1、Designation: D 2013 07Standard Practice forPreparing Coal Samples for Analysis1This standard is issued under the fixed designation D 2013; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in paren
2、theses 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.1. Scope1.1 This practice2covers the reduction and division of grossor divided s
3、amples, and the preparation of composite samples,up to and including the individual portions for laboratoryanalysis.1.2 Reduction and division procedures are prescribed forcoals of the following groups:1.2.1 Group A includes coals that have been cleaned in allsizes.1.2.2 Group B includes all other c
4、oals. Unknown coals areto be considered under Group B.1.2.3 Group A allows smaller weight laboratory samples tobe retained than Group B. These lower weights may be used forparticular coals if they have been shown, by using theprocedures of Annex A1.2, to give a sample preparation andanalysis varianc
5、e which is no more than 20 % of the totalanalysis variance.1.3 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-bi
6、lity of regulatory limitations prior to use.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are provided forinformation purposes only.2. Referenced Documents2.1 ASTM Standards:3D 121 Terminology of Coal and CokeD 2234/D 2234M Practice for Collection o
7、f a Gross Sampleof CoalD 3174 Test Method forAsh in theAnalysis Sample of Coaland Coke from CoalD 3302 Test Method for Total Moisture in CoalD 4749 Test Method for Performing the Sieve Analysis ofCoal and Designating Coal SizeE11 Specification for Wire Cloth and Sieves for TestingPurposesE 177 Pract
8、ice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to Quality and Statistics3. Terminology3.1 Definitions of Terms Specific to This StandardNoterms are used which are specific to this practice. Many termsused in this practice may be found in Terminologies D 121
9、 andE 456 and in Practice E 177.4. Summary of Practice4.1 Three processes of sample division and reduction arecovered as follows:4.1.1 Procedure AManual riffles are used for division ofthe sample and mechanical crushing equipment for the reduc-tion of the sample.4.1.2 Procedure BMechanical sample di
10、viders are usedfor the division of the sample and mechanical crushingequipment for the reduction of the sample.4.1.3 Combined Procedure A and BThe two proceduresmay be combined at any stage.5. Significance and Use5.1 Other standards are used to collect the gross sample:Practice D 2234/D 2234 M allow
11、s for one division of the grosssample before crushing. The mass and top size of the gross ordivided sample collected by using these guides and practicesare usually too large for chemical or physical testing. PracticeD 2013 provide instructions for reducing and dividing thegross or divided sample, by
12、 on-line or off-line processes, orboth, to a top size and mass suitable to the performance of1This practice is under the jurisdiction of ASTM Committee D05 on Coal andCoke and is the direct responsibility of Subcommittee D05.23 on Sampling.Current edition approved June 1, 2007. Published July 2007.
13、Originally approvedin 1962. Last previous edition approved in 2004 as D 2013 04.2For more detailed explanation of this practice see Keller, G. E., “Determinationof Quantities Needed in Coal Sample Preparation and Analysis,” Transactions,Vol232, 1965, pp. 218-226.3For referenced ASTM standards, visit
14、 the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
15、9, United States.testing. Any bias in the gross or divided sample beforeadherence to this practice will remain in the final sampleresulting from use of this practice. Therefore, carefully selectthe standard to be used to collect the gross sample.5.2 Division and reduction of a sample may occur at mo
16、rethan one location. Most often, the sample is collected, reduced,and divided (one or more times) by use of a mechanicalsampling system. The remaining sample may be further di-vided on-site to facilitate transporting it to the laboratory wherefurther reduction and division likely occurs before analy
17、sis.5.3 In places, this practice requires air drying the samplebefore subsequent reduction. Procedures for air drying andair-dry loss determination are provided in Test Method D 3302.5.4 Most often, samples are reduced and divided to ananalysis sample. However, some tests may require a sample ofdiff
18、erent mass or top size. This procedure may be used toprovide a sample of any mass and size consist from the grossor divided sample to, and including, the analysis sample.5.5 This practice also specifies how to prepare compositesamples, if required.6. Apparatus6.1 Crushers or GrindersJaw, cone, or ro
19、tary crusher;hammer mill; roll; or other suitable crusher to reduce thesample to pass the sieve designated in 6.4. Hard steel or chillediron plate with tamper, sledge, or hand bar may be used forpreliminary crushing of any large lumps in the sample beforefeeding into the crusher. Crushers should be
20、designed andoperated in a manner to minimize the effect of induced aircirculation and thus the potential for drying the coal.6.1.1 Pulverizer or MillFor final reduction of laboratorysample to the 250-m (No. 60) sieve size, the followingequipment may be used:6.1.2 Hammer MillCompletely enclosed to av
21、oid loss ofdust or moisture.6.1.3 Porcelain-Jar Ball MillThis mill shall be approxi-mately 230 mm (9.0 in.) in diameter and 250 mm (10.0 in.) inheight with smooth, hard, well-rounded, flint pebbles, orequivalent, that do not increase ash content of the sample.6.1.4 Bucking Board (Chrome Steel) or Mo
22、rtar (Agate orEquivalent) and PestleOnly for reducing the small fractionof sample, not passing a 250-m (No. 60) sieve after pulveri-zation.6.2 Sample Dividers:6.2.1 MechanicalA mechanical sample divider using areciprocating or rotating cutter, a rotating hopper and spout, arotating slotted cone, a r
23、eciprocating hopper and fixed cutter,bucket cutter with either bottom dump or inverting discharge,slotted belt, rotary disk divider, mechanical stopped or movingbelt sweeper, or other acceptable devices for dividing thesample. Typical mechanical sample dividers are shown in Fig.1. These illustrate v
24、arious designs, but other acceptable designsare available.6.2.2 RiffleA manual sample divider that splits the coalstream into a number of alternate elements. Riffle slots shouldbe at least three times the top size of coal being divided. Atypical riffle is shown in Fig. 2. It is preferable that feed
25、chutesand enclosed riffles be used. The slope of feed chutes and rifflesmust be at least 60.6.2.2.1 Feed ScoopA feed scoop or pan having straightsides and a width equal to the effective width of the riffle shallbe used to feed the riffle.6.2.2.2 Feed ChuteAfeed chute shall be used as shown inFig. 2.
26、 The minimum discharge opening of the feed chute shallbe the same width as the riffle slot opening.6.3 Mixing WheelOne type of a mechanical device usedfor mixing the analysis sample. In this device, the samples arein closed containers attached to the rim of a wheel at an angleof 45 with the horizont
27、al wheel shaft. The wheel providesspace for a number of containers depending on its diameter andis turned slowly by a small motor and reduction gear. Thewheel should be rotated at a speed so that the particles fallgently from top to bottom of the container, mixing the samplethoroughly. The container
28、 should be about half full and nevermore than two thirds full to obtain good mixing of the sample.6.4 SievesA set of sieves whose dimensions are in accor-dance with Specification E11, of the following sizes, withcover and receiver:No. Size4 4.75 mm8 2.36 mm20 850 m60 250 m6.5 Laboratory Sample Conta
29、inersHeavy vapor-impervious bags, properly sealed, or noncorroding cans such asthose with an airtight top, friction top, or screwtop sealed witha rubber gasket and pressure-sensitive tape for use in storageand transport of the laboratory sample. Glass containers, sealedwith rubber gaskets, may be us
30、ed, but care must be taken toavoid breakage in transport.7. Precautions7.1 GeneralThe preparation of the gross or dividedsample, or the composite sample, shall be performed by, orunder the direct supervision of, personnel knowledgeable ofproper sample handling practices. Sample preparation shouldbe
31、checked at intervals by the methods described in Annex A1or Annex A2. It is necessary that the variance of sampledivision and analysis Sda2be not more than 20 % of the totalvariance of sampling, division, and analysis So2.7.1.1 The sample preparation operations should be per-formed in an enclosed sp
32、ace, roofed, cool, and free fromexcessive air movements.7.2 Number of TestsBefore preparing the gross or dividedsample, or the composite sample, consider the number andnature of the analysis and tests to be performed. A separatemoisture laboratory sample may be required, and portions maybe required
33、for grindability and other tests. Also, a reservesample may be desired in case a check analysis or test isrequired.7.3 This practice specifies situations when air drying thesample is necessary during sample preparation. Test MethodD 3302 specifies procedures for air drying and calculation ofpercent
34、air dry loss.7.3.1 Calculate and record air-dry loss determination eachtime air drying is performed.D20130727.3.2 In handling, reducing, and dividing the sample, alloperations shall be done rapidly and in as few operations aspossible, since moisture loss depends on several factors otherthan total mo
35、isture content, such as time required for crushing,atmospheric temperature and humidity, and type of crushingequipment.7.3.3 While awaiting preparation, the gross or dividedsample shall be protected from moisture change as a result ofexposure to rain, snow, wind, and sun on contact withabsorbent mat
36、erials.7.3.4 Whenever subsamples are stored or transported, thecontainers and subsample shall be weighed and equilibrated to(a) Reciprocating CutterFig. 1(a) shows a section of a cutter which is moved across a stream of coal. At regular intervals, the cutter movement is reversed and a sampleincremen
37、t is collected on each trip through the coal stream.(b) Rotating CutterFig. 1(b) shows two cutters attached to a hollow, rotating shaft. Each cutter is designed to extract increments from the feed and to discharge theseinto the hollow shaft. One or more cutters may be used.(c) Rotating Hopper and Sp
38、outFig. 1(c) shows the totaling hopper that receives the crushed sample and discharges it through a spout over one or more stationarycutters.(d) Rotating ConeA sampler developed by the British National Coal Board. Two slotted cones are locked together and rotated on a vertical shaft so that on eachr
39、evolution the common slot operating intercepts the falling stream of coal and collects an increment.FIG. 1 Mechanical Sample DividersD2013073the new atmosphere by air drying, and the weight loss or gainshall be used in the calculation of moisture content.7.4 Whenever a distinct change of humidity oc
40、curs duringthe course of preparation of an air-dried subsample, thesubsample shall be weighed and its moisture equilibrated withthe new atmosphere, and the loss or gain in mass shall be usedin the calculation of moisture content.8. Sieve Tests8.1 The errors of sample division are sensitive to the to
41、psize, and therefore, it is important to make a periodic sieve testof the product of the sample crusher. Sieve tests shall be madeand reported in accordance with Test Method D 4749.9. Procedure9.1 MassThe minimum allowable mass of the sample atany stage depends on the top size, the variability of th
42、econstituent sought, and the degree of precision desired (Table1).9.2 Reduction and Division (See Fig. 3 for flowchart):9.2.1 It is permissible to air dry the sample before crushing.Samples may require air drying to feed properly through thereduction and dividing equipment. Sometimes there is aninte
43、rest in determining the air-dry loss value before crushing.Air dry in accordance with Test Method D 3302.9.2.2 In the reduction and division of gross or dividedsamples for which total moisture content is to be determined,the precautions in 7.3 and 7.4 must be followed.9.2.3 Procedure AManual Rifflin
44、g:FIG. 2 Sample Divider (Riffle)TABLE 1 Preparation of Laboratory SampleCrush to pass at least 95% through sieveDivide to a minimumweight of, gAGroup A Group BNo. 4 (4.75-mm) 2000 4000No. 8 (2.36-mm) 500 1000No. 20 (850 m) 250 500No. 60 (250 m) 50 50(100 % through)AIf a moisture sample is required,
45、increase the quantity of No. 4 (4.75-mm) orNo. 8 (2.36-mm) sieve subsample by 500 g.D20130749.2.3.1 Reduce the gross or divided sample to a top size of4.75-mm (No. 4) or 2.36-mm (No. 8) sieve taking precautionsin accordance with Section 7.9.2.3.2 Determine the number of passes required in therifflin
46、g operation from the total mass of the gross sample andthe minimum permissible mass in accordance with Table 1.9.2.3.3 Divide the crushed sample by using a large riffle.Riffles properly used will reduce sample variability but cannoteliminate it. A typical enclosed riffle is shown in Fig. 2 anddescri
47、bed in 6.2.2. Pass the coal through the riffle from a feedscoop, feed bucket, or riffle pan having a lip or opening the fullwidth of the riffle. When using any of the preceding containersto feed the riffle, spread the coal evenly in the container, raisethe container, and hold it with its front edge
48、resting on top ofthe feed chute, then slowly tilt it so that the coal flows in auniform stream through the hopper straight down over theFIG. 3 Sample Preparation FlowchartD2013075center of the riffle into all the slots, then into the riffle pans, onehalf of the sample being collected in each pan. Un
49、der nocircumstances shovel the sample into the riffle or dribble intothe riffle from a small-mouthed container. Do not allow thecoal to build up in or above the riffle slots. If it does not flowfreely through the slots, shake or vibrate the riffle to facilitateeven flow.9.2.3.4 If the initial crushing was only to 4.75-mm (No. 4)sieve size, reduce to 2.36-mm (No. 8) sieve size after dividingto no less than the quantity specified in Table 1 for a 4.75-mm(No. 4) sieve size.9.2.3.5 After reducing to 2.36-mm (No. 8) sieve size, dividethe subsample by riff
