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Incongruent weathering of Cd and Zn from mine tailings

Published online by Cambridge University Press:  05 July 2018

D. Kossoff*
Affiliation:
Research School of Earth Sciences at UCL-Birkbeck, University of London, Malet St., London WC1E 7HX, UK Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
K. A. Hudson-Edwards
Affiliation:
Research School of Earth Sciences at UCL-Birkbeck, University of London, Malet St., London WC1E 7HX, UK
W. E. Dubbin
Affiliation:
Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
M. Alfredsson
Affiliation:
School of Physical Sciences, Ingram Building, University of Kent, Canterbury CT2 7NH, UK

Abstract

Weathering ofdischarged mine tailings contaminates streams, rivers and floodplains with toxic metals on a vast scale. The magnitude of the problem depends on input tailings mineralogy, storage and dispersal, and climatic conditions. To better understand the mechanisms of long-term tailings weathering, a leaching column study was established, incorporating tailings and soil from Potosí, Bolivia, with the aim of modelling a 25 year field period. The Zn/Cd molar ratio ofthe tailings leachate water, initially 738 for the unaltered tailings, is highly variable over 15 model years of leaching, particularly in the mixed tailings-soil columns. Columns with soil have ratios as high as 2563, while pure tailings columns reach ratios of <376. We employ complementary techniques, involving atomistic computational modelling, leachate analysis and mineralogical characterization, to elucidate the mechanisms governing these incongruent Cd and Zn weathering dynamics.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2008

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