1、Designation: D7430 18D7430 18aStandard 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 parent
2、heses indicates 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, an
3、d determining plant or component efficiency.The task of obtaining a sample of reasonable mass 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 f
4、rom noncombus-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 practic
5、e gives 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 mech
6、anical coal 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 andmass of increm
7、ents, and the overall precision required.1. Scope1.1 This practice is divided into four parts: A, B, C, and D. These four parts represent the previous standards D7256/D7256M,D4916, D4702, and D6518. These four standards are the four that govern the mechanical sampling of coal and have been combinedi
8、nto one document for the ease of reference of the 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 32.1.6 This standard does
9、 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, health, and environmental practices and determine the applicability ofregulatory limitations prior to use. For specific hazard st
10、atements, see Sections 7, 11.2.2, 21, 1.4, and 38.1.1.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby
11、 the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD2013/D2013M Practice for Preparing Coal Samples for Analysis1 This practice is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is t
12、he direct responsibility of Subcommittee D05.23 on Sampling.Current edition approved March 1, 2018April 15, 2018. Published May 2018. Originally approved in 2008. Last previous edition approved in 20172018 asD7430 17.D7430 18. DOI: 10.1520/D7430-18.10.1520/D7430-18A.2 For referencedASTM standards, v
13、isit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM stan
14、dard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by AST
15、M is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D2234/D2234M Practice for Collection of a Gross Sample of CoalD3302 Test Method for Total Moisture in CoalD4621 Guide for Quality Management i
16、n an Organization That Samples or Tests Coal and Coke (Withdrawn 2010)3D4702 Practice for Quality Management of Mechanical Coal Sampling Systems (Withdrawn 2008)3D4749 Test Method for Performing the Sieve Analysis of Coal and Designating Coal SizeD4916 Practice for Mechanical Auger Sampling (Withdra
17、wn 2008)3D6518 Practice for Bias Testing a Mechanical Coal Sampling System (Withdrawn 2008)3D7256/D7256M Practice for Mechanical Collection and Within-System Preparation of a Gross Sample of Coal from MovingStreams (Withdrawn 2008)3E105 Practice for Probability Sampling of MaterialsE122 Practice for
18、 Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study to Det
19、ermine the Precision of a Test Method3. Terminology3.1 DefinitionsDefinitions applicable to this practice are listed in Terminology D121.3.2 Definitions of Terms Specific to This Standard:3.2.1 accuracy, n(1) generally, a term used to indicate the reliability of a sample, a measurement, or an observ
20、ation;(2) specifically, a measure of closeness of agreement between an experimental result and the true value. An example is theobserved and true sulfur content of a coal consignment. This measurement is affected by chance errors as well as by bias.3.2.2 activation interval, nfor a falling-stream or
21、 cross-belt cutter, the time from the beginning of movement for taking anincrement, to the beginning of movement for taking of the next increment.3.2.3 auger increment, nthe retained portion of one extraction operation of the auger.3.2.4 auger sampler, na mechanical device that extracts a columnar s
22、ample of coal from a railcar, truck, barge, or stockpileand any associated sub-system or within-system components.3.2.5 bias, nthe difference between the population mean of the mechanical sampler test results and the accepted referencevalue.3.2.6 confidence interval, na numeric interval with a lower
23、 limit and a higher limit within which the true parameter value isestimated to fall. The confidence interval percentage indicates the percentage of time the true value will fall within the interval ifthe procedure is continuously repeated.3.2.7 consignment, na discrete amount of coal, such as a ship
24、ment, a car load, a unit train, or a days production. Aconsignment may include more than one lot of coal and may correspond to a specific period of time, such as a sampling periodor a billing period.3.2.8 correlation, na measure of the linear dependence between paired system and reference measuremen
25、ts. Correlationfrequently is expressed by the correlation coefficient, which can take a value from minus one (perfect negative linear relationship)to plus one (perfect positive linear relationship).3.2.9 cross-belt sampler, na single sampling machine or component of a mechanical sampling system desi
26、gned to extract anincrement directly from a conveyor belt surface by sweeping a sampling device (cutter) through the material on the conveyor.3.2.10 delimitation error, na material error that occurs when all the elements in a cross section of a coal stream do not havean equal probability of being in
27、tercepted (captured) by the sampler cutter during increment collection.3.2.11 ellipsoidal region, nan area that is formed by plane sections of ellipses that are defined by the values selected for thelargest tolerable bias of each coal characteristic used in the bias test. The region will be used to
28、determine if the system is biased.3.2.12 falling-stream sampler, na single sampling machine or component of a mechanical sampling system designed to extractan increment from a falling stream of coal at the discharge end of a conveyor or chute by moving a sampling device (cutter) throughthe falling s
29、tream of material.3.2.13 Hotellings T 2 test, na statistical test that is used to evaluate multivariate data. It is the multivariate equivalent of theStudents t-test.3.2.14 largest tolerable bias (LTB), nan interval whose upper and lower bounds represent the limits of an acceptable bias.3.2.15 mecha
30、nical sampling system, na single machine or series of interconnected machines whose purpose is to extractmechanically, or process (divide and reduce), or a combination thereof, a sample of coal.3 The last approved version of this historical standard is referenced on www.astm.org.D7430 18a23.2.16 pai
31、red data set, nsystem and reference values observed on samples collected and compared from the same batch ofmaterial.3.2.17 precision, na term used to indicate the capability of a person, an instrument, or a method to obtain reproducible results;specifically, a measure of the chance error as express
32、ed by the variance, standard error, or a multiple of the standard error (seePractice E177).3.2.18 reference sample, na sample used in testing of a mechanical sampling system which is comprised of one or moreincrements collected from the test batch or lot of coal by the stopped belt method as describ
33、ed in Practice D2234/D2234M.3.2.19 reject stream, nthe coal flow within a mechanical sampling system, which occurs at each stage of division, before andafter reduction, and is not included in the system sample.3.2.20 sampling ratio, nthe mass of the system sample divided by the mass of the correspon
34、ding coal sampled.3.2.21 save stream, nthe coal flow within a mechanical sampling system which occurs at each stage of division, before andafter reduction, and after the final stage of division becomes the system sample.3.2.22 statistical independence, ntwo sample values are statistically independen
35、t if the occurrence of either one in no wayaffects the probability assigned to the occurrence of the other.3.2.23 surrogate sample, na sample, used in the evaluation of a mechanical sampling system, which is comprised of one ormore increments collected from a coal stream within the mechanical sampli
36、ng system in accordance with Practice D2234/D2234M,Conditions “A” or “B.” Such a sample may be considered acceptable for evaluation of a mechanical sampling systemscomponents, excluding the primary cutter, when demonstrated to be equivalent to the reference sample.3.2.24 system sample, na sample col
37、lected from a test batch or lot of coal by the final stage of a mechanical sampling system.3.2.25 unbiased sample (representative sample), na sample free of bias.3.2.26 Walsh averages, ngiven a series of observations (differences) x1, x2, . xn, the n (n + 1)/2 pair-wise averages givenby:xi1xj!/2,1#i
38、#j#n (1)3.2.26.1 DiscussionAs an example of Walsh averages, assume one has three observations (differences) designated as x1, x2, and x3. There are thena total of 3(4)/2 = 6 Walsh averages. They are as follows: x1, x2, x3, (x1 + x2)/2, (x1 + x3)/2, and (x2 + x3)/2.3.2.27 Wilcoxon Signed Rank Test, n
39、a non-parametric statistical procedure for calculating the point estimate and confidenceinterval for a sample drawn from a population with symmetric distribution.3.2.28 within-system preparation, nthe process of gross sample preparation carried out mechanically by sequential crushing(reduction) equi
40、pment and/or division equipment. It may be carried out by processing increments individually or by batchingincrements together and processing them together as a group. In any case, within-system preparation is conducted in a manner tominimize moisture changes and without removing the gross sample or
41、 its increments from the sampling system.D7430 18a3PART A MECHANICAL COLLECTION AND WITHIN-SYSTEM PREPARATION OF A GROSS SAMPLE OFCOAL FROM MOVING STREAMSOld Practice D7256/D7256M4. Scope4.1 Part AMechanical Collection and Within-System Preparation of a Gross Sample of Coal from Moving StreamsCovers
42、procedures for the mechanical collection of a sample under Classification I-B-1 and I-B-2 (Practice D2234/D2234M) and thewithin-system preparation (reduction and division) of gross samples utilizing various components of the mechanical samplingsystem.4.1.1 Part A describes mechanical sampling proced
43、ures for coals (1) by size and condition of preparation (for example,mechanically cleaned coal or raw coal), and (2) by sampling characteristics.4.1.2 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
44、equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.5. Summary of Practices5.1 The general-purpose sampling procedures are intended to provide, in 19 of 20 cases, dry ash results that are w
45、ithin aninterval of 6110 of the average dry ash results that would be obtained in hypothetical repeated sampling.5.2 Special-purpose sampling procedures apply to the sampling of coal when other precision limits are required, or when otherconstituents are used to specify precision, or for performance
46、 tests.5.3 For coals of known size and condition of preparation, a table (Table 1) is given for the determination of the number andmass of increments required for a gross sample for both general- and special-purpose sampling.5.4 The only processes of sample division and reduction covered in this doc
47、ument are the use of mechanical sample dividersfor the division of the sample, and mechanical crushing equipment for the reduction of the sample, both of which are within-systemcomponents of the mechanical sampling system.5.5 The procedures appear in the following order:Test Method SectionSampling o
48、f Coals Based on Size and Conditionof Preparation10.1General-Purpose Sampling Procedure 10.1.1Number and Mass of Increments 10.1.1.2Number of Gross Samples 10.1.1.4Special-Purpose Sampling 10.1.2Number and Mass of Increments 10.1.2.2Number of Gross Samples 10.1.2.3Division of the Gross Sample Before
49、 Crushing 10.2Reduction and Division 10.3TABLE 1 Number and Mass of Increments for General-PurposeSampling ProcedureATop Size 16 mm58 in.50 mm2 in.150 mm6 in.BMechanically Cleaned CoalCMinimum number ofincrements15 15 15Minimum mass ofincrements, kg lb1 2 3 6 7 15Raw (Uncleaned Coal)CMinimum number ofincrements35 35 35Minimum mass ofincrements, kg lb1 2 3 6 7 15A Conditions C and D are not addressed in this standard.B For coals above 150-mm 6-in. top size, the sampling procedure should bemutually agreed upon in
