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Per Persson. Photo.

Per Persson

Director

Per Persson. Photo.

Schwertmannite precipitated from acid mine drainage: phase transformation, sulphate release and surface properties

Author

  • J. Jonsson
  • Per Persson
  • S. Sjoberg
  • L. Lovgren

Summary, in English

Schwertmannite precipitated from acid mine drainage at the Kristineberg Zn-Cu mine in northern Sweden has been characterised regarding elemental composition, phase transformation as a function of pH and time. SO42- release and speciation of SO42- associated with the solid. The elemental analysis gave the composition FeSOS(OH)(5.02)(-SO4)(1.49) . 0.5H(2)O where approximately 1/3 of the SO42- is adsorbed to the surface. The conversion of schwertmannite to goethite at pH 9 was complete within 187 days; at pH 6. the conversion was still incomplete after 514 days. Lower pH and relatively high SO42- concentration decreased the conversion even further. Also temperature was shown to be an important parameter for this process and low temperature (+4 degreesC) effectively stopped the transformation at pH 3. The release of SO42- was linear with pH and X-ray photoelectron spectroscopy measurements confirming that the surface bound SO42- was released before bulk SO42-. Zeta potential measurements indicate a pH(IEP) of 7.2 for the schwertmannite sample. Prior to conversion into goethite, the SO42- associated with schwertmannite was indicated by attenuated total reflectance FTIR spectroscopy to be present both as bulk and surface species. Furthermore: the speciation of surface SO42- was shown to vary with pH and two predominating species were detected. As pH increases. SO42- is increasingly Coordinated in an outer sphere mode whereas a stronger. possibly inner sphere, complex dominates. at low pH. (C) 2004 Elsevier Ltd. All rights reserved.

Publishing year

2005

Language

English

Pages

179-191

Publication/Series

Applied Geochemistry

Volume

20

Document type

Journal article

Publisher

Elsevier

Topic

  • Earth and Related Environmental Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 0883-2927