ASTM D409-97e2
(Test Method)Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method
Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method
SCOPE
1.1 This test method covers the determination of the relative grindability or ease of pulverization of coals in comparison with coals chosen as standards. A prepared and sized sample receives a definite amount of grinding energy in a miniature pulverizer, and the size consist of the pulverized product is determined by sieving. The resultant size consist is used to produce an index relative to the ease of grinding (Hardgrove Grindability Index (HGI)).
1.1.1 Some coals, such as some high volatile bituminous, subbituminous and lignite coals, can undergo physical change as the natural or seam moisture is released during handling and preparation. This change is often sufficient to alter the grindability characteristics that will be reported when tested in the laboratory, and could produce different indices dependent on the conditions of drying and the moisture level of the 1.18 mm by 600 [mu]m (No. 16 X No. 30) (See Test Method D4749.) materials used for the test. Therefore, the repeatability and reproducibility cited in this test method may not apply for these high volatile bituminous, subbituminous, and lignite coals.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses may be approximate.
1.3 It is recognized that the term weight is considered equivalent to mass as used in this test method.
1.4 This standard does not purport to address all of the safety problems, 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)
e2
Designation: D 409 – 97
Standard Test Method for
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Grindability of Coal by the Hardgrove-Machine Method
This standard is issued under the fixed designation D 409; 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.
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e NOTE—Footnote 6 has been updated editorially in August 2000.
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1. Scope D 2234 Practice for Collection of a Gross Sample of Coal
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D 4749 Test Method for Performing the Sieve Analysis of
1.1 This test method covers the determination of the
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Coal and Designating Coal Size
relative grindability or ease of pulverization of coals in
E 11 Specification for Wire-Cloth Sieves for Testing Pur-
comparison with coals chosen as standards. A prepared and
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poses
sized sample receives a definite amount of grinding energy in
a miniature pulverizer, and the size consist of the pulverized
3. Significance and Use
product is determined by sieving. The resultant size consist is
3.1 This test method develops a measurement of grinding or
used to produce an index relative to the ease of grinding
pulverizing characteristics that can be used to evaluate the
(Hardgrove Grindability Index (HGI)).
yield, or energy input, or both, required in a grinding or
1.1.1 Some coals, such as some high-volatile bituminous,
pulverizing process.
subbituminous, and lignite coals, can undergo physical change
as the natural or seam moisture is released during handling and
4. Apparatus
preparation. This change is often sufficient to alter the grind-
4.1 Air-Drying Oven—A device for passing slightly heated
ability characteristics that will be reported when tested in the
air over the sample. The oven shall be capable of maintaining
laboratory and could produce different indices dependent on
a temperature of 10 to 15°C (18 to 27°F) above room
the conditions of drying and the moisture level of the 1.18-mm
temperature with a maximum oven temperature of 40°C
by 600-μm (No. 16 3 No. 30) (see Test Method D 4749)
(104°F) unless ambient temperature is above 40°C, in which
materials used for the test. Therefore, the repeatability and
case ambient temperature shall be used. In the case of easily
reproducibility cited in this test method may not apply for these
oxidized coals, the temperature shall not be over 10°C (18°F)
high-volatile bituminous, subbituminous, and lignite coals.
above room temperature unless ambient temperature is above
1.2 The values stated in SI units are to be regarded as the
37°C (100°F) in which case ambient temperature shall be used.
standard. The values given in parentheses may be approximate.
Air changes shall be at the rate of 1 to 4 air volumes of oven
1.3 It is recognized that the term weight is considered
capacity per minute.
equivalent to mass as used in this test method.
4.2 Drying Pans—Drying pans of sufficient size so that the
1.4 This standard does not purport to address all of the
sample may be spread to a depth of not more than 25 mm (1.0
safety concerns, if any, associated with its use. It is the
in.) with sides not more than 38 mm (1.5 in.) high. The pans
responsibility of the user of this standard to establish appro-
shall be nonreactive with coal and unaffected by the method of
priate safety and health practices and determine the applica-
air drying selected.
bility of regulatory limitations prior to use.
4.3 Balances—Two balances may be required: one with a
sensitivity of 10 mg and a minimum capacity of 800 g and one
2. Referenced Documents
with a sensitivity of 0.5 g in 1000 g and sufficient capacity to
2.1 ASTM Standards:
3 weigh a $1000-g sample along with the drying pan. A single
D 2013 Method of Preparing Coal Samples for Analysis
balance meeting these specifications is permitted.
4.3.1 Calibration Weights—These calibration weights shall
1 be used to monitor the response of each balance over the range
This test method is under the jurisdiction of ASTM Committee D-5 on Coal and
of normal use each time HGIs are determined.
Coke and is the direct responsibility of D05.07 on Physical Characteristics of Coal.
Current edition approved Nov. 10, 1997. Published May 1998. Originally
4.4 Sample Divider—An enclosed riffle divider as described
published as D 409 – 51. Last previous edition D 409 – 93a.
in Method D 2013 is required and shall be used.
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For information concerning the experimental work on which this test method is
4.5 Standard Sieves—A working set of circular, standard
based, see paper by Hardgrove, R. M., “Grindability of Coal,” Transactions,
American Society of Mechanical Engineers, Vol 54, F.S.P., p. 37, 1932. testing sieves which are 203 mm (8 in.) in diameter and
D05.07.02 on Grindability is conducting ongoing investigations in regard to
quality control during preparation, distribution, and use of standard reference
materials and during preparation
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