Coal Resource Classification System of the U.S. Geological Survey
By Gordon H. Wood, Jr., Thomas M. Kehn, M. Devereux Carter, and William C. Culbertson
GEOLOGICAL SURVEY CIRCULAR 891
Table 1. - Classification of coals by rank
|Class||Group||Fixed Carbon (Dry, Mineral- Matter-Free Basis)||Volatile Matter Limits, percent Limits, percent Dry, Mineral- Matter-Free Basis||Calorific Value
Limits BTU per pound (Moist,B
|Equal or Greater Than||Less Than
|Equal or Less Than||Equal or Greater Than||Less||Agglomerating Character|
|II Bituminous||1.Low volatile bituminous coal||78||86||14||22|
|2.Medium volatilebituminous coal||69||78||22||31|
|3.High volatile A bituminous coal||69||31||14000D||commonly|
|4.High volatile B bituminous coal||13000D||14000||agglomerating**E|
|5.High volatile C bituminous coal||11500||13000|
||1.Subbituminous A coal||10500||11500|
|2.Subbituminous B coal||9500||10500|
|3.Subbituminous C coal||8300||9500||nonagglomerating|
|IV. Lignite||1.Lignite A||6300||8300|
AThis classification does not
include a few coals, principally nonbanded varieties, which have
unusual physical and chemical properties and which come within
the limits of fixed carbon or calorific value of the
high-volatile bituminous and subbituminous ranks. All of these
coals either contain less than 48 percent dry,
mineral-matter-free fixed carbon or have more than 15 500 moist,
mineral-matter-free British thermal units per pound.
BMoist refers to coal containing its natural inherent moisture but not including visible water on the surface of the coal
CIf agglomerating, classify in low-volatile group of the bituminous class.
DCoals having 69 percent or more fixed carbon on the dry, mineral-matter-free basis shall be classified according to fixed carbon, regardless of calorific value.
EIt is recognized that there may be nonagglomerating varieties in these groups of the bituminous class, and there are notable exceptions in the high-volatile C bituminous group.
1ASTM, 1981, p. 215.
*Modified from ASTM, 1981.
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