1、Designation: D 2492 02 (Reapproved 2007)Standard Test Method forForms of Sulfur in Coal1This standard is issued under the fixed designation D 2492; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method applies to the determination of sulfatesul
3、fur and pyritic sulfur in coal and calculates organic sulfur bydifference. This test method is not applicable to coke or othercarbonaceous materials. Monosulfides (pyrites and FeS2aredisulfides) of iron and elements such as cadmium, lead,vanadium, and zinc can be present in coal. In the range of 0 t
4、o100 ppm, these monosulfides do not contribute significantly tothe total inorganic sulfide content.1.2 The values stated in SI units are to be regarded asstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the
5、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:2D 1193 Specification for Reagent WaterD 2013 Practice for Preparing Coal Samples for AnalysisD 3173 Test Meth
6、od for Moisture in theAnalysis Sample ofCoal and CokeD 3177 Test Methods for Total Sulfur in the AnalysisSample of Coal and CokeD 3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD 4239 Test Methods for Sulfur in the Analysis Sample ofCoal and Coke Using High-
7、Temperature Tube FurnaceCombustion MethodsE 832 Specification for Laboratory Filter Papers3. Summary of Test Method3.1 Sulfate Sulfur:3.1.1 Sulfate sulfur is extracted from the analysis samplewith dilute hydrochloric acid. The sulfate sulfur in the extractis determined gravimetrically. Sulfates are
8、soluble in hydro-chloric acid, but pyritic and organic sulfur are not.3.2 Pyritic Sulfur:3.2.1 Pyritic sulfur is calculated as a stoichiometric combi-nation with iron.3.2.2 Methods:3.2.2.1 Referee Method, which can be used in cases ofdispute or arbitration. The iron combined in the pyritic state ise
9、xtracted with dilute nitric acid from the coal residue remain-ing after sulfate extraction (see Note 1). The iron is determinedby atomic absorption techniques (see Note 2).NOTE 1The sulfate extraction step also removes hydrochloric acidsoluble iron (nonpyritic iron) from the test specimen. A test sp
10、ecimenseparate from that used for the sulfate extraction could be used for thenitric acid extraction of iron. In this case, both nonpyritic and pyritic ironare extracted from the test specimen. Since there is evidence that for somecoals the extraction of nonpyritic iron by nitric acids falls short o
11、f theamount extracted by hydrochloric acid,3,4the use of a separate testspecimen for the nitric acid extraction of iron with subsequent correctionfor the contribution of nonpyritic iron is not included in this test method.NOTE 2Round-robin testing of the coal samples used to generate datafor the pre
12、cision statement in this test method indicates that plasmaemission techniques give results equivalent to those from atomic absorp-tion analysis for the determination of iron. However, emission analysis ishighly susceptible to interferences from other analytes that may bedissolved during the extracti
13、on of iron. Selection of a wavelength that isfree from interferences and linear over the range of iron anticipated foremission analysis can require a detailed compositional analysis of the coalmineral matter, thus limiting the practicality of this approach.3.2.2.2 Alternative Method, which can be us
14、ed in routinepractice or when the concerned parties agree on this testmethod. The iron originally combined in the pyritic state canbe extracted with dilute hydrochloric acid from the ashobtained by incinerating the coal residue remaining aftersulfate extraction. The iron is determined by atomic abso
15、rptiontechniques (see Note 2).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, 2007. Published May 2007. Originallyapproved in 1966. Last previous edition ap
16、proved in 2002 as D 2492 02.2For 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.3Edwards, A. H., Daybell, G. N.,
17、and Pringle, W. J. S., “An Investigation intoMethods for the Determination of Forms of Sulfur in Coal,” Fuel, Vol 37, 1958, pp.4759.4Burns, M. S., “Determination of Pyritic Sulfur in Australian Coals,” Fuel,Vol49, 1970, pp. 12633.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
18、t Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 This test method provides for a separation of coal-associated sulfur into two commonly recognized forms: pyriticand sulfate. Organic sulfur is calculated by difference. Resultsobtained by the test method are used to serve a numb
19、er ofinterests, including the evaluation of coal preparation andprocessing operations designed to reduce coal sulfur levels.5. Analysis Sample5.1 The analysis sample is that sample which has beenpulverized to pass No. 60 (250-m) sieve as prepared inaccordance with Test Method D 2013. Moisture shall
20、bedetermined in accordance with Test Method D 3173 to permitcalculations to other than as-analyzed bases.6. Sulfate Sulfur6.1 Apparatus:6.1.1 Balance, sensitive to 0.1 mg.6.1.2 Crucibles, porcelain, platinum, alundum, or silica of10- to 25-mL capacity for ignition of barium sulfate (BaSO4).6.1.3 Hot
21、 Plate, electric or gas-heated with capability fortemperature control.6.1.4 Muffle Furnace, electrically heated and capable ofregulating the temperature at 800 6 25C for igniting BaSO4.6.2 Reagents and Materials:6.2.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherw
22、ise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided that the reagent is of sufficiently high purity topermit its use wit
23、hout lessening the accuracy of the determi-nation.6.2.2 Purity of WaterUnless otherwise indicated, refer-ences to water shall be understood to mean reagent waterconforming to Specification D 1193, Type III.6.2.3 Ammonium Hydroxide (14.9N, sp. gr. 0.90)concentrated aqueous ammonia.6.2.4 Ammonium Hydr
24、oxide Solution 1.5N, (1 + 10)Mixone volume of concentrated aqueous ammonia with ten vol-umes of water.6.2.5 Barium Chloride Solution (100 g/L)Dissolve 100 gof barium chloride (BaCl22H2O) in water and dilute to 1 L.6.2.6 Bromine Water (saturated)Add an excess of bro-mine to 1 L of water. (WarningStor
25、e in a dark bottle andkeep in a hood.) (Solubility, 42 g/L.)6.2.7 Ethanol, reagent grade, denatured.6.2.8 Filter PaperUnless otherwise indicated, referencesto filter paper shall be understood to mean filter paperconforming to Specification E 832.6.2.9 Hydrochloric Acid, 12N (sp. gr. 1.19)Concentrate
26、daqueous hydrochloric acid (HCl).6.2.10 Hydrochloric Acid, 4.8N (2 + 3)Mix two volumesof concentrated aqueous hydrochloric acid (HCl, sp. gr. 1.19)with three volumes of water.6.2.11 Methyl Orange Indicator Solution, (0.02 g/100mL)Dissolve 0.02 g of methyl orange in 100 mL of hotwater.6.2.12 Silver N
27、itrate Solution, (0.43 g/100 mL)Dissolve0.43 g of silver nitrate in 100 mL of water. Store in an amberglass bottle.6.3 Procedure:6.3.1 ExtractionWeigh to the nearest 1 mg a 2- to 5-g testspecimen of analysis sample (see Note 3) and transfer to a250-mL Erlenmeyer flask or beaker.Add 50-mL HCl (2 + 3)
28、 insmall increments while stirring to wet the coal thoroughly. Afew drops of ethanol added to the coal facilitates the wettingprocess. Place on a hotplate and boil gently for12 h. Carefullyfilter the contents into a 400-mL beaker, using a Type II, ClassF filter paper. Wash the filter paper and conte
29、nts with sufficientsmall water washings to ensure the transfer of all HCl extractto the beaker. Save the filter paper with extracted residue forsubsequent extraction of pyrites.NOTE 3It is practical to limit the sample weight to 2 g when the totalsulfur level is 2 % or above, to avoid handling an ex
30、cessive amount of ironin the pyritic extraction.6.3.2 Add 5 mL of bromine water to the extract and boil forat least 5 min to oxidize iron and expel excess bromide. Coolto room temperature.6.3.3 Precipitate the iron by slowly adding aqueous ammo-nium hydroxide (sp. gr. 0.90) until a slight excess is
31、present asmeasured by pH indicator paper.Add 5 mL more with constantstirring to coagulate the ferric hydroxide. Filter on a Type II,Class E filter paper into a 400-mL or larger beaker. Wash thefilter paper several times with hot ammoniacal solution (6.2.4).6.3.4 PrecipitationAdd two or three drops o
32、f methylorange solution and neutralize the filtrate (6.3.3) by cautiouslyadding aqueous HCl (sp. gr. 1.19) until the solution turns pink.Add 1 mL in excess. Heat to boiling and, while stirring slowly,add 10 mL of BaCl2solution. Continue boiling gently for 10 to15 min and allow to stand overnight at
33、room temperature or for4 h between 70 and 100C covered with a watch glass. Filterthrough a Type II, Class G filter paper and wash withintermittent small washings of hot water until one drop ofsilver nitrate solution produces no more than a slight opales-cence when added to 8 to 10 mL of the filtrate
34、.6.3.5 Sulfate BlankPrepare a sulfate blank following thesame procedure and using the same amounts of all reagents asdescribed in 6.3.1-6.3.4. Save the filter paper from 6.3.1 of theblank test for the pyritic iron blank in 7.3.3.6.3.6 DeterminationPreignite crucibles (6.1.2)at800625C for 30 min. Coo
35、l in a desiccator and weigh to the nearest0.1 mg. Place the specimen filter paper from 6.3.4 and theblank filter paper from 6.3.5 in separate preignited crucibles.Fold the filter papers over loosely to allow free access of air.Smoke the paper off gradually to prevent spattering.At no timeallow to bu
36、rn with flame. After the filter paper is practicallyconsumed, raise the temperature to 800 6 25C and maintainfor 1 h. Cool the crucibles in a desiccator until equilibrium isreached. Weigh the crucibles and contents to the nearest 0.15Reagent Chemicals, American Chemical Society Specifications , Amer
37、icanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USP
38、C), Rockville,MD.D 2492 02 (2007)2mg. Ignition is considered to be complete when the weight ofthe crucible and contents do not change by more than 0.2 mgafter reheating at 800 6 25C for 30 min.6.4 Calculation:6.4.1 Calculate the percentage of sulfate sulfur as follows:Sulfate sulfur % 5 $S 2 Cs! 2 B
39、 2 CB!# 3 13.735%/W (1)where:S = weight of sample crucible plus ignited BaSO4pre-cipitate, g,Cs= weight of sample crucible, g,B = weight of blank crucible plus ignited sulfate blank, g,CB= weight of blank crucible, g, andW = weight of test specimen used (6.3.1), g.METHODS FOR PYRITIC SULFUR7. Refere
40、e MethodUsing Coal Residue RemainingAfter Sulfate Extraction7.1 Apparatus:7.1.1 Atomic Absorption Spectrophotometer.7.1.2 Balance, see 6.1.1.7.1.3 Hot Plate, see 6.1.3.7.2 Reagents and Materials:7.2.1 Purity of Reagents, see 6.2.1.7.2.2 Purity of Water, see 6.2.2.7.2.3 Filter Paper, see 6.2.8.7.2.4
41、Hydrochloric Acid, 12N (sp. gr. 1.19)see 6.2.9.7.2.5 Hydrochloric Acid, 4.8N (2 + 3)see 6.2.10.7.2.6 Hydrochloric Acid, 0.24N, (1 + 49)Mix 1 volume ofconcentrated aqueous hydrochloric acid (HCl, sp. gr. 1.19) with49 volumes of water.7.2.7 Iron Standard, (400 ppm)Weigh 0.4000 g 6 0.1 mgof clean, pure
42、 iron wire or 0.5179 g 6 0.1 mg of high purityiron (III) oxide into a 250-mL beaker. Add 50 mL of HCl(7.2.5) and cover with a watch glass. Heat until the solutionboils gently for12 h or until no visible particles are left.Quantitatively transfer the contents to a 1000-mL volumetricflask and dilute t
43、o the mark with water. Alternatively, anappropriate commercially available iron standard with anequivalent acid concentration may be used.7.2.8 Lanthanum SolutionDissolve 175 g of lanthanumchloride (LaCl3) or 265 g of hydrated lanthanum chloride(LaCl37H2O) in water and dilute to 1 L. Alternatively,
44、slurry115 g of lanthanum oxide (La2O3) in 200 mL of water. Slowlyadd 200 mL of concentrated aqueous hydrochloric acid (HCl,sp. gr. 1.19), while mixing continually with the flask under coldwater, to dissolve the oxide. Dilute to 1 L.7.2.9 Nitric Acid, 2N (1 + 7)Mix one volume of concen-trated aqueous
45、 nitric acid (HNO3, sp. gr. 1.42) with sevenvolumes of water.7.3 Procedure:7.3.1 ExtractionTransfer the filter paper and extractedresidue from 6.3.1 to a 250-mL Erlenmeyer flask. Slowly add50 mL of HNO3(1 + 7) with stirring, to ensure completewetting and to help disintegrate the filter paper. Either
46、 boilgently for 30 min or let stand overnight at room temperature.Filter the flask and contents through a Type II, Class F filterpaper into a 400- to 600-mL beaker. Wash the residue at leastsix times with small increments of water, keeping the totalvolume of filtrate between 100 and 200 mL.7.3.2 Pre
47、paration of Test SolutionTransfer the filtratefrom 7.3.1 to a 200-mL volumetric flask and dilute to volumewith water. Transfer a 10-mL aliquot of the diluted filtrate to a100-mL volumetric flask. Add 10 mL of lanthanum solution(7.2.8) and dilute to volume with HCl (1 + 49). This is the testsolution.
48、7.3.3 Preparation of Blank TestPerform a parallel blanktest following the same procedure and reagents as described in7.3.1 and 7.3.2 using the filter paper generated in 6.3.1 of thesulfate blank test.7.3.4 Determination of Iron by Atomic Absorption:7.3.4.1 Spectrometric ConditionsSuitable conditions
49、 forthe determination of iron are as follows:Wavelength 248.3 nm (0- to 5-ppm Fe)Wavelength 372.0 nm (5- to 100-ppm Fe)Wavelength 344.1 nm (100-ppm Fe)Flame: air/acetylene (lean)7.3.4.2 Preparation of Calibration SolutionsPrepare a setof calibration solutions to cover the expected range of concen-tration in the test solution (7.3.2) by transferring appropriatevolumes of the iron standard solution (7.2.7) to a series of100-mL volumetric flasks. Add 10 mL of lanthanum solution(7.2.8). Dilute to the mark with HCl (1 + 49).7.3.4.3 Calibration
