ASTM D121-15(2024)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D121 − 15 (Reapproved 2024)
Standard Terminology of
Coal and Coke
This standard is issued under the fixed designation D121; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3172 Practice for Proximate Analysis of Coal and Coke
D3173 Test Method for Moisture in the Analysis Sample of
1.1 This terminology defines the technical terms used in
Coal and Coke
standards that are the responsibility of Committee D05 on Coal
D3174 Test Method for Ash in the Analysis Sample of Coal
and Coke. The terms are used in:
and Coke from Coal
1.1.1 The sampling of coal and coke under conditions
D3175 Test Method for Volatile Matter in the Analysis
required for most commercial and technical purposes related to
Sample of Coal and Coke
coal and coke.
D3176 Practice for Ultimate Analysis of Coal and Coke
1.1.2 Bias and related statistical testing,
D3180 Practice for Calculating Coal and Coke Analyses
1.1.3 The description of coal, both visually in the field and
from As-Determined to Different Bases
microscopically in the laboratory,
D3302 Test Method for Total Moisture in Coal
1.1.4 Chemical and physical analyses of coal and coke,
D4371 Test Method for Determining the Washability Char-
1.1.5 Classification of coal, and
acteristics of Coal
1.1.6 Certain other related practices and guides applicable
to the coal and coke industries. D4749 Test Method for Performing the Sieve Analysis of
Coal and Designating Coal Size
1.2 This international standard was developed in accor-
D5061 Test Method for Microscopical Determination of the
dance with internationally recognized principles on standard-
Textural Components of Metallurgical Coke
ization established in the Decision on Principles for the
D5114 Test Method for Laboratory Froth Flotation of Coal
Development of International Standards, Guides and Recom-
in a Mechanical Cell
mendations issued by the World Trade Organization Technical
D5192 Practice for Collection of Coal Samples from Core
Barriers to Trade (TBT) Committee.
D5263 Test Method for Determining the Relative Degree of
2. Referenced Documents
Oxidation in Bituminous Coal by Alkali Extraction
D5515 Test Method for Determination of the Swelling
2.1 ASTM Standards:
Properties of Bituminous Coal Using a Dilatometer
D388 Classification of Coals by Rank
D5865 Test Method for Gross Calorific Value of Coal and
D1412 Test Method for Equilibrium Moisture of Coal at 96
to 97 Percent Relative Humidity and 30 °C Coke
D6316 Test Method for Determination of Total, Combustible
D1857 Test Method for Fusibility of Coal and Coke Ash
D2013 Practice for Preparing Coal Samples for Analysis and Carbonate Carbon in Solid Residues from Coal and
D2234/D2234M Practice for Collection of a Gross Sample Coke
of Coal D7430 Practice for Mechanical Sampling of Coal
D2639 Test Method for Plastic Properties of Coal by the D7582 Test Methods for Proximate Analysis of Coal and
Constant-Torque Gieseler Plastometer
Coke by Macro Thermogravimetric Analysis
D2798 Test Method for Microscopical Determination of the
Vitrinite Reflectance of Coal
3. Terminology
air-dried moisture—this term has been used inappropriately
This terminology is under the jurisdiction of ASTM Committee D05 on Coal
to refer to both residual moisture and air-dry loss. Because of
and Coke and is the direct responsibility of Subcommittee D05.24 on Statistics.
the potential for confusion, this term shall not be used.
Current edition approved March 1, 2024. Published March 2024. Originally
approved in 1921. Last previous edition approved in 2015 as D121 – 15. DOI:
10.1520/D0121-15R24.
air drying, n—a process of partial drying of coal to bring its
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
moisture near to equilibrium with the atmosphere in the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
room in which further reduction and division of the sample
Standardsvolume information, refer to the standard’s Document Summary page on
the ASTM website. will take place.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D121 − 15 (2024)
air-dry loss, n— in coal, the loss in mass, expressed as a bed moisture—synonym for inherent moisture.
percentage, resulting from each air-drying stage or the sum
beehive coke—See beehive coke under coke.
of all sequential air-drying stages in which the results from
binder phase, n— as used in Test Method D5061, a continuous
each stage are adjusted to the as-received basis.
solid carbon matrix formed during the thermoplastic defor-
DISCUSSION—Air-dry loss is neither a standard state nor a character-
mation of those coal macerals that become plastic during
istic property of a coal. Air drying only removes water that can
evaporate at or near ambient laboratory conditions, leaving in the coal carbonization.
some fraction of the inherent moisture that is more tightly bound in the
DISCUSSION—The binder phase material is formed from the thermo-
pores (residual moisture). Different laboratory environments or differ-
plastic deformation of reactive (vitrinite and liptinite) and semi-inert
ent drying temperatures or both will result in significant differences in
(semifusinite) coal macerals of metallurgical bituminous coals. During
air-dry loss and residual moisture. D3302 thermoplasticity, the inert coal maceral and mineral are partly or wholly
incorporated into the binder phase. Also, most of the coke pores are
agglomerating, adj—as applied to coal, the property of
located in the binder phase. D5061
softening when it is heated to above about 400 °C in a
bituminous class—See bituminous class under rank.
nonoxidizing atmosphere, and then appearing as a coherent
mass after cooling to room temperature.
boghead coal—See boghead coal under coal.
bone coal—See bone coal under coal.
alginite—See alginite under maceral.
borehole, n—the circular hole through soil and rock strata
analysis sample—See analysis sample under sample.
made by boring.
angle of repose, n—the greatest angle, measured from
horizontal, attained by a coal so that material on the sides or
bottomsize, nominal— for the purpose of Test Method D4749,
top of the inverted cone or trench created in car top sampling
the sieve designating the lower limit or bottomsize shall be
remains stable, that is, will not shift or slide. Coal size and
that sieve of the series given in the Standard Series of Sieves
moisture content are contributing factors to this angle. In all
section with the largest openings through which passes a
cases, the coal shall be dug so that the physical angle is less
total of less than 15 % of the sample. This defined bottom-
than the angle of repose.
size is not to be confused with the size of the smallest
particles in the lot.
anisotropic, adj—as used in Test Method D5061, exhibiting
DISCUSSION—(Warning—In the case of a commercial, double-
optical properties of different values when viewed with an
1 3
screened product, for example, 37.5 by 9.5 mm (1 ⁄2 by ⁄8 in.), this
optical microscope having mutually exclusive polarized
designation may not be valid. In such commercial or contractual
light, for example, crossed nicols. D5061
situations, the amount of allowable material smaller than the bottom-
size (for example, 9.5 mm) must be specified by the contract under
anthracite—See anthracite under rank.
which the coal is bought and solid.) D4749
anthracitic class—See anthracitic class under rank.
apparent rank, n—of coal, the rank designation obtained on
briquette, n—a cylindrical block composed of granulated coal
samples other than channel samples, but otherwise conform-
or coke particles compressed and embedded with an epoxy
ing to procedures of Classification D388.
binder.
as-analyzed moisture—synonym for as-determined moisture.
by-product coke—See by-product coke under coke.
C test, n—a standard statistical test for homogeneity of
as-determined basis—See as-determined basis under report-
variance.
ing bases.
ash, n—inorganic residue remaining after ignition of combus-
calorific value, n—the heat of combustion of a unit quantity of
tible substances, determined by definite prescribed methods.
a substance.
DISCUSSION—Ash need not be identical, in composition or quantity,
DISCUSSION—It is expressed in ASTM test methods in British thermal
with the inorganic substances present in the material before ignition. In
units per pound (Btu/lb). Calorific value can also be expressed in
the case of coal and coke, the methods used shall be those prescribed
calories per gram (cal/g) or in the International System of Units, joules
in Test Method D3174 or D7582.
per gram (J/g), when required. D5865
as-mined coal—for the purpose of Test Method D4749, same
calorimeter, n— as used in Test Method D5865, the bomb and
as run-of-mine (ROM) coal. D4749
its contents, the calorimeter vessel with stirrer, the water in
which the bomb is immersed, and the portions of the
as-received basis—See as-received basis under reporting
bases. D3180 thermometer and the ignition leads within the calorimeter
vessel. D5865
as-shipped or produced coal—for the purpose of Test Method
D4749, raw or prepared coal in any state or condition at
calorimeter jacket, n—the insulating medium surrounding the
which it leaves the mine property or loading facility. D4749
calorimeter.
attrital coal—See attrital coal under coal.
cannel coal—See cannel coal under coal.
auger increment, n—the retained portion of one extraction
carbonate carbon, n—the carbon content present in the solid
operation of the auger.
products derived from the combustion or reaction of coal,
banded coal—See banded coal under coal.
coal by-products, or coke as carbonates and which is
basis—See reporting bases. noncombustible in standard industry practice. D6316
D121 − 15 (2024)
no interbedded vitrain. Nonbanded coal also is attrital coal but is not
carbon form, n— as used in Test Method D5061, microscopi-
usually referred to as such. In contrast to the coarser and more variable
cally distinguishable carbonaceous textural components of
texture of attrital coal in banded coal, nonbanded coal is notably
coke, but excluding mineral carbonates.
uniform and fine in texture, being derived from size-sorted plant debris.
DISCUSSION—Carbon forms are recognized on the basis of their
The luster of attrital coal, which ranges from bright (but less than that
reflectance, anisotropy, and morphology. They are derived from the
of associated vitrain) to dull, is commonly used to describe and
organic portion of coal and can be anisotropic or isotropic. D5061
characterize attrital coal. As an alternative, some petrographers subdi-
vide attrital coal into clarain and durain. Clarain has bright luster and
caves or washouts, n—zones of increased hole diameter
silky texture, being finely striated parallel to the coal bedding. Durain
caused by rock fragments that fall from the walls of a
has dull luster and sometimes is referred to as dull coal. Similarly, coal
borehole and can block the hole or contaminate the cuttings
consisting of vitrain or clarain or a mixture of the two is sometimes
and which erode or abrade the sidewall of the borehole by
referred to as bright coal.
the action of the drilling. These zones can affect the accuracy
banded coal, n—coal that is visibly heterogeneous in
of certain geophysical logs (especially density). Corrections
composition, being composed of layers of vitrain and attrital
to other geophysical logs can be made if a caliper log is
coal, and, commonly, fusain.
available. The most common causes of caves or washouts
boghead coal, n—nonbanded coal in which the liptinite (the
include soft or fractured lithologies, the presence of water-
waxy component) is predominantly alginite.
producing zones, and the downhole pressure of the drilling
medium (fluid or air) that often causes differential erosion of
bone coal, n—impure coal that contains much clay or other
various strata within the borehole.
fine-grained detrital mineral matter.
chance error, n—error that has equal probability of being cannel coal, n—nonbanded coal in which the liptinite is
positive or negative. The mean of the chance errors resulting predominantly sporinite.
from a series of observations tends toward zero as the DISCUSSION—Transitions between cannel and boghead, that is, coals
containing both types of liptinite, are also known. Microscopic exami-
number of observations approaches infinity.
nation is essential for differentiation of the two kinds of nonbanded coal
circular anisotropic phase, n—as used in Test Method D5061, and their transitions.
a group of binder-phase anisotropic carbon textures that are
fusain, n—coal layers composed of chips and other frag-
distinguished by approximately circular domains (that is
ments in which the original form of plant tissue structure is
length equals width) and composed of fine circular (0.5 to
preserved; commonly has fibrous texture with a very dull
1.0 μm), medium circular (1.0 to 1.5 μm), and coarse circular
luster.
(1.5 to 2.0 μm) size categories. D5061
DISCUSSION—Fusain is very friable and resembles charcoal.
Commonly, it is concentrated in bedding layers or lenses that form
cleat, n—the joint system of coal seams, usually oriented
planes of weakness in coal and thus is often exposed on bedding
normal or nearly normal to the bedding.
surfaces of broken coal. The many pores (cell cavities and cracks) of
DISCUSSION—Cleat is most commonly found in bituminous coal,
fusain are sometimes filled with mineral matter.
being most prominently developed in vitrain bands and bright layers.
impure coal, n—coal having 25 weight % or more, but less
Some cleat, especially the more widely separated joints, extend through
all or a large part of the seam. Cleat surfaces are commonly coated with than 50 weight %, of ash on the dry basis.
minerals such as calcite, kaolinite, and pyrite.
DISCUSSION—Bone coal with more than 50 weight % ash is properly
called coaly or carbonaceous shale or siltstone. Types of impure coal
coal, n—a brown to black combustible sedimentary rock (in the
other than bone coal and mineralized coal sometimes occur, for
geological sense) composed principally of consolidated and
example, sandy coal.
chemically altered plant remains.
lithotype, n— any of the constituents of banded coal: vitrain
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