ASTM C831-98(2013)
(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 contain magnesium. In addition, magnesium can react readily with atmospheric humidity. This must be kept in mind when storing brick that contain 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C831 − 98 (Reapproved 2013)
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 D2906 Practice for Statements on Precision and Bias for
Textiles (Withdrawn 2008)
1.1 These test methods cover the determination of residual
E11 Specification for Woven Wire Test Sieve Cloth and Test
carbon content in carbon-bearing brick and shapes after a
Sieves
prescribed coking treatment. They provide two procedures.
The first procedure is based on the combustion of carbon and
3. Significance and Use
its measurement as carbon dioxide. However, when using the
3.1 These test methods are designed for use with carbon-
first procedure for articles that contain silicon carbide or other
containing products. The residual carbon content of a coked
carbides,nodistinctionwillbemadebetweencarbonpresentin
carbon containing brick or shape is an indication of how much
the form of a carbide and carbon present as elemental carbon.
carbon may be available, in service, to resist slag attack on, or
The second procedure provides a method for calculating
oxidation loss of, that body. Apparent carbon yield gives an
apparent residual carbon (on the basis of weight loss after
estimate of the relative efficiency of the total carbonaceous
igniting the coked specimens), apparent carbonaceous material
matter to be retained as residual carbon.
content, and apparent carbon yield. If the second procedure is
used for brick or shapes that contain metallic additives or
3.2 Residual carbon has a direct bearing on several proper-
carbides, it must be recognized that there will be a weight gain
ties of a pitch or resin containing refractory such as ignited
associated with the oxidation of the metals, or carbides, or
porosity, density, strength, and thermal conductivity.
both. Such a weight gain can change the results substantially
3.3 These test methods are suitable for product
and this must be kept in mind when interpreting the data.
development, manufacturing control and specification accep-
1.2 The values stated in inch-pound units are to be regarded
tance.
as the standard. The values given in parentheses are for
3.4 These test methods are very sensitive to specimen size,
information only.
coking rates, etc.; therefore, strict compliance with these test
1.3 This standard does not purport to address all of the
methods is critical.
safety concerns, if any, associated with its use. It is the
3.5 Appreciable amounts of reducible components, such as
responsibility of the user of this standard to establish appro-
Fe O , will have a noticeable effect on the results.Thus, values
2 3
priate safety and health practices and determine the applica-
obtained by these test methods will be different when brick
bility of regulatory limitations prior to use.
removed from service is tested. This must be kept in mind
when attempting to use these test methods in an absolute sense.
2. Referenced Documents
3.6 Oxidizable components such as metals and carbides can
2.1 ASTM Standards:
have a noticeable effect on the results. This must be kept in
C571 Methods for Chemical Analysis of Carbon and
mind when using the second procedure, which is based on
Carbon-Ceramic Refractories (Withdrawn 1995)
measuring weight loss after igniting the coked specimens.
3.7 Testing of brick or shapes that contain magnesium metal
These test methods are under the jurisdiction of ASTM Committee C08 on
presentsspecialproblemssincethismetalishighlyvolatileand
Refractories and are the direct responsibility of Subcommittee C08.04 on Chemical
Behaviors.
substantial amounts of the magnesium can be lost from the
Current edition approved April 1, 2013. Published August 2013. Originally
sample during the coking procedure.This must be kept in mind
approved in 1976. Last previous edition approved in 2008 as C831 – 98 (2008).
when interpreting the results of testing of brick that contain
DOI: 10.1520/C0831-98R13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C831 − 98 (2013)
magnesium. In addition, magnesium can react readily with 4.2.1 Laboratory Pulverizer designed to provide a sealed,
atmospheric humidity. This must be kept in mind when storing dustproof grinding chamber, and having a capacity of at least
brick that contain magnesium. 50 g of sample.
4.2.2 Combustion-Tube Furnace capable of operating at
4. Apparatus
183°F (1000°C)
4.2.3 CO -Absorption Train as described in Fig. 4 and in
4.1 For Coking:
Method
4.1.1 Gas or Electric Furnace with heating chamber ca-
pable of receiving the coking box shown in Fig. 1.
NOTE 2—Commercial automatic and semi-automatic carbon determi-
nators may replace the apparatus described in 4.2.2 and 4.2.3.
NOTE 1—Samples should not be subjected to thermal gradients greater
than 40°F (22°C) during heatup. In electric furnaces with silicon carbide
4.3 The precision obtained with these instruments shall
heating elements, the length of the box should be parallel to these
meet the requirements specified in Section 10.
elements.
4.1.2 Inner and Outer Box, stainless steel (or equivalent 5. Preparation of Test Specimens
alloy), as shown in Figs. 1-3.
5.1 This method assumes that the number of specimens
4.2 For CO Absorption: tested will be a statistically valid sample of the entire lot of
Typical grinders are: Blueler Mill, Applied Research Laboratories, Sunland,
CA; Laboratory Disc Mill, Angstrom, Inc., Bellville, MI; and Shatter Box, Spex
Industries, Inc., Metuchen, NJ.
FIG. 1 Outer Coking Box (Dimensions are in Inches)
C831 − 98 (2013)
FIG. 2 Inner Coking Box
brick or shapes being evaluated. The exact number is usually sizeofeachsliceshallbe1by3by6in.(25by76by152mm).
arrived at by mutual agreement between parties concerned.
The two 1 by 3-in. faces and the two 1 by 6-in. faces must be
1 original surfaces.
5.2 Although sample brick from either the 4 ⁄2-in. (114-mm)
or the 6-in. (152-mm) series may be tested, it is preferable to
5.3 Test specimens may be cut wet or dry except for
use the larger size for the test. Cut slices 1 6 ⁄32 in. (25 6 0.8
products capable of hydration, such as dolomite brick, which
mm) in thickness perpendicular to the length at the mid-section
must be cut dry and stored in a dry container prior to coking.
of each sample brick or shape.As shown in Fig. 5, the nominal
C831 − 98 (2013)
FIG. 3 Coking Box Arrangement
FIG. 4 CO -Absorption Train
5.4 Specimens that are cut wet must be dried immediately pores of the brick. Drying can usually be done on a forced-air
with a paper or cloth towel and flash dried. For pitch- dryer at 220°F (105°C) by limiting exposure to 5 to 10 min.
impregnated samples, flash drying should be done at a suffi- Repeat if necessary. These drying procedures are especially
ciently low temperature to avoid “weeping” of pitch from the important for metal-containing brick because hydration of the
C831 − 98 (2013)
FIG. 5 Location of Test Specimen
metals can occur. Specimens containing a coating of pitch on 6.6 Heatthefurnacesothatthethermocouplewithinthebox
uncut surfaces, as is typical of an impregnation process, must registers 250°F (120°C) after the first hour, then heat the
be scraped clean prior to drying. furnace so that the box is heated at a rate of 400 6 20°F (2206
11°C)/h to 1800 6 20°F (980 6 11°C).
5.5 Weigh all specimens after drying to constant weight
(60.2g), recording weight to the nearest 0.1 g. This weight is
6.7 Holdthetemperaturefor3 6 ⁄2h,startingfromthetime
“as-received weight, A,” (This step may be omitted if residual
1780°F (970°C) is reached in the inner box.
carbon is to be determined by CO absorption, as indicated in
6.8 After completing the hold period, shut off the furnace
1.1.)
and allow the coking box to cool naturally within the furnace.
6. Procedure for Coking
6.9 Remove the samples from the coking box after the box
6.1 Place the test specimens randomly into the inner box, has cooled sufficiently to handle. After removing specimens
Fig. 2
from the inner box, clean by brushing carefully with a nylon or
naturalbristlebrushtoremoveclingingparticles.Thenproceed
NOTE 3—Burned pitch-impregnated magnesite brick should not be
to either of the two alternatives for analyzing the specimens.
coked with tempered, tar-bonded, or dolomite brick because of carbon
pickup by the impregnated samples and disruption of the bottom of
NOTE 6—After each run, clean the muffle and the bottom carbon plate
tempered samples. Pitch-bonded, pitch-bonded tempered magnesite brick
of any adhering coke breeze.
and dolomite brick may be coked in the same box or coking run.
NOTE 4—The number of samples coked per run should be constant
6.10 Samples that contain dolomite or aluminum metal
within a laboratory. Dummy uncoked samples consistent with Note 3 may
should be stored in a sealed container containing dessicant in
be used to fill any empty positions in the inner box.
the time interval between coking and measurement of carbon
6.2 Place the inner box into the center of the outer box (Fig.
content. This is to prevent hydration of dolomite or aluminum
3), on the bottom of which has first been placed a ⁄2-in.
carbide. The aluminum carbide is formed by reaction between
(13-mm) slab of carbon, covered with a thin layer of dust-free
aluminum and carbon in the shape during the coking operation.
metallurgical-grade coke breeze (No. 14 (1.40–mm) sieve size)
Aluminum carbide can react with a water source such as
(Note 5). To ensure that the coke breeze is free of moisture
atmos
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