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  • Dissolution of columbite and tantalite in acidic fluoride

    The dissolution reactions of Nb and Ta from columbite and tantalite in the aqueous solutions of HF, HF-HC1, NH4F-HCI, HF-H2SO4, and NH4F-H2SO4 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. The increase in these ion concentrations and the elevation of temperature

  • Dissolution of columbite and tantalite in acidic fluoride

    01/06/1988· 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. The increase in these ion concentrations and the elevation

  • Enhanced dissolution of tantalite/columbite following

    01/03/2001· 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 more rapid than a 2-h milled powder. The

  • Dissolution of columbite and tantalite in acidic fluoride

    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.

  • 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

  • INVESTIGATION OF DISSOLUTION KINETICS OF A NIGERIAN

    Dissolution of over 90 % of the columbite was achieved in 5 h, using 20 M HF at 90 oC with 100 µm particle sizes. Activation energy, E a of 15.70 KJ.mole-1 was obtained for the process. Keywords: columbite, tantalum, leaching, shrinking core model, PIXE 1. INTRODUCTION Tantalite-columbite and tantalite concentrates are

  • Open Research: Enhanced dissolution of

    22/01/2019· Enhanced dissolution of tantalite/columbite following milling. Request a Copy. link to publisher version. Statistics; Export Reference to BibTeX; Export Reference to EndNote XML; Altmetric Citations . Welham, N. Description. A tantalum/niobium concentrate has been ball-milled for up to 50 h in a laboratory mill without apparent phase change, other than a decrease in unit cell symmetry and

  • 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

  • COLOMBITE-TANTALITE Encyclopædia Universalis

    05/06/2020· La tantalite, (Fe,Mn)Ta2O6, et la colombite (on écrit aussi columbite), ou niobite (Fe,Mn)Nb2O6 constituent une série de mélanges minéraux isomorphes : les colombo-tantalites. Les teneurs en colombo-tantalates, ou niobo-tantalates, et en ferromagnésiens varient beaucoup, et même à l'intérieur d'un gîte de petite dimension. À cette série on trouve quelquefois associés l'

  • 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

  • INVESTIGATION OF DISSOLUTION KINETICS OF A NIGERIAN

    Dissolution of over 90 % of the columbite was achieved in 5 h, using 20 M HF at 90 oC with 100 µm particle sizes. Activation energy, E a of 15.70 KJ.mole-1 was obtained for the process. Keywords: columbite, tantalum, leaching, shrinking core model, PIXE 1. INTRODUCTION Tantalite-columbite and tantalite concentrates are

  • Open Research: Enhanced dissolution of

    The extent of dissolution in a mixture of hydrochloric acid and sodium fluoride increased with milling time. For a powder milled for 50 h, over 95% of the concentrate were solubilised in 24 h compared with ∼ 50% in 48 h for a 2-h milled powder. The kinetics of dissolution changed with the milling time,...

  • Open Research: Enhanced dissolution of

    Enhanced dissolution of tantalite/columbite following milling. Request a Copy. link to publisher version. Statistics; Export Reference to BibTeX; Export Reference to EndNote XML; Altmetric Citations . Welham, N. Description. A tantalum/niobium concentrate has been ball-milled for up to 50 h in a laboratory mill without apparent phase change, other than a decrease in unit cell symmetry and some

  • 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

  • Textural and mineral-chemistry constraints on columbite

    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 between 0.07 and 0.93. Wodginite and microlite formed as late replacements of CGM and occur associated with tantalite and cassiterite. Subhedral to anhedral cassiterite crystals, usually up to 200 μm across, occur

  • U-Pb isotopic dating of columbite-tantalite minerals

    05/05/2019· Selective dissolution of columbite-tantalite minerals may remove metamict domains and result in concordant data (e.g., Lindroos et al., 1996; Romer and Smeds, 1996). This procedure, however, is not applicable for samples to be dated by SIMS. Thus, there are two questions of interest for in situ age determination: (i) does non-ideal behavior during leaching affect the age obtained by ID-TIMS and (ii)

  • Original paper Accessory columbite to tantalite, tapiolite

    Columbite–tantalite crystals show coarse oscillatory zoning, usually with border parts enriched in Ta. Locally, there is a reversal trend of zoning (decrease of Ta towards the border parts), or irregular convoluted zoning as a result of late-magmatic to subsolidus dissolution-reprecipitation. The composition of columbite–tantalite shows a relatively constant

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

    Conventional TIMS analyses of these columbite-tantalite crystals produce scattered data and reverse discordance even after HF leaching of the grains prior to dissolution, possibly reflecting the incomplete removal of the open-system metamict segments during sample preparation. LA-MC-ICP-MS analyses of unleached, primary columbite free from inclusions and alteration give consistent and precise (<0.5%)

  • A Review of Niobium-Tantalum Separation in Hydrometallurgy

    industrial scale to achieve simultaneous breakdown of columbite and tantalite concentrate and upgrading of niobium and tantalum values by leaching out of iron, manganese, tin, titanium and silicon. 2.4 Leaching Leaching is the removal of material by dissolving them away from the solids. In chemical