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Mode of occurrence of chromium in four US coals

Fuel Processing Technology

By:
, , , , , ,
DOI: 10.1016/S0378-3820(99)00090-9

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Abstract

The mode of occurrence of chromium in three US bituminous coals and one US subbituminous has been examined using both X-ray absorption fine structure (XAFS) spectroscopy and a selective leaching protocol supplemented by scanning electron microscopy (SEM) and electron microprobe measurements. A synthesis of results from both methods indicates that chromium occurs principally in two forms in the bituminous coals: the major occurrence of chromium is associated with the macerals and is not readily leached by any reagent, whereas a second, lesser occurrence, which is leachable in hydrofluoric acid (HF), is associated with the clay mineral, illite. The former occurrence is believed to be a small particle oxyhydroxide phase (CrO(OH)). One coal also contained a small fraction (<5%) of the chromium in the form of a chromian magnetite, and the leaching protocol indicated the possibility of a similar small fraction of chromium in sulfide form in all three coals. There was little agreement between the two techniques on the mode of occurrence of chromium in the subbituminous coal; however, only a limited number of subbituminous coals have been analyzed by either technique. The chromium in all four coals was trivalent as no evidence was found for the Cr6+ oxidation state in any coal.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Mode of occurrence of chromium in four US coals
Series title:
Fuel Processing Technology
DOI:
10.1016/S0378-3820(99)00090-9
Volume
63
Issue:
2
Year Published:
2000
Language:
English
Publisher:
Elsevier Science Publishers B.V.
Publisher location:
Amsterdam, Netherlands
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
79
Last page:
92
Number of Pages:
14