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The Granular Nature of High Rank Coals

Published online by Cambridge University Press:  28 February 2011

George D. Cody Jr. ,
John W. Larsen ,
Michael Siskin  and
George D. Cody Sr.
George D. Cody Jr.
Affiliation:
The Pennsylvania State University, Dept. of Geosciences, University Park, PA 16802
John W. Larsen
Affiliation:
Corporate Research Laboratory, Exxon Research and Engineering Co., Annandale, NJ 08801
Michael Siskin
Affiliation:
Corporate Research Laboratory, Exxon Research and Engineering Co., Annandale, NJ 08801
George D. Cody Sr.
Affiliation:
Corporate Research Laboratory, Exxon Research and Engineering Co., Annandale, NJ 08801
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Abstract

We present optical evidence in the visible and mid-infrared for the coal to graphite transformation proceeding via a nucleation mechanism. In the visible region, we show that changes in reflectivity that occur with increasing coal rank can be understood by an increase in the volume fraction of sub-microscopic “graphite-like” nuclei and a subsequent increase of the complex part of the dielectric constant with increasing coal rank. Optical phenomena associated with the granular nature of coal is also observed in the mid-infrared; specifically, measurements of absorption across the mid-infrared show a significant increase of absorption with increasing coal rank. This increase can be ascribed to absorption arising from a plasma resonance “graphite-like” material of the granular composite. A broad range of the optical repsroopnearntciees foofr hitghhe rank coals in the visible and mid-infrared can thus be readily understood and quantitatively modeled in terms of a granular medium consisting of nuclei of “graphite-like” material imbedded in an insulating organic matrix. If validated by further experimentation, this model should greatly expand current capabilities in the opticalcharacterization of high rank carbonaceous materials.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 195: Symposium S – Physical Phenomena in Granular Materials , 1990 , 559
Copyright
Copyright © Materials Research Society 1990

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References

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