ASTM D720/D720M-15

Standard Test Method for Free-Swelling Index of Coal

SIGNIFICANCE AND USE
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 a broad indication of the degree of oxidation of a coal.
SCOPE
1.1 This test method2 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.3  
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with 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

• Status: Historical
• Publication Date: 31-Dec-2014
• ICS: 73.040 - Coals
• Technical Committee: D05 - Coal and Coke
• Drafting Committee: D05.15 - Metallurgical Properties of Coal and Coke

Relations

• Replaces: ASTM D720-91(2010) - Standard Test Method for Free-Swelling Index of Coal
• Effective Date: 01-Jan-2015
• Referred By: ASTM D388-23 - Standard Classification of Coals by Rank
• Effective Date: 01-Jan-2015

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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/D720M − 15
StandardTest Method for
Free-Swelling Index of Coal
This standard is issued under the fixed designation D720/D720M; 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 U.S. 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 E691 Practice for Conducting an Interlaboratory Study to
characteristic of the coal when burned as a fuel.This test is not Determine the Precision of a Test Method
recommended as a method for the determination of expansion
3. Significance and Use
of coals in coke ovens.
3.1 This test method, in addition to indicating the caking
1.2 Warning—Breathing of asbestos dust is hazardous.
properties of a coal when burned as a fuel, can be used to give
Asbestos and asbestos products present demonstrated health
a broad indication of the degree of oxidation of a coal.
risksforusersandforthosewithwhomtheycomeintocontact.
In addition to other precautions, when working with asbestos-
4. Apparatus
cement products, minimize the dust that results. For informa-
4.1 This test method can be made with either electric or gas
tion on the safe use of chrysoltile asbestos, refer to, Safe Use
heating. When using electric heating, the results obtained must
of Chrysotile Asbestos: A Manual on Preventive and Control
be the same as those obtained when using the gas heating
Measures.
method. The apparatus common to both electric and gas
1.3 The values stated in either SI units or inch-pound units
methods shall consist of the following:
are to be regarded separately as standard. The values stated in
4.1.1 Crucible, translucent silica, low-form, with a flat,
each system may not be exact equivalents; therefore, each
close-fitting silica ring-handle lid and an extra pierced lid for
system shall be used independently of the other. Combining
use in determining the crucible temperature, conforming to the
values from the two systems may result in non-conformance
following requirements:
with the standard.
Weight, g 11.0 to 12.75
1.4 This standard does not purport to address all of the
External height, mm 26 ± 0.5
External diameter at top, mm 41 ± 0.75
safety concerns, if any, associated with its use. It is the
Internal diameter at base, min, mm 11
responsibility of the user of this standard to establish appro-
Capacity (approximate), cm 17
priate safety and health practices and determine the applica-
4.1.2 Sight Tube, as shown in Fig. 1, for viewing the coke
bility of regulatory limitations prior to use.
buttons so that the effect of parallax will be eliminated. Make
the tube of any rigid and preferably opaque material and
support vertically on a ring stand.
This test method is under the jurisdiction of ASTM Committee D05 on Coal
4.1.3 Thermocouple and Potentiometer.
and Coke and is the direct responsibility of Subcommittee D05.15 on Metallurgical
4.1.4 Weight, 500 g.
Properties of Coal and Coke.
Current edition approved Jan. 1, 2015. Published January 2015. Originally
4.2 The electric apparatus shall consist of the following:
approved in 1943. Last previous edition approved in 2010 as D720 – 91 (2010).
4.2.1 Furnace, consisting of a base, a heating element, and
DOI: 10.1520/D0720/D0720M-15.
This test method is an adaptation of the Crucible Swelling Test for Coal of the
a chimney. The unit is shown in Fig. 2.
British Standards Institution. For information concerning the experimental work on
4.2.1.1 Chimney—Fig. 2 shows the chimney design. Make
which this adaptation is based, see paper by Ostborg, H. N., Limbacker, H. R., and
the unit from firebrick and coat with firebrick bonding mortar.
Sherman, R.A., “An Experimental Investigation of the British Standard Method for
Maintain the chimney under compression by a sheet-metal
the Crucible Swelling Test for Coal,” Proceedings,Am. Soc. Testing Mats., Vol 42,
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 [e-mail]. 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/D720M − 15
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
temperature to reach equilibrium.
FIG. 1 Sight Tube
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.
envelope (Fig. 2) to prevent cracking. Make the envelope in
Measure the temperature at the inside base of the crucible with
four pieces, each piece covering a corner. The pieces shall
a thermocouple and a potentiometer. The unprotected junction
overlap at the center of the flat faces and be held together by
of the thermocouple must be in contact with the inside base of
bolts and springs. Place two layers of asbestos paper between
thecrucible.Attheendof1 ⁄2min,thetemperatureshouldread
the chimney brick and the envelope. Cut two grooves in the
800 6 10°C [1472 6 18°F].Adjust the variable transformer as
upper inside chimney walls to accommodate the crucible
necessary to provide this temperature.
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
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
of 2 ⁄2 min should be attained. Several trials will no doubt be
hold the wire legs of the support in place.
1 1
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
Rheostat 100 W, 10Ω
5.1.4 After each calibration attempt or sample run, switch
Variable transformer 7.4 A, 120 V
the timer to the HOLD position, and allow about 1 min for the
Timer mechanical, 0–5 min minimum span, with a hold
position, and electrical contact closed during furnace to reach equilibrium.
timing cycle
5.2 Gas Burner:
4.2.3.1 One timer shall actuate the rheostat, at a predeter-
1 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
voltage to the furnace.
5.2.2 After placing a crucible in position adjust the flow of
gas and the relative positions of the burner and the draft shield
4.3 The gas apparatus shall consist of the following:
so that the temperature of the inner surface of the bottom of the
4.3.1 BurnerAssembly—Agasburnerwithagridofexternal
crucible reaches 800 6 10°C [1472 6 18°F] in 1 ⁄2 min and
diameter, 30 to 42 mm [1.18 to 1.65 in.], a draft shield, and a
820 6 5°C [1508 6 9°F] in 2 ⁄2 min. These desired tempera-
triangular crucible support as shown in Fig. 3. Make the draft
tures may usually be obtained by setting the draft shield so that
shield, conforming to the dimensions shown in Fig. 3 fro
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D720 − 91 (Reapproved 2010) D720/D720M − 15
Standard Test Method for
Free-Swelling Index of Coal
This standard is issued under the fixed designation D720;D720/D720M; 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 U.S. Department of Defense.
1. 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 either SI units or inch-pound units are to be regarded separately as the standard. The values given in
parentheses are for information only. stated in each system may not be exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two systems may result in non-conformance with 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.
2. Referenced Documents
2.1 ASTM Standards:
D2013 Practice for Preparing Coal Samples for Analysis
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Significance and Use
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 a broad
indication of the degree of oxidation of a coal.
4. Apparatus
4.1 This test method can be made with either electric or gas heating. When using electric heating, the results obtained must be
the same as those obtained when using the gas heating method. The apparatus common to both electric and gas methods shall
consist of the following:
4.1.1 Crucible, translucent silica, low-form, with a flat, close-fitting silica ring-handle lid and an extra pierced lid for use in
determining the crucible temperature, conforming to the following requirements:
This test method is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.15 on Metallurgical Properties
of Coal and Coke.
Current edition approved May 15, 2010Jan. 1, 2015. Published July 2010January 2015. Originally approved in 1943. Last previous edition approved in 20042010 as
ε1
D720 – 91 (2004)(2010). . DOI: 10.1520/D0720-91R10.10.1520/D0720/D0720M-15.
This test method is an adaptation of the Crucible Swelling Test for Coal of the British Standards Institution. For information concerning the experimental work on which
this adaptation is based, see paper by Ostborg, H. N., Limbacker, H. R., and 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, 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.
Safe Use of Chrysotile Asbestos: A Manual on Preventive and Control Measures Chrysotile Institute 1200, McGill College Suite 1640 Montreal, Quebec Canada H3B
4G7
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D720/D720M − 15
Weight, g 11.0 to 12.75
External height, mm 26 ± 0.5
External diameter at top, mm 41 ± 0.75
Internal diameter at base, min, mm 11
Capacity (approximate), cm 17
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 support vertically on a ring stand.
4.1.3 Thermocouple and Potentiometer.
4.1.4 Weight, 500 g.
4.2 The electric apparatus shall consist of the following:
4.2.1 Furnace, consisting of a base, a heating element, and a chimney. The unit is shown in Fig. 2.
4.2.1.1 Chimney—Fig. 2 shows the chimney design. Make the unit from firebrick and coat with firebrick bonding mortar.
Maintain the chimney under compression by a sheet-metal envelope (Fig. 2) to prevent cracking. Make the envelope in four pieces,
each piece covering a corner. The pieces shall overlap at the center of the flat faces and be held together by bolts and springs. Place
two layers of asbestos paper between the chimney brick and the envelope. Cut two grooves in the upper inside chimney walls to
accommodate the crucible support. In cases in which the furnace is located in a drafty area, it is advisable to shield the chimney
to prevent large fluctuations in furnace temperature.
4.2.2 Crucible Support—A convenient crucible support consists of a cradle support made from nickel-chromium wire suspended
from a metal ring. The height of the support inside the furnace can be adjusted by loosening the two screws that hold the wire legs
of the support in place.
4.2.3 Electric Controls, consisting of a rheostat, an a-c ammeter, and two timers. These components shall conform to the
following specifications:
Ammeter a-c, 0 to 10-A range
Rheostat 100 W, 10 Ω
Variable transformer 7.4 A, 120 V
Timer mechanical, 0–5 min minimum span, with a hold
position, and electrical contact closed during
timing cycle
4.2.3.1 One timer shall actuate the rheostat, at a predetermined setting, after 1 ⁄2 min of operation. Preset the rheostat to reduce
the rate of heating of the furnace so that a temperature of 820 6 5°C (1508[1508 6 9°F)9°F] is achieved at the end of 2 ⁄2 min.
A variable transformer is desirable for establishing the input voltage to the furnace.
4.3 The gas apparatus shall consist of the following:
4.3.1 Burner Assembly—A gas burner with a grid of external diameter, 30 to 42 mm (1.18[1.18 to 1.65 in.),in.], a draft shield,
and a triangular crucible support as shown in Fig. 3. Make the draft shield, conforming to the dimensions shown in Fig. 3 from
the asbestos-cement pipe, and at the top it shall have three slots, 25 mm (1 in.)[1 in.] in depth, in which the wires of the crucible
support rest. Support the draft shield on a ring stand, so that the distance between the base of the crucible and the top of the burner
grid may be adjusted by raising or lowering the draft shield. Make the triangular crucible support from three pieces of translucent
silica tubing each 63 mm (2.5 in.)[2.5 in.] in length, 6 to 6.5 mm (0.24[0.24 to 0.26 in.)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.).[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.
FIG. 1 Sight Tube
D720/D720M − 15
FIG. 2 Furnace Base and Chimney
FIG. 3 Details of Burner Assembly
4.3.2 Flowmeter—A capillary flowmeter with water manometer 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 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. Measure
the temperature at the inside base of the crucible with a thermocouple and a potentiometer. The unprotected junction of the
D720/D720M − 15
thermocouple must be in contact with the inside base of the crucible. At the end of 1 ⁄2 min, the temperature should read 800 6
10°C (1472[1472 6 18°F).18°F]. Adjust the variable transformer as necessary to provide this temperature.
5.1.3 A temperature of 820 6 5°C (1508[1508 6 9°F)9°F] must be attained at the end of 2 ⁄2 min. The second timer shall be
used here. The control unit rheostat must be properly adjusted to reduce the heating rate at the end of 2 ⁄2 min. If the rheostat is
set initially so that at the end of 1 ⁄2 min the ammeter reading is reduced by 0.6 or 0.7 A, the specified temperature at the end of
1 1 1
2 ⁄2 min should be attained. Several trials will no doubt be necessary before the proper temperatures at 1 ⁄2 and 2 ⁄2 min are reached;
however, the information given above provides a general guide for calibration. The silica crucible and cover must be at room
temperature b
...