ASTM D1857-87(1994)
(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.
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Designation:D1857–87(Reapproved 1994)
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 (ε) 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
Shrinkage or warping of the cone ignored if the tip remains
the requirements and conditions is necessary to obtain repro-
sharp. In Fig. 1, the first cone shown is an unheated one; the
ducible temperatures and enable different laboratories to obtain
secondconeITisatypicalconeattheinitialdeformationstage.
concordant results.
3.1.5 softening temperature, ST—the temperature at which
1.3 The values stated in inch-pound units are to be regarded
the cone has fused down to a spherical lump in which the
as the standard.
height is equal to the width at the base as shown by the third
1.4 This standard does not purport to address all of the
cone, ST, in Fig. 1.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Significance and Use
priate safety and health practices and determine the applica-
4.1 Design of most coal combustion and coal conversion
bility of regulatory limitations prior to use.
equipment anticipates that the ash either remain solid or
2. Referenced Documents
assume some degree of fluidity, depending on the particular
design.Ash fusibility temperatures predict whether the ash will
2.1 ASTM Standards:
perform properly in the process for which the coal was chosen.
D 2013 Method of Preparing Coal Samples for Analysis
D 3174 TestMethodforAshintheAnalysisSampleofCoal
5. Apparatus and Materials
and Coke from Coal
5.1 Furnace—Any gas-fired or electric furnace conforming
3. Terminology
to the following requirements may be used:
5.1.1 Capable of maintaining a uniform temperature zone in
3.1 Definitions of Terms Specific to This Standard:
which to heat the ash cones. This zone shall be such that the
3.1.1 The critical temperature points to be observed are as
difference in the melting point of ⁄2-in. (12.7-mm) pieces of
follows, denoting the atmosphere used:
pure gold wire when mounted in place of the ash cones on the
3.1.2 fluid temperature, FT—the temperature at which the
cone support shall be not greater than 20°F (11°C) in a
fused mass has spread out in a nearly flat layer with a
reducing atmosphere test run.
maximum height of ⁄16 in. (1.6 mm) as shown by the fifth
5.1.2 Capable of maintaining the desired atmosphere sur-
cone, FT, in Fig. 1.
rounding the cones during heating. The composition of the
3.1.3 hemispherical temperature, HT—the temperature at
atmosphere, reducing or oxidizing, shall be maintained within
which the cone has fused down to a hemispherical lump at
the limits specified in Section 6. The desired atmosphere in the
which point the height is one half the width of the base as
gas-fired furnace surrounding the cones shall be obtained by
shown by the fourth cone, HT, in Fig. 1.
regulation of the ratio of gas to air in the combustion mixture.
3.1.4 initial deformation temperature, IT—the temperature
The desired atmosphere in the electric furnace shall be ob-
at which the first rounding of the apex of the cone occurs.
tained by means of gases introduced into the heating chamber.
The muffle shall be gas-impervious, free from cracks, and the
ThistestmethodisunderthejurisdictionofASTMCommitteeD-5onCoaland
closure-plug tight fitting.The gas supply tube shall be sealed to
Coke, and is the direct responsibility of D05.21 on Methods of Analysis.
the back wall of the preheating chamber and shall not extend to
Current edition approved Feb. 10, 1987. Published April 1987. Originally
ε1
the front of the preheating chamber against the perforated
published as D 1857 – 61 T. Last previous edition D 1857 – 68 (1980) .
Annual Book of ASTM Standards, Vol 05.05. baffle.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1857–87 (1994)
5.1.3 Capable of regulation so that the rate of temperature thermocouple protective sheath shall be checked periodically
rise shall be 156 5°F (86 3°C)/min. for cracks. The thermocouple and its meter shall meet the
5.1.4 Providingmeansofobservingtheashconesduringthe requirements of Section 99. The potentiometer or millivoltme-
heating. Observation on the same horizontal plane as the ter shall be so located or adequately shielded as to prevent
cone-support surface shall be possible. radiant and convection heating of the cold junction. The room
5.2 Cone Mold—A commercially available cone mold as temperature compensator shall be adjusted to the existing
shown in Fig. 2.The cone shall be ⁄4 in. (19 mm) in height and temperature.
⁄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-
measurements, conforming to the following requirements: µm) 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.Asidemold 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
larger round wire of 99.98 % purity, but drawn from metal of
certified by the Bureau of Standards.
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,
millivoltmeterorpotentiometeraccurateandreadabletowithin
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-
sphere surrounding the cones shall be maintained during the
test in the gas-fired furnace. Hydrogen, hydrocarbons, and
carbon monoxide shall be considered as reducing gases;
oxygen,carbondioxide,andwatervaporshallbeconsideredas
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.
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 PassaicAve., East Newark, NJ 07029 or from Leico
⁄4 6.4
Industries, Inc., 250 West 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 0.00673 Ω/Ω·deg C,
2 50.2
from the Leico Industries, Inc., 250 West 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.
D1857–87 (1994)
On a nitrogen-free basis, the volume of reducing gases present 8. Preparation of Cones
in the atmosphere shall not exceed volume 10 %. Combustion
8.1 Thoroughly mix the ignited ash in a mechanical mixer
with the maximum possible quantity of air with preservation of
or on a sheet of glazed paper or oil cloth by raising first one
the specified rate of temperature increase has been found to
corner to roll the ash over, and then raising each of the other
provide an atmosphere within the specified limits. A com-
corners in rotation in the same manner until each corner has
pletely blue flame, not over 2 in. (50 mm) in height above the
been raised five times or more.
outlet at the beginning of the test, provides the desired
8.2 Take sufficient ash for the number of cones desired from
atmosphere; and, by regulation of the combustion gas-air ratio,
various parts of the bulk ash. Moisten the ash with a few drops
the specified atmosphere and temperature rise can be main-
of a clear, filtered (if necessary) 10 % solution of dextrin
tained.
containing 0.1 % salicylic acid as a preservative and work it
6.2 Electric Furnace:
intoastiffplasticmasswithaspatula.Presstheplasticmaterial
6.2.1 Reducing Atmosphere
...
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