1、Designation: D1412 07D1412/D1412M 15Standard Test Method forEquilibrium Moisture of Coal at 96 to 97 Percent RelativeHumidity and 30C1This standard is issued under the fixed designation D1412;D1412/D1412M; the number immediately following the designation indicatesthe year of original adoption or, in
2、 the case of revision, the year of last revision. 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 determination of the equilibrium moisture of coal in an atm
3、osphere over a saturated solution ofpotassium sulfate at 30C.NOTE 1For information concerning the experimental work on which this test method is based, see (1-5).21.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values given inparentheses ar
4、e for information only.stated in each system may not be exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the two systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of the safety concerns, i
5、f 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 Documents2.1 ASTM Standards:3D121 Terminology of Coal and CokeD388 Classificat
6、ion of Coals by RankD2013 Practice for Preparing Coal Samples for AnalysisD2234/D2234M Practice for Collection of a Gross Sample of CoalD3172 Practice for Proximate Analysis of Coal and CokeD3173 Test Method for Moisture in the Analysis Sample of Coal and CokeD3302 Test Method for Total Moisture in
7、CoalD4596 Practice for Collection of Channel Samples of Coal in a Mine3. Significance and Use3.1 This test method affords a means of estimating the bed moisture of either coal that is wet and shows visible surface moistureor coal that may have lost some moisture. It may be used for estimating the su
8、rface, or extraneous moisture of wet coal, suchmoisture being the difference between the total moisture as determined by Test Method D3302 and the equilibrium moisture.3.2 When samples are collected in conformity with Classification D388, the equilibrium moisture is considered to be equal tobed mois
9、ture with the exception of some low rank coals that yield equilibrium moisture values below bed moisture.3.3 The results obtained by this test method are sensitive to many influences, and therefore, raw (uncorrected) equilibriummoisture data may be of limited value in and of themselves. When working
10、 with low rank coals, the results yielded by this testmethod require critical assessments. It is recommended that the procedure outlined in the Appendix X1 be applied, and the resultscorrected before use in situations where a more reliable estimation inherent or bed moisture for low rank coals is re
11、quired. TheAppendix also provides useful quality assurance information which is applicable to coals of all ranks.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
12、 Oct. 1, 2007Sept. 1, 2015. Published October 2007 September 2015. Originally approved in 1956 . Last previous edition approved in 20042007as D1412 04.D1412 07. DOI: 10.1520/D1412-07.10.1520/D1412_D1412M-15.2 The boldface numbers in parentheses refer to a list of references at the end of this standa
13、rd.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only
14、 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 possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versio
15、nof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Apparatus4.1 Water Bath or Insulated Air CabinetThe bath or cabinet shall be of sufficient size to acco
16、mmodate several vacuum-typedesiccators, and shall be provided with a temperature regulator to maintain a uniform temperature of 30.0 6 0.2C.4.2 Moisture OvenThe oven shall be so constructed as to have a uniform temperature in all parts and a minimum of air space.It may be of the type shown in the Ap
17、paratus section of Test Method D3173. Provision shall be made for renewing the air (or, ifdesired, dry oxygen-free nitrogen for subbituminous and lignitic coals) in the oven at a rate of two times per minute, with the airdried as defined in 5.1.4.3 Mechanical Vacuum Pump.4.4 Crusher, laboratory, cof
18、fee-mill type.4.5 Sieve, 203-mm (8-in.)8-in. diameter, with 1.18-mm (No. 16) openings.4.6 Shaking Machine.4.7 DesiccatorSmall vacuum-type desiccator, 160 mm in diameter (see Fig. 1).4.8 Weighing Bottles, glass, low-form, flat-bottom, cylindrical, 70 mm in diameter, with well-fitting covers.4.9 Filte
19、r Pump, aspirator.4.10 Buchner-Type Funnel, approximately 64 mm (2212 in.)in. in diameter.5. Reagents5.1 Dry airAir used to purge the drying oven should be dried to a moisture content of 1.9 mg/L or less. (Dew point of -10Cor less.) Any desiccant or drying method capable of achieving this degree of
20、dryness is suitable.5.2 DesiccantsMaterials suitable for use in the desiccator may be chosen from the following:5.2.1 Anhydrous Calcium Sulfate (0.004 mg/L).5.2.2 Silica Gel.5.2.3 Magnesium Perchlorate (0.0005 mg/L).5.2.4 Sulfuric Acid, Concentrated (0.003 mg/L).5.2.5 The desiccant must be kept fres
21、h enough to assure that the air in the desiccator is dry as defined in 5.1. Values inparentheses ( ) are literature values for the residual amount of moisture in air at equilibrium with these desiccants. (Warning:Sulfuric acid is corrosive and can cause severe damage to eyes, skin, and clothing. Mag
22、nesium perchlorate is a strong oxidant andcan react violently with organic materials.)FIG. 1 Vacuum-Type DesiccatorD1412/D1412M 1525.3 K2SO4Crystalline Potassium Sulfate6. Technical Hazards6.1 In collecting, containing, handling, reducing, and dividing the gross moisture sample, all operations must
23、be doneexpeditiously and in a manner that attempts to preserve the original sample moisture integrity.6.2 If the gross sample is too wet to allow reduction and division, spread sample in a thin layer and expose to the air of thelaboratory. Dry no more than necessary to enable satisfactory reduction
24、and division of sample.6.3 Take particular care not to overdry low rank coals, especially lignites. Drying will accelerate oxidation and can also resultin shrinkage of pore size and volume which will affect the moisture-holding capacity.7. Collection of Gross Samples7.1 Samples shall not be taken fr
25、om outcrop, weathered, or oxidized coal.7.1.1 Mine SamplesTake mine samples in accordance with Practice D4596.7.1.2 Tipple or Shipment SamplesCollect a representative gross sample of coal in accordance with Practice D2234/D2234M.If only the equilibrium moisture is desired, use the General Purpose Sa
26、mpling Procedure. If the surface moisture of wet coal isto be determined, use the procedure for sampling the special total moisture subsample described in Practice D2234/D2234M.8. Preparation of Laboratory Samples8.1 Crush the gross sample to No. 4 No. 4 (4.75-m) sieve size in accordance with Practi
27、ce D2013; however, it is importantto also observe the technical hazards stated in Section 6 of this test method.8.1.1 Divide sample in accordance with Practice D2013.8.1.2 Rapidly stage crush the divided sample to pass a No. 16 (1.18-mm) sieve by means of a coffee-mill-type crusher. Thisstage crushi
28、ng produces a minimum amount of fine material; however, it increases segregation so the crushed sample shall bethoroughly mixed.8.1.3 Divide out the equilibration moisture subsample to be used for testing.9. Procedure9.1 Place 20 to 25 g of the crushed coal into a 250-mL Erlenmeyer flask and add 100
29、 mL of recently boiled, cooled, distilledwater (Note 2). Shake the flask mechanically for 30 min, 30 min, and then place it in the constant-temperature bath for 3 h at 30C.At the end of the wetting period, remove the excess water from the coal by filtering on a Bchner-type funnel approximately 64mm
30、(2212 in.)in. in diameter, using suction supplied by a water filter pump. Use a minimum amount of water to transfer the coalto the filter. After transfer of the coal, close the funnel with a rubber stopper fitted with a glass tube through which air saturatedwith water vapor is passed to prevent dryi
31、ng of the coal. Thoroughly mix the wet coal in the funnel with a spoon and place about5.0 g in a uniform layer in a weighing bottle of known weight. Place the uncovered weighing bottle in the small vacuum-typedesiccator containing a saturated solution of K2SO4 for maintaining the relative humidity o
32、f 96 to 97 %. An excess of crystallineK2SO4 shall extend above the solution level. Evacuate the desiccator to an absolute pressure equivalent to about 30 mm Hg bymeans of a mechanical vacuum pump and then totally immerse in a constant-temperature water bath or place in an insulated aircabinet mainta
33、ined at 30 6 0.2C for 48 h for all coals higher in rank than lignite. Lignite will require 72 h to reach equilibriumfor practical purposes.NOTE 2Mine samples and certain coals that deteriorate when treated with water may be equilibrated directly without wetting, provided the samplesare collected and
34、 prepared with a minimum loss of moisture. Unwetted coals should be equilibrated for varying periods of time, in units of 24 h, in orderthat equilibrium may be attained.9.2 After equilibration of the coal, restore the pressure in the desiccator to atmospheric, with the desiccator still in the bath,
35、byslowly admitting dry air for a period of not less than 15 min.Admit the air to the inlet tube of the desiccator after passing it througha train consisting first of a bubbler containing H2SO4 (sp gr 1.84), then a capillary tube with one end drawn out to a tip havinga suitable bore for regulating th
36、e rate of air flow, and finally a coiled copper tube placed in the constant-temperature bath. Removethe desiccator from the bath and open immediately. Quickly close the weighing bottle and weigh to the nearest 0.2 mg. Uncoverthe weighing bottle, place it in the moisture oven preheated to 105C, and h
37、eat for 112 h. Then remove the weighing bottle fromthe oven, cool for 30 min, over one of the desiccants specified in 5.2, in a desiccator, and weigh.10. Calculation10.1 Calculate the percent equilibrium moisture in the analysis sample as follows:Equilibrium Moisture in Analysis Sample,%5B 2C!B2A! x
38、 100where:A = weight of weighing bottle, grams,D1412/D1412M 153B = weight of weighing bottle and wet coal, grams, andC = weight of weighing bottle and dried coal, grams.11. Report11.1 Report the equilibrium or bed moisture to the nearest 0.1 % as the percentage loss in weight of the equilibrated coa
39、l.12. Precision and Bias12.1 The precision of this test method for the determination of Equilibrium Moisture in Coal are shown in Table 1.12.1.1 Repeatability Limit (r)The value below which the absolute difference between two test results of separate andconsecutive test determinations, carried out o
40、n the same sample, in the same laboratory, by the same operator, using the sameapparatus on samples taken at random from a single quantity of homogeneous material, may be expected to occur with a probabilityof approximately 95 %.12.1.2 Reproducibility Limit (R)The value below which the absolute diff
41、erence between two test results carried out in differentlaboratories, using samples taken at random from a single quantity of material that is as homogeneous as possible, may be expectedto occur with a probability of approximately 95 %.12.2 BiasCertified standards or absolute methods are not availab
42、le for this test; therefore, bias of results cannot be determined.13. Keywords13.1 bed moisture; coal; equilibrium moisture; extraneous moisture; surface moistureAPPENDIX(Nonmandatory Information)X1. PRACTICE FOR COMPARING THE RELATIONSHIP BETWEEN INHERENT ANDEQUILIBRIUM MOISTUREX1.1 The purpose of
43、the equilibrium moisture test is to provide an estimate of the inherent (bed) moisture. However, evidence hasshown that equilibrium moisture results on many low rank coals, including most lignite coal, are often lower than inherentmoisture. The procedure described in this appendix can be used where
44、there is a question about the applicability of the equilibriummoisture result as an estimator of inherent moisture. The method is straightforward and has proven effective in many situationsfor examining this moisture relationship.X1.2 Special coal samples, collected at their inherent moisture level,
45、 are analyzed for both total (inherent) and equilibriummoisture. The results are then compared to see if differences exist between the two moisture parameters, and the end user(s) canthen determine whether such differences have any practical significance. This procedure does not directly yield inher
46、ent moisturevalues for an entire coal seam or mine, because the samples are not necessarily representative of the full seam as would be thecase for face channel samples (Practice D4596). Nevertheless, the procedure does provide a tool for evaluating the relationshipbetween inherent and equilibrium m
47、oisture for a given area. See (6)X1.3 The most critical step in evaluating this relationship is the collection of samples containing their full complement of inherentmoisture. Occasionally, it may be difficult to obtain a channel sample that contains no surface moisture. Also, obtaining a channelsam
48、ple from thick coal seams, such as those in the Western United States, is generally impractical, especially from a safetystandpoint. However, the collection of fresh, unfractured pieces of coal without visible surface moisture is usually feasible. Suchsamples are considered to contain only inherent
49、moisture (Terminology D121, Classification D388).NOTE X1.1The collection of coal at its inherent moisture levels requires some degree of judgement, and the sampler should have the necessaryTABLE 1 Concentrations Range and Limits for Repeatability andReproducibility of Equilibrium Moisture in CoalRepeatability ReproducibilityRange, Limit, Limit,% r RUnder 5 0.3 0.55 to 15 0.5 1.0Over 15 1.0 1.5D1412/D1412M 154experience. For increased confidence, multiple comparisons are recommended to define the variability of the data.X1.4 Characteristics a
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