ASTM D5061-92(2004)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D 5061 – 92 (Reapproved 2004)
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 liptinite) and semi-inert (semifusinite) coal macerals of metal-
lurgical bituminous coals. During thermoplasticity, the inert
1.1 This test method covers the equipment and procedures
coalmaceralandmineralarepartlyorwhollyincorporatedinto
used for determining the types and amounts of coke carbon
thebinderphase.Also,mostofthecokeporesarelocatedinthe
forms and associated recognizable coal- and process-derived
binder phase.
textural components in metallurgical coke in terms of volume
3.2.3 carbon form, n—microscopically distinguishable car-
percent. This test method does not include coke structural
bonaceous textural components of coke, but excluding mineral
componentssuchascokepores,cokewalldimensions,orother
carbonates.
structural associations.
3.2.3.1 Discussion—Carbon forms are recognized on the
1.2 This standard does not purport to address all of the
basisoftheirreflectance,anisotropy,andmorphology.Theyare
safety concerns, if any, associated with its use. It is the
derived from the organic portion of coal and can be anisotropic
responsibility of the user of this standard to establish appro-
or isotropic.
priate safety and health practices and determine the applica-
3.2.4 circular anisotropic phase, n—a group of binder-
bility of regulatory limitations prior to use.
phase anisotropic carbon textures that are distinguished by
2. Referenced Documents
approximately circular domains (that is length equals width)
and composed of fine circular (0.5 to 1.0-µm), medium circular
2.1 ASTM Standards:
(1.0 to 1.5-µm), and coarse circular (1.5 to 2.0-µm) size
D 121 Terminology of Coal and Coke
categories.
D 3997 Practice for Preparing Coke Samples for Micro-
3.2.5 coke pore, n—a microscopically distinguishable void
scopical Analysis by Reflected Light
that is a structural element of coke.
3. Terminology
3.2.5.1 Discussion—Coke pores are considered to be nearly
spherical-shaped voids created by the entrapment of gaseous
3.1 Definitions—For additional definitions of terms used in
volatiles during the solidification of thermoplastic coal. How-
this test method, refer to Terminology D 121.
ever, other types of voids can be distinguished in coke that
3.2 Definitions of Terms Specific to This Standard:
include fractures or cracks, interconnected and elongated
3.2.1 anisotropic, adj—exhibiting optical properties of dif-
pores, and the open cell lumens of fusinite and semifusinite.
ferent values when viewed with an optical microscope having
The size and shape of the voids are coal rank and grade, and to
mutuallyexclusivepolarizedlight,forexample,crossednicols.
some degree, process dependent. Pore sizes vary from tens of
3.2.2 binder phase, n—a continuous solid carbon matrix
angstroms to tens of millimetres in any given coke.
formed during the thermoplastic deformation of those coal
3.2.6 coke reactivity, n—a measure of the mass loss when
macerals that become plastic during carbonization.
coke, held at a designated temperature, is contacted with
3.2.2.1 Discussion—The binder phase material is formed
gaseous carbon dioxide over a specific time interval.
from the thermoplastic deformation of reactive (vitrinite and
3.2.7 coke wall, n—a predominantly carbonaceous layer
that encloses a coke pore and which is a structural element and
This test method is under the jurisdiction of ASTM Committee D05 on Coal
essence of coke.
and Coke and is the direct responsibility of Subcommittee D05.28 on Petrographic
3.2.8 depositional carbon, n—a group of carbon forms that
Analysis of Coal and Coke.
are formed from cracking and nucleation of gas-phase hydro-
Current edition approved April 1, 2004. Published April 2004. Originally
approved in 1992. Last previous edition approved in 1997 as D 5061 - 92 (1997).
carbon molecules during coal carbonization.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.8.1 pyrolytic carbon, n—ananisotropiccarbonformthat
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
is formed by the deposition of carbon parallel to an inert
Standards volume information, refer to the standard’s Document Summary page on
substrate causing the resulting texture to appear ribbon-like.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5061 – 92 (2004)
3.2.8.2 sooty carbon, n—an isotropic carbon form com- 4. Summary of Test Method
prised of approximately spherical particles of less than 1-µm
4.1 The textural components of coke (coke carbon forms
diameter sometimes referred to as combustion black.
and associated coal- and process-related components) in a
3.2.8.3 spherulitic carbon, n—a spherical anisotropic car-
representative crushed particulate coke sample, prepared in the
bon form sometimes referred to as thermal black that is formed form of a briquetted, polished specimen as described in
by the deposition of carbon concentrically around a nucleus. Practice D 3997, are identified under a microscope according
to their degree of anisotropism, carbon form domain sizes,
3.2.9 domain, n—a region of anisotropy in a carbon form
boundary size, color of individual isochromatic domains, their
that is distinctively marked by its isochromatic boundary and
morphology, relative reflectance, and other optical properties.
cleavage.
The proportions of these textural components in a sample are
3.2.10 filler phase, n—a discontinuous solid formed from
determined by observing a statistically adequate number of
coal macerals and minerals that do not deform thermoplasti-
points, and summing those representative of each component.
cally during carbonization.
Only area proportions of components are observed on the
3.2.10.1 Discussion—The filler phase material is formed
briquette surface. However, the area and volume proportions
from coal macerals that are inert with respect to development
are the same when the components are randomly distributed
of thermoplasticity (inertinite), the inorganic components of
throughout the sample.
coal (minerals), as well as normally reactive coal entities that
are noncoking or have been rendered inert by thermal oxida-
5. Significance and Use
tion, natural weathering or brecciation. These inert materials
5.1 The determination of the volume percent of the textural
possess their original morphologies, but their reflectance and
components in coke is useful to characterize the optical
chemical properties have been altered prior to or during
properties of coke as it relates to utilization. Specifically, the
carbonization.
technique has been used as an aid in determining coal blend
3.2.11 green coke, n—carbonaceous binder or filler phase
proportions(aftercorrectingforcokeyield),andrecognitionof
material that has exceeded the temperature of thermoplasticity,
features present in the coke that can be responsible for coke
but has not obtained the temperature of metallurgical coke.
quality or production problems such as reduced coke strength
3.2.11.1 Discussion—Green coke is recognized on the basis
or difficulty in removing coke from commercial coke ovens, or
of relative reflectance in comparison to fully carbonized coke.
both. The study of coke textures is also useful in promoting a
Green coke exhibits varying degrees of lower reflectance than
better understanding of coke reactivity, and the relationship
fully carbonized coke.
between coal petrography and its conversion to 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
the measuring resolution of the light microscope.
6. Apparatus
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
tionswhenviewedwithanopticalmicroscopehavingmutually
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
which span 0.1 % reflectance intervals.
3.2.17.1 Discussion—This term is commonly referred to as
Gray, R. J., and DeVanney, K. F., “Coke Carbon Forms: Microscopic
V-Type. For example, V-type 6 includes vitrinite reflectance
ClassificationAnd IndustrialApplications,” International Journal of Coal Geology,
values from 0.6 through 0.69 %. Vol 6, 1986, pp. 277–297.
D 5061 – 92 (2004)
discretion of the operator or based on agreement between such parties
6.1.2 Mechanical Stage—The mechanical stage shall be of
involved.
such type that the specimen can be quickly advanced by
definite fixed increments in two perpendicular directions (re-
8. Procedure
ferred to as the X and Y directions).
8.1 Mount the coke briquette on a glass slide containing
6.2 Counter—The counter shall be capable of recording
modelingclay,levelusingaspecimenlevelingpress,andplace
counts for at least eight components (preferably twelve or
on the stage of the microscope. Use a few drops of immersion
more) equipped with a totalizer. The counter design can either
oil on the briquette surface.
be mechanical or electrical.
8.2 Adjust the microscope polarizer and analyzer to a
6.3 Immersion Oil—The oil shall be a nondrying, noncor-
crossed polarized position. Mount the accessory plate between
rosive, noncarcinogenic type having similar properties as used
thepolarizerandtheanalyzertothepositionthatyieldsoptimal
for coal microscopic techniques.
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
allocatedtotheappropriatebinderphasecategorywithinwhich
1 mm to the next field in the X direction and identify four
they are
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