1、Designation: D 409 08Standard Test Method forGrindability of Coal by the Hardgrove-Machine Method1This standard is issued under the fixed designation D 409; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript 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.INTRODUCTIONThis test method is structured into the following p
3、arts:The body of the test method discusses the scope, referenced documents, significance and use,apparatus, gross samples, preparation of test samples, procedure, calculation and report, precision andbias, and keywords.Annex A1 through Annex A5 contain the methods used to prepare, homogenize, and as
4、sign HGIvalues to the international HGI reference materials (primary HGI RMs) and to calibrate an individuallaboratorys HGI machine using these HGI RMs.Annex A1 contains the method to obtain and prepare international HGI standard reference coalsample feedstock for potential use as international (pri
5、mary) HGI RMs (reference materials).Annex A2 contains the method to divide and containerize the candidate international HGI standardreference coal samples (candidate RMs) prepared from the feedstock prepared in Annex A1.AnnexA3 contains the method for homogeneity testing of the candidate internation
6、al HGI standardreference coal samples (candidate RMs) containerized in Annex A2.Annex A4 contains the method for determining the Hardgrove grindability index (HGI) to beassigned to each lot of the candidate international HGI standard reference coal samples (RMs).Annex A5 contains the method used to
7、calibrate the individual laboratorys Hardgrove grindabilitymachine using the international HGI RMs.Annex A6 through Annex A10 contain the methods used to prepare, homogenize, and assign HGIvalues to the national HGI reference materials (secondary HGI RMs) and to calibrate a national HGImachine using
8、 the international (primary) HGI RMs.Annex A6 contains the method to obtain and prepare national HGI standard reference coal samplefeedstock for potential use as national (secondary) HGI RMs (reference materials).AnnexA7 contains the method to divide and containerize candidate national HGI standard
9、referencecoal samples (candidate national RMs) prepared from the feedstock prepared in Annex A6.Annex A8 contains the method for homogeneity testing of candidate national HGI standardreference coal samples (candidate national RMs) containerized in Annex A7.Annex A9 contains the method for determinin
10、g the Hardgrove grindability index to be assigned toeach lot of the candidate national HGI standard reference coal samples (national RMs).Annex A10 contains the method to calibrate a national Hardgrove machine using the international(primary) HGI RMs.Annex A11 contains the method for determining the
11、 moisture content of the 1.18 3 0.60 mm (No.16 3 30) test sample.1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of D05.07 on Physical Characteristics ofCoal.Current edition approved May 15, 2008. Published June 2008. Originallyappro
12、ved in 1951. Last previous edition approved in 2007 as D 409 02 (2007)1.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1. Scope1.1 This test method2covers the determination of therelative grindability or ease of pulverization of coa
13、ls incomparison with coals chosen as standards. A prepared andsized sample receives a definite amount of grinding energy ina miniature pulverizer, and the size consist of the pulverizedproduct is determined by sieving. The resultant size consist isused to produce an index relative to the ease of gri
14、nding(Hardgrove Grindability Index (HGI).1.1.1 Some coals, such as some high-volatile bituminous,subbituminous, and lignite coals, can undergo physical changeas the natural or seam moisture is released during handling andpreparation. This change is often sufficient to alter the grind-ability charact
15、eristics that will be reported when tested in thelaboratory and could produce different indices dependent onthe conditions of drying and the moisture level of the 1.18-mmby 600-m (No. 16 3 No. 30) (see Test Method D 4749)materials used for the test. Therefore, the repeatability andreproducibility ci
16、ted in this test method may not apply for thesehigh-volatile bituminous, subbituminous, and lignite coals.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses may be approximate.1.3 It is recognized that the term weight is consideredequivalent to mass
17、as used in this test method.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations
18、prior to use.2. Referenced Documents2.1 ASTM Standards:3D 2013 Practice for Preparing Coal Samples for AnalysisD 4749 Test Method for Performing the Sieve Analysis ofCoal and Designating Coal SizeD 4916 Practice for Mechanical Auger SamplingD 6609 Guide for Part-Stream Sampling of CoalD 6883 Practic
19、e for Manual Sampling of Stationary Coalfrom Railroad Cars, Barges, Trucks, or StockpilesD 7256/D 7256M Practice for Mechanical Collection andWithin-System Preparation of a Gross Sample of Coalfrom Moving StreamsE11 Specification for Wire Cloth and Sieves for TestingPurposesE 826 Practice for Testin
20、g Homogeneity of Materials forDevelopment of Reference Materials4NOTE 1Part stream samples should be used for this test only if allparties find part stream sampling acceptable.NOTE 2If the topsize of the final sample product produced from amechanical sampling system (whether auger, cross-stream, or
21、cross-belt)is smaller than 4.75 mm (No. 4), the sample is unsuitable for this testprocedure.3. Significance and Use3.1 This test method develops a measurement of grinding orpulverizing characteristics that can be used to evaluate theyield, or energy input, or both, required in a grinding orpulverizi
22、ng process.4. Apparatus4.1 Air-Drying Oven for air-drying the 1000 g, 4.75 mm(No. 4) sampleA device for passing slightly heated air overthe sample. The oven shall be capable of maintaining atemperature of 10 to 15C (18 to 27F) above room tempera-ture with a maximum oven temperature of 40C (104F) unl
23、essambient temperature is above 40C, in which case ambienttemperature shall be used. In the case of easily oxidized coals,the temperature shall not be over 10C (18F) above roomtemperature unless ambient temperature is above 37C (100F)in which case ambient temperature shall be used. Air changesshall
24、be at the rate of 1 to 4 air volumes of oven capacity perminute.4.2 Drying Pans for air-drying the 1000 g, 4.75 mm (No. 4)sampleDrying pans of sufficient size so that the sample maybe spread to a depth of not more than 25 mm (1.0 in.) withsides not more than 38 mm (1.5 in.) high. The pans shall beno
25、nreactive with coal and unaffected by the method of airdrying selected.4.3 Balance for weighing the 1000-g sample before andafter air-drying and the sieve fractions formed during stage-crushingWith a sensitivity of 0.5 g in 1000 g and sufficientcapacity to weigh a $ 1000-g sample along with the dryi
26、ngpan.4.4 Balance for weighing the 50-g test sample and the sievefractions formed during millingWith a sensitivity of 10 mgand a minimum capacity of 800 g.NOTE 3A single balance meeting the specifications of 4.3 and 4.4 ispermitted.4.5 Calibration WeightsThese calibration weights shallbe used to mon
27、itor the response of each balance over the rangeof normal use each time HGIs are determined.4.6 Sample Divider An enclosed riffle divider with feedchute as described in Practice D 2013 is required and shall beused. Alternatively, a rotary sample divider, which has beenproven to be free of significan
28、t bias, may be used.2For information concerning the experimental work on which this test method isbased, see paper by Hardgrove, R. M., “Grindability of Coal,” Transactions,American Society of Mechanical Engineers, Vol 54, F.S.P., p. 37, 1932.D05.07.02 on Grindability is conducting ongoing investiga
29、tions in regard toquality control during preparation, distribution, and use of standard referencematerials and during preparation and testing of actual samples.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
30、 ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Withdrawn.D4090824.7 Standard SievesA working set of circular, standardtesting sieves, which are 203 mm (8 in.) in diameter andconform to Specification E11, are required in the followingsizes, togethe
31、r with cover and catch pan (receiver):TABLE 1 Standard Sieves for HGI TestingE11Specification U.S.A. Standard Sieve Series Designation16.0 mm58 in.4.75 mm No. 42.36 mm No. 81.18 mm No. 16600 m No. 3075 m No. 2004.7.1 These working sieves must be periodically inspectedfor wear or damage. Any excessiv
32、ely worn or damaged sieves(for example, sieves with holes, tears, cracks; see Note 4) mustbe replaced immediately, and the HGI calibration proceduremust be repeated after the damaged sieves are replaced (seeAnnexA5). Since the HGI depends upon the sieve analysis andsince the 75-m (No. 200) sieve is
33、fragile, it is recommendedthat at least one set of working sieves be obtained, identified,and used exclusively for HGI determinations and that only thisexclusive set of sieves be used.NOTE 4Excessive wear may be indicated by poor repeatability or byfailure of quality control checks (A5.4.1.1) to agr
34、ee reasonably with theinitial calibration data.4.7.2 Normal wear on sieves is compensated by the use ofinternational HGI standard reference samples (HGI RMs) andproper calibration of equipment; excessive wear (such as holesor tears in the sieve cloth, and so forth) is not compensated byHGI RMs. Beca
35、use excessive wear is unacceptable, inspectsieves carefully before each test to ensure the absence ofexcessive wear. For the 75- and 600-m (No. 200 and 30)sieves, use only a soft-bristled brush (such as short-bristledcamel hair) for brushing and cleaning.NOTE 5It is good practice to keep a separate
36、primary 75-m (No. 200)check sieve to be used only to check the 75-m working sieve describedin 4.7.1 when the working sieve becomes suspect. This check is done byrunning a comparative HGI test between the two 75-m sieves. Use of theworking sieve for HGIs should be discontinued if HGI difference betwe
37、enthe sieves is greater than 1 HGI unit.4.8 CrusherA laboratory plate mill capable of reducing4.75-mm (No. 4) sieve size coal particles with the productionof a minimum of minus 600-m (minus No. 30) sieve sizematerial (Note 6). The crusher plates shall be serrated andabout 100 mm (4 in.) in diameter
38、(Note 7). The distancebetween the plates shall be adjustable, and the relative speed ofrotation of the plates shall not exceed 200 r/min.NOTE 6Evidence from HGI standard reference sample user-responseforms (A5.4.4) indicates that the median value of % Yield (8.3)ofthe4.75-mm (No. 4) material as 1.18
39、-mm by 600-m (Nos. 16 by 30)material, regardless of the HGI level, is about 55 %. Use this median valueto gage the effectiveness/efficiency of the stage-crusher and of thestage-crushing process.NOTE 7The most frequently used plate mill can be equipped with“fine” or “coarse” plates. One independent s
40、tudy5has found evidence ofdifferences in percent recovery resulting from use of different types ofplate. Only the coarse plate should be used in preparation of both HGIcalibration standards and unknown samples.4.9 Mechanical Sieving MachineThe mechanical sievingmachine shall accept an assembly of ve
41、rtically nested circularsieves of 203 mm (8 in.) in diameter, together with cover andreceiver. The machine shall simulate the motions given testingsieves during hand sieving by imparting a horizontal oscilla-tory motion of approximately 28-mm (1.1-in.) amplitude at arate of approximately 300 oscilla
42、tions or cycles per minute(cpm). Simultaneously, the top of the oscillating assembly isstruck at a rate of approximately 150 blows per minute by aweight of 1.9 kg (4.2 lb) moving through a vertical distance ofapproximately 28 mm (1.1 in.) under the influence of gravity.4.10 Grindability MachineThe H
43、ardgrove GrindabilityMachine such as is shown in Fig. 1 is required for this test.Essential tolerances and specifications are shown in Fig. 2. Thegrindability machine includes a stationary grinding bowl ofpolished cast iron, with a circular horizontal track that holdseight polished steel balls, each
44、 25.40 6 0.13 mm (1.000 60.005 in.) in diameter. The balls are driven by an uppergrinding ring which is rotated at 20 6 1 r/min by means of theupper spindle and which, in turn, is driven by an electric motorthrough reduction gears and, in newer models, belts. Weightsare added to the driving spindle
45、so that the total vertical forceon the balls as a result of the weights, shaft, top grinding ring,and gear is equal to 29.0 6 0.2 kg (64 6 0.5 lb). The machineis equipped with a counter and automatic device which can beproperly adjusted for stopping the machine after 60 6 0.25revolutions.NOTE 8It is
46、 good laboratory practice to have the dimensions and thetolerances of the grinding balls verified by a qualified machine shop (orequivalent) on an annual basis.4.10.1 The position of the counter trip mechanism beforeand after the test must be used to determine the number ofrevolutions completed. Som
47、etimes, it may be necessary toposition strategically the counter trip mechanism at the begin-ning of the test to accomplish the desired number of revolu-tions (that is, watch where the trip mechanism is initially, countthe number of revolutions from the point of origin, determinewhere the trip mecha
48、nism is at the end of the test, anddetermine if the specified 60 6 0.25 revolutions are obtained.If not, adjust the position of the trip mechanism at thebeginning of the test until the specified number of revolutionsare obtained).5. Gross Samples5.1 Collect a gross sample of coal, representative of
49、thematerial from which it is taken, in accordance with PracticeD 4916 (Note 2), D 6883,orD 7256/D 7256M (Note 2) orGuide D 6609 (Note 1), and prepare the sample in accordancewith Practice D 2013 except that the sample topsize shall notbe reduced beyond the 4.75-mm (No. 4) sieve and the sampleshall weigh at least 1000 g.6. Preparation of Test Samples6.1 Prepare a 1.18-mm 3 600-m (No. 16 3 No. 30) testsample for establishing the HGI of HGI RMs (Annex A4 and5D05.07 Minutes, J. Gardner, Georgia Power and G. Linton, October 1990.D409083A
