ASTM D5061-92(1997)

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Designation: D 5061 – 92 (Reapproved 1997)
Standard Test Method for
Microscopical Determination of Volume Percent of Textural
Components in Metallurgical Coke
This standard is issued under the fixed designation D 5061; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope coal maceral and mineral are partly or wholly incorporated into
the binder phase. Also, most of the coke pores are located in the
1.1 This test method covers the equipment and procedures
binder phase.
used for determining the types and amounts of coke carbon
3.2.3 carbon form, n—microscopically distinguishable car-
forms and associated recognizable coal- and process-derived
bonaceous textural components of coke, but excluding mineral
textural components in metallurgical coke in terms of volume
carbonates.
percent. This test method does not include coke structural
3.2.3.1 Discussion—Carbon forms are recognized on the
components such as coke pores, coke wall dimensions or other
basis of their reflectance, anisotropy, and morphology. They are
structural associations.
derived from the organic portion of coal and can be anisotropic
1.2 This standard does not purport to address all of the
or isotropic.
safety concerns, if any, associated with its use. It is the
3.2.4 domain, n—a region of anisotropy in a carbon form
responsibility of the user of this standard to establish appro-
that is distinctively marked by its isochromatic boundary and
priate safety and health practices and determine the applica-
cleavage.
bility of regulatory limitations prior to use.
3.2.5 circular anisotropic phase, n—a group of binder-
2. Referenced Documents
phase anisotropic carbon textures that are distinguished by
approximately circular domains (that is length equals width)
2.1 ASTM Standards:
and composed of fine circular (0.5 to 1.0-μm), medium circular
D 121 Terminology of Coal and Coke
(1.0 to 1.5-μm), and coarse circular (1.5 to 2.0-μm) size
D 346 Practice for Collection and Preparation of Coke
categories.
Samples for Laboratory Analyses
3.2.6 coke pore, n—a microscopically distinguishable void
D 3997 Practice for Preparing Coke Samples for Micro-
that is a structural element of coke.
scopical Analysis by Reflected Light
3.2.6.1 Discussion—Coke pores are considered to be nearly
3. Terminology
spherical-shaped voids created by the entrapment of gaseous
volatiles during the solidification of thermoplastic coal. How-
3.1 Definitions—For additional definitions of terms used in
ever, other types of voids can be distinguished in coke that
this test method, refer to Terminology D 121.
include fractures or cracks, interconnected and elongated
3.2 Definitions of Terms Specific to This Standard:
pores, and the open cell lumens of fusinite and semifusinite.
3.2.1 anisotropic, adj—exhibiting optical properties of dif-
The size and shape of the voids are coal rank and grade, and to
ferent values when viewed with an optical microscope having
some degree, process dependent. Pore sizes vary from tens of
mutually exclusive polarized light, for example, crossed nicols.
angstroms to tens of millimetres in any given coke.
3.2.2 binder phase, n—a continuous solid carbon matrix
3.2.7 coke reactivity, n—a measure of the mass loss when
formed during the thermoplastic deformation of those coal
coke, held at a designated temperature, is contacted with
macerals that become plastic during carbonization.
gaseous carbon dioxide over a specific time interval.
3.2.2.1 Discussion—The binder phase material is formed
3.2.8 coke wall, n—a predominantly carbonaceous layer
from the thermoplastic deformation of reactive (vitrinite and
that encloses a coke pore and which is a structural element and
liptinite) and semi-inert (semifusinite) coal macerals of metal-
essence of coke.
lurgical bituminous coals. During thermoplasticity, the inert
3.2.9 depositional carbon, n—a group of carbon forms that
are formed from cracking and nucleation of gas-phase hydro-
This test method is under the jurisdiction of ASTM Committee D-5 on Coal and
carbon molecules during coal carbonization.
Coke and is the direct responsibility of Subcommittee D05.28 on Petrographic
3.2.9.1 pyrolytic carbon, n—an anisotropic carbon form that
Analysis of Coal and Coke.
is formed by the deposition of carbon parallel to an inert
Current edition approved Feb. 15, 1992. Published June 1992.
Annual Book of ASTM Standards, Vol 05.05. substrate causing the resulting texture to appear ribbon-like.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5061
3.2.9.2 sooty carbon, n—an isotropic carbon form com- Practice D 3997, are identified under a microscope according
prised of approximately spherical particles of less than 1-μm to their degree of anisotropism, carbon form domain sizes,
diameter sometimes referred to as combustion black. boundary size, color of individual isochromatic domains, their
3.2.9.3 spherulitic carbon, n—a spherical anisotropic car- morphology, relative reflectance, and other optical properties.
bon form sometimes referred to as thermal black that is formed The proportions of these textural components in a sample are
by the deposition of carbon concentrically around a nucleus. determined by observing a statistically adequate number of
3.2.10 filler phase, n—a discontinuous solid formed from points, and summing those representative of each component.
coal macerals and minerals that do not deform thermoplasti- Only area proportions of components are observed on the
cally during carbonization. briquette surface. However, the area and volume proportions
3.2.10.1 Discussion—The filler phase material is formed are the same when the components are randomly distributed
from coal macerals that are inert with respect to development throughout the sample.
of thermoplasticity (inertinite), the inorganic components of
5. Significance and Use
coal (minerals), as well as normally reactive coal entities that
are noncoking or have been rendered inert by thermal oxida- 5.1 The determination of the volume percent of the textural
tion, natural weathering or brecciation. These inert materials
components in coke is useful to characterize the optical
possess their original morphologies, but their reflectance and
properties of coke as it relates to utilization. Specifically, the
chemical properties have been altered prior to or during
technique has been used as an aid in determining coal blend
carbonization.
proportions (after correcting for coke yield), and recognition of
3.2.11 green coke, n—carbonaceous binder or filler phase
features present in the coke that can be responsible for coke
material that has exceeded the temperature of thermoplasticity,
quality or production problems such as reduced coke strength
but has not obtained the temperature of metallurgical coke.
or difficulty in removing coke from commercial coke ovens, or
3.2.11.1 Discussion—Green coke is recognized on the basis
both. The study of coke textures is also useful in promoting a
of relative reflectance in comparison to fully carbonized coke.
better understanding of coke reactivity, and the relationship
Green coke exhibits varying degrees of lower reflectance than
between coal petrography and its conversion to coke.
fully carbonized coke.
5.2 This test method is used in scientific and industrial
3.2.12 incipient anisotropic phase, n—a binder-phase car-
research, but not for compliance or referee tests.
bon texture having a domain size (less than 0.5 μm) that is near
6. Apparatus
the measuring resolution of the light microscope.
3.2.13 isotropic phase, n—a binder-phase carbon texture
6.1 Microscope—A high quality reflected-light microscope
that exhibits optical properties that are the same in all direc-
with a vertical illuminator and rotating mechanical stage is
tions when viewed with an optical microscope having mutually
used, provided that the objective and eyepiece lenses permit
exclusive polarized light, for example, crossed nicols.
resolution of objects on the order of 0.5 μm. The objective lens
3.2.14 lenticular anisotropic phase, n—a group of binder-
shall be of such construction that samples can be studied in oil
phase anisotropic carbon textures distinguished by their lens-
with plane-polarized light. A minimum total magnification of
shaped domains (that is, length (L) to width (W) ratio of 2W <
approximately 500 diameters is recommended. Use of an
L <4W) and subdivided based on domain widths as fine
accessory plate (quartz, gypsum, or mica), an analyzer, and
lenticular (1.0 to 3.0-μm), medium lenticular (3.0 to 8.0-μm),
polarizer combination is recommended to achieve optimum
and coarse lenticular (8.0 to 12.0-μm) size categories.
optical effect for discriminating among the various textural
3.2.15 ribbon anisotropic phase, n—a group of binder-
components. Either a prism or a partially reflecting glass plate
phase anisotropic carbon textures distinguished by their
may be employed in the illuminator. One eyepiece of the
ribbon-like domains (that is, length (L) to width (W) ratio of L
microscope must be fitted with a special ruled graticule disc.
>4W), and subdivided based on domain width as fine ribbon
6.1.1 Eyepiece Disc—The eyepiece shall contain a ruled
(2.0 to 12.0-μm), medium ribbon (12.0 to 25.0-μm), and coarse
graticule disc to enable size estimations and to provide a
ribbon (>25.0-μm) size categories.
field-of-view grid for point counting. The design may be a
3.2.16 textural component, n—the collective term used to
squared pattern (10 by 10 squares) containing a bolder
describe carbon forms and recognizable coal- and process-
crosshair with one of the squares near the center crosshair
derived components (binder-phase, filler-phase, and miscella-
intersection divided into 25 subsquares. The ruled portion of
neous material) in coke.
the disc shall cover at least one third of the field of view.
3.2.17 vitrinite type, n—reflectance classes of vitrinite
6.1.2 Mechanical Stage—The mechanical stage shall be of
which span 0.1 % reflectance intervals.
such type that the specimen can be quickly advanced by
3.2.17.1 Discussion—This term is commonly referred to as
definite fixed increments in two perpendicular directions (re-
V-Type. For example, V-type 6 includes vitrinite reflectance
ferred to as the X and Y directions).
values from 0.6 through 0.69 %.
6.2 Counter—The counter shall be capable of recording
counts for at least eight components (preferably twelve or
4. Summary of Test Method
4.1 The textural components of coke (coke carbon forms
and associated coal- and process-related components) in a
Gray, R. J., and DeVanney, K. F., “Coke Carbon Forms: Microscopic
representative crushed particulate coke sample, prepared in the
Classification And Industrial Applications,” International Journal of Coal Geology,
form of a briquetted, polished specimen as described in Vol 6, pp. 277–297.
D 5061
more) equipped with a totalizer. The counter design can either on the stage of the microscope. Use a few drops of immersion
be mechanical or electrical. oil on the briquette surface.
6.3 Immersion Oil—The oil shall be a nondrying, noncor- 8.2 Adjust the microscope polarizer and analyzer to a
rosive, noncarcinogenic type having similar properties as used crossed polarized position. Mount the accessory plate between
for coal microscopic techniques. the polarizer and the analyzer to the position that yields optimal
retardation and color enhancement.
7. Organization of Analysis
8.3 Binder Phase Counting—Position the coke briquette by
means of the mechanical stage to the starting position. Identify
7.1 Textural components are grouped into three major
four points per field under the special graticule or whipple disc
categories; (1) binder phase carbon forms, (2) filler phase
(the intersection at each of the outermost corners). The exact
carbon forms (including coal-related inorganic material), and
directions traversed on the briquette are up to the preference of
(3) miscellaneous materials. These categories are shown in
the operator. An example of one type of surface traverse is to
summary form in Table 1. Volume percent of the various types
move the mechanical stage 1 mm to the next field in the X
of binder phase carbon forms should be determined during the
direction and identify four points. Movement can be from left
first microscopic analyses. The volume percent of the filler
to right. Continue movement and counting in the X direction
phase (including coal-related inorganic material) should be
until the edge of the specimen is reached then move the
determined as a second analysis. The miscellaneous materials
specimen by means of the mechanical stage down 1 mm in the
are commonly determined during analysis of the filler phase.
Y direction and begin traversing from the left to the right in the
7.1.1 Binder Phase Carbon Form Determinations—The
X direction. Continue this until a total of at least 1000 binder
components counted and kept separate shall be the following:
phase points (500 points on each of two different briquettes)
isotropic, incipient, circular anisotropic (fine), circular aniso-
are counted.
tropic (medium), circular anisotropic (coarse), lenticular aniso-
8.4 Filler Phase and Miscellaneous Counting—Position the
tropic (fine), lenticular anisotropic (medium), lenticular aniso-
coke briquette by means of the mechanical stage to the starting
tropic (coarse), ribbon anisotropic (fine), ribbon anisotropic
position. Identify four points per field under the special
(medium), ribbon anisotropic (coarse). These binder phase
graticule or whipple disc (the intersection at each of the
categories relate to parent coal rank. When other components
outermost corners). The exact directions traversed on the
(filler phase, including coal-related inorganic material, and
briquette are up to the preference of the operator. An example
miscellaneous materials) are encountered, they are to be
of one type of surface traverse is to move the mechanical stage
allocated to the appropriate binder phase category within which
1 mm to the next field in the X direction and identify four
they are incorporated.
points. Movement can be from left to right. Continue move-
7.1.2 Filler Phase Carbon Form Determinations (Including
ment and counting in the X direction until the edge of the
Coal-Related Inorganic Material)—The components counted
specimen is reached then move the specimen by means of the
and kept separate shall be the following: one categ
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