1、Designation: D7430 16bStandard 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 in
2、dicates 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 determ
3、ining 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 no
4、ncombus-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 give
5、s 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
6、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 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 fo
8、r 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 32.1.6 This standard does not purport to addr
9、ess 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, 39.1.6, 2
10、1, 1.4, and 38.1.1.2. 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 CoalD3302 Test Method for Total Moisture in CoalD4621 Guide for Quality Management in an
11、 OrganizationThat Samples or Tests Coal and Coke (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)3
12、D6518 Practice for Bias Testing a Mechanical Coal Sam-pling System (Withdrawn 2008)3D7256/D7256M Practice for Mechanical Collection and1This 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 ap
13、proved Sept. 15, 2016. Published October 2016. Originallyapproved in 2008. Last previous edition approved in 2016 as D743016a. DOI:10.1520/D7430-16B.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStanda
14、rds 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 States1Within-System
15、Preparation of a Gross Sample of Coalfrom Moving Streams (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
16、 and Bias inASTM Test MethodsE456 Terminology Relating 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
17、Specific to This Standard:3.2.1 accuracy, n(1) generally, 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
18、a coal consignment. Thismeasurement is affected by chance 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 incremen
19、t, nthe retained portion of one ex-traction operation of 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 mea
20、nof the mechanical sampler test results and the acceptedreference 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 wil
21、l fall withinthe interval if the procedure is continuously 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 samplingp
22、eriod or a billing period.3.2.8 correlation, na measure 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 posit
23、ive linear relationship).3.2.9 cross-belt sampler, na single 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 mate
24、rial error that occurswhen all the elements in a cross 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 val
25、ues selected forthe largest tolerable bias of each coal 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 fall
26、ing stream of coal at thedischarge end of a conveyor or 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 tol
27、erable bias (LTB), nan interval whoseupper and lower bounds 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
28、 coal.3.2.16 paired data set, nsystem and reference valuesobserved 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 er
29、ror as expressedby the variance, standard error, or a multiple 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
30、 as described in Practice D2234/D2234M.3.2.19 reject stream, 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
31、corresponding coal sampled.3.2.21 save stream, nthe coal 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 inde
32、pendent if the occurrence of either one in noway affects 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 s
33、ampling system in accordance with PracticeD2234/D2234M, Conditions “A” or “B.” Such a sample mayD7430 16b2be considered acceptable for evaluation of a mechanicalsampling systems components, excluding the primary cutter,when demonstrated to be equivalent to the reference sample.3.2.24 system sample,
34、na sample collected from a testbatch or lot of coal by the 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:xi1
35、xj!/2, 1#i#j#n (1)3.2.26.1 DiscussionAs an example of Walsh 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,
36、 na non-parametricstatistical procedure for calculating 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) equip
37、ment and/or division equipment. Itmay be carried out by 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
38、 increments from the sampling system.D7430 16b3PART 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-SystemPreparation of a Gross Sample of Coal from Moving StreamsCovers proc
39、edures for the mechanical collection of a sampleunder Classification 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
40、forcoals (1) by size and condition of preparation (for example,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 equivale
41、nts; therefore, eachsystem shall be used independently of 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 anint
42、erval of 6110 of the average dry ash results that would beobtained 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
43、 For coals of known size and condition of preparation, atable (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 t
44、he use of mechanical sampledividers for the division of the 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 Bas
45、ed on Size and Conditionof Preparation10.1General-Purpose 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 Crushi
46、ng 10.2Reduction and Division 10.36. Significance and Use6.1 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
47、all stages of the sample collection process, the designof 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 di
48、fferent parameters. These param-eters may define the lots 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
49、user of this standard to establish appro-priate safety and 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 w
