1、Designation: D7430 16Standard Practice forMechanical Sampling of Coal1This standard is issued under the fixed designation D7430; 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 parentheses ind
2、icates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONAnalysis data obtained from coal samples are used in establishing price, controlling mine andcleaning plant operations, allocating production costs, and determi
3、ning plant or component efficiency.The task of obtaining a sample of reasonable weight to represent an entire lot presents a number ofproblems and emphasizes the necessity for using standard sampling procedures.Coal is one of the most difficult of materials to sample, varying in composition from non
4、combus-tible particles to those which can be burned completely, with all gradations in between. The task isfurther complicated by the use of the analytical results, the sampling equipment available, the quantityto be represented by the sample, and the degree of precision required.This practice gives
5、 the overall requirements for the collection and within-system preparation of coalsamples through the use of mechanical sampling systems utilizing falling stream, cross belt and augerdesigns. This practice also gives the overall requirements for the bias testing and quality managementof mechanical c
6、oal sampling systems. The wide varieties of coal-handling facilities preclude thepublication of detailed procedures for every sampling situation. The proper collection of the sampleinvolves an understanding and consideration of the physical character of the coal, the number andweight of increments,
7、and the overall precision required.1. Scope1.1 This practice is divided into 4 parts A, B, C, and D.These 4 parts represent the previous standards D7256/D7256M, D4916, D4702, and D6518. These 4 standards arethe 4 that govern the mechanical sampling of coal and havebeen combined into one document for
8、 the ease of reference ofthe users of these standards.1.2 The scope of Part A can be found in Section 4.1.3 The scope of Part B can be found in Section 13.1.4 The scope of Part C can be found in Section 19.1.5 The scope of Part D can be found in Section 31.1.6 This standard does not purport to addre
9、ss 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 prior to use. For specific hazardstatements, see Sections 7, 16, 21, 34
10、, and 37.1.1.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD2013/D2013M Practice for Preparing Coal Samples forAnalysisD2234/D2234M Practice for Collection of a Gross Sampleof CoalD4621 Guide for Quality Management in an OrganizationThat Samples or Tests Coal and Coke (
11、Withdrawn 2010)3D4702 Practice for Quality Management of MechanicalCoal Sampling Systems (Withdrawn 2008)3D4749 Test Method for Performing the Sieve Analysis ofCoal and Designating Coal SizeD4916 Practice for MechanicalAuger Sampling (Withdrawn2008)3D6518 Practice for Bias Testing a Mechanical Coal
12、Sam-pling System (Withdrawn 2008)3D7256/D7256M Practice for Mechanical Collection andWithin-System Preparation of a Gross Sample of Coal1This 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 a
13、pproved June 1, 2016. Published July 2016. Originally approvedin 2008. Last previous edition approved in 2015 as D743015b. DOI: 10.1520/D7430-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
14、volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1from Moving Stream
15、s (Withdrawn 2008)3E105 Practice for Probability Sampling of MaterialsE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating
16、to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsDefinitions applicable to this practice arelisted in Terminology D121.3.2 Definitions of Terms Specific to This Standard:3.2.1 accuracy, n(1) generall
17、y, a term used to indicate thereliability of a sample, a measurement, or an observation; (2)specifically, a measure of closeness of agreement between anexperimental result and the true value. An example is theobserved and true sulfur content of a coal consignment. Thismeasurement is affected by chan
18、ce errors as well as by bias.3.2.2 activation interval, nfor a falling-stream or cross-belt cutter, the time from the beginning of movement for takingan increment, to the beginning of movement for taking of thenext increment.3.2.3 auger increment, nthe retained portion of one ex-traction operation o
19、f the auger.3.2.4 auger sampler, na mechanical device that extracts acolumnar sample of coal from a railcar, truck, barge orstockpile and any associated sub-system or within-systemcomponents.3.2.5 bias, nthe difference between the population meanof the mechanical sampler test results and the accepte
20、dreference value.3.2.6 confidence interval, na numeric interval with alower limit and a higher limit within which the true parametervalue is estimated to fall. The confidence interval percentageindicates the percentage of time the true value will fall withinthe interval if the procedure is continuou
21、sly repeated.3.2.7 consignment, na discrete amount of coal, such as ashipment, a car load, a unit train, or a days production. Aconsignment may include more than one lot of coal and maycorrespond to a specific period of time, such as a samplingperiod or a billing period.3.2.8 correlation, na measure
22、 of the linear dependencebetween paired system and reference measurements. Correla-tion frequently is expressed by the correlation coefficient,which can take a value from minus one (perfect negative linearrelationship) to plus one (perfect positive linear relationship).3.2.9 cross-belt sampler, na s
23、ingle sampling machine orcomponent of a mechanical sampling system designed toextract an increment directly from a conveyor belt surface bysweeping a sampling device (cutter) through the material onthe conveyor.3.2.10 delimitation error, na material error that occurswhen all the elements in a cross
24、section of a coal stream do nothave an equal probability of being intercepted (captured) by thesampler cutter during increment collection.3.2.11 ellipsoidal region, nan area that is formed by planesections of ellipses that are defined by the values selected forthe largest tolerable bias of each coal
25、 characteristic used in thebias test. The region will be used to determine if the system isbiased.3.2.12 falling-stream sampler, na single sampling ma-chine or component of a mechanical sampling system designedto extract an increment from a falling stream of coal at thedischarge end of a conveyor or
26、 chute by moving a samplingdevice (cutter) through the falling stream of material.3.2.13 Hotellings T2test, na statistical test that is used toevaluate multivariate data. It is the multivariate equivalent ofthe Students t-test.3.2.14 largest tolerable bias (LTB), nan interval whoseupper and lower bo
27、unds represent the limits of an acceptablebias.3.2.15 mechanical sampling system, na single machine orseries of interconnected machines whose purpose is to extractmechanically, or process (divide and reduce), or a combinationthereof, a sample of coal.3.2.16 paired data set, nsystem and reference val
28、uesobserved on samples collected and compared from the samebatch of material.3.2.17 precision, na term used to indicate the capability ofa person, an instrument, or a method to obtain reproducibleresults; specifically, a measure of the chance error as expressedby the variance, standard error, or a m
29、ultiple of the standarderror (see Practice E177).3.2.18 reference sample, na sample used in testing of amechanical sampling system which is comprised of one ormore increments collected from the test batch or lot of coal bythe stopped belt method as described in Practice D2234/D2234M.3.2.19 reject st
30、ream, nthe coal flow within a mechanicalsampling system, which occurs at each stage of division, beforeand after reduction, and is not included in the system sample.3.2.20 sampling ratio, nthe mass of the system sampledivided by the mass of the corresponding coal sampled.3.2.21 save stream, nthe coa
31、l flow within a mechanicalsampling system which occurs at each stage of division, beforeand after reduction, and after the final stage of divisionbecomes the system sample.3.2.22 statistical independence, ntwo sample values arestatistically independent if the occurrence of either one in noway affect
32、s the probability assigned to the occurrence of theother.3.2.23 surrogate sample, na sample, used in the evalua-tion of a mechanical sampling system, which is comprised ofone or more increments collected from a coal stream within themechanical sampling system in accordance with PracticeD2234/D2234M,
33、 Conditions “A” or “B.” Such a sample maybe considered acceptable for evaluation of a mechanicalD7430 162sampling systems components, excluding the primary cutter,when demonstrated to be equivalent to the reference sample.3.2.24 system sample, na sample collected from a testbatch or lot of coal by t
34、he final stage of a mechanical samplingsystem.3.2.25 unbiased sample (representative sample), nasample free of bias.3.2.26 Walsh averages, ngiven a series of observations(differences) x1, x2, . xn, the n (n + 1)/2 pair-wise averagesgiven by:xi1xj!/2, 1#i#j#n (1)3.2.26.1 DiscussionAs an example of Wa
35、lsh averages,assume one has three observations (differences) designated asx1, x2, and x3. There are then a total of 3(4)/2 = 6 Walshaverages. They are as follows: x1, x2, x3, (x1+x2)/2, (x1+x3)/2, and (x2+x3)/2.3.2.27 Wilcoxon Signed Rank Test, na non-parametricstatistical procedure for calculating
36、the point estimate andconfidence interval for a sample drawn from a population withsymmetric distribution.3.2.28 within-system preparation, nthe process of grosssample preparation carried out mechanically by sequentialcrushing (reduction) equipment and/or division equipment. Itmay be carried out by
37、processing increments individually or bybatching increments together and processing them together asa group. In any case, within-system preparation is conducted ina manner to minimize moisture changes and without removingthe gross sample or its increments from the sampling system.D7430 163PART A MEC
38、HANICAL COLLECTION AND WITHIN-SYSTEM PREPARATION OF A GROSS SAMPLE OFCOAL FROM MOVING STREAMSOld Practice D7256/D7256M4. Scope4.1 Part AMechanical Collection and Within-SystemPreparation of a Gross Sample of Coal from Moving StreamsCovers procedures for the mechanical collection of a sampleunder Cla
39、ssification I-B-1 and I-B-2 (Practice D2234/D2234M) and the within-system preparation (reduction anddivision) of gross samples utilizing various components of themechanical sampling system.4.1.1 Part A describes mechanical sampling procedures forcoals (1) by size and condition of preparation (for ex
40、ample,mechanically cleaned coal or raw coal), and (2) by samplingcharacteristics.4.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of
41、 the other. Combiningvalues from the two systems may result in non-conformancewith the standard.5. Summary of Practices5.1 The general-purpose sampling procedures are intendedto provide, in 19 of 20 cases, dry ash results that are within aninterval of 6110 of the average dry ash results that would b
42、eobtained in hypothetical repeated sampling.5.2 Special-purpose sampling procedures apply to the sam-pling of coal when other precision limits are required, or whenother constituents are used to specify precision, or for perfor-mance tests.5.3 For coals of known size and condition of preparation, at
43、able (Table 1) is given for the determination of the number andweight of increments required for a gross sample for bothgeneral- and special-purpose sampling.5.4 The only processes of sample division and reductioncovered in this document are the use of mechanical sampledividers for the division of t
44、he sample, and mechanicalcrushing equipment for the reduction of the sample, both ofwhich are within-system components of the mechanical sam-pling system.5.5 The procedures appear in the following order:Test Method SectionSampling of Coals Based on Size and Conditionof Preparation10.1General-Purpose
45、 Sampling Procedure 10.1.1Number and Weight of Increments 10.1.1.2Number of Gross Samples 10.1.1.4Special-Purpose Sampling 10.1.2Number and Weight of Increments 10.1.2.2Number of Gross Samples 10.1.2.3Division of the Gross Sample Before Crushing 10.2Reduction and Division 10.36. Significance and Use
46、6.1 It is intended that this practice be used to provide asample representative of the coal from which it is collected.Because of the variability of coal and the wide variety ofmechanical sampling equipment available, caution should beused in all stages of the sample collection process, the designof
47、 sampling system specifications, the equipment procurementand the acceptance testing of installed equipment.6.2 After removal from the sampling system and furtherpreparation (Practice D2013/D2013M), the sample may beanalyzed for a number of different parameters. These param-eters may define the lots
48、 value, its ability to meetspecifications, its environmental impact, as well as otherproperties.7. Hazards7.1 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 an
49、d health practices and determine the applica-bility of regulatory limitations prior to use.7.2 WarningThe operation, inspection, maintenance, andcleaning of mechanical sampling equipment involves hazard-ous operations, conditions, and equipment that may result inserious bodily harm or death. These hazards include, but arenot limited to, intermittent operation, remote startup, powerfulelectrical or hydraulic drives, moving conveyors, crushers, etc.7.3 It is essential that personnel wear all required personalprotective equipment. Personnel
