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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 Ta2O5 (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)50 at low HF concentration and pH ~1-3. At higher HF concentration, tantalum mobility is controlled by the species TaF3(OH)3- and TaF5; the presence of TaF50 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 Ta2O5 and from -8.24 ± 0.64 to -8.55 ± 0.68 for the formation of TaF3(OH)3- at 100 and 250 °C, respectively. For TaF50, they were determined to be 0.13 at 100 °C and -0.35 at 150 °C.
Authors:
 [1] ;  [2] ;  [1]
  1. McGill Univ., Montreal, QC (Canada)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
1331289
Report Number(s):
LA-UR--16-25513
Journal ID: ISSN 0016-7037
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Name: Geochimica et Cosmochimica Acta; Journal ID: ISSN 0016-7037
Publisher:
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
Language:
English
Subject:
58 GEOSCIENCES earth sciences