ASTM C831-18(2023)
(Test Method)Standard Test Methods for Residual Carbon, Apparent Residual Carbon, and Apparent Carbon Yield in Coked Carbon-Containing Brick and Shapes
Standard Test Methods for Residual Carbon, Apparent Residual Carbon, and Apparent Carbon Yield in Coked Carbon-Containing Brick and Shapes
SIGNIFICANCE AND USE
3.1 These test methods are designed for use with carbon-containing products. The residual carbon content of a coked carbon-containing brick or shape is an indication of how much carbon may be available, in service, to resist slag attack on, or oxidation loss of, that body. Apparent carbon yield gives an estimate of the relative efficiency of the total carbonaceous matter to be retained as residual carbon.
3.2 Residual carbon has a direct bearing on several properties of a pitch or resin-containing refractory, such as ignited porosity, density, strength, and thermal conductivity.
3.3 These test methods are suitable for product development, manufacturing control, and specification acceptance.
3.4 These test methods are very sensitive to specimen size, coking rates, etc.; therefore, strict compliance with these test methods is critical.
3.5 Appreciable amounts of reducible components, such as Fe2O3, will have a noticeable effect on the results. Thus, values obtained by these test methods will be different when brick removed from service is tested. This must be kept in mind when attempting to use these test methods in an absolute sense.
3.6 Oxidizable components such as metals and carbides can have a noticeable effect on the results. This must be kept in mind when using the second procedure, which is based on measuring weight loss after igniting the coked specimens.
3.7 Testing of brick or shapes that contain magnesium metal presents special problems since this metal is highly volatile and substantial amounts of the magnesium can be lost from the sample during the coking procedure. This must be kept in mind when interpreting the results of testing of brick that contains magnesium. In addition, magnesium can react readily with atmospheric humidity. This must be kept in mind when storing brick that contains magnesium.
SCOPE
1.1 These test methods cover the determination of residual carbon content in carbon-bearing brick and shapes after a prescribed coking treatment. They provide two procedures. The first procedure is based on the combustion of carbon and its measurement as carbon dioxide. However, when using the first procedure for articles that contain silicon carbide or other carbides, no distinction will be made between carbon present in the form of a carbide and carbon present as elemental carbon. The second procedure provides a method for calculating apparent residual carbon (on the basis of weight loss after igniting the coked specimens), apparent carbonaceous material content, and apparent carbon yield. If the second procedure is used for brick or shapes that contain metallic additives or carbides, it must be recognized that there will be a weight gain associated with the oxidation of the metals, or carbides, or both. Such a weight gain can change the results substantially, and this must be kept in mind when interpreting the data.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 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.
General Information
Relations
Standards Content (Sample)
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: C831 − 18 (Reapproved 2023)
Standard Test Methods for
Residual Carbon, Apparent Residual Carbon, and Apparent
Carbon Yield in Coked Carbon-Containing Brick and
Shapes
This standard is issued under the fixed designation C831; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 These test methods cover the determination of residual
D2906 Practice for Statements on Precision and Bias for
carbon content in carbon-bearing brick and shapes after a
Textiles (Withdrawn 2008)
prescribed coking treatment. They provide two procedures.
E11 Specification for Woven Wire Test Sieve Cloth and Test
The first procedure is based on the combustion of carbon and
Sieves
its measurement as carbon dioxide. However, when using the
first procedure for articles that contain silicon carbide or other
3. Significance and Use
carbides, no distinction will be made between carbon present in
3.1 These test methods are designed for use with carbon-
the form of a carbide and carbon present as elemental carbon.
containing products. The residual carbon content of a coked
The second procedure provides a method for calculating
carbon-containing brick or shape is an indication of how much
apparent residual carbon (on the basis of weight loss after
carbon may be available, in service, to resist slag attack on, or
igniting the coked specimens), apparent carbonaceous material
oxidation loss of, that body. Apparent carbon yield gives an
content, and apparent carbon yield. If the second procedure is
estimate of the relative efficiency of the total carbonaceous
used for brick or shapes that contain metallic additives or
matter to be retained as residual carbon.
carbides, it must be recognized that there will be a weight gain
3.2 Residual carbon has a direct bearing on several proper-
associated with the oxidation of the metals, or carbides, or
ties of a pitch or resin-containing refractory, such as ignited
both. Such a weight gain can change the results substantially,
porosity, density, strength, and thermal conductivity.
and this must be kept in mind when interpreting the data.
3.3 These test methods are suitable for product
1.2 The values stated in inch-pound units are to be regarded
development, manufacturing control, and specification accep-
as the standard. The values given in parentheses are for
tance.
information only.
3.4 These test methods are very sensitive to specimen size,
1.3 This standard does not purport to address all of the
coking rates, etc.; therefore, strict compliance with these test
safety concerns, if any, associated with its use. It is the
methods is critical.
responsibility of the user of this standard to establish appro-
3.5 Appreciable amounts of reducible components, such as
priate safety, health, and environmental practices and deter-
Fe O , will have a noticeable effect on the results. Thus, values
mine the applicability of regulatory limitations prior to use.
2 3
obtained by these test methods will be different when brick
1.4 This international standard was developed in accor-
removed from service is tested. This must be kept in mind
dance with internationally recognized principles on standard-
when attempting to use these test methods in an absolute sense.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.6 Oxidizable components such as metals and carbides can
have a noticeable effect on the results. This must be kept in
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. mind when using the second procedure, which is based on
measuring weight loss after igniting the coked specimens.
1 2
These test methods are under the jurisdiction of ASTM Committee C08 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Refractories and are the direct responsibility of Subcommittee C08.04 on Chemical contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Behaviors. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2023. Published November 2023. Originally the ASTM website.
approved in 1976. Last previous edition approved in 2018 as C831 – 18. DOI: The last approved version of this historical standard is referenced on
10.1520/C0831-18R23. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C831 − 18 (2023)
3.7 Testing of brick or shapes that contain magnesium metal 4.2 For CO Absorption:
presents special problems since this metal is highly volatile and 4.2.1 Laboratory Pulverizer, designed to provide a sealed,
substantial amounts of the magnesium can be lost from the dust-proof grinding chamber, and having a capacity of at least
sample during the coking procedure. This must be kept in mind 50 g of sample.
when interpreting the results of testing of brick that contains 4.2.2 Combustion Tube Furnace, capable of operating at
magnesium. In addition, magnesium can react readily with 1832 °F (1000 °C)
atmospheric humidity. This must be kept in mind when storing 4.2.3 CO Absorption Train, as described in Fig. 4.
brick that contains magnesium.
NOTE 2—Commercial automatic and semi-automatic carbon determi-
nators may replace the apparatus described in 4.2.2 and 4.2.3.
4. Apparatus
4.3 The precision obtained with these instruments shall
4.1 For Coking:
meet the requirements specified in Section 10.
4.1.1 Gas or Electric Furnace, with heating chamber ca-
5. Preparation of Test Specimens
pable of receiving the coking box shown in Fig. 1.
5.1 This method assumes that the number of specimens
NOTE 1—Samples should not be subjected to thermal gradients greater
tested will be a statistically valid sample of the entire lot of
than 40 °F (22 °C) during heatup. In electric furnaces with silicon carbide
brick or shapes being evaluated. The exact number is usually
heating elements, the length of the box should be parallel to these
elements. arrived at by mutual agreement between parties concerned.
4.1.2 Inner and Outer Box, stainless steel (or equivalent 5.2 Although sample brick from either the 4 ⁄2-in. (114 mm)
alloy), as shown in Figs. 1-3. or the 6-in. (152 mm) series may be tested, it is preferable to
FIG. 1 Outer Coking Box (Dimensions are in Inches)
C831 − 18 (2023)
FIG. 2 Inner Coking Box
use the larger size for the test. Cut slices 1 in. 6 ⁄32 in. (25 mm 5.4 Specimens that are cut wet must be dried immediately
6 0.8 mm) in thickness perpendicular to the length at the with a paper or cloth towel and flash dried. For pitch-
mid-section of each sample brick or shape. As shown in Fig. 5,
impregnated samples, flash drying should be done at a suffi-
the nominal size of each slice shall be 1 in. by 3 in. by 6 in.
ciently low temperature to avoid “weeping” of pitch from the
(25 mm by 76 mm by 152 mm). The two 1-in. by 3-in. faces
pores of the brick. Drying can usually be done on a forced-air
and the two 1-in. by 6-in. faces must be original surfaces.
dryer at 220 °F (105 °C) by limiting exposure to 5 min to
10 min. Repeat if necessary. These drying procedures are
5.3 Test specimens may be cut wet or dry except for
especially important for metal-containing brick because hydra-
products capable of hydration, such as dolomite brick, which
must be cut dry and stored in a dry container prior to coking. tion of the metals can occur. Specimens containing a coating of
C831 − 18 (2023)
FIG. 3 Coking Box Arrangement
FIG. 4 CO Absorption Train
pitch on uncut surfaces, as is typical of an impregnation 6. Procedure for Coking
process, must be scraped clean prior to drying.
6.1 Place the test specimens randomly into the inner box,
5.5 Weigh all specimens after drying to constant weight
Fig. 2.
(60.2 g), recording weight to the nearest 0.1 g. This weight is
NOTE 3—Burned pitch-impregnated magnesite brick should not be
“as-received weight, A.” (This step may be omitted if residual
coked with tempered, tar-bonded, or dolomite brick because of carbon
carbon is to be determined by CO absorption, as indicated in
2 pickup by the impregnated samples and disruption of the bottom of
1.1.) tempered samples. Pitch-bonded, pitch-bonded tempered magnesite brick,
C831 − 18 (2023)
FIG. 5 Location of Test Specimen
and dolomite brick may be coked in the same box or coking run. NOTE 6—After each run, clean the muffle and the bottom carbon plate
NOTE 4—The number of samples coked per run should be constant of any adhering coke breeze.
within a laboratory. Dummy uncoked samples consistent with Note 3 may
6.10 Samples that contain dolomite or aluminum metal
be used to fill any empty positions in the inner box.
should be stored in a sealed container containing dessicant in
6.2 Place the inner box into the center of the outer box (Fig.
the time interval between coking and measurement of carbon
3), on the bottom of which has first been placed a ⁄2-in.
content. This is to prevent hydration of dolomite or aluminum
(13 mm) slab of carbon, covered with a thin layer of dust-free
carbide. The aluminum carbide is formed by reaction between
metallurgical-grade coke breeze (No. 14 (1.40 mm) sieve size)
aluminum and carbon in the shape during the coking operation.
(Note 5). To ensure that the coke breeze is free of moisture
Aluminum carbide can react with a water source such as
which could oxidize carbon during coking, dry the coke at
atmospheric humidity to form methane. Care should be taken
400 °F (205 °C) for 24 h, and keep in a closed container at
since methane can be an explosion hazard.
room temperature until needed.
CO ABSORPTION (FIRST ALTERNATIVE
NOTE 5—Detailed requirements for sieves are given in Specification
PROCEDURE)
E11.
6.3 Place the thermocouple well into the center of the inner 7. Preparation of Sample
box and put the lid on the inner box. The thermocouple well
7.1 A sample consists of a single slice or multiple specimens
must be long enough to extend above the cover of the outer
of brick prepared as described in Sections 5 and 6.
box.
7.2 Crush the sample in a laborato
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