1、Designation: D 2234/D 2234M 07Standard Practice forCollection of a Gross Sample of Coal1This standard is issued under the fixed designation D 2234/D 2234M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONData obtained from coal samples are used in establishing price, controlling mine and cleaning plantoperations, allocating production
3、 costs, and determining plant or component efficiency. The task ofobtaining a sample of reasonable weight to represent an entire lot presents a number of problems andemphasizes the necessity for using standard sampling procedures.Coal is one of the most difficult of materials to sample, varying in c
4、omposition from 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.
5、This practice gives the overall requirements for the collection of coal samples. The wide varietiesof coal-handling facilities preclude the publication of detailed procedures for every sampling situation.The proper collection of the sample involves an understanding and consideration of the physicalc
6、haracter of the coal, the number and weight of increments, and the overall precision required.1. Scope1.1 This practice covers procedures for the collection of asample under various conditions of sampling. The sample is tobe crushed and further prepared for analysis in accordance withMethod D 2013.
7、However, the procedures for dividing largesamples before any crushing are given in this practice.1.2 This practice describes general and special purposesampling procedures for coals (1) by size and condition ofpreparation (for example, mechanically cleaned coal or rawcoal) and (2) by sampling charac
8、teristics.1.3 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, use eachsystem independently of the other. Combining values from thetwo systems may result in nonconformance with
9、the standard.1.4 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-bility of regulatory limitations prior to use.2.
10、 Referenced Documents2.1 ASTM Standards:2D 121 Terminology of Coal and CokeD 2013 Practice for Preparing Coal Samples for AnalysisD 6518 Practice for Bias Testing a Mechanical Coal Sam-pling SystemE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to
11、 Quality and Statistics3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 accuracy:3.1.1.1 generallya term used to indicate the reliability ofa sample, a measurement, or an observation.3.1.1.2 specificallya measure of closeness of agreementbetween an experimental result and the t
12、rue value. Example:the observed and true sulfur content of a coal consignment.This measure is affected by chance errors as well as by bias.1This practice is under the jurisdiction of ASTM Committee D05 on Coal andCoke and are the direct responsibility of Subcommittee D05.23 on Sampling.Current editi
13、on approved May 1, 2007. Published June 2007. Originallyapproved in 1963. Last previous edition approved in 2003 as D 2234 03e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio
14、n, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 activation intervalfor a falling stream or cross-beltcutter, the time from the beginning of movement for taking
15、anincrement, to the beginning of movement for taking of the nextincrement.3.1.3 mechanical sampling systema single machine orseries of interconnected machines whose purpose is to extractmechanically, or process (divide and reduce), or a combinationthereof, a sample of coal.3.1.4 cross-belt samplera
16、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.3.1.5 falling-stream samplera single sampling machine orcomponent of a mechanical sampli
17、ng system designed toextract an increment from a falling stream of coal at thedischarge end of a conveyor or chute by moving a samplingdevice (cutter) through the falling stream of material.3.1.6 gross samplea sample representing one lot of coaland composed of a number of increments on which neither
18、reduction nor division has been performed.3.1.7 incrementa small portion of the lot collected by oneoperation of a sampling device and normally combined withother increments from the lot to make a gross sample.3.1.8 probability samplea sample collected using a sam-pling process such that at each sta
19、ge of the process, a specifiednon-zero probability of being selected for the sample can beattached to every sampling unit in the lot to be sampled. Givenadequate information about the sample results obtained usingprobability sampling, the probability distribution of samplingerrors can be estimated.3
20、.1.9 samplea quantity of material taken from a largerquantity for the purpose of estimating properties or composi-tion of the larger quantity.3.1.10 size consistthe particle size distribution of a coal.4. Summary of Practice4.1 The general-purpose sampling procedures are intendedto provide, in 19 of
21、 20 cases, dry ash results that are within aninterval of 6110 of the average dry ash results that would beobtained in hypothetical repeated sampling.4.2 Special-purpose sampling procedures apply to the sam-pling of coal when other precision limits are required, or whenother constituents are used to
22、specify precision, or for perfor-mance tests.4.3 For coals of known size and condition of preparation,tables are given for the determination of the number and weightof increments required for a gross sample for both general andspecial-purpose sampling.4.4 The procedures appear in the following order
23、:Test Method SectionSampling of Coals Based on Size and Condition of Preparation 8.1General-Purpose Sampling Procedure 8.1.1Number and Weight of Increments 8.1.1.2Number of Gross Samples 8.1.1.4Special-Purpose Sampling 8.1.2Number and Weight of Increments 8.1.2.2Number of Gross Samples 8.1.2.3Divisi
24、on of the Gross Samples Before Crushing 8.2Sampling of Coal for Total Moisture Determination 8.3Types of Moisture Samples 8.3.1Entire Gross Samples 8.3.1.1Special Moisture Subsamples 8.3.1.2Other Subsamples for Moisture Testing 8.3.1.3Special Precautions 8.3.2Weight of Increments 8.3.3Number of Incr
25、ements 8.3.4Moisture Sampling Based Only on Size 8.3.4.15. Significance and Use5.1 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 ofsampling equipment, caution should be used i
26、n all stages ofsampling from system specifications and equipment procure-ment to equipment acceptance testing and actually taking thefinal sample.5.2 After further processing (Method D 2013), the samplemay be analyzed for a number of different parameters. Theseparameters may affect the lots value, i
27、ts ability to meetspecifications, its environmental impact, as well as otherproperties.6. Increment Collection Classification6.1 The type of selection, the conditions under whichindividual increments are collected, and the method of spacingof increments from the coal consignment or lot are classifie
28、daccording to the following descriptions and Table 1. Thesedesignations are to be used for sampling specifications and fordescriptions of sampling programs and sampling equipment.6.2 Types of IncrementsThe types of selection of incre-ments are based on whether or not there is human discretion inthe
29、selection of the pieces of coal or portions of the coalstream.6.2.1 Type I, in which specific pieces or portions are notsubject to selection on a discretionary basis. This includes thatin which the increment is collected in precise accord withCondition of Increment Collectionfrom the Main Body of Co
30、alTypes of IncrementType INo Human Discretion Is UsedType IIHuman Discretion Is UsedSpacing of Increments Spacing of Increments1. Systematic 2. Random 1. Systematic 2. RandomCondition A, stopped belt cut I-A-1 I-A-2 II-A-1 II-A-2Condition B, full-stream cut I-B-1 I-B-2 II-B-1 II-B-2Condition C, part
31、-stream cut I-C-1 I-C-2 II-C-1 II-C-2Condition D, stationary sampling I-D-1 I-D-2 II-D-1 II-D-2D 2234/D 2234M 072previously assigned rules on timing or location that are free ofany bias. Type I selection increments generally yield moreaccurate results.6.2.2 Type II, in which some measure of human di
32、scretion isexercised in the selection of specific pieces of coal or ofspecific portions of the stream, pile, or shipment.6.3 Conditions of Increment CollectionThe conditionsunder which individual increments are collected are the con-ditions of the main body of coal relative to the portionwithdrawn.
33、Four conditions are recognized:6.3.1 Condition A (Stopped-Belt Cut), in which a loadedconveyor belt is stopped and a full cross-section cut withparallel sides is removed from the coal stream. The distancebetween the parallel faces shall not be less than three times thenormal top size of the coal.6.3
34、.2 Condition B (Full-Stream Cut), in which a full cross-section cut is removed from a moving stream of coal.6.3.3 Condition C (Part-Stream Cut), in which a portion,not a full cross section, is removed from a moving stream ofcoal.6.3.4 Condition D (Stationary Coal Sampling), in which aportion of coal
35、 is collected from a pile, a rail car, a barge, or ashiphold.6.4 Spacing of IncrementsThe spacing of incrementspertains to the kind of intervals between increments. Twospacing methods are recognized: systematic and random.Systematic spacing is usually preferable.6.4.1 Systematic Spacing 1, in which
36、the movements ofindividual increment collection are spaced evenly in time or inposition over the lot.6.4.2 Random Spacing 2, in which the increments arespaced at random in time or in position over the lot.7. Organization and Planning of Sampling Operations7.1 This practice provides definitive proced
37、ures for thecollection of a gross sample. Parties claiming to use thispractice must adhere to the procedures as set out in thisstandard. If the sampling is not done in accordance with theprocedures set out in this practice then that sample may not besuitable for comparison with a sample collected by
38、 the proce-dures described in this practice. Since it may be impracticableor impossible to take another sample of a given lot of coal it isessential that parties agree on sampling procedures prior toundertaking sampling.7.2 Selection of Appropriate Sampling ProcedureVariations in coal-handling facil
39、ities make it impossible topublish rigid rules covering every sampling situation in com-plete and exact details. Proper sampling involves an under-standing and proper consideration of the minimum number andweight of increments, the size consist of the coal, the conditionof preparation of the coal, t
40、he variability of the constituentsought, and the degree of precision required.7.2.1 Number and Weight of IncrementsThe number andweight of increments required for a given degree of precisiondepends upon the variability of the coal. This variabilityincreases with an increase in free impurity. A coal
41、high ininherent impurity and with comparatively little free impuritymay exhibit much less variability than a coal with a lowinherent impurity and a relatively high proportion of freeimpurity. For most practical purposes, an increase in the ashcontent of a given coal usually indicates an increase inv
42、ariability. It is imperative that not less than the minimumspecified number of increments of not less than the minimumspecified weight be collected from the lot. For Condition D, theincrements shall be of equal weight.7.2.2 Increment Collection Method to Be UsedTo obtaincomplete representation of al
43、l sizes, it is most desirable that thesample increments be withdrawn from the full cross section ofthe stream. The best possible increment is a full cross-sectioncut removed from a stopped belt, Classification I-A-1 in Table1. The best possible increment from a flowing stream of coal isone obtained
44、by moving a cutter device entirely across thestream at a uniform speed, the same for each increment, intoone side of the stream and out of the other, without allowingthe receptacle to overflow (Classification I-B-1 in Table 1).Classification methods given in Table 1 are listed in order ofdecreasing
45、reliability. The highest possible classificationmethod, wherever feasible, should be used. Details of samplingprocedures should be agreed upon in advance by all partiesconcerned. Whenever circumstances dictate utilization of in-crement collection classifications “Condition C” or “ConditionD” or “Typ
46、e II,” details of sampling procedure shall be agreedupon in advance by all parties concerned.7.3 Distribution of IncrementsIt is essential that theincrements be distributed throughout the lot to be sampled.This distribution is related to the entire volume of the lot, notmerely its surface or any lin
47、ear direction through it or over it.If circumstances prevent the sampler from applying thisprinciple, the lot is sampled only in part, and the gross sampleis representative only of this part. The spacing of the incre-ments shall be varied if the possibility exists that incrementcollection may get “i
48、n phase” with the sequence of coalvariability. Example: routine sampling of commercial coalfrom a continuous stream (conveyor belt) in which incrementcollection is automatic and its sequence coincides with the“highs” or “lows” in the content of fines.7.4 Dimensions of Sampling DeviceThe opening of t
49、hesampling device shall be no less than 2.5 times the nominal topsize of the coal and no less than 30 mm 1.25 in. Thesampling device shall be of sufficient capacity to completelyretain or entirely pass the increment without spillage at themaximum rate of coal flow.7.5 Characteristics and Movement of Sampling DeviceInsampling from moving streams of coal, the sampling deviceshall be designed to collect each increment with no selectiverejection of material by size and with no contamination bynonsample material.7.5.1 Falling-Stream SamplerIn collecting an increm
