1、Designation: D4326 13Standard Test Method forMajor and Minor Elements in Coal and Coke Ash By X-RayFluorescence1This standard is issued under the fixed designation D4326; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the analysis of the commonlydetermined major and minor elements in ash from coal or cokeusing
3、X-ray fluorescence (XRF) techniques.NOTE 1Test Method D5016 is used for determination of sulfur.NOTE 2Although not included in the present method, the determina-tion of barium, strontium, and manganese may be required to yieldadequate totals.1.2 The values stated in SI units are to be regarded assta
4、ndard. No other units of measurement are included in thisstandard.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 app
5、lica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD346 Practice for Collection and Preparation of CokeSamples for Laboratory AnalysisD2013 Practice for Preparing Coal Samples for AnalysisD3173 Test Method for Moisture in th
6、e Analysis Sample ofCoal and CokeD3174 Test Method for Ash in the Analysis Sample of Coaland Coke from CoalD5016 Test Method for Total Sulfur in Coal and CokeCombustion Residues Using a High-Temperature TubeFurnace Combustion Method with Infrared AbsorptionD7348 Test Methods for Loss on Ignition (LO
7、I) of SolidCombustion ResiduesD7582 Test Methods for Proximate Analysis of Coal andCoke by Macro Thermogravimetric AnalysisE2 Methods of Preparation of Micrographs of Metals andAlloys (Including Recommended Practice for Photogra-phy As Applied to Metallography); Replaced by E 883(Withdrawn 1983)3E11
8、 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Terminology3.1 DefinitionsDefinitions applicable to this test methodare listed in D121, Terminology of Coal and Coke.4. Summary of Test Method4.1 The coal or coke to be analyzed is ashed under standardconditions and ignited to constant
9、weight. Previously ashedmaterials are ignited to constant weight under standard condi-tions. The ash is fused with lithium tetraborate (Li2B4O7)orother suitable flux and either ground and pressed into a pelletor cast into a glass disk. The pellet or disk is then irradiated byan X-ray beam of short w
10、avelength (high energy). The char-acteristic X-rays of the atom that are emitted or fluorescedupon absorption of the primary or incident X-rays are dispersedand intensities at selected wavelengths are measured by sensi-tive detectors. Detector output is related to concentration bycalibration curves
11、or by computerized data-handling equip-ment.4.2 The K spectral lines are used for all of the elementsdetermined by this procedure.4.3 All elements are determined as the element and reportedas the oxide and include Si, Al, Fe, Ca, Mg, Na, K, P, Ti, Mn,Sr, and Ba.5. Significance and Use5.1 Acompositio
12、nal analysis of ash is used in describing thequality of coal for its complete characterization. Ash compo-sition is useful in predicting slagging and fouling characteris-tics of combusted materials as well as the potential utilizationof ash by-products.1This test method is under the jurisdiction of
13、ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.29 on MajorElements in Ash and Trace Elements of Coal.Current edition approved Sept. 1, 2013. Published September 2013. Originallyapproved in 1984. Last previous edition approved 2011 as D4326 11. DOI:10.1520/D43
14、26-13.2For 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.3The last approved version of this historical standard
15、is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 The chemical composition of laboratory prepared coalor coke ash is rarely, if ever, representative of the compositionof the mineral matter in the coal be
16、cause the ashing process canalter some minerals. However, it can approximate the compo-sition of the fly ash and slag resulting from commercialcombustion of coal or coke.6. Apparatus6.1 Ashing Furnace, with an adequate air circulation andcapable of having its temperature regulated at 500C and750C.6.
17、2 Fusion Furnace or Fluxing Device, with an operatingtemperature of at least 1000C.6.3 Fusion Crucibles, either high-purity graphite (22 mmhigh and 19 mm wide, inside diameter) or platinum-gold alloyof a similar or larger capacity.6.4 Pulverizers, including agate, mullite or tungsten carbidemortar,
18、and pestle, minimum capacity 25 mL.6.5 Sieves, 250-m (No. 60) and 75-m (No. 200) U.S.Astandard sieve as specified in Specification E11.6.6 CompactorA press equipped with a gage enablingreproducible pressures (exceeding 1.72 108Pa (25 000 psi)if pressed pellets are utilized.6.7 Excitation Source, wit
19、h a stable electrical power supply(61 %) and a high-intensity, short-wavelength X-ray capabil-ity.6.8 SpectrometerA wavelength or energy dispersive sys-tem equipped with a vacuum sample chamber.6.8.1 Analyzing Crystal (Wavelength Units)The choice ofthe analyzing crystal is made on the basis of the e
20、lement to bedetermined. An attempt should be made to use the crystal thatyields the maximum sensitivity with minimum interferences.The same crystal must be used for standards and unknowns.6.8.2 DetectorsScintillation and gas-flow counters areused with wavelength systems while lithium-drifted diodes
21、areused for energy dispersive systems.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. 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 su
22、ch specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Detector GasThe usual gas composition of the gasused in the flow-proportional counters is
23、 90 % argon, 10 %methane, although other compositions may be used.7.3 Heavy AbsorberWhere heavy absorbers, such as lan-thanum oxide or barium oxide, are used they shall be aminimum of 99.99 % purity.7.4 FluxesLithium or sodium borates or carbonates, orcombination thereof, are often used for sample f
24、usion. Lithiumor ammonium iodide used as a nonwetting agent and potassiumor ammonium nitrate used as an oxidizing agent may be usedprovided they do not contribute to spectral interference.7.5 BindersWhere pressed pellets are used for analysis,the binder used shall contribute no spectral interference
25、s duringthe determination.8. Sample Preparation8.1 Coal and CokePrepare the analysis sample in accor-dance with Practice D2013 for coal or Practice D346 for cokeby pulverizing the material to pass a 250-m (No. 60) U. S. A.standard sieve.8.1.1 Analyze separate test portions for moisture and ashconten
26、ts in accordance with Test Methods D3173, D3174,orD7582, so that calculations to other bases can be made.8.2 Laboratory Ashing of Coal and Coke Analysis SamplePrepare the ash from a thoroughly mixed analysis sample ofcoal or coke (see 7.1). Spread the coal and coke in a layer notover 6 mm (1/4 in.)
27、in depth in a porcelain, quartz, or fusedsilica roasting dish. Place the dish in a muffle furnace that is atambient temperature and heat gradually so that the temperaturereaches 500 6 10C at the end of 1 h. Continue the gradualheating until the temperature rises from 500 6 10C to 750 615C at the end
28、 of 1 h. Maintain the 750C temperature untilthe test specimen reaches a constant mass or for an additionaltwo hours. Allow the dish to cool, transfer to an agate mortar,and grind to pass a 75-m (No. 200) U. S. A. standard sieve.Reignite the ash at 750C for 1 h, cool rapidly, and weighportions for an
29、alysis.8.3 Solid Combustion ResidueDry a representative por-tion of the solid residue to constant mass at 107 6 3C.Determine the moisture loss during this drying step if it isdesirable to calculate results to an as-received basis. Crush thedried portion of the sample to pass a 75-m (No. 200) U. S. A
30、.standard sieve. Use a mill that minimizes metal contamination.8.4 Ashing Solid Combustion ResidueSpread an appropri-ate amount of the prepared sample in a layer not over 2 mm ina porcelain, quartz, or fused silica roasting dish. Place the dishin a muffle furnace that is at ambient temperature and h
31、eatgradually so that the temperature reaches 500 6 10C at theend of 1 h. Continue the gradual heating until the temperaturerises from 500 6 10C to 750 6 15C at the end of 1 h.Maintain the 750C temperature until the combustion residuereaches a constant mass or for an additional two h. Cool the testsp
32、ecimen, grind to pass a 75-m (No. 200) U. S. A. standardsieve, and reignite at 750C for 1 h.8.5 If previously ignited samples are stored and the absorp-tion of moisture of CO2, or both, is in question, reignite the ashat 750C before use. Alternatively, determine loss on ignitionusing Test Method D73
33、48 on a separate sample weighed out at4Reagent 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,
34、U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.D4326 132the same time as the test portion and make the necessarycorrections. Thoroughly mix each sample before weighing.9. Preparation of Analytical Sample9.1 Mix the powdered s
35、ample, weigh a portion of thesample, and mix with a suitable amount of flux (2 to 10 g offlux per gram of sample) (Note 3). When a heavy absorber isused (Note 4), it is added at this point in an amount equal to theamount of sample and thoroughly blended with the mix. Aportion of the flux used as a c
36、ap on the mix ensures washingdown any of the material from the sides of the crucible.NOTE 3The amount of sample and flux used are determined by thenecessity of forming a disk or pellet of 2-mm thickness to fit the sampleholder of the spectrometer used. All fluxes and other additives should beadded i
37、n an appropriate manner at the time of sample preparation.9.1.1 Fluxing materials commonly available are not consis-tent and can vary in volatile losses upon fusing. In order toeliminate errors caused by this loss, one of three methods mustbe employed. First, the entire bottle of flux may be heated
38、tothe fused state, then cooled, reground, and stored in a desic-cator. Second, a weighed sample from each bottle is fused anda loss on fusion is determined, which is then applied as acorrection for each sample prepared from that bottle. Third, theentire mass of each sample prepared (flux, sample, an
39、d heavyabsorber, if used) may be weighed and an independent fusionloss calculated.NOTE 4Use of a heavy absorber has the advantage of allowing the useof a much smaller sample weight to reach infinite thickness and allows forcalculation of concentrations using a simple linear regression coefficient.It
40、 does, however, prevent determination of a number of trace elements andmay be impractical for energy dispersive systems where its addition maycause increased detector dead time and complicate correction procedures.The use of a heavy absorber is recommended only when its absence isimpractical or inco
41、nvenient.9.2 The sample mix is fused at approximately 1000C, in afusion furnace of fluxing device, for a length of time sufficientto guarantee complete dissolution of the sample. Some type ofagitation of the crucible, such as swirling or shaking, must beused in order to ensure a uniform melt.9.3 The
42、 fusion melt will then be made into a suitable mountby casting the liquid into a mold and forming a glass disk or byallowing the pellet to cool, grinding to a fine powder with 2 %of a plasticizer or binder, and pressing into a pellet at aminimum of 1.72 108Pa pressure with a suitable backing asadded
43、 support.9.4 The glass disk must be cooled at a rate that is fastenough to prevent any segregation occurring and, at the sametime, slowly enough to prevent stresses that will crack theglass. Cracked glass disks may be refused and recast withoutloss of precision.9.5 Whichever method of preparation of
44、 the analyticalmount is used, it is essential that a smooth, uniform, and flatsurface is exposed to the exciting radiation.9.6 It is essential that the entire sample preparation proce-dure (including sample weight, flux weight and ratio, grinding,casting, and so forth) be followed precisely for all
45、analyticalmounts and standards. Even a small change in the selectedprocedures will require remaking of all standards to match thechanged procedure.All calibration standards and the unknownsto be used with them must be prepared in exactly the samemanner with all weighings to be made to the nearest 1
46、mg.10. Preparation of XRF Spectrometer10.1 Follow the manufacturers instruction for the initialassembly, conditioning, and preparation of the XRF unit.10.2 Follow the manufacturers instructions with respect tocontrol setting and operation.11. Excitation and Exposure11.1 Position the sample in the ch
47、amber provided for thispurpose. Avoid touching or otherwise contaminating thesample surface. Produce and record the spectrum at the settingsrecommended for the instrument. Prepare and analyze dupli-cate mounts for all samples with duplicate readings on eachmount. For in-house laboratories, single de
48、terminations may beperformed as long as the precision and bias limits are met.12. Safety Precautions12.1 It is necessary to obtain training before using X-rayfluorescence equipment and important to understand com-pletely the operation of the instrument to ensure that theprovisions of 1.3 are met.13.
49、 Calculations and Calibration13.1 Standards for calibration may be prepared from stan-dard reference materials or synthetically blended pure com-pounds. It is required that the range of concentrations repre-sented by the standards exceeds that of any unknown.13.2 Calculation of elemental concentrations may be ac-complished by empirical fundamental parameter or linearregression in accordance with Practice E2.14. Precision and Bias514.1 PrecisionThe relative precision of this test methodfor the determination of major and minor elements i
