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Title:
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Leaching of ferrochrome slag in the marine environment
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Author(s):
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Published by:
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Publication date:
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ECN
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1998
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ECN report number:
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Document type:
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ECN-C--98-012
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ECN publication
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Number of pages:
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Full text:
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26
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Download PDF
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Abstract:
The leaching of Ferrochrome slag was investigated using seawater asleaching medium. Compared to the natural concentration of different elements
apparent in seawater, the contribution of ferrochrome stag leaching is
minimal. Exact determination of the leaching is difficult certainly if the
leached concentrations are lower than the concentration already apparent in
the seawater. This implies that the impact from the slag leaching to the
marine environment is small. An exception is the leaching of Mn. The enhanced
leaching of Mn can be explained by the execution of the test. In order to
test the leaching properties the slag is size reduced with a top size of 4
min. Due to the size-reduction, fresh leaching surface is generated. The
oxidation of liberated Mn to MnO2 is a slow process which is slower than the
surface oxidation of the slag. Within the time frame of the test the surface
oxidation is still continuing. In practice the slag will not be size reduced,
no fresh surface will be generated and Mn leaching will not be of great
importance. In addition, Mn is not an element specified in existing
regulations. The Cr-content in the slag is high (1.3 %) but it is very
important to consider that the potential for leaching (in seawater) is small
(0.6 mg/kg). Studying the actual leaching under seawater conditions the
exposure is marginal because the leached concentrations are not exceeding the
natural seawater concentrations. The measurement of Pb in seawater using the
ICP-AES technique is difficult and not very accurate. Upon request these can
be analyzed using another more accurate technique. However, based on the
experience with steeIslag, materials which posses the same features (low Pb
content together with a relatively high Pb availability) the leachability is
also low in the pH region of interest. 4 refs.
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