ASTM E953-88(1998)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E 953 – 88 (Reapproved 1998)
Standard Test Method for
Fusibility of Refuse-Derived Fuel (RDF) Ash
This standard is issued under the fixed designation E 953; 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 RDF
ash attain and pass through certain stages of fusing and flow
when heated at a specific rate in controlled, mildly-reducing,
FIG. 1 Critical Temperature Points
and oxidizing atmospheres.
1.2 The test method is empirical, and strict observance of
the requirements and conditions is necessary to obtain repro-
3.3 softening temperature, ST—the temperature at which
ducible temperatures and enable different laboratories to obtain
the cone has fused down to a spherical lump in which the
concordant results.
height is equal to the width at the base as shown by the third
1.3 The values stated in SI units are to be regarded as the
cone, ST, in Fig. 1.
standard. The values given in parentheses are for information
3.4 hemispherical temperature, HT—the temperature at
only.
which the cone has fused down to a hemispherical lump at
1.4 This standard does not purport to address all of the
which point the height is one half the width of the base as
safety problems, if any, associated with its use. It is the
shown by the fourth cone, HT, in Fig. 1.
responsibility of the user of this standard to establish appro-
3.5 fluid temperature, FT—the temperature at which the
priate safety and health practices and determine the applica-
fused mass has spread out in a nearly flat layer with a
bility of regulatory limitations prior to use. See Section 6 for
maximum height of 1.6 mm ( ⁄16 in.) as shown in the fifth
additional hazard information.
cone, FT, in Fig. 1.
2. Referenced Documents 3.6 forms of refuse-derived fuel (RDF):
RDF-1—Waste used as a fuel in as-discarded form.
2.1 ASTM Standards:
RDF-2—Waste processed to coarse particle size with or
E 180 Practice for Determining the Precision Data of
without ferrous metal separation.
ASTM Methods for Analysis and Testing of Industrial
RDF-3—Shredded fuel derived from municipal solid waste
Chemicals
(MSN) that has been processed to remove metal, glass, and
E 829 Practice for Preparing Refuse-Derived Fuel (RDF)
other inorganics. This material has a particle size such that 95
Laboratory Samples for Analysis
weight % passes through a 2-in. square mesh screen.
3. Terminology
RDF-4—Combustible waste processed into powder form, 95
weight % passing a 10-mesh screening.
3.1 Definitions and Symbols:
RDF-5—Combustible waste densified (compressed) into the
3.1.1 The critical temperature points to be observed are as
form of pellets, slugs, cubettes, or briquettes.
follows, denoting the atmosphere used:
RDF-6—Combustible waste processed into liquid fuel.
3.2 initial deformation temperature, IT—the temperature at
RDF-7—Combustible waste processed into gaseous fuel.
which the first rounding of the apex of the cone occurs.
Shrinking or warping of the cone is ignored if the tip remains
4. Significance and Use
sharp. In Fig. 1, the first cone shown is an unheated one; the
4.1 The standard is available to producers and users of RDF
second cone, IT, is a typical cone at the initial deformation
to use in determining the fusibility of ash produced from RDF.
stage.
4.2 Limitations of Ash Fusibility Data—Ash fusibility data
are too often over-interpreted. In practice, types of burning
equipment, rate of burning, temperature and thickness of fire
This test method is under the jurisdiction of ASTM Committee D34 on Waste
Management and is the direct responsibility of Subcommittee D34.03 on Treatment.
bed or ball, distribution of ash forming mineral matter in the
Current edition approved March 25, 1988. Published May 1988. Originally
RDF, and viscosity of the molten ash may influence ash
published as E 953 – 83. Last previous edition E 953 – 83.
behavior more than the ash fusibility characteristics determined
Annual Book of ASTM Standards, Vol 15.05.
Annual Book of ASTM Standards, Vol 11.04. by the laboratory test. Furthermore, conditions existing during
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 953 – 88 (1998)
applied combustion of RDF are so complex that they are 5.2.1 A steel spatula with a pointed tip, ground off to fit the
impossible to duplicate completely in a small-scale laboratory cone depression in the mold, is suitable for removal of the ash
test. Therefore, the test should be considered an empirical one cone.
and the data, at best, only qualitative.
5.3 Optical Pyrometer or Thermocouple, for temperature
measurements, conforming to the following requirements:
5. Apparatus
5.3.1 Optical Pyrometer—An optical pyrometer of the dis-
5.1 Furnace—Any gas-fired or electric furnace conforming
appearing filament type shall be used. The instrument shall
to the following requirements may be used.
have been calibrated to be accurate within 11°C (20°F) up to
5.1.1 The furnace shall be capable of maintaining a uniform
1400°C (2550°F) and within 16°C (30°F) from 1400 to 1600°C
temperature zone in which to heat the ash cones. This zone
(2550°F to 2900°F) (Note 2). The pyrometer filament shall be
shall be such that the difference in the melting point of 12.7
sighted on the cones until the softening point temperature (Fig.
mm ( ⁄2 in.) pieces of pure gold wire when mounted in place of
1) has been passed, and then sighted on the cone support. The
the ash cones on the cone support shall be not greater than
pyrometer shall have readable graduations not larger than
11°C (20°F) in a reducing atmosphere test run.
5.5°C (10°F).
5.1.2 The furnace shall be capable of maintaining the
NOTE 1—The pyrometer equipment shall be standardized periodically
desired atmosphere surrounding the cones during heating. The
by a suitably equipped standardizing laboratory such as that of the
composition of the atmosphere, reducing or oxidizing, shall be
National Bureau of Standards, or checked periodically against equipment
maintained within the limits specified in Section 7. The desired
certified by the National Bureau of Standards.
atmosphere in the gas-fired furnace surrounding the cones shall
be obtained by regulation of the ratio of gas to air in the 5.3.2 Thermocouple—A thermocouple of platinum and
combustion mixture. The desired atmosphere in the electric
platinum-rhodium, protected from the furnace gases by a
furnace shall be obtained by means of gases introduced into the glazed porcelain sheath, shall be used with a high-resistance
heating chamber. The muffle shall be gas-impervious, free from
millivoltmeter or potentiometer accurate and readable to within
cracks, and the closure-plug tight fitting. Since state-of-the-art 5.5°C (10°F). The sheath shall be sealed to the furnace wall by
furnaces vary somewhat in design, the gas supply inlet tube
alundum cement. The hot junction of the thermocouple shall
shall be installed per instructions of furnace manufacturer. touch the end of the sheath and shall be located in the center of
5.1.3 The furnace shall be capable of regulation so that the the muffle and immediately to the rear of the cones. The
rate of temperature rise shall be 8 6 3°C (15 6 5°F) per thermocouple protective sheath shall be checked periodically
minute. for cracks. The thermocouple and its meter shall meet the
5.1.4 The furnace shall provide a means of observing the requirements of Section 10. The potentiometer or millivoltme-
ash cones during the heating. Observation shall be on the same ter shall be located or shielded adequately as to prevent radiant
horizontal plane as the cone-support surface. or convection heating of the cold junction. The room tempera-
5.2 Cone Mold—A commercially available cone mold as ture compensator shall be adjusted to the existing temperature.
shown in Fig. 2 shall be used. The cone shall be 19 mm ( ⁄4 in.)
5.4 Ash-Cone Refractory Support—The ash cone shall be
in height and 6.4 mm ( ⁄4 in.) in width at each side of the base
mounted on a refractory base composed of a mixture of equal
which is an equilateral triangle.
parts by weight of kaolin and alumina conforming to the
following requirements:
5.4.1 Kaolin—NF-Grade powder passing a No. 200 (0.074
mm) sieve.
5.4.2 Aluminum Oxide—Reagent grade powder passing a
No. 100 (0.149 mm) sieve.
5.5 Refractory Support Mold—A mold with flat top and
bottom surfaces to provide a refractory support of suitable
thickness to minimize warping shall be used. A side mold not
over ⁄4 in. (6.4 mm) high of any convenient shape, placed on
an iron plate so that the top surface of the refractory mix can
be struck off flat and parallel to the base by means of a
straightedge, is satisfactory. For electric furnace use, legs not
over3mm( ⁄8 in.) long may be provided on the corners of the
cone support by suitable holes bored in the iron base plate of
the mold.
5.6 Gold Wire, Twenty-four gage or larger round wire of
U.S. Customary Units. SI Units,
99.98 % purity, but drawn from metal of 99.99 % purity, and
in. mm
having a melting point of 1063°C (1945°F).
⁄4 6.4
⁄4 19.1
1 ⁄2 38.1
2 50.2
3 76.2
Gold wire of this purity can be purchased from the Baker Dental Division of
FIG. 2 Brass Cone Mold Engelhard Industries, Inc., 850 Passaic Ave., East Newark, NJ 07029.
E 953 – 88 (1998)
5.7 Nickel Wire, Twenty-four gage or larger round wire of The gas stream shall be regulated by any convenient means to
CP nickel 99.98 % pure, fully annealed, and having a melting provide a measured flow of 1.3 to 1.5 furnace volumes per
point of 1452°C (2645°F). minute.
NOTE 2—New cylinders of the mixed gas for which a certified analysis
6. Hazards
is not available should be mixed before use by laying the cylinder on its
side with the protective screw cap in place. The cylinder should then be
6.1 Due to the origins of RDF in municipal waste, common
rolled back and forth, 6 to 10 ft in each direction, approximately 15 times.
sense dictates that some precautions should be observed when
Certified analyses of each cylinder or batch can be obtained for a small
conducting tests on the samples. Recommended hygenic prac-
extra charge.
tices include use of gloves when handling RDF; wearing dust
7.2.2 Oxidizing Atmosphere Test—A regulated stream of air
masks (NIOSH-approved type); especially while milling RDF
shall be maintained throughout the test in the electric furnace.
samples; conducting tests under a negative pressure hood when
The gas stream shall be regulated by any convenient means to
possible; and washing hands before eating or smoking.
provide a measured flow of 1.3 to 1.5 furnace volumes per
6.2 Good laboratory practices dictate the precautions that
minute.
should be observed when using compressed gases such as
hydrogen or carbon monoxide as reducing gases.
8. Preparation of Ash
7. Test Atmosphere 8.1 Use RDF milled to passing a 0.5-mm (0.02-in.) sieve
prepared in accordance with Practice E 829 to obtain the ash by
7.1 Gas Fired Furnace:
incineration in a well-ventilated muffle furnace. The quantity of
7.1.1 Reducing Atmosphere Test—A mildly reducing atmo-
RDF required will vary with the ash content; usually 3 to 5 g
sphere surrounding the cones shall be maintained during the
of ash will suffice for cones for several check determinations.
test in the gas-fired furnace. Hydrogen, hydrocarbons, and
Spread out the analysis sample of RDF in a layer approxi-
carbon monoxide shall be considered as reducing gases;
mately 6.4 mm ( ⁄4 in.) in depth in a fireclay or porcelain
oxygen, carbon dioxide, and water vapor shall be considered as
roasting dish. Place the dish in the muffle at a low temperature,
oxidizing gases. Nitrogen is inert. The ratio by volume of
and gradually heat to redness at such a rate as to avoid
reducing gases to oxidizing gases in the atmosphere shall be
mechanical loss from too rapid expulsion of volatile matter.
between the limits of 20 to 80 %, that is, on a nitrogen-free
The rate of temperature rise of 500°C (932°F) in 1 h was found
basis, the total amount of reducing gases present shall be
to be satisfactory. Complete the conversion to ash at a
between the limits of 20 and 80 volume %. A flame 150 to 200
temperature of 800 to 900°C (1470 to 1650°F). Transfer the ash
mm (6 to 8 in.) in height and tinged with yellow above the
to an agate mortar (Note 3), and grind so it will pass a No. 200
furnace outlet has been found to provide an atmosphere within
(0.074 mm) sieve.
the specified limits.
7.1.2 Oxidizing Atmosphere Test—An atmosphere contain-
NOTE 3—A mechanical agate mortar grinder will save time where many
ing a minimum amount of reducing gases shall be maintained determinations are made. An iron mortar or pestle is not recommended
because of metallic contamination.
surrounding the cones during the test in the gas-fired furnace.
On a nitrogen-free basis, the volume of the reducing gases
8.2 Spread the ash in a thin layer in a fireclay, silica, or
present in the atmosphere will not exceed 10 volume %. 1
porcelain dish and ignite it in a stream of oxygen for 1 ⁄2 hat
Combustion with the maximum possible quantity of air with
800 to 850°C (1470 to 1560°F) to ensure complete and uniform
preservation of the specified rate of temperature increase has
oxidation of the ash. Any tube or muffle-type furnace which,
been found to provide an atmosphere within the specified
when supplied with an oxygen flow of not less than one furnace
limits. A completely blue flame, not over 50 mm (2 in.) in
volume in 5 min will maintain a highly oxidizing atmosphere,
height above the outlet at the beginning of the test, provides the
is suitable.
desired atmosphere; and, by regulation of the combustion
NOTE 4—It has been found that in most samples, the initial ignition
gas-air ratio, the specified atmosphere and temperature rise can
outlined in 8.1 is sufficient to convert the RDF to ash and the reignition
be maintained.
step in 8.2 is not necessary. Reignition of the ash should be made only if
7.2 Electric Furnace:
an observable amount of noncombustible matter or carbon is present.
7.2.1 Reducing Atmosphere Test—A regulated flow of gas
of the nominal composition, 60 % carbon monoxide and 40 6 9. Preparation of Cones
5 volume % carbon dioxide, shall be maintained in the heating
9.1 Thoroughly mix the ignited ash in a mechanical mixer
chamber throughout the test (Note 2) in the
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