high U and low common Pb contents. In situ isotopic dating of columbite-Tantalite by LA-ICP-MS or SIMS requires certified reference material to properly account for potential matrix effects linked to substitutions between Nb and Ta and between Mn and Fe. Our study has two objectives: i) establish a database of reference materials for in situ U-Pb isotopic dating of columbite-Tantalite minerals and ii) test the capability of SIMS to in situ U-Pb date columbite-Tantalite minerals of different chemical composition. Tests of in situ U-Pb dating demonstrate that SIMS can easily be used to date columbite-Tantalite minerals with errors and precisions overlapping the reference ID-TIMS age. There are, however, significant matrix effects for non-matching Nb-Ta-Fe-Mn compositions of sample and reference material. Matrix effects are highly correlated with the Ta/(Ta + Nb) ratio of columbite-Tantalite, due to the significant difference in the atomic mass of Nb and Ta. The Mn/(Mn + Fe) ratio does not significantly contribute to the observed matrix effect as the two elements have similar atomic masses. The linear correlation between Ta/(Nb + Ta) and ((206Pb/238U)SIMS/(206Pb/238U)ID-TIMS) obtained for columbite-Tantalite minerals of known ID-TIMS age demonstrates that the SIMS matrix-effect can be properly accounted for by using the chemical composition as determined by EMPA. The ability to measure 204Pb by SIMS also allows the use of reference materials with a small common lead contribution and to calculate accurate and precise ages for columbite-Tantalite minerals with contributions of common lead.
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chemical evolution and late stage re equilibration of zr hf u bearing columbite group minerals in the koktokay no 1 granitic pegmatite altai northwestern china
Canadian Mineralogist, 2015Co-Authors: Rong Yin, Can Rao, Rucheng Wang, Aicheng Zhang, Jin Chu Zhu, Hui ZhangAbstract:The Koktokay No. 1 pegmatite in northwestern China is a highly fractionated Li-Cs-Ta (LCT) - type granitic pegmatite. As main Nb - Ta oxides in this pegmatite, columbite-group minerals (CGMs) not only display variations in Nb/Ta and Fe/Mn, but also are typified by noticeable Zr, Hf, and U contents. Here, we report on the chemical evolution and late-stage re-equilibration of CGMs in the processes of crystallization and evolution of this pegmatite. Columbite-group minerals record large variations in Ta/(Nb + Ta) values (0.06–0.98) and moderate variations in Mn/(Fe + Mn) values (0.58–0.99), which could be a result of fractional crystallization of pegmatite magma. The concentrations of ZrO 2 , HfO 2 , and UO 2 in CGMs from the contact zone inwards to zone II of this pegmatite are uniformly less than 0.35 wt.%. However, primary Tantalite-(Mn) with Ta/(Nb + Ta) and Mn/(Fe + Mn) values of 0.63–0.98 and 0.86–0.99, respectively, show relatively high contents of ZrO 2 , HfO 2 , and UO 2 , up to 1.68, 0.73, and 1.25 wt.%, respectively. The contents of ZrO 2 , HfO 2 , and UO 2 are positively correlated with variations in Ta/(Nb + Ta) values within different grains and single grains of primary Tantalite-(Mn). Crystal-chemical considerations suggest that Zr, Hf, and U are possibly present in the Tantalite-(Mn) structure due to the substitution 3(Zr,Hf,U) 4+ = 2(Nb,Ta) 5+ + (Fe,Mn) 2+ . In some areas within the primary Tantalite-(Mn) crystals in zone III, specific Tantalite-(Mn) has been identified with sharp but irregular contacts with the host Tantalite. Such Tantalite-(Mn) is chemically depleted in Zr, Hf, and U, but contains many small inclusions of zircon, the MnZrTa 2 O 8 phase, uraninite, and U-rich member of the microlite group of minerals. In a similar way, the primary Zr-Hf-U-bearing Tantalite-(Mn) experienced late-stage local re-equilibration, giving rise to the formation of secondary Zr-Hf-U-depleted Tantalite-(Mn) and other Zr- or U-rich mineral inclusions in an open fluid-mediated system. The behaviors of Zr, Hf, and U in CGMs in the Koktokay No. 1 pegmatite are indicative of Zr, Hf, and U enrichment during fractional crystallization of a highly fractionated pegmatite magma on one hand and imply late-stage activities of fluids on the other. Considerable enrichment of U and Hf in CGMs indicates that this type of mineral may act as a target for in situ LA-ICP-MS U-Pb dating and Lu-Hf isotope measurements, which may provide key information for understanding the source of the magma and the evolution mechanism of the Nb-Ta mineralization.
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complex internal textures in oxide minerals from the nanping no 31 dyke of granitic pegmatite fujian province southeastern china
Canadian Mineralogist, 2009Co-Authors: Can Rao, Rucheng Wang, Wen Lan ZhangAbstract:The Nanping No. 31 granitic pegmatite, a highly evolved spodumene-type pegmatite in the Nanping pegmatite district, southeastern China, can be divided into five internal zones from the border inward: zones I–III as the outer zones and zones IV–V as the inner zones. It is strongly mineralized with Nb–Ta–Sn oxide minerals. We investigated these minerals by using back-scattered electron (BSE) imaging and quantitative electron-microprobe analyses (EMPA) to characterize their complex internal textures. The primary Nb–Ta oxide minerals show a sequence from columbite-(Fe) (zone I) through Tantalite-(Fe) (zone II) to Tantalite-(Mn) (zone III), but distinctly become columbite + wodginite in zone IV and, rarely, columbite in the zone V. Microscopic tapiolite-(Fe) is identified as a product of exsolution in cassiterite from the zones II–III, whereas complex associations of wodginite, columbite–Tantalite and tapiolite-(Fe) are characteristic of cassiterite in zone IV. The classic variation of the columbite-group minerals from the zones I to III seems to result from the greater stability of Tantalite than columbite components during fractional crystallization of the melt. However, decreasing values of Ta/(Nb + Ta) in columbite-group minerals in the inner zones are more probably compensated by crystallization of abundant primary wodginite-group minerals, controlled by the f (O2) of the magma. Columbite-group minerals commonly exhibit zoning, but complex and multiple-generation phenomena are notable in columbite–Tantalite crystals from zones IV–V. In the latter case, later generations of columbite–Tantalite overgrow or cross-cut the earlier ones. Irregular patterns of zoning are linked to the activity of hydrothermal fluids at the late stages of pegmatite evolution. The high mobility of Ta in such fluids is supported by the development of veinlets of Tantalite. They cross-cut first the earlier-formed columbite + wodginite aggregates, and later fill brittle-deformation-induced fissures in the columbite, forming a network texture. The complex internal textures of Nb–Ta–Sn oxide minerals from the zones IV–V indicate a distinctly fluid-rich environment at the late stage of crystallization of the Nanping No. 31 pegmatite.
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chemical evolution of nb ta oxides and zircon from the koktokay no 3 granitic pegmatite altai northwestern china
Mineralogical Magazine, 2004Co-Authors: Aicheng Zhang, Rucheng Wang, Jin Chu Zhu, Hui Zhang, Xiaoming ChenAbstract:The Koktokay No. 3 granitic pegmatite, Altai, northwestern China, is a strongly zoned rare-element granitic pegmatite, where the petrographic zones were distinguished into two groups: outer zones (I to IV) and inner zones (V to IX). Nb-Ta oxides and zircon are investigated in this paper by using quantitative electron-microprobe analyses (EMPA) and backscattered-electron (BSE) imaging. Columbite-Tantalite and zircon occur in most textural zones, whereas tapiolite and uranmicrolite are mainly restricted to zone VII. Manganocolumbite and zircon from the outer zones (zones II and IV) are homogeneous except for a few exceptions, whereas manganoTantalite and hafnian zircon from the inner zones (V–VII) are obviously heterogeneous and strongly zoned. Chemically, Ta/(Nb+Ta) in columbite-Tantalite and Hf/(Zr+Hf) in zircon increase from the outer to the inner zones on one hand, and from core to rim in single zoned crystals on the other hand. Observations of intra-zonal variations of the chemical composition of Nb-Ta oxides and zircon in the Koktokay No. 3 granitic pegmatite may suggest that the outer zones crystallize under magmatic conditions, whereas the inner zones crystallize under fluid-rich magmatic conditions, and locally under hydrothermal conditions. The extreme enrichments of columbite-Tantalite in Ta, and of zircon in Hf, as well as the occurrence of uranmicrolite and tapiolite, indicate an elevated evolution of the Koktokay No. 3 granitic pegmatite.
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Tantalite in suzhou granite mineralogy and geological implications
Chinese Journal of Geochemistry, 1997Co-Authors: Rucheng Wang, Fontan Francois, Chengyi LinAbstract:Tantalite, occurring as intergranular tabular crystals, was reported for the first time in the Suzhou granite. Electron microprobe analyses show that it is rich in W and Ti, with a Ta/(Ta + Nb) ratio ranging from 0.5 to 0.73 and a Mn/(Mn + Fe) ratio between 0.20 and 0.40. It is structurally distinct from isomorphic tapiolite by a remarked Ag Raman peak at 880 cm−1. The associated zircon is striking by significant enrichment of Hf, with the HfO2 content amounting up to 35% – 40%. The discovery of Tantalite suggests that the Suzhou granite should be classified as a S-type granite instead of A-type as considered previously.
J T Nel - One of the best experts on this subject based on the ideXlab platform.
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non fluoride dissolution of tantalum and niobium oxides and their separation using ion exchange
Hydrometallurgy, 2017Co-Authors: M Nete, Walter Purcell, J T NelAbstract:Abstract The study involved the separation of Ta and Nb in a phosphate matrix using ion exchange chromatography. Experimental variations included different types of Ta/Nb containing samples, types of resin, phosphoric acid concentration as eluent, flow rate and column dimensions. Experimental conditions were developed and refined using a pure 1:1 (Ta/Nb) 2 O 5 synthetic mixture and the optimum conditions were then applied to a real Tantalite mineral sample. Experimental results indicated the successful separation of the Ta and Nb in the synthetic sample using the weak basic Dowex Mathon and Dowex 66 free base resins. Almost complete recovery of Nb was achieved with 200 mL of 8 M H 3 PO 4 . It was found that Ta was more strongly absorbed but by using a stronger acid concentration of 10 M H 3 PO 4 , almost complete recovery was also obtained for Ta. Excellent elemental separation (α = 11.5) and recoveries were also obtained with Tantalite mineral as sample under identical experimental conditions. Almost complete recoveries for both Nb and Ta were obtained after elution with 8.0 M and 10.0 M H 3 PO 4 respectively. Apart from the complete separation of Ta and Nb, minor elements which are also present in Tantalite like Fe, Mn and U could also be successfully separated and quantitatively recovered. However, the Nb fraction was contaminated with Ti because under these conditions these two elements are simultaneously eluted. The successful separation and recovery of both Ta and Nb from a phosphate matrix suggest a possible alternative to the conventional fluoride beneficiation methods. This method also has the potential of industrial applications.
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Primary beneficiation of Tantalite using magnetic separation and acid leaching
International Journal of Minerals Metallurgy and Materials, 2014Co-Authors: M Nete, F. Koko, T. Theron, W. Purcell, J T NelAbstract:Primary beneficiation was successfully performed prior to dissolution of manganoTantalite (sample A) and ferroTantalite (sample C) samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H_2SO_4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and ∼2wt% each of Nb_2O_5 and Ta_2O_5 were removed from sample C (ferroTantalite) using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe_2O_3 and TiO_2, respectively, and ∼2wt% each of Nb_2O_5 and Ta_2O_5 were removed from sample A (manganoTantalite). A temperature of 50°C and a leaching time of 3 h in the presence of concentrated H_2SO_4 were observed to be the most appropriate leaching conditions for removal of radioactive elements from the Tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U_3O_8 and 60.77wt% ThO_2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb_2O_5 and Ta_2O_5, respectively.
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separation and isolation of tantalum and niobium from Tantalite using solvent extraction and ion exchange
Hydrometallurgy, 2014Co-Authors: M Nete, Walter Purcell, J T NelAbstract:Abstract A step-wise separation process for niobium and tantalum from Tantalite by extraction and ion exchange was developed. A Tantalite mineral was dissolved by a fusion technique using ammonium bifluoride as flux. Tantalum and niobium form stable anionic fluoride complexes in fluoride solutions. This fact was used to develop an analytical method to separate tantalum and niobium from other metals within the Tantalite mineral and from each other. Tantalum was separated from the rest of the mineral matrix by solvent extraction using methyl isoamyl ketone. The analytical results indicated that 98.9(9)% Ta2O5 was recovered from the organic portion while 101.6(3)% Nb2O5 and the rest of the elements were recovered from the aqueous solution. Niobium was subsequently separated from the Tantalite matrix by anion exchange technique using Dowex Marathon resin and HCl solution as a mobile solvent. The analytical results indicated Nb2O5 recovery of 101(2)%.
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comparative study of Tantalite dissolution using different fluoride salts as fluxes
Journal of Fluorine Chemistry, 2014Co-Authors: M Nete, Walter Purcell, J T NelAbstract:Abstract Six different fluoride salts, NH 4 F·HF, KF, KF·HF, CaF 2 , NaF and HF·NaF, were evaluated as fluxes in the fusion dissolution of Ta/Nb containing minerals, and compared with the commercially employed HF dissolution. The cold fusion products were dissolved in dilute H 2 SO 4 for both the dissolution and matrix matching purposes. Analytical results indicated that the KF, KF·HF and NH 4 F·HF dissolution procedures were the most effective for dissolving and recovering the main elements from the Tantalite mineral. CaF 2 , NaF and NaF·HF yielded the lowest recoveries of Ta and Nb from the Tantalite mineral sample under study. This comparative study indicated that the dissolution and separation of Ta and Nb from one another and from other elements in minerals depended heavily on fluoride concentration, acidity as well as temperature for the formation of the metal–halogen complexes. Dissolution of the minerals using KF·HF and NH 4 F·HF as fluxes are recommended as alternatives to HF dissolution due lower energy demands, elemental recoveries, cost, separation efficiency and ease of the dissolution step.
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characterization and alternative dissolution of Tantalite mineral samples from mozambique
Journal of The South African Institute of Mining and Metallurgy, 2012Co-Authors: M Nete, Walter Purcell, J T Nel, Ettienne Snyders, G BeukesAbstract:Synopsis Qualitative analysis of three mineral samples from northern Mozambique was accomplished by X-ray diffraction (XRD), microscopy, scintillation, and magnetic determination. Chemical characterization was accomplished using ICP-OES and pressed powder XRF after dissolution using microwave-assisted digestion and flux fusion. The samples consisted of a mixture of minerals with Tantalite as the major component, with minor amounts of microlite, quartz, mica, accessory garnet, and tourmaline. Incomplete dissolution was obtained using microwave digestion, with maximum recoveries of 90.25 ± 0.06% and 88.90 ± 0.04% for Nb 2O5 and Ta2O5 respectively. Complete dissolution using Li 2B4O7 resulted in recoveries of 98.5 ± 0.2% Nb2O5 and 100.4 ± 0.3% Ta2O5.
M Nete - One of the best experts on this subject based on the ideXlab platform.
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non fluoride dissolution of tantalum and niobium oxides and their separation using ion exchange
Hydrometallurgy, 2017Co-Authors: M Nete, Walter Purcell, J T NelAbstract:Abstract The study involved the separation of Ta and Nb in a phosphate matrix using ion exchange chromatography. Experimental variations included different types of Ta/Nb containing samples, types of resin, phosphoric acid concentration as eluent, flow rate and column dimensions. Experimental conditions were developed and refined using a pure 1:1 (Ta/Nb) 2 O 5 synthetic mixture and the optimum conditions were then applied to a real Tantalite mineral sample. Experimental results indicated the successful separation of the Ta and Nb in the synthetic sample using the weak basic Dowex Mathon and Dowex 66 free base resins. Almost complete recovery of Nb was achieved with 200 mL of 8 M H 3 PO 4 . It was found that Ta was more strongly absorbed but by using a stronger acid concentration of 10 M H 3 PO 4 , almost complete recovery was also obtained for Ta. Excellent elemental separation (α = 11.5) and recoveries were also obtained with Tantalite mineral as sample under identical experimental conditions. Almost complete recoveries for both Nb and Ta were obtained after elution with 8.0 M and 10.0 M H 3 PO 4 respectively. Apart from the complete separation of Ta and Nb, minor elements which are also present in Tantalite like Fe, Mn and U could also be successfully separated and quantitatively recovered. However, the Nb fraction was contaminated with Ti because under these conditions these two elements are simultaneously eluted. The successful separation and recovery of both Ta and Nb from a phosphate matrix suggest a possible alternative to the conventional fluoride beneficiation methods. This method also has the potential of industrial applications.
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Primary beneficiation of Tantalite using magnetic separation and acid leaching
International Journal of Minerals Metallurgy and Materials, 2014Co-Authors: M Nete, F. Koko, T. Theron, W. Purcell, J T NelAbstract:Primary beneficiation was successfully performed prior to dissolution of manganoTantalite (sample A) and ferroTantalite (sample C) samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H_2SO_4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and ∼2wt% each of Nb_2O_5 and Ta_2O_5 were removed from sample C (ferroTantalite) using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe_2O_3 and TiO_2, respectively, and ∼2wt% each of Nb_2O_5 and Ta_2O_5 were removed from sample A (manganoTantalite). A temperature of 50°C and a leaching time of 3 h in the presence of concentrated H_2SO_4 were observed to be the most appropriate leaching conditions for removal of radioactive elements from the Tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U_3O_8 and 60.77wt% ThO_2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb_2O_5 and Ta_2O_5, respectively.
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separation and isolation of tantalum and niobium from Tantalite using solvent extraction and ion exchange
Hydrometallurgy, 2014Co-Authors: M Nete, Walter Purcell, J T NelAbstract:Abstract A step-wise separation process for niobium and tantalum from Tantalite by extraction and ion exchange was developed. A Tantalite mineral was dissolved by a fusion technique using ammonium bifluoride as flux. Tantalum and niobium form stable anionic fluoride complexes in fluoride solutions. This fact was used to develop an analytical method to separate tantalum and niobium from other metals within the Tantalite mineral and from each other. Tantalum was separated from the rest of the mineral matrix by solvent extraction using methyl isoamyl ketone. The analytical results indicated that 98.9(9)% Ta2O5 was recovered from the organic portion while 101.6(3)% Nb2O5 and the rest of the elements were recovered from the aqueous solution. Niobium was subsequently separated from the Tantalite matrix by anion exchange technique using Dowex Marathon resin and HCl solution as a mobile solvent. The analytical results indicated Nb2O5 recovery of 101(2)%.
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comparative study of Tantalite dissolution using different fluoride salts as fluxes
Journal of Fluorine Chemistry, 2014Co-Authors: M Nete, Walter Purcell, J T NelAbstract:Abstract Six different fluoride salts, NH 4 F·HF, KF, KF·HF, CaF 2 , NaF and HF·NaF, were evaluated as fluxes in the fusion dissolution of Ta/Nb containing minerals, and compared with the commercially employed HF dissolution. The cold fusion products were dissolved in dilute H 2 SO 4 for both the dissolution and matrix matching purposes. Analytical results indicated that the KF, KF·HF and NH 4 F·HF dissolution procedures were the most effective for dissolving and recovering the main elements from the Tantalite mineral. CaF 2 , NaF and NaF·HF yielded the lowest recoveries of Ta and Nb from the Tantalite mineral sample under study. This comparative study indicated that the dissolution and separation of Ta and Nb from one another and from other elements in minerals depended heavily on fluoride concentration, acidity as well as temperature for the formation of the metal–halogen complexes. Dissolution of the minerals using KF·HF and NH 4 F·HF as fluxes are recommended as alternatives to HF dissolution due lower energy demands, elemental recoveries, cost, separation efficiency and ease of the dissolution step.
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characterization and alternative dissolution of Tantalite mineral samples from mozambique
Journal of The South African Institute of Mining and Metallurgy, 2012Co-Authors: M Nete, Walter Purcell, J T Nel, Ettienne Snyders, G BeukesAbstract:Synopsis Qualitative analysis of three mineral samples from northern Mozambique was accomplished by X-ray diffraction (XRD), microscopy, scintillation, and magnetic determination. Chemical characterization was accomplished using ICP-OES and pressed powder XRF after dissolution using microwave-assisted digestion and flux fusion. The samples consisted of a mixture of minerals with Tantalite as the major component, with minor amounts of microlite, quartz, mica, accessory garnet, and tourmaline. Incomplete dissolution was obtained using microwave digestion, with maximum recoveries of 90.25 ± 0.06% and 88.90 ± 0.04% for Nb 2O5 and Ta2O5 respectively. Complete dissolution using Li 2B4O7 resulted in recoveries of 98.5 ± 0.2% Nb2O5 and 100.4 ± 0.3% Ta2O5.
Alysha G Mcneil - One of the best experts on this subject based on the ideXlab platform.
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solubility of wodginite titanowodginite microlite pyrochlore columbite mn and Tantalite mn in flux rich haplogranitic melts between 700 and 850 c and 200 mpa
Lithos, 2020Co-Authors: Alysha G Mcneil, Robert L Linnen, Roberta L FlemmingAbstract:Abstract Ore minerals of niobium and tantalum are typically associated with pegmatites and rare metal granites; these include columbite, Tantalite, wodginite, titanowodginite, microlite and pyrochlore. Solubility and crystallization mechanisms for columbite-(Mn) and Tantalite-(Mn) have been extensively studied in haplogranitic melts, with little research into other ore minerals. In this study the solubilities of wodginite, titanowodginite, microlite and pyrochlore are compared to those for columbite-(Mn) and Tantalite-(Mn) in a flux-rich haplogranitic melt of alumina saturation index (ASI) 1.0 (ASILi of 0.83) at 700–850 °C and 200 MPa. The effect of melt composition on the solubilities of wodginite, titanowodginite, and microlite compared to Tantalite-(Mn) is also investigated in highly fluxed haplogranitic melts of ASI 1.0, 1.10, and 1.24 (ASILi of 0.83, 0.90, 1.02), at 700 °C and 800 °C and 200 MPa. The log solubility product (logKsp) at 750 °C and melt ASI of 1.0 is highest for Tantalite-(Mn) (−2.32 mol2/kg2) followed by columbite-(Mn) (−2.68 mol2/kg2), and pyrochlore (−3.71 mol3/kg3) titanowodginite (−3.73 mol3/kg3), wodginite (−3.77 mol3/kg3), and microlite (−3.78 mol3/kg3), the latter four of which are almost identical within error. However, solubility can also be expressed as a mineral-melt partition coefficient, with higher partition coefficients reflecting lower solubilities. The tantalum mineral-melt partition coefficients of wodginite (27.0), titanowodginite (30.2), and Tantalite-(Mn) (29.6) are identical within error; microlite is higher (80.3, reflected by lower concentrations of tantalum in the melt for stoichiometric saturation) because it contains a major melt cation, sodium. The niobium mineral-melt partition coefficient for columbite-(Mn) (66.1) is higher than for pyrochlore (50.1). Wodginite, titanowodginite, pyrochlore, columbite-(Mn) and Tantalite-(Mn) have similar temperature and melt composition dependences, but conversely, microlite solubility increases with ASI. As all studied minerals have been shown to have similar relative solubilities at stoichiometric saturation, it can be concluded that, in general, the presence of bivalent (Ca, Mn, Fe) and some tetravalent cations (Sn, Ti) control which tantalum and niobium phases crystallize in rare metal deposits.
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hydrothermal synthesis of columbite mn Tantalite mn hafnon and zircon at 800 850 c and 200 mpa
Canadian Mineralogist, 2015Co-Authors: Alysha G Mcneil, Robert L Linnen, Roberta L FlemmingAbstract:Fully ordered columbite-(Mn), Tantalite-(Mn), hafnon, and zircon were successfully synthesized using an acid solution of 6N:1N (N = normal) HF:H 2 SO 4 and stoichiometric oxide mixtures. The mixtures and solutions were sealed and placed in rapid-quench cold-seal pressure vessels (CSPV) at 800–850 °C and 200 MPa. Mineral structures and compositions have been confirmed by scanning electron microscope (SEM), micro X-ray diffraction (μXRD), and electron probe microanalysis (EPMA). The unit cell parameters of the minerals determined by μXRD: Orthorhombic ( Pbcn ) columbite-(Mn) a 14.434(2), b 5.768(1), c 5.084(1) A; orthorhombic ( Pbcn ) Tantalite-(Mn) a 14.457(3), b 5.773(1), c 5.096(1) A; tetragonal hafnon ( I 4 1 /amd ) a 6.582(2), c 5.9702(1) A; and tetragonal zircon ( I 4 1 /amd ) a 6.607(4), c 5.9898(2) A. The chemical formulae as determined by EPMA are very close to stoichiometric: Mn 0.96 Nb 2.02 O 6 , Mn 0.99 Ta 2.01 O 6 , Hf 0.99 Si 1.01 O 4 , and Zr 1.00 Si 1.00 O 4 , respectively.
