ASTM C831-98

Standard Test Methods for Residual Carbon, Apparent Residual Carbon, and Apparent Carbon Yield in Coked Carbon-Containing Brick and Shapes

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

• Status: Historical
• Publication Date: 09-Mar-1998
• ICS: 91.100.15 - Mineral materials and products
• Technical Committee: C08 - Refractories
• Drafting Committee: C08.04 - Chemical Behaviors

Relations

• Replaced By: ASTM C831-98(2003) - Standard Test Methods for Residual Carbon, Apparent Residual Carbon, and Apparent Carbon Yield in Coked Carbon-Containing Brick and Shapes
• Effective Date: 01-Nov-2003
• Referred By: ASTM C1190-18(2022) - Standard Practice for Location of Test Specimens from Magnesia-Carbon and Impregnated Burned Basic Brick
• Effective Date: 10-Mar-1998
• Referred By: ASTM C607-88(2016) - Standard Practice for Coking Large Shapes of Carbon-Bearing Materials
• Effective Date: 10-Mar-1998

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: C 831 – 98
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 C 831; 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 E 11 Specification for Wire-Cloth Sieves for Testing Pur-
poses
1.1 These test methods cover the determination of residual
carbon content in carbon-bearing brick and shapes after a
3. Significance and Use
prescribed coking treatment. They provide two procedures.
3.1 These test methods are designed for use with carbon-
The first procedure is based on the combustion of carbon and
containing products. The residual carbon content of a coked
its measurement as carbon dioxide. However, when using the
carbon containing brick or shape is an indication of how much
first procedure for articles that contain silicon carbide or other
carbon may be available, in service, to resist slag attack on, or
carbides, no distinction will be made between carbon present in
oxidation loss of, that body. Apparent carbon yield gives an
the form of a carbide and carbon present as elemental carbon.
estimate of the relative efficiency of the total carbonaceous
The second procedure provides a method for calculating
matter to be retained as residual carbon.
apparent residual carbon (on the basis of weight loss after
3.2 Residual carbon has a direct bearing on several proper-
igniting the coked specimens), apparent carbonaceous material
ties of a pitch or resin containing refractory such as ignited
content, and apparent carbon yield. If the second procedure is
porosity, density, strength, and thermal conductivity.
used for brick or shapes that contain metallic additives or
3.3 These test methods are suitable for product develop-
carbides, it must be recognized that there will be a weight gain
ment, manufacturing control and specification acceptance.
associated with the oxidation of the metals, or carbides, or
3.4 These test methods are very sensitive to specimen size,
both. Such a weight gain can change the results substantially
coking rates, etc., therefore, strict compliance with these test
and this must be kept in mind when interpreting the data.
methods is critical.
1.2 The values stated in inch-pound units are to be regarded
3.5 Appreciable amounts of reducible components, such as
as the standard. The values given in parentheses are for
Fe O , will have a noticeable effect on the results. Thus, values
2 3
information only.
obtained by these test methods will be different when brick
1.3 This standard does not purport to address all of the
removed from service is tested. This must be kept in mind
safety concerns, if any, associated with its use. It is the
when attempting to use these test methods in an absolute sense.
responsibility of the user of this standard to establish appro-
3.6 Oxidizable components such as metals and carbides can
priate safety and health practices and determine the applica-
have a noticeable effect on the results. This must be kept in
bility of regulatory limitations prior to use.
mind when using the second procedure, which is based on
2. Referenced Documents measuring weight loss after igniting the coked specimens.
3.7 Testing of brick or shapes that contain magnesium metal
2.1 ASTM Standards:
presents special problems since this metal is highly volatile and
C 571 Methods for Chemical Analysis of Carbon and
substantial amounts of the magnesium can be lost from the
Carbon-Ceramic Refractories
sample during the coking procedure. This must be kept in mind
D 2906 Practice for Statements on Precision and Bias for
when interpreting the results of testing of brick that contain
Textiles
magnesium. In addition, magnesium can react readily with
atmospheric humidity. This must be kept in mind when storing
These test methods are under the jurisdiction of ASTM Committee C-8 on brick that contain magnesium.
Refractories and are the direct responsibility of Subcommittee C08.04 on Chemical
Behaviors.
Current edition approved March 10, 1998. Published December 1998. Originally
published as C 831 – 76. Last previous edition C 831 – 97.
Discontinued. See 1996 Annual Book of ASTM Standards, Vol 03.05
3 4
Annual Book of ASTM Standards, Vol 07.01 Annual Book of ASTM Standards, Vol 14.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 831–98
4. Apparatus 4.2.2 Combustion-Tube Furnace capable of operating at
183°F (1000°C)
4.1 For Coking:
4.2.3 CO -Absorption Train as described in Fig. 4 and in
4.1.1 Gas or Electric Furnace with heating chamber ca- 2
Method C 571
pable of receiving the coking box shown in Fig. 1.
NOTE 2—Commercial automatic and semi-automatic carbon determi-
NOTE 1—Samples should not be subjected to thermal gradients greater
nators may replace the apparatus described in 4.2.2 and 4.2.3.
than 40°F (22°C) during heatup. In electric furnaces with silicon carbide
heating elements, the length of the box should be parallel to these
4.3 The precision obtained with these instruments shall
elements.
meet the requirements specified in Section 10.
4.1.2 Inner and Outer Box, stainless steel (or equivalent
5. Preparation of Test Specimens
alloy), as shown in Figs. 1-3.
4.2 For CO Absorption: 5.1 This method assumes that the number of specimens
tested will be a statistically valid sample of the entire lot of
4.2.1 Laboratory Pulverizer designed to provide a sealed,
dustproof grinding chamber, and having a capacity of at least brick or shapes being evaluated. The exact number is usually
50 g of sample. arrived at by mutual agreement between parties concerned.
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
use the larger size for the test. Cut slices 1 6 ⁄32 in. (25 6 0.8
mm) in thickness perpendicular to the length at the mid-section
Typical grinders are: Blueler Mill, Applied Research Laboratories, Sunland,
CA; Laboratory Disc Mill, Angstrom, Inc., Bellville, MI; and Shatter Box, Spex
of each sample brick or shape. As shown in Fig. 5, the nominal
Industries, Inc., Metuchen, NJ.
FIG. 1 Outer Coking Box (Dimensions are in Inches)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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C 831–98
FIG. 2 Inner Coking Box
size of each slice shall be 1 by 3 by 6 in. (25 by 76 by 152 mm). impregnated samples, flash drying should be done at a suffi-
The two 1 by 3-in. faces and the two 1 by 6-in. faces must be ciently low temperature to avoid “weeping” of pitch from the
original surfaces.
pores of the brick. Drying can usually be done on a forced-air
5.3 Test specimens may be cut wet or dry except for
dryer at 220°F (105°C) by limiting exposure to 5 to 10 min.
products capable of hydration, such as dolomite brick, which
Repeat if necessary. These drying procedures are especially
must be cut dry and stored in a dry container prior to coking.
important for metal-containing brick because hydration of the
5.4 Specimens that are cut wet must be dried immediately
metals can occur. Specimens containing a coating of pitch on
with a paper or cloth towel and flash dried. For pitch-
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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C 831–98
FIG. 3 Coking Box Arrangement
FIG. 4 CO -Absorption Train
uncut surfaces, as is typical of an impregnation process, must 6. Procedure for Coking
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
(60.2g), recording weight to the nearest 0.1 g. This weight is
“as-received weight, A,” (This step may be omitted if residual
NOTE 3—Burned pitch-impregnated magnesite brick should not be
carbon is to be determined by CO absorption, as indicated in
coked with tempered, tar-bonded, or dolomite brick because of carbon
1.1.) pickup by the impregnated samples and disruption of the bottom of
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 831–98
FIG. 5 Location of Test Specimen
tempered samples. Pitch-bonded, pitch-bonded tempered magnesite brick
6.10 Samples that contain dolomite or aluminum metal
and dolomite brick may be coked in the same box or coking run.
should be stored in a sealed container containing dessicant in
NOTE 4—The number of samples coked per run should be constant
the time interval between coking and measurement of carbon
within a laboratory. Dummy uncoked samples consistent with Note 3 may
content. This is to prevent hydration of dolomite or aluminum
be used to fill any empty positions in the inner box.
carbide. The aluminum carbide is formed by reaction between
6.2 Place the inner box into the center of the outer box (Fig.
aluminum and carbon in the shape during the coking operation.
3), on the bottom of which has first been placed a ⁄2-in.
Aluminum carbide can react with a water source such as
(13-mm) slab of carbon, covered with a thin layer of dust-free
atmospheric humidity to form methane. Care should be taken
metallurgical-grade coke breeze (No. 14 (1.40–mm) sieve size)
since methane can be an explosion hazard.
(Note 5). To ensure that the coke breeze is free of moisture
which could oxidize carbon during cooking, dry the coke at CO ABSORPTION (FIRST ALTERNATIVE
PROCEDURE)
400°F (205°C) for 24 h, and keep in a closed container at room
temperature until needed.
7. Preparation of Sample
NOTE 5—Detailed requirements for sieves are given in Specification E
7.1 A sample consists of a single slice or multiple specimens
of brick prepared as described in Sections 5 and 6.
6.3 Place the thermocouple well into the center of the inner
7.2 Crush the sample in a laboratory jaw crusher, or other
box and put the lid on the inner box. The thermocouple well
impact-type crusher, to pass a No. 4 (4.75-mm) sieve (
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