1、Designation: D 4239 08Standard Test Methods forSulfur in the Analysis Sample of Coal and Coke Using High-Temperature Tube Furnace Combustion Methods1This standard is issued under the fixed designation D 4239; the number immediately following the designation indicates the year oforiginal adoption or,
2、 in the case of revision, the year of last revision. A number 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.
3、1 These test methods cover two alternative proceduresusing high-temperature tube furnace combustion methods forthe rapid determination of sulfur in samples of coal and coke.1.2 These test methods appear in the following order:SectionsMethod AHigh-Temperature CombustionMethod with Acid Base Titration
4、 Detec-tion Procedures 6-9Method BHigh-Temperature CombustionMethod with Infrared Absorption Detec-tion Procedures 10-12NOTE 1High Temperature Combustion Method with Iodimetric De-tection procedures, formally Method B in the 2000 version of this standardis still a viable method that may be used.1.2.
5、1 When automated equipment is used to perform any ofthe two methods of this test method, the procedures can beclassified as instrumental methods. There are several manufac-turers that offer to the coal industry equipment with instrumen-tal analysis capabilities for the determination of the sulfurcon
6、tent of coal and coke samples.1.3 This standard does not 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 limitation
7、s prior to use. See 7.7 and 11.2.2. Referenced Documents2.1 ASTM Standards:2D 346 Practice for Collection and Preparation of CokeSamples for Laboratory AnalysisD 1193 Specification for Reagent WaterD 2013 Practice for Preparing Coal Samples for AnalysisD 2361 Test Method for Chlorine in CoalD 3173 T
8、est Method for Moisture in theAnalysis Sample ofCoal and CokeD 3176 Practice for Ultimate Analysis of Coal and CokeD 3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD 4208 Test Method for Total Chlorine in Coal by theOxygen Bomb Combustion/Ion Selective Elect
9、rodeMethodD 4621 Guide for Quality Management in an OrganizationThat Samples or Tests Coal and CokeD 5142 Test Methods for Proximate Analysis of the Analy-sis Sample of Coal and Coke by Instrumental Procedures3. Summary of Test Methods3.1 Method AHigh-Temperature Combustion Method withAcid-Base Titr
10、ation Detection ProceduresA weighed sampleis burned in a tube furnace at a minimum operating temperatureof 1350C in a stream of oxygen. During combustion, all sulfurcontained in the sample is oxidized to gaseous oxides of sulfur(sulfur dioxide, SO2, and sulfur trioxide, SO3) and the chlorinein the s
11、ample is released as Cl2. These products are thenabsorbed into a solution of hydrogen peroxide (H2O2) wherethey dissolve forming dilute solutions of sulfuric (H2SO4) andhydrochloric (HCl) acids. The quantities of both acids pro-duced are directly dependent upon the amounts of sulfur andchlorine pres
12、ent in the original coal sample. Once the amountsof each acid present have been determined, the percentage ofsulfur contained in the coal may be calculated.3.1.1 This method is written to include commercially avail-able sulfur analyzers that must be calibrated with appropriatecertified reference mat
13、erials to establish recovery factors or acalibration curve based on the range of sulfur in the coal orcoke samples being analyzed.NOTE 2Elements ordinarily present in coal do not interfere in MethodA(3.1), with the exception of chlorine; results must be corrected forchlorine content of the samples (
14、9.1).3.2 Method BHigh-Temperature Combustion Method withInfrared Absorption Detection ProceduresThe sample isburned in a tube furnace at a minimum operating temperature1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D
15、05.21 on Methods ofAnalysis.Current edition approved Feb. 1, 2008. Published March 2008. Originallyapproved in 1983. Last previous edition approved in 2005 as D 4239 05.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annua
16、l Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of 1350C in a stream of oxygen to oxidize the sulfur. Moistureand particulate
17、s are removed from the gas by traps filled withanhydrous magnesium perchlorate. The gas stream is passedthrough a cell in which sulfur dioxide is measured by aninfrared (IR) absorption detector. Sulfur dioxide absorbs IRenergy at a precise wavelength within the IR spectrum. Energyis absorbed as the
18、gas passes through the cell body in which theIR energy is being transmitted: thus, at the detector, less energyis received.All other IR energy is eliminated from reaching thedetector by a precise wavelength filter. Thus, the absorption ofIR energy can be attributed only to sulfur dioxide whoseconcen
19、tration is proportional to the change in energy at thedetector. One cell is used as both a reference and a measure-ment chamber. Total sulfur as sulfur dioxide is detected on acontinuous basis. This method is empirical; therefore, theapparatus must be calibrated by the use of certified referencemate
20、rials.3.2.1 This method is for use with commercially availablesulfur analyzers equipped to carry out the preceding operationsautomatically and must be calibrated using certified referencematerials of known sulfur content based on the range of sulfurin each coal or coke sample analyzed.4. Significanc
21、e and Use4.1 Determination of sulfur is, by definition, part of theultimate analysis of coal.4.2 Results of the sulfur analysis are used to serve a numberof interests: evaluation of coal preparation, evaluation ofpotential sulfur emissions from coal combustion or conversionprocesses, and evaluation
22、of the coal quality in relation tocontract specifications, as well as other scientific purposes.4.3 The instrumental analysis provides a reliable, rapidmethod for determining the concentration of sulfur in a lot ofcoal or coke and are especially applicable when results must beobtained rapidly for th
23、e successful completion of industrial,beneficiation, trade, or other evaluations.5. Sample5.1 The sample shall be the material pulverized to pass No.60 (250-m) sieve and mixed thoroughly in accordance withMethod D 2013 or Practice D 346.NOTE 3It may be difficult to meet the precision statements of S
24、ection14 when high mineral content coals are ground to pass 60 mesh. When theprecision of analysis required cannot be obtained, it is recommended thatthe coals be ground to pass through a No. 100 (150-m) sieve. Thereduced particle size should result in a more homogeneous sample.5.2 A separate portio
25、n of the analysis sample should beanalyzed for moisture content in accordance with Test MethodD 3173, so that calculation to other than the as-determinedbasis can be made.5.3 Procedures for converting as-determined sulfur valuesobtained from the analysis sample to other bases are describedin Practic
26、es D 3176 and D 3180.5.4 Certified Reference Materials, or other commerciallyavailable reference coals or calibrating agents with certifieddry-basis values must be used. The materials must be suppliedby or have traceability to internationally recognized certifyingorganizations (Note 4).NOTE 4 Certif
27、ied Reference Materials such as those available as theStandard Reference Materials (SRMs) Series 2682 through 2685 from theNational Institute of Standards and Technology (NIST) or South AfricanReference Materials (SARMs) from the South African Bureau of Stan-dards have proven to be suitable for cali
28、bration. Other Certified ReferenceMaterials can be used provided they are supplied by an internationallyrecognized certifying agency.METHOD AHIGH-TEMPERATURECOMBUSTION METHOD WITH ACID-BASETITRATION DETECTION PROCEDURES36. Apparatus6.1 Tube FurnaceCapable of heating 150- to 175-mmarea (hot zone) of
29、the combustion tube (6.2) to at least 1350C.It is usually heated electrically using resistance rods, a resis-tance wire, or molybdenum disilicide elements. Specific di-mensions may vary with manufacturers design.NOTE 5Induction furnace techniques may be used provided it can beshown that they meet th
30、e precision requirements of Section 14.6.2 Combustion TubeApproximately 28-mm internal di-ameter with a 3-mm wall thickness and 750 mm in length madeof porcelain, zircon, or mullite. It must be gastight at workingtemperature. The combustion may be carried out in a tapered-end tube that is closely co
31、nnected to the gas absorber byhigh-temperature tubing with gastight joints. Acceptable con-figurations include connecting the tapered-end tube directly tothe elbow of the fritted gas bubbler or to a 10/30 standardtaper-ground joint that is attached to a heat-resistant glass rightangle bend. The temp
32、erature at the tapered end of the tubeshould be maintained high enough to prevent condensation inthe tube itself.6.2.1 Alternatively, a high-temperature straight refractorytube may be used, if available. It requires a silica adaptor (6.11)with a flared end that fits inside the combustion tube and se
33、rvesas an exit for the gases.6.3 Flowmeter, for measuring an oxygen flow rate up to 2.0L/min.6.4 Sample Combustion Boats, must be made of iron-freematerial and of a convenient size suitable for the dimensions ofthe instrument being used.6.5 Boat PullerRod of a heat-resistant material with abent or d
34、isk end to insert and remove boats from the combus-tion tube.6.5.1 If the boat puller is to remain within the combustiontube while the boat is moved into the hot zone, it is necessaryto pass the puller through a T-piece that is fitted into a rubberstopper at the inlet of the combustion tube. The ope
35、n end of theT-piece is sealed with a rubber stopper to permit movement ofthe pusher and prevent escape of the oxygen that enters at theside limb of the T. The rubber stopper or tube should bechecked often to avoid leakage.3Based on the method of Mott, R. A., and Wilkinson, H. C., “Determination ofSu
36、lfur in Coal and Coke by the Sheffield High Temperature Method,” Fuel, Fuel B,Vol. 35, 1956, p. 6. This method is designed for the rapid determination of sulfur incoal and coke. It is not applicable to coals or coal density fractions that have beensubjected to treatment with chlorinated hydrocarbons
37、 because of the potentially highacidity of the combustion gases.D42390826.6 Gas Absorber or Analyzer Titration VesselA narrowvessel of such diameter that the end of the tube from which thegasses exit is inside the vessel and submerged to a depth of atleast 90 mm, when 200 mL of the peroxide solution
38、 (7.4)isadded to the vessel.6.6.1 Alternatively, 125-mL capacity bottles with fritteddisk can be used for gas absorption. The bottles should be ofsuch a diameter that the fritted end is covered by the peroxidesolution to a depth of at least 50 mm. The fritted glass endporosity should be 15 to 40 m.
39、The bottles are fitted in a seriesof two to the outlet end of the combustion tube.6.7 Gas-Purifying TrainDesigned to be used with specificinstruments, or a gas scrubber containing 0.1N Sodium Hy-droxide Solution, may be used to remove carbon dioxide forthe oxygen purification train. See configuratio
40、n in Fig. 1.6.8 Vacuum SourceNeeded if a negative pressure is usedto transport the gasses and combustion products through thesystem.6.9 Vacuum Regulating Device, such as a mass flow con-troller.6.10 Silica Adaptor, 300 mm long by 8 mm in outsidediameter and flared at one end to 26 mm. To be used wit
41、h astraight refractory combustion tube.6.11 Other Configurations of ApparatusComplete sulfuranalyzer assembly units designed to perform functions similarto this method with automated features that perform the sulfuranalysis in a more rapid manner are commercially available.These instruments may have
42、 combustion tube dimensions andoxygen-purifying apparatus that differ slightly from thosedescribed in this method, but are acceptable, provided equiva-lent values within the precision statement of Section 14 areobtained. (See Fig. 1 and Fig. 2.)7. Reagents7.1 Purity of ReagentsReagent grade chemical
43、s shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Available Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained tha
44、t the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water, Type IV,conforming to Specification D 1193.7.3 Aluminum Oxide (Al2O3)Finely di
45、vided and dried at1350C.7.4 Hydrogen Peroxide (H2O2) SolutionOne volume per-cent (50 mL of 30 % H2O2with 1450 mL of water). The pH isadjusted (using NaOH or H2SO4as appropriate) to that whichis used for the end point in the titration. Solutions should bediscarded after two or three days.7.5 Indicato
46、rIndicators that change color (titration endpoint) between pH 4 and 5 are recommended, but in no caseshould the pH exceed 7. Adequate lighting and stirring toensure proper detection of the end point is essential. A choiceof indicators or use of a pH meter is permitted (Note 6).Directions for prepari
47、ng two acceptable mixed indicators are asfollows:7.5.1 Mix one part methyl red solution (dissolve 0.125 g in60 mL of ethanol and dilute to 100 mL with water) with threeparts bromcresol green solution (dissolve 0.083 g in 20 mL ofethanol and dilute to 100 mL with water). Discard the mixedsolution aft
48、er one week.7.5.2 Mix equal volumes of methyl red solution (dissolve0.125 g in 60 mL of ethanol and dilute to 100 mL with water)and methylene blue solution (dissolve 0.083 g in 100 mL ofethanol and store in a dark glass bottle). Discard the mixedsolution after one week.NOTE 6Although two end-point i
49、ndicators or a pH meter method are4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical 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. (USPC), Rockville,MD.FIG. 1 Apparatus for the Determination of Sulfur Using Acid-Base TitrationD4239083described, the use of the pH meter is accepted as more de
