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Interfacial Structure Change and Selective Dissolution of ...

The goal of the paper is to study the charge transfer and reactions at the columbite-(Fe) (FeNb2O6) mineral surface during the HF leaching process. In this paper, X-ray photoelectron spectroscopy (XPS), leaching experiments, and density functional theory (DFT) calculations were used to study the surface element adsorption, charge distribution, chemical state, and energy …

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Leaching of a Nigerian Columbite in Hydrochloric Acid ...

rate of columbite dissolution. i.e the rate of columbite dissolution is affected directly by hydrogen ion[H +] concentration. This agrees with several reported work on acid dissolution of solid mineral ores [12-15]. The result also showed that 11.04% columbite was dissolved by contacting columbite sample with 8.0M HCl at a temperature of 55℃

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Enhanced dissolution of tantalite/columbite following ...

The dissolution of a tantalite/columbite concentrate was substantially affected by milling for an extended period. Dry milling was found to be more effective than wet milling, despite the latter attaining a somewhat greater surface area due to the prevention of agglomeration.

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Columbite-tantalite - Wikipedia

La columbite-tantalite, (detta anche Coltan) è una miscela complessa di columbite (Fe, Mn)Nb 2 O 6 e tantalite (Fe, Mn)Ta 2 O 6, due minerali della classe degli ossidi che si trovano molto raramente come termini puri.. Il termine "coltan" è usato colloquialmente in Africa per riferirsi ad una columbite-tantalite a relativamente alto tenore di tantalio.La miscela estratta in diversi …

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Leaching of a Nigerian Columbite in Hydrochloric Acid ...

With 4.0 M HCl solution, about 15.37% of columbite was dissolved within 120 minutes using < 0.15 mm particle size at a temperature of 80℃ and a stirring speed of 360 rpm. The result of the study indicated that the leaching data fitted a diffusion model.

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Coltan - Wikipedia

Coltan (short for columbite–tantalites and known industrially as tantalite) is a dull black metallic ore from which the elements niobium and tantalum are extracted. The niobium-dominant mineral in coltan is columbite (after niobium's original American name columbium), and the tantalum-dominant mineral is the tantalite.. Tantalum from coltan is used to manufacture tantalum …

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A Review of Niobium-Tantalum Separation in Hydrometallurgy

compound form, chlorination, alkaline fusion and acid dissolution (leaching) [7]. 2.1 Reduction One of the simplest methods for the breakdown treatment of primary concentrates of niobium and tantalum, particularly pyrochlore and columbite-tantalite, is direct reduction with aluminum

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Textural and mineral-chemistry constraints on columbite ...

This corrosion destroys columbite that is replaced by tantalite. Similar dissolution textures are evident in other Nb-Ta minerals from pegmatites (e.g. Wise and Brown, Reference Wise and Brown 2010; Dill et al., Reference Dill, Doann, Kaufhold and Balaban 2015).

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REPRESENTATIVE COMPOSITIONS OF CASSITERITE FROM …

Dissolution textures resulting from the corrosion of columbite and tantalite rims, in particular, are common. The Mn/ (Mn + Fe) ratio varies between 0.33 and 0.97 and the Ta/ (Ta + Nb) ratio ...

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Experimental studies of Ta2O5 and columbite–tantalite ...

Low solubility experimental data for columbite–tantalite in HCl, Na 2 CO 3, and NaHCO 3 solutions is important for understanding the genesis of hydrothermal Nb and Ta deposits. In HCl solutions, the Ta concentration ranges from 10 −7 to 10 −4 m under the P-T conditions of the experiments. In Na 2 CO 3 and NaHCO 3 solutions, the columbite–tantalite …

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Dissolution of columbite and tantalite in acidic fluoride ...

12%The dissolution reactions of Nb and Ta from columbite and tantalite in the aqueous solutions of HF, HF-HC1, NH 4 F-HCI, HF-H 2 SO 4, and NH 4 F-H 2 SO 4 were kinetically studied in the temperature range of 333 to 353 K. The presence of both H + and F - in the leachant is necessary for the fast dissolution of columbite and tantalite.

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Occurrence and Composition of Columbite-(Fe) In the ...

Columbite-(Fe) is a post-magmatic accessory mineral occurring within syenogranites and greisens from the Desemborque Pluton. The petrographic (SEM) and geochemical (EPMA and LA-ICPMS) examination of this mineral shows two distinct textural types within both the rocks, named columbite-1 and columbite-2. The columbite-1 type is characterized by zoned …

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Textural and mineral-chemistry constraints on columbite ...

Dissolution textures resulting from the corrosion of columbite and tantalite rims, in particular, are common. TheMn/(Mn + Fe) ratio varies between 0.33 and 0.97 and the Ta/(Ta + Nb) ratio between 0.07 and 0.93. Wodginite and microlite formed as late replacements of CGM and occur associated with tantalite and cassiterite.

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Interfacial Structure Change and Selective Dissolution of ...

In nature, columbite is a multi-component ore mineral. The (Fe,Mn)(Ta,Nb) 2 O 6 group compounds include columbite–(Fe) (FeNb 2 O 6), columbite–(Mn) (MnNb 2 O 6), tapiolite–(Mn) (MnTa 2 O 6), and tapiolite–(Fe) FeTa 2 O 6.There are two types of FeNb 2 O 6 crystal structures. One is the orthorhombic niobium mineral found in columbite (Fe, Mn) (Nb, Ta) 2 O 6, and the …

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Enhanced dissolution of tantalite/columbite following ...

Welham et al. employed ball milling to enhance the dissolution of ilmenite and tantalite/columbite (Welham, 2001; Welham and Llewellyn, 1998). Therefore, wet ball milling may have great influence ...

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Tantalum Dissolution Rate in Simulant Lung Fluid ...

12%The dissolution life-time ( τ) in columbite is 34 h, in pyrochlore, 54 h and in columbite–tantalite, 64 h. The dissolution fraction of Ta observed in the columbite–tantalite samples could be explained by physical characteristics of each mineral such as crystal lattice and mineral density.

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Columbite-(Mn) with Tantalite-(Mn) - YouTube

#RadioactiveOrigin: Antsongombato Gem Mine, Antsentsindrano, Anosiarivo Manapa, Betafo, Vakinankaratra, Madagascar

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(PDF) Columbite solubility in granitic melts: Consequences ...

Columbite-tantalite solubilities in subalu- minous and peraluminous melts (A.S.I. 1.02 and 1.22) are strongly temperature dependent, increasing by a factor of 10 to 20 from 800 to 1035 °C. By...

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U-Pb columbite-tantalite chronology of rare-element ...

U-Pb isotopic analyses using TIMS and Laser Ablation-Multi Collector-ICP-MS were carried out on columbite-tantalite minerals from three suites of rare-element (Li, Cs, Ta) pegmatites in the Superior Province of Canada. Conventional TIMS analyses of these columbite-tantalite crystals produce scattered data and reverse discordance even after HF leaching of the grains prior to …

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An investigation on hydrofluoric (HF) acid-free extraction ...

The areas (1) and (2) correspond to phases with a triple stored α-PbO 2 structure (orthorhombic), which form a continuous series of solid solutions between columbite and tantalite, being rich in Nb and Ta elements, respectively. The FeTa 2 O 6 corner represents the mineral tapiolite (area 3) with a tri-rutile crystal structure (tetragonal). The shaded area defines …

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MONAZITE SANDS OF BIHAR AND WEST BENGAL (Technical …

To check for such behavior, 20 to 100 mg samples of 12 chemically resistant minerals were fused. Nine (cassiterite, ilmenite, rutile, wolfamite, magnetite, zircon, corundum, beryl, columbite-tantalite) gave melts which dissolved to give clear, stable solutions in 3% HNO/sub 3/ containing, in some cases, appropriate additives.

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TANTALUM SOLUBILITY IN SIMULANT LUNG FLUID

columbite-tantalite and columbite. Tantalum dissolution in vitro samples were obtained using the Gamble solution as a simulated solution for body fluids and PIXE (Particle Induced X rays Emissions) technique was used to characterize them. In order to characterize the worker exposure to Ta bearing particles a Brazilian

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(PDF) Dissolution Kinetics of Columbite in Nitric Acid

An investigation of the dissolution kinetics of a Nigerian columbite mineral ore sample in nitric acid media has been undertaken. The effects of acid concentration, process temperature, stirring ...

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US7182925B2 - Tantalum concentrates dissolution and ...

A method for the dissolution and purification of tantalum ore and synthetic concentrates is described. The method preferably uses ammonium bifluoride as the fluoride source in place of the hydrofluoric acid used in the conventional methods. Other fluoride compounds such as NaF, KF, and CaF 2 may be used alone or in combination with ammonium bifluoride.

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Enhanced dissolution of tantalite/columbite following ...

The dissolution of a tantalite/columbite concentrate was substantially affected by milling for an extended period. Dry milling was found to be more effective than wet milling, despite the latter attaining a somewhat greater surface area due to the prevention of agglomeration. A powder dry milled for 50 h showed a dissolution rate over 300 times ...

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Characterization and alternative dissolution of tantalite ...

dissolution, while flux fusion of Nb2O5 with Li2B4O7 yielded 103% Nb recovery. The successful recovery of Nb2O5 using these two methods prompted us to investigate their usefulness on tantalite-columbite itself, which normally consists mainly of Nb2O5 and Ta2O5. Research also indicated that the difference in chemical composition of the minerals

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Original paper Oxide minerals in the granitic cupola of ...

crystallization of tantalite-(Fe), and (ii) greisen-like bodies, which contain high amounts of columbite-(Fe), columbite- (Mn), tantalite-(Mn) I and II as well as cassiterite. The primary oxide assemblage in both types of the peribatholithic pegmatite dikes would have crystallized as a result

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Investigation of Dissolution Kinetics of A Nigerian ...

Tantalite-columbite, which is the major source for tantalum, occurs mainly as accessory minerals disseminated in granitic rocks or in pegmatite associated with granites. The proper name for the mineral is tantalite when tantalum predominates over columbium. When the reverse is true, the proper name is columbite [1].

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Dissolution of Pyrochlore and Microlite in Alkaline ...

12%Thus, upon dissolution of niobium-rich pyrochlore (67 wt % of Nb 2 O 5), the Nb content in the melt was lower by several times than that upon dissolution of less niobium-rich columbite (58 wt % of Nb 2 O 5) [6, 8] and even considerably lower compared to the dissolution of tantalite (38 wt % of Nb 2 O 5) . The dependence of the Nb content on …

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Columbite-(Fe): Mineral information, data and localities.

Columbite was the second species named from the USA, after celestine (q.v.) Type Locality: ⓘ Green's Well pegmatite (Green's Tank), Pilgangoora, East Pilbara Shire, Western Australia, Australia. Columbite- (Fe)-Tantalite- (Fe) Series and the Columbite- (Fe)-Columbite- (Mn) Series. Formerly known as columbite and ferrocolumbite. Compare also ...

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Coltan and Mobile Phones: The Wonders & the Sad Truth About It

Coltan, short for columbite-tantalite, is a conflict mineral that is usually mined by hand. It's a grayish, metallic ore that may look like just an ordinary rock to you. But for those with an eye for it, it's a precious soil deposit that makes technological advances run. It has much more uses than you can imagine.

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