1、Designation: D3302/D3302M 17Standard Test Method forTotal Moisture in Coal1This standard is issued under the fixed designation D3302/D3302M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revision. A number in par
2、entheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the totalmoisture in coal as it exists at the site, at the time, and underthe conditions it is sampled. I
3、t is applicable to coals as mined,processed, shipped, or used in normal commercial pursuits. Itis not applicable to coal-water slurries, sludges, or pulverizedproducts under 0.5-mm-diameter sieve size. It is applicable tocoals of all ranks within the recognized limitations imposed byoxidation and de
4、composition characteristics of lower rankcoals. Because of its empirical nature, strict adherence to basicprinciples and permissive procedures are required for validresults (see Appendix X1). This complete standard is availableto producers, sellers, and consumers as a total moisture methodwhen other
5、 procedures or modifications are not mutuallyagreed on.1.2 Since coal can vary from extremely wet (water-saturated) to completely dry, special emphasis must be placedon the sampling, sample preparation, and the moisture deter-mination itself to ensure total reliability of measurement.Therefore, this
6、 standard entails collection of the gross sample,sample preparation, and the method of determination.1.3 While it is recognized that such a standard may beunwieldy for routine usage in commercial operations, it canprovide a common base for agreement in cases of dispute orarbitration. The complete st
7、andard is referred to as the refereemethod. Embodied in the standard is the commercial methodstarting with the crushed and divided sample when the grosssample is not too wet to crush and divide. See Test MethodsD2961 and D3173 for other moisture methods.1.4 The values stated in either SI units or in
8、ch-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 the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purpor
9、t 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. Referenced Documents2.1 ASTM Standards:2D121
10、Terminology of Coal and CokeD388 Classification of Coals by RankD2013 Practice for Preparing Coal Samples for AnalysisD2234/D2234M Practice for Collection of a Gross Sampleof CoalD2961 Test Method for Single-Stage Total Moisture Lessthan 15 % in Coal Reduced to 2.36-mm (No. 8 Sieve)TopsizeD3173 Test
11、 Method for Moisture in the Analysis Sample ofCoal and CokeD5865 Test Method for Gross Calorific Value of Coal andCokeD7430 Practice for Mechanical Sampling of Coal3. Terminology3.1 DefinitionsFor additional definitions of terms used inthis test method, refer to Terminology D121.3.2 Definitions of T
12、erms Specific to This Standard:3.2.1 air dryinga process of partial drying of a coalsample to bring it to near equilibrium with the atmosphere inthe room in which further reduction/division of the sample is totake place.3.2.2 air-dry lossthe loss in weight, expressed as apercent, resulting from each
13、 air-drying operation.3.2.3 easily oxidized coalslow-rank coals such as subbi-tuminous or lignitic coals.3.2.4 equilibriumcondition reached in air drying when thechange in weight of the sample, under conditions of ambienttemperature and humidity, is no more than 0.1 % h or0.05 % 12 h.1This test meth
14、od is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.21 on Methods ofAnalysis.Current edition approved Feb. 1, 2017. Published February 2017. Originallyapproved in 1974. Last previous edition approved in 2015 as D3302/D3302M15.DOI: 1
15、0.1520/D3302_D3302M-17.2For referenced ASTM standards, visit 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.Copyright ASTM International, 100 Barr
16、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recomme
17、ndations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.5 residual moisturethat moisture remaining in thesample after air drying.3.2.6 total moisturesee Terminology D121.4. Summary of Test Method (See Fig. 1)4.1 This test method is based on the loss in weight
18、 of a coalsample in an air atmosphere under rigidly controlled conditionsof temperature, time, and airflow.4.2 Alternative Methods:4.2.1 Referee Method, which may be used in cases ofdispute or arbitration. The gross moisture sample is air dried toequilibrate it with the atmosphere at each stage of d
19、ivision andreduction. No air drying is necessary if the sample is already atequilibrium with the atmosphere as indicated by stable weight.4.2.2 Commercial Method, which may be used in routinecommercial practice or when the concerned parties agree uponFIG. 1 Total Moisture Determination on Gross Samp
20、le, Special Moisture Subsample, or on Crushed and Divided SampleD3302/D3302M 172this method. The crushed and divided moisture sample is airdried to equilibrate it with the atmosphere in which furtherdivision and reduction are to occur.4.2.3 Residual moisture determination is made in a heatedforced-a
21、ir circulation oven under rigidly defined conditions.4.3 Total moisture is calculated from loss (or gains) in airdrying and the residual moisture.5. Significance and Use5.1 The collection and treatment of the sample as specifiedfor the referee method is intended for the express purpose ofdetermining
22、 the total moisture in coal. The standard is avail-able to producers, sellers, and consumers as a method ofdetermination when other techniques or modifications are notmutually agreed upon.5.2 The commercial method, which determines total mois-ture content of the crushed and divided sample, is design
23、ated asthe method for total moisture for routine commercial practice.6. Apparatus6.1 Drying FloorA smooth clean floor area in a room freeof contamination by dust or other material and that permits aircirculation without excessive heat or air currents. Conditionsfor an air-drying floor should approac
24、h those established foroven drying as much as possible.6.2 Air-Drying OvenA device for passing slightly heatedair over the sample. The oven should be capable of maintaininga temperature of 10 to 15C (18 to 27F above ambienttemperature with a maximum oven temperature of 40C104F unless ambient tempera
25、ture is above 40C 104F, inwhich case ambient temperature shall be used. In the case ofeasily oxidized coals, the temperature should not be more than10C 18F above ambient temperature. Air changes shall beat the rate of one to four per minute. A typical oven is shownin Fig. 2.6.3 Drying Pans:6.3.1 Pan
26、s for Gross Sample, noncorroding, weight-stableat temperature used, of sufficient size so that the sample can bespread to a depth of not more than twice the diameter of thelargest particles if larger than 13 mm 0.5 in. or not more than25-mm 1.0-in. depth for smaller coal, with pan sides about 50to 7
27、5 mm 2 to 3 in. high.6.3.2 Pans for Crushed and Divided Sample, noncorroding,weight-stable at temperature used, of sufficient size so that thesample can be spread to a depth of not more than 25 mm1.0 in. with sides not more than 38 mm 1.5 in. high.6.4 Scale (Gross Sample)a scale of at least 45-kg 10
28、0-lbs capacity and sensitive to 23 g 0.05 lbs in 45 kg 100 lbs.6.5 Balance (Crushed Sample), sensitive to 0.1 g with acapacity sufficient to weigh pan, sample, and container.6.6 Laboratory Sample Containersheavy vapor-impervious bags, properly sealed, or noncorroding cans such asthose with an airtig
29、ht, friction top or screw top sealed with arubber gasket and pressure-sensitive tape for use in storage andtransport of the laboratory sample. Glass containers, sealedwith rubber gaskets, can be used, but care must be taken toavoid breakage in transport.6.7 Drying Oven (for residual moisture on 250-
30、m (No. 60)sieve by 0 sample)This oven is described in Test MethodD3173 and can be of the form illustrated in Fig. 1 in TestMethod D3173.6.8 Analytical Balance, sensitive to 0.1 mg (for residualmoisture on 250-m (No. 60) by 0 sample).6.9 Capsules, with covers, described in Test Method D3173.7. Precau
31、tions7.1 In collecting, handling, reducing, and dividing anymoisture sample, all operations shall be done rapidly and in asfew operations as possible, since moisture loss depends onseveral factors other than total moisture content, such as timerequired for crushing, atmospheric temperature and humid
32、ity,and type of crushing equipment.7.2 While awaiting preparation, the uncrushed gross mois-ture sample shall be sealed in appropriate containers in orderthat it be protected from moisture change as a result ofFIG. 2 Air-Drying OvenD3302/D3302M 173exposure to ambient air, rain, snow, wind, and sun,
33、or contactwith absorbent materials.7.3 If the gross sample requires air drying, then the initialweight of the original gross moisture sample and containershall be recorded, and the moisture loss or gain of sample andcontainers shall be determined before the sample is reduced.7.4 Whenever a distinct
34、change of humidity occurs duringthe course of preparation of an air-dried sample, the subsampleshould be weighed and equilibrated with the new atmosphereand the weight loss or gain used in the calculation of totalmoisture content.7.5 Whenever subsamples are stored or transported andmoisture condense
35、s on the container, then the container andsubsample shall be weighed, equilibrated to the new atmo-sphere by air drying, and the weight loss or gain shall be usedin the calculation of total moisture content.7.6 Since most coals have a tendency to oxidize on exposureto air, the air-drying procedure s
36、hould not be prolonged pastthe time necessary to bring the sample to equilibrium with thetemperature and humidity of the air in the room in whichfurther reduction and division are to be made. Easily oxidizedcoals must not be air dried at a temperature exceeding 10Cabove ambient temperature. In no ca
37、se shall the air drying bedone at a temperature over 40C. Air drying of low-rank coalsshould not exceed 18 h because of oxidation. In the case oflignite, the goal of reaching equilibrium should be weighedagainst the possibility of oxidation.7.7 Protect crushed, divided, pulverized, or pulverizingsam
38、ples from atmospheric changes affecting surface moistureor otherwise affecting sample integrity.7.7.1 Procedures useful in maintaining uniform temperatureand humidity conditions and minimum airflow in moisturedetermination and sample preparation area include the follow-ing: (1) closed dust control s
39、ystem, recycling filtered air; (2)hood over dust-producing equipment to minimize airflowrequired to remove dust; and (3) pulling makeup air fromwithin the building to replace exhausted air or using temperedor conditioned makeup air.7.7.2 Avoid heatup of pulverizer by: (1) using pulverizerlarge enoug
40、h to process sample quickly and (2) allowing timefor pulverizer to come to room temperature before reuse.8. Sampling8.1 The principles, terms, organization, and collection as setforth in Practice D2234/D2234M and Practice D7430 shallapply to the collection of the total moisture sample. Particularatt
41、ention is directed to Section 8 of Practice D2234/D2234Mand Section 7 of Practice D7430. The increments as establishedin Table 2 of Practice D2234/D2234M or Table 1 of PracticeD7430 for mechanically cleaned coal are deemed adequate forgeneral purpose sampling for total moisture.8.2 Sampling of Coal
42、for Total Moisture Determinations:8.2.1 Types of Moisture SamplesMoisture determinationsas specified in the method to be used are to be made on thefollowing kinds of samples.8.2.1.1 Entire Gross SampleFor referee tests, air dry theentire gross sample and measure the weight loss from the entiregross
43、sample during this drying. This procedure can be carriedout on the entire gross sample as a single batch or on groups ofprimary increments or as separate operations on the individualprimary increments; obtain, by one of these means, the totalweight loss from the entire gross sample. After this air d
44、rying,the sample can be crushed or divided, or both, as required bythe referee test for moisture.8.2.1.2 Special Moisture SubsampleFor moisture testing,a special subsample can be taken from a gross sample beforeany operations of air drying or crushing. Take this subsamplefrom the gross sample in acc
45、ordance with the requirements of8.2 of Practice D2234/D2234M or 8.2 of Practice D7430.8.2.1.3 Other Subsamples for Moisture TestingFor mois-ture testing, a subsample can be used that is collected after theinitial crushing and dividing of a gross sample. The proceduresfor the crushing and dividing, a
46、nd for this subsequent subsam-pling for moisture, are given in Practice D2013.8.2.2 Special PrecautionsCollect samples and subsamplesfor moisture in such a manner that there is no unmeasured lossof moisture of significant amount. Make adequate weighingsbefore and after drying or other operations to
47、measure allsignificant weight losses.8.2.3 Weight of IncrementsThe minimum weight of eachincrement must be that which is sufficient as to be free of bias.This depends on the top size of the coal in the stream beingsampled, the dimensions of the collection device, and otherfactors of the withdrawal o
48、f the increment. Since much of themoisture tends to be distributed uniformly across the surface,moisture bias is present when the size consist of the sample isnot the same as the size consist of the lot sampled. In addition,when there is no knowledge of the sampling characteristics formoisture, each
49、 increment shall not weigh less than the values inTable 2 of Practice D2234/D2234M or Table 1 of PracticeD7430.8.2.4 Number of IncrementsThe number of incrementsrequired for a given degree of precision depends on the weightof the increments, the distribution of the moisture, and the totalamount of moisture. The distribution of moisture, however, isnot easily evaluated independent of total moisture;consequently, the combined effects can be measured by deter-mining the sampling characteristics for moisture.8.2.4.
