Experimental study of the transformation of smectite at 80 and 300°C in the presence of Fe oxides

D. Guillaume, A. Neaman, M. Cathelineau, R. Mosser-Ruck, C. Peiffert, M. Abdelmoula, J. Dubessy, F. Villiéras, N. Michau

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62 Scopus citations

Abstract

The alteration and transformation behaviour of montmorillonite (Wyoming bentonite) was studied experimentally to simulate the mineralogical and chemical reaction of clays in contact with steel in a nuclear waste repository. Batch experiments were conducted at 80 and 300°C, in low-salinity solutions (NaCl, CaCl2) and in the presence or otherwise of magnetite and hematite, over a period of 9 months. The mineralogical and chemical evolution of the clays was studied by XRD, SEM, transmission Mössbauer spectroscopy and EDS-TEM. Experimental solutions were characterized by ICP-AES and ICP-MS. The main results are that no significant change in the crystal chemistry of the montmorillonite occurred at 80°C, while at 300°C, the presence of Fe oxides leads to a partial replacement of montmorillonite by high-charge trioctahedral Fe2+-rich smectite (saponite-like) together with the formation of feldspars, quartz and zeolites.

Original languageEnglish
Pages (from-to)17-34
Number of pages18
JournalClay Minerals
Volume39
Issue number1
DOIs
StatePublished - Mar 2004
Externally publishedYes

Keywords

  • Bentonite
  • EDS-TEM
  • Experimental synthesis
  • Hematite
  • Magnetite
  • Mössbauer spectroscopy
  • Saponite
  • Smectite
  • Transmission
  • X-ray diffraction

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