Heating Fe oxide-rich soils increases the dissolution rate of metals

Evidence for fire affecting the solubility of metals in Fe oxide-rich Oxisols of the Koniambo Massif of New Caledonia is presented. Acid-dissolution studies showed that Ni, Al and Cr are substituted for Fe in the structure of the Fe oxides. Thermal dehydroxylation of goethite under oxidizing conditi...

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Bibliographic Details
Published in:Clays and clay minerals 2006-04, Vol.54 (2), p.165-175
Main Authors: Perrier, Nicolas, Gilkes, Robert J, Colin, Fabrice
Format: Article
Language:English
Subjects:
chemical properties
clay mineralogy
Dehydroxylation Acid Dissolution
Earth sciences
Earth, ocean, space
Exact sciences and technology
experimental studies
geochemistry
Goethite
heating
Hematite
iron oxides
Koniambo Massif
Lateritic Ore
Maghemite
Melanesia
metals
migration of elements
Mineralogy
New Caledonia
Oceania
oxides
Oxisols
rock, sediment, soil
sed rocks, sediments
Sedimentary petrology
Silicates
soils
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Summary:Evidence for fire affecting the solubility of metals in Fe oxide-rich Oxisols of the Koniambo Massif of New Caledonia is presented. Acid-dissolution studies showed that Ni, Al and Cr are substituted for Fe in the structure of the Fe oxides. Thermal dehydroxylation of goethite under oxidizing conditions led to the formation of hematite and to the migration of some of these metals towards the surface of hematite crystals as indicated by their enhanced release during the early stage of dissolution. Dehydroxylation of goethite under reducing conditions led to the formation of hematite and maghemite. Nickel and Al were released preferentially during the early stages of dissolution whereas Cr was not released preferentially and may be uniformly incorporated within maghemite and hematite crystals. These results have significance to the mineral-processing industry, to geochemical exploration and to the availability of these metals to plants growing on burnt soils.
ISSN:0009-8604
1552-8367
DOI:10.1346/CCMN.2006.0540203