ASTM D720-91(2010)
(Test Method)Standard Test Method for Free-Swelling Index of Coal
Standard Test Method for Free-Swelling Index of Coal
SIGNIFICANCE AND USE
This test method, in addition to indicating the caking properties of a coal when burned as a fuel, can be used to give a broad indication of the degree of oxidation of a coal.
SCOPE
1.1 This test method is a small-scale test for obtaining information regarding the free-swelling properties of a coal. The results may be used as an indication of the caking characteristic of the coal when burned as a fuel. This test is not recommended as a method for the determination of expansion of coals in coke ovens.
1.2 Warning—Breathing of asbestos dust is hazardous. Asbestos and asbestos products present demonstrated health risks for users and for those with whom they come into contact. In addition to other precautions, when working with asbestos-cement products, minimize the dust that results. For information on the safe use of chrysoltile asbestos, refer to, Safe Use of Chrysotile Asbestos: A Manual on Preventive and Control Measures.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D720 − 91 (Reapproved 2010)
StandardTest Method for
Free-Swelling Index of Coal
This standard is issued under the fixed designation D720; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 2. Referenced Documents
2 4
1.1 This test method is a small-scale test for obtaining 2.1 ASTM Standards:
information regarding the free-swelling properties of a coal. D2013 Practice for Preparing Coal Samples for Analysis
The results may be used as an indication of the caking
3. Significance and Use
characteristic of the coal when burned as a fuel.This test is not
recommended as a method for the determination of expansion 3.1 This test method, in addition to indicating the caking
properties of a coal when burned as a fuel, can be used to give
of coals in coke ovens.
a broad indication of the degree of oxidation of a coal.
1.2 Warning—Breathing of asbestos dust is hazardous.
Asbestos and asbestos products present demonstrated health
4. Apparatus
risksforusersandforthosewithwhomtheycomeintocontact.
4.1 This test method can be made with either electric or gas
In addition to other precautions, when working with asbestos-
heating. When using electric heating, the results obtained must
cement products, minimize the dust that results. For informa-
be the same as those obtained when using the gas heating
tion on the safe use of chrysoltile asbestos, refer to, Safe Use
method. The apparatus common to both electric and gas
of Chrysotile Asbestos: A Manual on Preventive and Control
3 methods shall consist of the following:
Measures.
4.1.1 Crucible, translucent silica, low-form, with a flat,
1.3 The values stated in SI units are to be regarded as the
close-fitting silica ring-handle lid and an extra pierced lid for
standard. The values given in parentheses are for information
use in determining the crucible temperature, conforming to the
only.
following requirements:
1.4 This standard does not purport to address all of the
Weight, g 11.0 to 12.75
External height, mm 26 ± 0.5
safety concerns, if any, associated with its use. It is the
External diameter at top, mm 41 ± 0.75
responsibility of the user of this standard to establish appro-
Internal diameter at base, min, mm 11
priate safety and health practices and determine the applica-
Capacity (approximate), cm 17
bility of regulatory limitations prior to use.
4.1.2 Sight Tube, as shown in Fig. 1, for viewing the coke
buttons so that the effect of parallax will be eliminated. Make
the tube of any rigid and preferably opaque material and
This test method is under the jurisdiction of ASTM Committee D05 on Coal
support vertically on a ring stand.
and Coke and is the direct responsibility of Subcommittee D05.15 on Metallurgical
Properties of Coal and Coke.
4.1.3 Thermocouple and Potentiometer.
Current edition approved May 15, 2010. Published July 2010. Originally
4.1.4 Weight, 500 g.
´1
approved in 1943. Last previous edition approved in 2004 as D720 – 91 (2004) .
DOI: 10.1520/D0720-91R10.
4.2 The electric apparatus shall consist of the following:
This test method is an adaptation of the Crucible Swelling Test for Coal of the
4.2.1 Furnace, consisting of a base, a heating element, and
British Standards Institution. For information concerning the experimental work on
a chimney. The unit is shown in Fig. 2.
which this adaptation is based, see paper by Ostborg, H. N., Limbacker, H. R., and
4.2.1.1 Chimney—Fig. 2 shows the chimney design. Make
Sherman, R.A., “An Experimental Investigation of the British Standard Method for
the Crucible Swelling Test for Coal,” Proceedings,Am. Soc. Testing Mats., Vol 42,
the unit from firebrick and coat with firebrick bonding mortar.
1042, p. 851. See also a paper by Selvig, W.A., and Ode, W. H., “An Investigation
of a Laboratory Test for Determination of the Free-Swelling Index of Coal,” U.S.
Bureau of Mines Report of Investigation 4238, Revision of R. I. 3989, 1948. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Safe Use of Chrysotile Asbestos: A Manual on Preventive and Control contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Measures Chrysotile Institute 1200, McGill College Suite 1640 Montreal, Quebec Standards volume information, refer to the standard’s Document Summary page on
Canada H3B 4G7 the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D720 − 91 (Reapproved 2010)
shield. Make the triangular crucible support from three pieces
of translucent silica tubing each 63 mm (2.5 in.) in length, 6 to
6.5 mm (0.24 to 0.26 in.) in external diameter, and mounted on
chromium-nickel wire so that the diameter of the inscribed
circle is approximately 32 mm (1.26 in.). The twisted ends of
the triangle may be joined together by a loop of wire to
facilitate removal of the hot crucible.
4.3.2 Flowmeter—A capillary flowmeter with water ma-
nometer placed in the gas line before the burner as a guide to
the control of the rate of gas flow (Fig. 3).
5. Calibration
5.1 Electric Furnace:
5.1.1 Turn the main power switch on and set the timer to the
HOLD position. Adjust the variable transformer so that the
ammeter reads 5.8 A. Allow at least 45 min for the furnace
FIG. 1 Sight Tube
temperature to reach equilibrium.
1 1
5.1.2 Set the timer just beyond the 1 ⁄2-min mark. At 1 ⁄2
min, lower an empty crucible with pierced lid into the furnace.
Maintain the chimney under compression by a sheet-metal
Measure the temperature at the inside base of the crucible with
envelope (Fig. 2) to prevent cracking. Make the envelope in
a thermocouple and a potentiometer. The unprotected junction
four pieces, each piece covering a corner. The pieces shall
of the thermocouple must be in contact with the inside base of
overlap at the center of the flat faces and be held together by
thecrucible.Attheendof1 ⁄2min,thetemperatureshouldread
bolts and springs. Place two layers of asbestos paper between
the chimney brick and the envelope. Cut two grooves in the 800 6 10°C (1472 6 18°F).Adjust the variable transformer as
necessary to provide this temperature.
upper inside chimney walls to accommodate the crucible
support. In cases in which the furnace is located in a drafty
5.1.3 A temperature of 820 6 5°C (1508 6 9°F) must be
area, it is advisable to shield the chimney to prevent large
attained at the end of 2 ⁄2 min. The second timer shall be used
fluctuations in furnace temperature.
here. The control unit rheostat must be properly adjusted to
4.2.2 CrucibleSupport—Aconvenientcruciblesupportcon-
reduce the heating rate at the end of 2 ⁄2 min. If the rheostat is
sists of a cradle support made from nickel-chromium wire 1
set initially so that at the end of 1 ⁄2 min the ammeter reading
suspended from a metal ring. The height of the support inside
is reduced by 0.6 or 0.7A, the specified temperature at the end
the furnace can be adjusted by loosening the two screws that 1
of 2 ⁄2 min should be attained. Several trials will no doubt be
1 1
hold the wire legs of the support in place.
necessary before the proper temperatures at 1 ⁄2 and 2 ⁄2 min
4.2.3 Electric Controls, consisting of a rheostat, an a-c
are reached; however, the information given above provides a
ammeter, and two timers. These components shall conform to
general guide for calibration. The silica crucible and cover
the following specifications:
must be at room temperature before each calibration run.
Ammeter a-c, 0 to 10-A range
5.1.4 After each calibration attempt or sample run, switch
Rheostat 100 W, 10Ω
the timer to the HOLD position, and allow about 1 min for the
Variable transformer 7.4 A, 120 V
Timer mechanical, 0–5 min minimum span, with a hold furnace to reach equilibrium.
position, and electrical contact closed during
timing cycle
5.2 Gas Burner:
4.2.3.1 One timer shall actuate the rheostat, at a predeter-
5.2.1 With the burner assembly arranged as shown in Fig. 3,
mined setting, after 1 ⁄2 min of operation. Preset the rheostat to
and with an empty crucible in position, light the burner about
reduce the rate of heating of the furnace so that a temperature
15 min before making a determination to allow the draft shield
of 820 6 5°C (1508 6 9°F) is achieved at the end of 2 ⁄2 min.
to rise to an equilibrium temperature.
A variable transformer is desirable for establishing the input
5.2.2 After placing a crucible in position adjust the flow of
voltage to t
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