1、Designation: D2492 02 (Reapproved 2012)Standard Test Method forForms of Sulfur in Coal1This standard is issued under the fixed designation D2492; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 sulfatesulfur
3、 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 to10
4、0 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 use
5、r 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:2D1193 Specification for Reagent WaterD2013 Practice for Preparing Coal Samples for AnalysisD3173 Test Method for
6、 Moisture in the Analysis Sample ofCoal and CokeD3177 Test Methods for Total Sulfur in theAnalysis Sampleof Coal and CokeD3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD4239 Test Method for Sulfur in the Analysis Sample ofCoal and Coke Using High-Temperatur
7、e Tube FurnaceCombustionE832 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 soluble in hydro-ch
8、loric 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 isextracted with dilut
9、e 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 specimenseparate from
10、 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 of theamount extract
11、ed 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 precision statement in
12、 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 extraction of iron. Selecti
13、on 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 used in routinepracti
14、ce 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 after1This test method is under the jurisdiction of ASTM Committee D05 on Coaland
15、 Coke and is the direct responsibility of Subcommittee D05.21 on Methods ofAnalysis.Current edition approved Sept. 1, 2012. Published November 2012. Originallyapproved in 1966. Last previous edition approved in 2007 as D2492 02(2007).DOI: 10.1520/D2492-02R12.2For referenced ASTM standards, visit the
16、 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., and Pringle, W. J. S., “An Investigation intoMethods for the Determin
17、ation 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1sulfate extraction. The i
18、ron is determined by atomic absorptiontechniques (see Note 2).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 use
19、d to serve a number 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 D2013.
20、 Moisture shall be deter-mined in accordance with Test Method D3173 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
21、(BaSO4).6.1.3 Hot 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 tes
22、ts. Unless otherwise 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 top
23、ermit its use without 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 D1193, Type III.6.2.3 Ammonium Hydroxide (14.9N, sp. gr. 0.90)concentrated aqueous ammonia.6.2
24、.4 Ammonium Hydroxide 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 bromineto 1 L of water. (
25、WarningStore in a dark bottle and keep ina 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 E832.6.2.9 Hydrochloric Acid,12N (sp. gr. 1.19)Co
26、ncentratedaqueous 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 S
27、ilver Nitrate 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
28、(2 + 3) 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 an
29、d contents 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 handlin
30、g an excessive 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 exc
31、ess is 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
32、drops of 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 overni
33、ght at 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 f
34、iltrate.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 m
35、in. Cool 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.5Reagent Chemicals, American Chemical Society Specifications , Ame
36、ricanChemical 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. (US
37、PC), Rockville,MD.D2492 02 (2012)2Smoke the paper off gradually to prevent spattering.At no timeallow to burn 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 c
38、rucibles and contents to the nearest 0.1mg. 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 C
39、s! 2 B 2 CB!# 313.735%/W (1)where:S = weight of sample crucible plus ignited BaSO4precipitate, 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. Re
40、feree 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.
41、2.4 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, pur
42、e 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
43、to 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 n
45、itric 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 b
46、oilgently 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 Prepa
47、ration 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.7.
48、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 f
49、orthe 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
