1、Designation: D3302/D3302M 10Standard 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 andCoke3. Terminology3.1 DefinitionsFor additional definitions of terms used inthis test method, refer to Terminology D121.3.2 Definitions of Terms Specific to This Standard:3.2.1 air dryin
12、ga 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 air-drying operation.3.2.3 easily oxidized co
13、alslow-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 or 0.05 %/12 h.1This test method is under the jurisdiction of ASTM Committe
14、e D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.21 on Methods ofAnalysis.Current edition approved Jan. 1, 2010. Published January 2010. Originallyapproved in 1974. Last previous edition approved in 2009 as D3302/D3302M09.DOI: 10.1520/D3302_D3302M-10.2For referenced ASTM st
15、andards, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken
16、, PA 19428-2959, United States.3.2.5 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 of a coalsample in an air atmosphere under rigidly controlled
17、 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 division andreduction. No air drying is necessary if the sample
18、 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 uponthis method. The crushed and divided moisture sample is airdried to equilibrate it with the atmosphere in which
19、 furtherdivision and reduction are to occur.4.2.3 Residual moisture determination is made in a heatedforced-air circulation oven under rigidly defined conditions.FIG. 1 Total Moisture Determination on Gross Sample, Special Moisture Subsample, or on Crushed and Divided SampleD3302/D3302M 1024.3 Total
20、 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 the total moisture in coal. The standard is avail-able to pro
21、ducers, 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 designated asthe method for total moisture for routine commercial pr
22、actice.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 approach those established foroven drying as much as possible.6.2 Air
23、-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 temperature is above 40C 104F, inwhich case ambient temperature shall
24、 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 Pans for Gross Sample, noncorroding, weight-stableat temperature
25、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 75 mm 2 to 3 in. high.6.3.2 Pans for Crushed and Divided Sample
26、, noncorroding,weight-stable at temperature used, of sufficient size so that thesample can be spread to a depth of not more than 25 mm 1.0in. with sides not more than 38 mm 1.5 in. high.6.4 Scale (Gross Sample)a scale of at least 45-kg 100-lbs capacity and sensitive to 23 g 0.05 lbs in 45 kg 100 lbs
27、.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 airtight, friction top or screw top sealed with arubber gasket and p
28、ressure-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-m (No. 60)sieve by 0 sample)This oven is described in Test Met
29、hodD3173 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. Precautions7.1 In collecting, handling, reducing, and dividing the g
30、rossmoisture 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 humidity,and type of crushing equipment.7.2 While awaiting pr
31、eparation, the uncrushed gross mois-ture sample shall be sealed in appropriate containers in orderthat it be protected from moisture change as a result ofexposure to ambient air, rain, snow, wind, and sun, or contactwith absorbent materials.7.3 If the gross sample requires air drying, then the initi
32、alweight 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 change of humidity occurs duringthe course of preparation of an air-dried sample, the subsampl
33、eshould be weighed and equilibrated with the new atmosphereand the weight loss or gain used in the calculation of totalmoisture content.FIG. 2 Air-Drying OvenD3302/D3302M 1037.5 Whenever subsamples are stored or transported andmoisture condenses on the container, then the container andsubsample shal
34、l 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 should not be prolonged pastthe time necessary to bring t
35、he 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 case shall the air drying bedone at a temperature over 40C
36、. 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 pulverizingsamples from atmospheric changes affecting surface moisture
37、or 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 system, recycling filtered air; (2)hood over dust-produci
38、ng 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 enough to process sample quickly and (2) allowing timefor pul
39、verizer to come to room temperature before reuse.8. Sampling8.1 The principles, terms, organization, and collection as setforth in Practice D2234/D2234M shall apply to the collectionof the total moisture sample. Particular attention is directed toSection 8. The increments as established in Table 2 o
40、f PracticeD2234/D2234M for mechanically cleaned coal are deemedadequate for general purpose sampling for total moisture.9. Procedure9.1 Air-Drying Loss on Gross SampleReferee Method:9.1.1 Procedure A, Drying FloorThis procedure is par-ticularly applicable if the gross moisture sample is too large an
41、amount to ship reasonably or is too wet to handle or shipwithout loss of moisture.9.1.1.1 Weigh and record the weight of the gross moisturesample. Spread the sample on the drying floor to a depth of notmore than twice the top size of the coal. Mix or stir the coalfrom time to time, being careful not
42、 to lose any of the coalparticles. Continue the air drying and mixing until the surfaceof the sample appears dry. Weigh the entire sample andredistribute over the floor for additional drying. Continue thedrying and stirring, weighing at 1- to 2-h intervals until theweight loss of the total sample be
43、comes no more than 0.1 %/h(Note 1). Record the weight of the air dry sample.Avoid excessdrying.NOTE 1If the sample surface appears dry, and the time required forreduction and division is well established, air drying can be stopped whenthe weight loss is less than 0.1 % per twice the required time fo
44、rprocessing. Example: If reduction and division of the sample is expectedto require 20 min, the air-drying procedure can be stopped when the rateof moisture loss is less than 0.1 %/40 min. If this procedure is used, asecond air drying is required to establish the 0.1 %/h rate before the finalprepara
45、tion of the laboratory sample.9.1.1.2 Proceed with sample reduction and division inaccordance with Practice D2013, Section 9.2.3 or 9.2.4,observing precautions of Practice D2013, Section 7. Useenclosed equipment where possible to minimize moisturechange.9.1.2 Procedure B, Air Drying Oven:9.1.2.1 Dis
46、tribute the gross moisture sample over the re-quired number of tared pans. Weigh each pan with sample as itis filled from the gross sample. Place in an air-drying oven thathas been adjusted to maintain temperature no more than 10C18F above ambient temperature for easily oxidized coals orno more than
47、 15C 27F above ambient temperature for othercoals (oven temperature not to exceed 40C). Ambient air maybe used with no heating. Maintain air circulation through theoven at a rate of one to four air exchanges per minute, but inno case should it be sufficiently high to blow fine particles fromthe pans
48、. Gently stir the sample from time to time to ensureuniform drying throughout the sample. Continue drying withintermittent stirring until the coal surfaces appear to be dry.Remove from oven, weigh, and record the weight. Return thepans with sample to the oven and continue the operation.Calculate the
49、 percent weight loss. Repeat the drying andweighing process at 1- to 2-h intervals until the weight loss isless than 0.1 %/h (Note 1). Allow the sample to reach equilib-rium with ambient temperature and humidity before the finalair dry weight is recorded. Avoid excess drying.9.1.2.2 Proceed with sample reduction and division inaccordance with Practice D2013, Section 9.2.3 or 9.2.4,observing precautions of Practice D2013, Section 7. Useenclosed equipment where possible to minimize moisturechange.9.2 Air-Drying Loss on Crush
