1、Designation: D 409 02 (Reapproved 2007)e1Standard 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 ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTESection 10.2 was editorially correct
3、ed in October 2007.1. Scope1.1 This test method2covers the determination of therelative grindability or ease of pulverization of coals incomparison with coals chosen as standards. A prepared andsized sample receives a definite amount of grinding energy ina miniature pulverizer, and the size consist
4、of the pulverizedproduct is determined by sieving. The resultant size consist isused 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 changeas the nat
5、ural or seam moisture is released during handling andpreparation. This change is often sufficient to alter the grind-ability characteristics 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-
6、mmby 600-m (No. 16 3 No. 30) (see Test Method D 4749)materials used for the test. Therefore, the repeatability andreproducibility cited 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 thesta
7、ndard. The values given in parentheses may be approximate.1.3 It is recognized that the term weight is consideredequivalent to mass 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 use
8、r of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 2013 Practice for Preparing Coal Samples for AnalysisD 2234/D 2234M Practice for Collection of a Gross Sampleo
9、f CoalD 4749 Test Method for Performing the Sieve Analysis ofCoal and Designating Coal SizeE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Significance and Use3.1 This test method develops a measurement of grinding orpulverizing characteristics that can be used to evaluate theyield
10、, or energy input, or both, required in a grinding orpulverizing process.4. Apparatus4.1 Air-Drying OvenA device for passing slightly heatedair over the sample. The oven shall be capable of maintaininga temperature of 10 to 15C (18 to 27F) above roomtemperature with a maximum oven temperature of 40C
11、(104F) unless ambient temperature is above 40C, in whichcase ambient temperature shall be used. In the case of easilyoxidized coals, the temperature shall not be over 10C (18F)above room temperature unless ambient temperature is above37C (100F) in which case ambient temperature shall be used.Air cha
12、nges shall be at the rate of 1 to 4 air volumes of ovencapacity per minute.4.2 Drying PansDrying pans of sufficient size so that thesample may be spread to a depth of not more than 25 mm (1.0in.) with sides not more than 38 mm (1.5 in.) high. The pansshall be nonreactive with coal and unaffected by
13、the method ofair drying selected.4.3 BalancesTwo balances may be required: one with asensitivity of 10 mg and a minimum capacity of 800 g and onewith a sensitivity of 0.5 g in 1000 g and sufficient capacity to1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is th
14、e direct responsibility of D05.07 on Physical Characteristics ofCoal.Current edition approved Oct. 1, 2007. Published July 2002. Originally approvedin 1951. Last previous edition approved in 2002 as D 409 e1.2For information concerning the experimental work on which this test method isbased, see pap
15、er 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 investigations in regard toquality control during preparation, distribution, and use of standard referencematerials and d
16、uring preparation and testing of actual samples.3Annual Book of ASTM Standards, Vol 05.06.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.weigh a $1000-g sample along with the drying pan. A singlebalance meeting these specifications
17、is permitted.4.3.1 Calibration WeightsThese calibration weights shallbe used to monitor the response of each balance over the rangeof normal use each time HGIs are determined.4.4 Sample DividerAn enclosed riffle divider as describedin Method D 2013 is required and shall be used.4.5 Standard SievesA
18、working set of circular, standardtesting sieves which are 203 mm (8 in.) in diameter andconform to Specification E11, are required in the followingsizes, together with cover and catch pan (receiver):Sieve DesignationStandard Alternate(ISO Designation) (U.S.A. Designation)16.0 mm58 in.4.75 mm No. 42.
19、36 mm No. 81.18 mm No. 16600 m No. 3075 m No. 2004.5.1 These working sieves must be periodically inspectedfor wear or damage. Any excessively worn or damaged sieves(sieves with holes, tears cracks, and so forth, see Note 1). mustbe replaced immediately, and the HGI calibration proceduremust be repea
20、ted after the damaged sieves are replaced (seeSection 8). Since the HGI depends upon the sieve analysis andsince the 75-m (No. 200) sieve is fragile, it is recommendedthat at least one set of working sieves be obtained, identified,and used exclusively for HGI determinations and that only thisexclusi
21、ve set of sieves be used.NOTE 1Excessive wear may be indicated by poor repeatability or byfailure of quality control checks (8.1.1) to agree reasonably with the initialcalibration data.4.5.2 Normal wear on sieves is compensated by the use ofproper standard reference samples (SRSs) and proper calibra
22、-tion of equipment; excessive wear such as holes or tears in thesieve cloth, and so forth is not compensated by SRSs. Becauseexcessive wear is unacceptable, inspect sieves carefully beforeeach test to ensure the absence of excessive wear. For the 75-and 600-m (No. 200 and 30) sieves, use only a soft
23、-bristledbrush (such as short-bristled camel hair) for brushing andcleaning.NOTE 2It is good practice to keep a separate primary 75-m (No. 200)check sieve to be used only to check the 75-m working sieve describedin 4.5.1 when the working sieve becomes suspect. This check is done byrunning a comparat
24、ive HGI test between the two 75-m sieves. Use of theworking sieve for HGIs should be discontinued if HGI difference betweenthe sieves is greater than 1 HGI unit.4.6 CrusherA laboratory plate mill capable of reducing4.75-mm (No. 4) sieve size coal particles with the productionof a minimum of minus 60
25、0-m (minus No. 30) sieve sizematerial (Note 3). The crusher plates shall be serrated andabout 100 mm (4 in.) in diameter (Note 4). The distancebetween the plates shall be adjustable, and the relative speed ofrotation of the plates shall not exceed 200 r/min.NOTE 3Evidence from HGI standard reference
26、 sample user-responseforms (8.4) indicates that the median value of percent recovery of the4.75-mm (No. 4) material as 1.18-mm by 600-m (Nos. 16 by 30)material, regardless of the HGI level, is about 55 %.NOTE 4The most frequently used plate mill can be equipped with“fine” or “coarse” plates. One ind
27、ependent study4has 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.4.7 Mechanical Sieving MachineThe mechanical sievingmachine shall accept an asse
28、mbly of vertically 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 3
29、00 oscillations 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.4.8 Grindability Mac
30、hineThe Hardgrove 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 ba
31、lls, each 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
32、 spindle 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.4.
33、8.1 The position of the counter trip mechanism before andafter the test must be used to determine the number ofrevolutions completed. Sometimes, 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 (tha
34、t is, watch where the trip mechanism is initially, countthe number of revolutions from the point of origin, determinewhere the trip mechanism 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
35、of the test until the specified number of revolutionsare obtained).5. Standard Reference Samples (SRSs) for Calibration55.1 Four SRSs prepared especially for this purpose (inaccordance with Annex A1) and representing grindabilityindices of approximately 40, 60, 80, and 100 shall be used forcalibrati
36、on. (See Section 8.)4D05.07 Minutes, J. Gardner, Georgia Power and G. Linton, October 1990.5Primary standard reference samples are available from The Pennsylvania StateUniversity, Ronald S. Wasco The Energy Institute, C-211 CUL, University Park, PA16802, Telephone: 814-863-5384, Fax: 814-863-7432, e
37、mail: rxw19psu.edu,www.energy.psu.edu/HGI. ASTM Subcommittee D05.07 and the ASTM/DOELiaison Task Group maintain oversight for production of only the primary standardreference samples. Secondary standard reference samples are available from othersources.D 409 02 (2007)e125.1.1 Upon receipt, each of t
38、he SRSs should be examinedfor the following:5.1.1.1 Preparation date (no more than six months old).5.1.1.2 Oversize (material retained on a 4.75-mm (No. 4)sieve). Less than 5 % + 4.75 mm and no particle on a 6.30-mm(14-in. square-holed sieve). (See 7.3.)5.1.1.3 Foreign, noncoal material (no wood, ro
39、ck, slate, andso forth).5.1.1.4 Excessive fines (600-m (No. 30) material) (lessthan 30 %). (See 7.3.)5.1.2 When any of these parameters are unacceptable,contact the agency responsible for production of the SRSs andreport the data on the response form accompanying the SRSs(see 8.4).6. Gross Samples6.
40、1 Collect a gross sample of coal, representative of thematerial from which it is taken, in accordance with PracticeD 2234/D 2234M, and prepare the sample in accordance withMethod D 2013 except that the sample topsize shall not bereduced beyond the 4.75-mm (No. 4) sieve, and the sampleshall weigh at
41、least 1000 g.7. Preparation of Test Samples7.1 Prepare a 1.18-mm 3 600-m (No. 16 3 No. 30) testsample for establishing the HGI of SRSs, for calibration, or forroutine determination of HGI.7.2 When necessary, divide the quantity of 4.75-mm (No. 4)sieve size coal to not less than 1000-g lots using an
42、enclosedriffle, and air dry each sample in conformance with MethodD 2013.7.3 Sieve the entire amount (1000 g) of air-dried 4.75-mm(No. 4) sieve size sample in lots of no greater than 250 g, for2 min 6 10 s in the mechanical sieving machine. Use a set ofnested sieves consisting of a 1.18-mm (No. 16)
43、sieve on top ofa 600-m (No. 30) sieve. It may be appropriate to include a4.75-mm (No. 4) and a 2.36-mm (No. 8) sieve in this nest ofFIG. 1 Hardgrove Grindability MachineD 409 02 (2007)e13sieves to record the particle size distribution and the topsize ofthe sample. Weigh and record the mass of each s
44、ieve size.7.4 Stage crush the material retained on the 1.18-mm (No.16) sieve with the crusher adjusted so that only the largestparticles are crushed. Take the crushed material in lots nogreater than 250 g and sieve for 2 min 6 10 s in the mechanicalsieving machine. Return the oversize to the crusher
45、, aftersetting the crusher so that only the largest particles are crushed.Continue the stage crushing and sieving procedure until all thematerial passes the 1.18-mm sieve. Retain the 1.18-mm 3 600-m (No. 16 3 No. 30) material.7.5 Mix well all the 1.18-mm 3 600-m (No. 16 3 No. 30)material accumulated
46、 from the stage crushing and sieving anddivide the quantity using an enclosed riffle to obtain approxi-mately 120 6 10 g.7.6 As the final step in preparation of the test sample, dedustthe 120- 6 10-g sample from 7.5 by sieving on a 600-m (No.30) sieve for 5 min 6 10 s using the mechanical sievingmac
47、hine.8. Calibration8.1 Calibrate each grindability machine, together with allancillary equipment including sieves and plate mill, that will beused for this test when new, modified, repaired, suspected ofbeing defective, or when operated by new personnel.8.1.1 SRSs shall not be used for calibration b
48、eyond 18months from their preparation date. It is good practice to checkthe calibration of the HGI apparatus periodically with at leastone of the SRSs (quality control check sample) even if none ofthe conditions in 8.1 apply. This will ensure that the system isstill in control and it will allow for
49、detection of problemspreviously unnoticed or not then occurring, and it will allowfor use of the SRSs before their expiration date.8.2 For each calibration, process four standard referencesamples with indices of approximately 40, 60, 80, and 100separately as described above. Process the samples as outlinedbelow (Section 9), and use the results to determine the equationof the line by use of the sum of least squares method (8.3) and,if desired, to prepare a calibration chart (8.3.1).8.3 By the method of the sum of least squares, determine
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