1、Designation: D409/D409M 11a1 D409/D409M 12Standard Test Method forGrindability of Coal by the Hardgrove-Machine Method1This standard is issued under the fixed designation D409/D409M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision,
2、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 NOTEFigure 1 was editorially correc
3、ted and footnote 5 was editorially added in February 2012.INTRODUCTIONThis test method is structured into the following parts:The body of the test method discusses the scope, referenced documents, significance and use,apparatus, gross samples, preparation of test samples, procedure, calculation and
4、report, precision andbias, and keywords.Annex A1 contains the method to obtain and prepare coal feedstock for potential use as HGI RMs(reference materials).Annex A2 contains the method to divide and containerize the candidate HGI RMs (candidate HGIRMs) from the feedstock prepared in Annex A1.Annex A
5、3 contains the method for homogeneity testing of the candidate HGI RMs containerized inAnnex A2.Annex A4 contains the method for determining the Hardgrove grindability index (HGI) to beassigned to each lot of the candidate HGI RMs.Annex A5 contains the method used to calibrate a Hardgrove grindabili
6、ty machine using theprimary or secondary HGI RMs.Annex A6 contains the method for determining the moisture content of the 1.18 0.60 mm (No.16 30) test sample.1. Scope1.1 This test method2 covers the determination of the relative grindability or ease of pulverization of coals in comparison withcoals
7、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 indexrelative to the ease of grinding Hardgrove Grindabil
8、ity Index (HGI).1.1.1 Some coals, such as some high-volatile bituminous, subbituminous, and lignite coals, can undergo physical change as thenatural or seam moisture is released during handling and preparation. This change is often sufficient to alter the grindabilitycharacteristics that will be rep
9、orted when tested in the laboratory and could produce different indices dependent on the conditionsof drying and the moisture level of the 1.18 0.60 mm (No. 16 30) (see Test Method D4749) materials used for the test.Therefore, the repeatability and reproducibility cited in this test method may not a
10、pply for these high-volatile bituminous,subbituminous, and lignite coals.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the oth
11、er. Combining values from thetwo systems may result in non-conformance with the standard.1 This test method is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of D05.07 on Physical Characteristics of Coal.Current edition approved Dec. 1, 2011Oct. 1, 201
12、2. Published January 2012December 2012. Originally approved in 1951. Last previous edition approved in 2011 asD409 11.D409 11a1. DOI: 10.1520/D0409_D0409M-11A.10.1520/D0409_D0409M-12.2 For information concerning the experimental work on which this test method is based, see paper by Hardgrove, R. M.,
13、 “Grindability of Coal,” Transactions, AmericanSociety of Mechanical Engineers, Vol 54, F.S.P., p. 37, 1932.D05.07 on Physical Characteristics on Coal is conducting ongoing investigations in regard to quality control during preparation, distribution, and use of standard referencematerials and during
14、 preparation and testing of actual samples.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. Becauseit may not be technically possible to adequately depict all changes accurately, A
15、STM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.3 T
16、his standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Document
17、s2.1 ASTM Standards:3D2013 Practice for Preparing Coal Samples for AnalysisD2234/D2234M Practice for Collection of a Gross Sample of CoalD3302 Test Method for Total Moisture in CoalD4749 Test Method for Performing the Sieve Analysis of Coal and Designating Coal SizeD6708 Practice for Statistical Ass
18、essment and Improvement of Expected Agreement Between Two Test Methods that Purportto Measure the Same Property of a MaterialD6883 Practice for Manual Sampling of Stationary Coal from Railroad Cars, Barges, Trucks, or StockpilesD7430 Practice for Mechanical Sampling of CoalE11 Specification for Wove
19、n Wire Test Sieve Cloth and Test Sieves3. Significance and Use3.1 This test method develops a measurement of grinding or pulverizing characteristics that can be used to evaluate the yield,or energy input, or both, required in a grinding or pulverizing process, which can impact a wide variety of proc
20、esses, includingcombustion, coke-making, liquefaction, and gasification.4. Apparatus4.1 Air-Drying Oven for air-drying the 1000 g, 4.75 mm (No. 4) sampleA device for passing slightly heated air over thesample. The oven shall be capable of maintaining a temperature of 10 to 15 C 18 to 27 F above room
21、 temperature with amaximum oven temperature of 40 C 104 F unless ambient temperature is above 40 C, in which case ambient temperature shallbe used. In the case of easily oxidized coals, the temperature shall not be over 10 C 18 F above room temperature unlessambient temperature is above 37 C 100 F i
22、n which case ambient temperature shall be used. Air changes shall be at the rate of1 to 4 air volumes of oven capacity per minute.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.
23、with sides not more than 38 mm 1.5 in. high. The pans shall be nonreactivewith coal and unaffected by the method of air drying selected.4.3 Balance for weighing the 1000-g sample before and after air-drying and the sieve fractions formed during stage-crushingWith a sensitivity of at least 0.5 g in 1
24、000 g and sufficient capacity to weigh a sample with a mass of greater than orequal to 1000g along with the drying pan.4.4 Balance for weighing the 50-g test sample and the sieve fractions formed during millingWith a sensitivity of at least10 mg and a minimum capacity of 800 g.NOTE 1A single balance
25、 meeting the specifications of 4.3 and 4.4 is permitted.4.5 Calibration WeightsThese calibration weights shall be used periodically to monitor the response of each balance over theworking range.4.6 Sample DividerAn enclosed riffle divider with feed chute as described in Practice D2013 or a rotary sa
26、mple divider, whichhas been proven to be free of significant bias, may be used.4.7 Standard SievesA working set of circular, standard testing sieves, which are 203 mm 8 in. in diameter and conform toSpecification E11, are required in the following sizes, together with cover and catch pan (receiver):
27、TABLE 1 Standard Sieves for HGI TestingE11 Specification U.S.A. Standard Sieve Series Des-ignation16.0 mm 58 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 inspected for wear or damage. Any excessively worn or damaged sieves (forexa
28、mple, sieves with holes, tears, cracks; etc.) must be replaced immediately, and the HGI calibration procedure must be repeated3 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume informatio
29、n, refer to the standards Document Summary page on the ASTM website.D409/D409M 122after the damaged sieves are replaced (see Annex A5). Since the HGI depends upon the sieve analysis and since the 75-m (No.200) sieve is fragile, it is recommended that at least one set of working sieves be obtained, i
30、dentified, and used exclusively for HGIdeterminations and that only this exclusive set of sieves be used for determining HGI.4.7.1.1 Excessive wear may be indicated by poor repeatability or by failure of quality control checks (A5.4.1.1) to agreereasonably with the initial calibration data.4.7.2 Nor
31、mal wear on sieves is compensated by the use of primary HGI standard reference samples (HGI RMs) and propercalibration of equipment; excessive wear (such as holes or tears in the sieve cloth, and so forth) is not compensated by HGI RMs.Because excessive wear is unacceptable, inspect sieves carefully
32、 before each test to ensure the absence of excessive wear. For the75- and 600-m (No. 200 and 30) sieves, use only a soft-bristled brush (such as short-bristled camel hair) for brushing andcleaning.4.7.2.1 It is good practice to keep a separate primary 75-m (No. 200) check sieve to be used only to ch
33、eck the 75-m (No.200) working sieves described in 4.7.1 whenever the working sieve becomes suspect. This check is done by running a comparativeHGI test between the two 75-m (No. 200) sieves. Use of the working sieve for HGIs should be discontinued if HGI differencebetween the sieves is greater than
34、1 HGI unit.4.8 Plate Mill CrusherA laboratory plate mill capable of reducing 4.75-mm (No. 4) sieve size coal particles with theproduction of a minimum of minus 0.60-mm (minus No. 30) sieve size material. The crusher plates shall be serrated and about100 mm 4 in. in diameter. The distance between the
35、 plates shall be adjustable, and the relative speed of rotation of the plates shallnot exceed 200 r/min.4.8.1 Evidence from HGI standard reference sample user-response forms (A5.4.4) indicates that the median value of % Yield(8.3) of the 4.75-mm (No. 4) material as 1.18 0.60 mm (No. 16 30) material,
36、 regardless of the HGI level, is about 55 %. Usethis median value to gage the effectiveness/efficiency of the stage-crusher and of the stage-crushing process, while noting that, insome situations, the % Yield has been as low as 45%.4.8.2 The most frequently used plate mill can be equipped with “fine
37、” or “coarse” plates. One independent study4 has foundevidence of differences in percent recovery resulting from use of different types of plate. In order to obtain the maximum % Yield,only the coarse plate should be used in preparation of both HGI calibration standards and unknown samples.4.9 Mecha
38、nical Sieving MachineThe mechanical sieving machine shall accept an assembly of vertically nested circular sievesof 203 mm 8 in. in diameter, together with cover and receiver. The machine shall simulate the motions given testing sieves duringhand sieving by imparting a horizontal oscillatory motion
39、of approximately 28-mm 1.1-in. amplitude at a rate of approximately300 oscillations or cycles per minute (cpm). Simultaneously, the top of the oscillating assembly is struck at a rate of approximately150 blows per minute by a mass of 1.9 kg 4.2 lb moving through a vertical distance of approximately
40、28 mm 1.1 in. under theinfluence of gravity.4.9.1 Whenever a mechanical sieving machine other than the reference machine described above is used, the method may beshown to be equivalent by one of two methods (1) side x side equivalency testing of the alternative machine vs. the referencemachine (wit
41、h both calibration and test samples that cover the working range), using the equivalency testing statistical techniqueof D6708 or (2) acceptable performance in an appropriate proficiency test program that covers the working range.4.10 Grindability MachineThe Hardgrove Grindability Machine such as is
42、 shown in Fig. 1 is required for this test. Essentialtolerances and specifications are shown in Fig. 2. The grindability machine includes a stationary grinding bowl of polished castiron, with a circular horizontal track that holds eight polished steel balls, each 25.40 6 0.13 mm 1.000 6 0.005 in. in
43、 diameter.The balls are driven by an upper grinding ring which is rotated at 20 6 1 r/min by means of the upper spindle and which, in turn,is driven by an electric motor through reduction gears or, in newer models, belts. Weights are added to the driving spindle so thatthe total vertical force on th
44、e balls as a result of the weights, shaft, top grinding ring, and gear is equal to 29.0 6 0.2 kg 64 60.5 lb. The machine is equipped with a counter and automatic device, which can be properly adjusted for stopping the machineafter 60 6 0.25 revolutions.4.10.1 It is good laboratory practice to have t
45、he dimensions and the tolerances components that are subject to wear verified ona periodic basis.4.10.2 The position of the counter trip mechanism before and after the test must be used to determine the number of revolutionscompleted. With some machines, it may be necessary to position strategically
46、 the counter trip mechanism at the beginning of thetest to accomplish the desired number of revolutions (that is, during a set-up period, watch where the trip mechanism is initially,count the number of revolutions from the point of origin, determine where the trip mechanism is at the end of the test
47、, anddetermine if the specified 60 6 0.25 revolutions are obtained. If not, adjust the position of the trip mechanism at the beginningof the test until the specified number of revolutions are obtained). Periodically, verify that the machine is operated to obtain thespecified number of revolutions pe
48、r test.5. Gross Samples5.1 Collect a gross sample of coal, representative of the material from which it is taken. The sample may be collected, inaccordance with Practice D2234/D2234M, D6883, or D7430 (or equivalent other international or national standard), and prepared4 D05.07 Minutes, J. Gardner,
49、Georgia Power and G. Linton, October 1990.D409/D409M 123in accordance with Practice D2013 (or equivalent other international or national standard) except that the sample topsize shall notbe reduced beyond the 4.75-mm (No. 4) sieve and the sample shall have a mass of at least 1000 g.5.2 If the topsize of the final sample product produced from mechanical sampling system is smaller than 4.75mm (No. 4), thesample does not meet the requirements of this test procedure.6. Preparation of Test Samples6.1
