ASTM D1857-87(2000)
(Test Method)Standard Test Method for Fusibility of Coal and Coke Ash
Standard Test Method for Fusibility of Coal and Coke Ash
SCOPE
1.1 This test method covers the observation of the temperatures at which triangular pyramids (cones) prepared from coal and coke ash attain and pass through certain defined stages of fusing and flow when heated at a specified rate in controlled, mildly reducing, and where desired, oxidizing atmospheres.
1.2 The test method is empirical, and strict observance of the requirements and conditions is necessary to obtain reproducible temperatures and enable different laboratories to obtain concordant results.
1.3 The values stated in inch-pound units are to be regarded as the standard.
1.4 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)
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Designation: D 1857 – 87 (Reapproved 2000)
Standard Test Method for
Fusibility of Coal and Coke Ash
This standard is issued under the fixed designation D 1857; 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
1.1 This test method covers the observation of the tempera-
tures at which triangular pyramids (cones) prepared from coal
and coke ash attain and pass through certain defined stages of
fusing and flow when heated at a specified rate in controlled,
mildly reducing, and where desired, oxidizing atmospheres. FIG. 1 Critical Temperature Points
1.2 The test method is empirical, and strict observance of
sharp. In Fig. 1, the first cone shown is an unheated one; the
the requirements and conditions is necessary to obtain repro-
second cone IT is a typical cone at the initial deformation stage.
ducible temperatures and enable different laboratories to obtain
3.1.5 softening temperature, ST—the temperature at which
concordant results.
the cone has fused down to a spherical lump in which the
1.3 The values stated in inch-pound units are to be regarded
height is equal to the width at the base as shown by the third
as the standard.
cone, ST, in Fig. 1.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 Design of most coal combustion and coal conversion
priate safety and health practices and determine the applica-
equipment anticipates that the ash either remain solid or
bility of regulatory limitations prior to use.
assume some degree of fluidity, depending on the particular
2. Referenced Documents design. Ash fusibility temperatures predict whether the ash will
perform properly in the process for which the coal was chosen.
2.1 ASTM Standards:
D 2013 Method of Preparing Coal Samples for Analysis
5. Apparatus and Materials
D 3174 Test Method for Ash in the Analysis Sample of Coal
2 5.1 Furnace—Any gas-fired or electric furnace conforming
and Coke from Coal
to the following requirements may be used:
3. Terminology 5.1.1 Capable of maintaining a uniform temperature zone in
which to heat the ash cones. This zone shall be such that the
3.1 Definitions of Terms Specific to This Standard:
difference in the melting point of ⁄2-in. (12.7-mm) pieces of
3.1.1 The critical temperature points to be observed are as
pure gold wire when mounted in place of the ash cones on the
follows, denoting the atmosphere used:
cone support shall be not greater than 20°F (11°C) in a
3.1.2 fluid temperature, FT—the temperature at which the
reducing atmosphere test run.
fused mass has spread out in a nearly flat layer with a
1 5.1.2 Capable of maintaining the desired atmosphere sur-
maximum height of ⁄16 in. (1.6 mm) as shown by the fifth
rounding the cones during heating. The composition of the
cone, FT, in Fig. 1.
atmosphere, reducing or oxidizing, shall be maintained within
3.1.3 hemispherical temperature, HT—the temperature at
the limits specified in Section 6. The desired atmosphere in the
which the cone has fused down to a hemispherical lump at
gas-fired furnace surrounding the cones shall be obtained by
which point the height is one half the width of the base as
regulation of the ratio of gas to air in the combustion mixture.
shown by the fourth cone, HT, in Fig. 1.
The desired atmosphere in the electric furnace shall be ob-
3.1.4 initial deformation temperature, IT—the temperature
tained by means of gases introduced into the heating chamber.
at which the first rounding of the apex of the cone occurs.
The muffle shall be gas impervious, free from cracks, and the
Shrinkage or warping of the cone ignored if the tip remains
closure plug tight fitting. The gas supply tube shall be sealed to
the back wall of the preheating chamber and shall not extend to
This test method is under the jurisdiction of ASTM Committee D05 on Coal
the front of the preheating chamber against the perforated
and Coke, and is the direct responsibility of D05.21 on Methods of Analysis.
baffle.
Current edition approved Feb. 10, 1987. Published April 1987. Originally
e1 5.1.3 Capable of regulation so that the rate of temperature
published as D 1857 – 61 T. Last previous edition D 1857 – 68 (1980) .
Annual Book of ASTM Standards, Vol 05.06. rise shall be 15 6 5°F (8 6 3°C)/min.
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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.
D 1857
5.1.4 Providing means of observing the ash cones during the requirements of Section 9. The potentiometer or millivoltmeter
heating. Observation on the same horizontal plane as the shall be so located or adequately shielded as to prevent radiant
cone-support surface shall be possible. and convection heating of the cold junction. The room tem-
5.2 Cone Mold—A commercially available cone mold as perature compensator shall be adjusted to the existing tempera-
shown in Fig. 2. The cone shall be ⁄4 in. (19 mm) in height and ture.
⁄4 in. (6.4 mm) in width at each side of the base which is an 5.4 Ash-Cone Refractory Support—The ash cones shall be
equilateral triangle. A steel spatula with a pointed tip, ground mounted on a refractory base composed of a mixture of equal
off to fit the cone depression in the mold, is suitable for parts by weight of kaolin and alumina conforming to the
removal of the ash cone. following requirements:
5.3 Optical Pyrometer or Thermocouple, for temperature 5.4.1 Kaolin—NF-grade powder passing a No. 200 (75-μm)
measurements, conforming to the following requirements: sieve.
5.3.1 Optical Pyrometer—An optical pyrometer of the dis- 5.4.2 Aluminum Oxide—Reagent grade ignited powder
appearing filament type shall be used. The instrument shall passing a No. 100 (150-μm) sieve.
have been calibrated to be accurate within 20°F (11°C) up to 5.5 Refractory Support Mold—A mold with flat top and
2550°F (1400°C) and within 30°F (16°C) from 2550 to 2900°F bottom surfaces to provide a refractory support of suitable
(1400 to 1600°C) (Note 1). The pyrometer filament shall be thickness to minimize warping. A sidemold not over ⁄4 in. (6.4
sighted on the cones until the softening point temperature C mm) high of any convenient shape, placed on an iron plate so
(Fig. 1) has been passed, and then sighted on the cone support. that the top surface of the refractory mix can be struck off flat
The pyrometer shall have readable graduations not larger than and parallel to the base by means of a straightedge, is
10°F (5.5°C). satisfactory. For electric furnace use, legs not over ⁄8 in. (3
mm) long may be provided on the corners of the cone support
NOTE 1—The pyrometer equipment shall be standardized periodically
by suitable holes bored in the iron base plate of the mold.
by a suitably equipped standardizing laboratory such as that of the
5.6 Gold Wire —Twenty-four gage (0.51-mm diameter) or
National Bureau of Standards, or checked periodically against equipment
certified by the Bureau of Standards. larger round wire of 99.98 % purity, but drawn from metal of
99.99 % purity, and having a melting point of 1945°F
5.3.2 Thermocouple—A thermocouple of platinum and
(1063°C).
platinum-rhodium, protected from the furnace gases by a
5.7 Nickel Wire —Twenty-four gage (0.51-mm diameter) or
glazed porcelain sheath, shall be used with a high-resistance
larger round wire of CP nickel, 99.98 % pure, fully annealed,
millivoltmeter or potentiometer accurate and readable to within
and having a melting point of 2645°F (1452°C).
10°F (5.5°C). The sheath shall be sealed to the furnace wall by
alundum cement. The hot junction of the thermocouple shall
6. Test Atmosphere
touch the end of the sheath and shall be located in the center of
6.1 Gas-Fired Furnace:
the muffle and immediately to the rear of the cones. The
6.1.1 Reducing Atmosphere Test—A mildly reducing atmo-
thermocouple protective sheath shall be checked periodically
sphere surrounding the cones shall be maintained during the
for cracks. The thermocouple and its meter shall meet the
test in the gas-fired furnace. Hydrogen, hydrocarbons, and
carbon monoxide shall be considered as reducing gases;
oxygen, carbon dioxide, and water vapor shall be considered as
oxidizing gases. Nitrogen is inert. The ratio by volume of
reducing gases to oxidizing gases in the atmosphere shall be
between the limits of 20 to 80 and 80 to 20, that is, on a
nitrogen-free basis, the total amount of reducing gases present
shall be between the limits of 20 and 80 volume %. A flame 6
to 8 in. (152 to 203 mm) in height and tinged with yellow
above the furnace outlet has been found to provide an
atmosphere within the specified limits.
6.1.2 Oxidizing Atmosphere Test—An atmosphere contain-
ing a minimum amount of reducing gases shall be maintained
surrounding the cones during the test in the gas-fired furnace.
On a nitrogen-free basis, the volume of reducing gases present
in the atmosphere shall not exceed volume 10 %. Combustion
with the maximum possible quantity of air with preservation of
Inch-pound
SI Units,
Units,
mm 3
Gold wire of this purity can be purchased from the Baker Dental Division of
in.
Engelhard Industries, Inc., 850 Passaic Ave., East Newark, NJ 07029 or from Leico
⁄4 6.4
Industries, Inc., 250 W. 57th St., New York, NY 10019.
⁄4 19.1
Nickel wire of this purity can be purchased with the additional specification of
1 ⁄2 38.1
having a minimum coefficient of resistance for 0 to 100°C of 0.006 73 V/V·°C, from
2 50.2
Leico Industries, Inc., 250 W. 57th St., New York, NY 10019.
3 76.2
For information concerning the effect of various atmospheres, see U.S. Bureau
FIG. 2 Brass Cone Mold of Mines Bulletin 129, 1918.
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.
D 1857
the specified rate of temperature increase has been found to corners in rotation in the same manner until each corner has
provide an atmosphere within the specified limits. A com- been raised five times or more.
pletely blue flame, not over 2 in. (50 mm) in height above the 8.2 Take sufficient ash for the number of cones desired from
outlet at the beginning of the test, provides the desired various parts of the bulk ash. Moisten the ash with a few drops
atmosphere; and, by regulation of the combustion gas-air ratio, of a clear, filtered (if necessary) 10 % solution of dextrin
the specified atmosphere and temperature rise can be main- containing 0.1 % salicylic acid as a preservative and work it
tained. into a stiff plastic mass with a spatula. Press the plastic material
6.2 Electric Furnace: firmly with a spatula into the cone mold to form the triangular
6.2.1 Reducing Atmosphere Test—A regulated flow of gas pyramids. Strike off the exposed surfaces of the material
of the nominal composition, 60 % carbon monoxide and 40 6 smooth and remove the cones from the mold by applying
5 volume % carbon dioxide, shall be maintained in the heating pressure at the base with a suitably pointed spatula. Previous
chamber throughout the test (Note 2) in the electric furnace. coating of the mold with a thin layer of petroleum jelly, thinned
The gas stream shall be regulated by any convenient means to with kerosene (if necessary), aids in preventing adherence of
provide a measured flow of 1.3 to 1.5 furnace volumes per the cones to the mold and in providing the sharp point and
minute. edges desired in the cone. With certain coal ashes, cones with
6.2.2 Oxidizing Atmosphere Test—A regulated stream of air sharp points and edges can be obtained using distilled water in
shall be maintained throughout the test in the electric furnace. place of the dextrin solution and without the use of petroleum
The gas stream shall be regulated by any convenient means to jelly.
provide a measured flow of 1.3 to 1.5 furnace volumes per 8.3 Place the cones in a suitable location to dry sufficiently
minute. to permit handling without deformation. Mount the dried cone
vertically on a freshly prepared refractory base. Moisten a
NOTE 2—Before using new cylinders of CO/CO reducing gas, the
portion of the well-mixed kaolin-alumina mixture with the
contents should be mixed according to the gas manufacturer’s recommen-
minimum amount of water to make a workable, but stiff, plastic
dations. To assure that the gas remains mixed, the temperature of the
cylinder contents should be maintained above the critical temperature at mass, and firmly press it into the support mold. Strike off the
which CO can liquify and separate.
surface of the mass flat and smooth with a steel spatula,
moistening with one or two drops of water if necessary to
7. Preparation of Ash
obtain a smooth surface. A number of cones may be mounted
7.1 Use coal or coke passing a No. 60 (250-μm) sieve
on one base. Make shallow triangular depressions, not over ⁄32
prepared in accordance with Method D 2013, to obtain the ash
in. (0.8 mm) in depth, with a triangular file ground to the
by incineration in a well-ventilated muffle furnace. The quan-
correct size to produce a depression to fit the base of the cone,
tity of coal or coke required will vary with the ash content;
and locate the cones sufficiently distant from adjacent cones so
usually 3 to 5 g of ash will be sufficient for cones for several
that no merging of the fusing material of the cones shall occur
check determinations, if necessary. Spread out the coal or coke
during the test. Mount the cones vertically in the depressions
in a layer not over ⁄4 in. (6.4 mm) in depth in a fireclay or
while the base is still wet without the use of ash or refractory
porcelain roasting dish. Place the dish in the cold muffle or on
as a mounting aid (Note 5 and Note 6).
the hearth at a low temperature and gradually heat to redness at
NOTE 5—The intent of the triangular depression is to enable the cones
such a rate as to avoid mechanical loss from too rapid
to be mounted in a sufficiently stable manner to permit handling of the
expulsion of volatile matter (Note 3). Complete the conversion
prepared support with cones.
to ash at a temperature of 1470 to 1650°F (800 to 900°C).
NOTE 6—Gold wires can be mounted on each cone support beside the
Transfer the ash to an agate mortar (Note 4)
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