1、Designation: D3302/D3302M 12D3302/D3302M 15Standard 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.
2、A number in 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 total moisture in coal as it exists at the site, at the time, and under theconditions
3、it is sampled. It is applicable to coals as mined, processed, shipped, or used in normal commercial pursuits. It is notapplicable to coal-water slurries, sludges, or pulverized products under 0.5-mm-diameter sieve size. It is applicable to coals of allranks within the recognized limitations imposed
4、by oxidation and decomposition characteristics of lower rank coals. Because ofits empirical nature, strict adherence to basic principles and permissive procedures are required for valid results (see Appendix X1).This complete standard is available to producers, sellers, and consumers as a total mois
5、ture method when other procedures ormodifications are not mutually agreed on.1.2 Since coal can vary from extremely wet (water-saturated) to completely dry, special emphasis must be placed on thesampling, sample preparation, and the moisture determination itself to ensure total reliability of measur
6、ement. Therefore, thisstandard entails collection of the gross sample, sample preparation, and the method of determination.1.3 While it is recognized that such a standard may be unwieldy for routine usage in commercial operations, it can provide acommon base for agreement in cases of dispute or arbi
7、tration. The complete standard is referred to as the referee method.Embodied in the standard is the commercial method starting with the crushed and divided sample when the gross sample is nottoo wet to crush and divide. See Test Methods D2961 and D3173 for other moisture methods.1.4 The values state
8、d in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.5
9、This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documen
10、ts2.1 ASTM Standards:2D121 Terminology of Coal and CokeD388 Classification of Coals by RankD2013 Practice for Preparing Coal Samples for AnalysisD2234/D2234M Practice for Collection of a Gross Sample of CoalD2961 Test Method for Single-Stage Total Moisture Less than 15 % in Coal Reduced to 2.36-mm (
11、No. 8 Sieve) TopsizeD3173 Test Method for Moisture in the Analysis Sample of Coal and CokeD5865 Test Method for Gross Calorific Value of Coal and CokeD7430 Practice for Mechanical Sampling of Coal3. Terminology3.1 DefinitionsFor additional definitions of terms used in this test method, refer to Term
12、inology D121.3.2 Definitions of Terms Specific to This Standard:1 This test method is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.21 on Methods of Analysis.Current edition approved April 1, 2012Jan. 1, 2015. Published June 2012Ja
13、nuary 2015. Originally approved in 1974. Last previous edition approved in 20102012 asD3302/D3302M10.12. DOI: 10.1520/D3302_D3302M-12.10.1520/D3302_D3302M-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of AS
14、TM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically p
15、ossible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
16、 West Conshohocken, PA 19428-2959. United States13.2.1 air dryinga process of partial drying of a coal sample to bring it to near equilibrium with the atmosphere in the roomin which further reduction/division of the sample is to take place.3.2.2 air-dry lossthe loss in weight, expressed as a percent
17、, resulting from each air-drying operation.3.2.3 easily oxidized coalslow-rank coals such as subbituminous or lignitic coals.3.2.4 equilibriumcondition reached in air drying when the change in weight of the sample, under conditions of ambienttemperature and humidity, is no more than 0.1 %h or 0.05 %
18、12 h.3.2.5 residual moisturethat moisture remaining in the sample after air drying.3.2.6 total moisturesee Terminology D121.4. Summary of Test Method (See Fig. 1)FIG. 1 Total Moisture Determination on Gross Sample, Special Moisture Subsample, or on Crushed and Divided SampleD3302/D3302M 1524.1 This
19、test method is based on the loss in weight of a coal sample 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 of dispute or arbitration. The gross moisture sample is air dried to equilibr
20、ateit with the atmosphere at each stage of division and reduction. No air drying is necessary if the sample is already at equilibriumwith the atmosphere as indicated by stable weight.4.2.2 Commercial Method, which may be used in routine commercial practice or when the concerned parties agree upon th
21、ismethod. The crushed and divided moisture sample is air dried to equilibrate it with the atmosphere in which further division andreduction are to occur.4.2.3 Residual moisture determination is made in a heated forced-air circulation oven under rigidly defined conditions.4.3 Total moisture is calcul
22、ated from loss (or gains) in air drying and the residual moisture.5. Significance and Use5.1 The collection and treatment of the sample as specified for the referee method is intended for the express purpose ofdetermining the total moisture in coal. The standard is available to producers, sellers, a
23、nd consumers as a method of determinationwhen other techniques or modifications are not mutually agreed upon.5.2 The commercial method, which determines total moisture content of the crushed and divided sample, is designated as themethod for total moisture for routine commercial practice.6. Apparatu
24、s6.1 Drying FloorA smooth clean floor area in a room free of contamination by dust or other material and that permits aircirculation without excessive heat or air currents. Conditions for an air-drying floor should approach those established for ovendrying as much as possible.6.2 Air-Drying OvenA de
25、vice for passing slightly heated air over the sample. The oven should be capable of maintaining atemperature of 10 to 15C (18 to 27F above ambient temperature with a maximum oven temperature of 40C 104F unlessambient temperature is above 40C 104F, in which case ambient temperature shall be used. In
26、the case of easily oxidized coals,the temperature should not be more than 10C 18F above ambient temperature. Air changes shall be at the rate of one to fourper minute. A typical oven is shown in Fig. 2.6.3 Drying Pans:6.3.1 Pans for Gross Sample, noncorroding, weight-stable at temperature used, of s
27、ufficient size so that the sample can be spreadto a depth of not more than twice the diameter of the largest particles if larger than 13 mm 0.5 in. or not more than 25-mm1.0-in. depth for smaller coal, with pan sides about 50 to 75 mm 2 to 3 in. high.6.3.2 Pans for Crushed and Divided Sample, noncor
28、roding, weight-stable at temperature used, of sufficient size so that thesample can be spread to a depth of not more than 25 mm 1.0 in. with sides not more than 38 mm 1.5 in. high.6.4 Scale (Gross Sample)a scale of at least 45-kg 100-lbs capacity and sensitive to 23 g 0.05 lbs in 45 kg 100 lbs.6.5 B
29、alance (Crushed Sample), sensitive to 0.1 g with a capacity sufficient to weigh pan, sample, and container.6.6 Laboratory Sample Containersheavy vapor-impervious bags, properly sealed, or noncorroding cans such as those with anairtight, friction top or screw top sealed with a rubber gasket and press
30、ure-sensitive tape for use in storage and transport of thelaboratory sample. Glass containers, sealed with rubber gaskets, can be used, but care must be taken to avoid 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 Meth
31、od D3173and can be of the form illustrated in Fig. 1 in Test Method D3173.6.8 Analytical Balance, sensitive to 0.1 mg (for residual moisture 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
32、gross any moisture sample, all operations shall be done rapidly and inas few operations as possible, since moisture loss depends on several factors other than total moisture content, such as timerequired for crushing, atmospheric temperature and humidity, and type of crushing equipment.7.2 While awa
33、iting preparation, the uncrushed gross moisture sample shall be sealed in appropriate containers in order that itbe protected from moisture change as a result of exposure to ambient air, rain, snow, wind, and sun, or contact with absorbentmaterials.7.3 If the gross sample requires air drying, then t
34、he initial weight of the original gross moisture sample and container shall berecorded, and the moisture loss or gain of sample and containers shall be determined before the sample is reduced.D3302/D3302M 1537.4 Whenever a distinct change of humidity occurs during the course of preparation of an air
35、-dried sample, the subsampleshould be weighed and equilibrated with the new atmosphere and the weight loss or gain used in the calculation of total moisturecontent.7.5 Whenever subsamples are stored or transported and moisture condenses on the container, then the container and subsampleshall be weig
36、hed, equilibrated to the new atmosphere by air drying, and the weight loss or gain shall be used in the calculationof total moisture content.7.6 Since most coals have a tendency to oxidize on exposure to air, the air-drying procedure should not be prolonged past thetime necessary to bring the sample
37、 to equilibrium with the temperature and humidity of the air in the room in which furtherreduction and division are to be made. Easily oxidized coals must not be air dried at a temperature exceeding 10C above ambienttemperature. In no case shall the air drying be done at a temperature over 40C. Air
38、drying of low-rank coals should not exceed18 h because of oxidation. In the case of lignite, the goal of reaching equilibrium should be weighed against the possibility ofoxidation.7.7 Protect crushed, divided, pulverized, or pulverizing samples from atmospheric changes affecting surface moisture oro
39、therwise affecting sample integrity.7.7.1 Procedures useful in maintaining uniform temperature and humidity conditions and minimum airflow in moisturedetermination and sample preparation area include the following: (1) closed dust control system, recycling filtered air; (2) hoodover dust-producing e
40、quipment to minimize airflow required to remove dust; and (3) pulling makeup air from within the buildingto replace exhausted air or using tempered or conditioned makeup air.7.7.2 Avoid heatup of pulverizer by: (1) using pulverizer large enough to process sample quickly and (2) allowing time forpulv
41、erizer to come to room temperature before reuse.FIG. 2 Air-Drying OvenD3302/D3302M 1548. Sampling8.1 The principles, terms, organization, and collection as set forth in Practice D2234/D2234M and Practice D7430 shall applyto the collection of the total moisture sample. Particular attention is directe
42、d to Section 8 of Practice D2234/D2234M and Section7 of Practice D7430. The increments as established in Table 2 of Practice D2234/D2234M or Table 1 of Practice D7430 formechanically cleaned coal are deemed adequate for general purpose sampling for total moisture.8.2 Sampling of Coal for Total Moist
43、ure Determinations:8.2.1 Types of Moisture SamplesMoisture determinations as specified in the method to be used are to be made on the followingkinds of samples.8.2.1.1 Entire Gross SampleFor referee tests, air dry the entire gross sample and measure the weight loss from the entire grosssample during
44、 this drying. This procedure can be carried out on the entire gross sample as a single batch or on groups of primaryincrements or as separate operations on the individual primary increments; obtain, by one of these means, the total weight loss fromthe entire gross sample. After this air drying, the
45、sample can be crushed or divided, or both, as required by the referee test formoisture.8.2.1.2 Special Moisture SubsampleFor moisture testing, a special subsample can be taken from a gross sample before anyoperations of air drying or crushing. Take this subsample from the gross sample in accordance
46、with the requirements of 8.2 ofPractice D2234/D2234M or 8.2 of Practice D7430.8.2.1.3 Other Subsamples for Moisture TestingFor moisture testing, a subsample can be used that is collected after the initialcrushing and dividing of a gross sample. The procedures for the crushing and dividing, and for t
47、his subsequent subsampling formoisture, are given in Practice D2013.8.2.2 Special PrecautionsCollect samples and subsamples for moisture in such a manner that there is no unmeasured loss ofmoisture of significant amount. Make adequate weighings before and after drying or other operations to measure
48、all significantweight losses.8.2.3 Weight of IncrementsThe minimum weight of each increment must be that which is sufficient as to be free of bias. Thisdepends on the top size of the coal in the stream being sampled, the dimensions of the collection device, and other factors of thewithdrawal of the
49、increment. Since much of the moisture tends to be distributed uniformly across the surface, moisture bias ispresent when the size consist of the sample is not the same as the size consist of the lot sampled. In addition, when there is noknowledge of the sampling characteristics for moisture, each increment shall not weigh less than the values in Table 2 of PracticeD2234/D2234M or Table 1 of Practice D7430.8.2.4 Number of IncrementsThe number of increments required for a given degree of precision depends on the weight of
