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Title: An experimental study of the solubility and speciation of tantalum in fluoride-bearing aqueous solutions at elevated temperature

Here, the solubility of Ta 2O 5 (solid) and the speciation of tantalum in HF-bearing aqueous solutions have been determined at temperatures of 100-250 °C and vapour-saturated water pressure. Tantalum is transported as the species Ta(OH) 5 0 at low HF concentration and pH ~1-3. At higher HF concentration, tantalum mobility is controlled by the species TaF 3(OH) 3- and TaF 5; the presence of TaF 5 0 is only evident at ≤150 °C. Equilibrium constants range from -17.4 ± 0.45 to -16.4 ± 0.12 for the formation of Ta(OH) 5 from crystalline Ta 2O 5 and from -8.24 ± 0.64 to -8.55 ± 0.68 for the formation of TaF 3(OH) 3- at 100 and 250 °C, respectively. For TaF 5 0, they were determined to be 0.13 at 100 °C and -0.35 at 150 °C.
 [1] ; ORCiD logo [2] ;  [1]
  1. McGill Univ., Montreal, QC (Canada)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0016-7037
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Name: Geochimica et Cosmochimica Acta; Journal ID: ISSN 0016-7037
The Geochemical Society; The Meteoritical Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Foreign Funding; USDOE
Country of Publication:
United States
58 GEOSCIENCES; Earth Sciences