Analysis of sub-micron mineral matter in coal via scanning transmission electron microscopy

Conference · Fri Jan 01 04:00:00 EST 1982 · Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States)

OSTI ID:6680630

Allen, R M ^[1]; VanderSande, J B

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1. Sandia National Labs., Livermore, CA

The Scanning Transmission Electron Microscope (STEM) is an instrument well suited for the characterization of the sub-micron sized mineral matter in coal and can also be used to identify inorganic elements atomically bound in the organic coal matrix. For the three coals studied, a random survey was taken of mineral inclusions < 100nm in mean diameter observed within coal particles in powdered coal samples. The results indicate that the predominant mineral species making up these inclusions differ from those species predominating in mineral particles at larger size ranges. Two of the coals examined showed characteristic matrix signatures of inorganic elements which were observed in greater than or equal to 90% of the matrix areas examined. The third coal did not. All three coals exhibited various elements with Z greater than or equal to 11, most notably S, which were only irregularly associated with the matrix signal (i.e., found <50% of the time). For all three coals, the predominant mineral species observed in the less than or equal to 100nm size range would not be predicted from the results of the chemical analyses of the high temperature ash of the coals. None of the major elements (Z greater than or equal to 11) observed (with the exception of sulfur in the Ba, s-rich particles) constitutes more than 10% of the HTA for the respective coals; indeed, Ba, in the lignite, Ti in the bituminous coal, and Ca in the semianthracite all make up less than 1% of the respective ashes. Encountering these elements as the major constituents in the predominant mineral species observed in a random sampling of particles <100nm in diameter indicates that the distribution of inorganic elements must not be uniform over all size ranges of mineral inclusions. In particular, for all three coals, the predominant mineral species observed in the <100nm size range must therefore differ from those species predominating at larger size ranges.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6680630
• Report Number(s): CONF-820304-Vol.2
• Conference Information: Journal Name: Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States) Journal Volume: 27:1
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010600* -- Coal
Lignite
&amp; Peat-- Properties &amp; Composition
CARBONACEOUS MATERIALS
CHEMICAL ANALYSIS
COAL
ELECTRON MICROSCOPY
ENERGY SOURCES
FOSSIL FUELS
FUELS
MATERIALS
MICROSCOPY
NONDESTRUCTIVE ANALYSIS
X-RAY EMISSION ANALYSIS