1、Designation: D 3302/D 3302M 09Standard Test Method forTotal Moisture in Coal1This standard is issued under the fixed designation D 3302/D 3302M; 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
2、 parentheses 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 sample
3、d. It 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 an
4、d decomposition 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 o
5、ther 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,
6、this 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 complet
7、e standard 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 MethodsD 2961 and D 3173 for other moisture methods.1.4 The values stated in either SI units
8、 or inch-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
9、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. Referenced Documents2.1 ASTM Standards:
10、2D 121 Terminology of Coal and CokeD 388 Classification of Coals by RankD 2013 Practice for Preparing Coal Samples for AnalysisD 2234/D 2234M Practice for Collection of a Gross Sampleof CoalD 2961 Test Method for Single-Stage Total Moisture Lessthan 15 % in Coal Reduced to 2.36-mm (No. 8 Sieve)Topsi
11、zeD 3173 Test Method for Moisture in theAnalysis Sample ofCoal and CokeD 5865 Test Method for Gross Calorific Value of Coal andCoke3. Terminology3.1 DefinitionsFor additional definitions of terms used inthis test method, refer to Terminology D 121.3.2 Definitions of Terms Specific to This Standard:3
12、.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 air-drying operation.3.2.3 easi
13、ly 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 or 0.05 %/12 h.3.2.5 residual moisturethat moisture remaining
14、 in thesample after air drying.3.2.6 total moisturesee Terminology D 121.1This test method 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 May 1, 2009. Published July 2009. Original
15、ly approvedin 1974. Last previous edition approved in 2007 as D 330207a1.2For 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 A
16、STM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 conditionsof temperat
17、ure, 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 is already atequilibr
18、ium 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 furtherdivision and r
19、eduction are to occur.4.2.3 Residual moisture determination is made in a heatedforced-air circulation oven under rigidly defined conditions.4.3 Total moisture is calculated from loss (or gains) in airdrying and the residual moisture.FIG. 1 Total Moisture Determination on Gross Sample, Special Moistu
20、re Subsample, or on Crushed and Divided SampleD 3302/D 3302M 0925. 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 producers, sellers, and
21、 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 practice.6. Apparatus6
22、.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-Drying OvenA device
23、 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 be used. In the cas
24、e 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 used, of sufficient
25、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, noncorroding,weigh
26、t-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.6.5 Balance (Crushe
27、d 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 pressure-sensitive ta
28、pe 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 MethodD 3173 and can be
29、 of the form illustrated in Fig. 1 in TestMethod D 3173.6.8 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 MethodD 3173.7. Precautions7.1 In collecting, handling, reducing, and dividing the grossmoisture sampl
30、e, 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 preparation, the unc
31、rushed 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 initialweight of the or
32、iginal 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 subsampleshould be weighed
33、 and equilibrated with the new atmosphereand the weight loss or gain used in the calculation of totalmoisture content.FIG. 2 Air-Drying OvenD 3302/D 3302M 0937.5 Whenever subsamples are stored or transported andmoisture condenses on the container, then the container andsubsample shall be weighed, eq
34、uilibrated 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 the sample to equ
35、ilibrium 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. Air drying of
36、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 moistureor otherwise aff
37、ecting 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-producing equipment to
38、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 pulverizer to come
39、to room temperature before reuse.8. Sampling8.1 The principles, terms, organization, and collection as setforth in Practice D 2234/D 2234M shall apply to the collectionof the total moisture sample. Particular attention is directed toSection 8. The increments as established in Table 2 of PracticeD 22
40、34/D 2234M 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 anamount to sh
41、ip 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 to lose any
42、 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 becomes no mor
43、e 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 forprocessing.
44、 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 finalpreparation of the
45、laboratory sample.9.1.1.2 Proceed with sample reduction and division inaccordance with Practice D 2013, Section 9.2.3 or 9.2.4,observing precautions of Practice D 2013, Section 7. Useenclosed equipment where possible to minimize moisturechange.9.1.2 Procedure B, Air Drying Oven:9.1.2.1 Distribute th
46、e 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 15C 27F a
47、bove 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. Gently s
48、tir 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 percent w
49、eight 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 D 2013, Section 9.2.3 or 9.2.4,observing precautions of Practice D 2013, Section 7. Useenclosed equipment where possible to minimize moisturechange.9.2 Air-Drying Loss on Crushed and
