1、Designation: D 6376 06An American National StandardStandard Test Method forDetermination of Trace Metals in Petroleum Coke byWavelength Dispersive X-ray Fluorescence Spectroscopy1This standard is issued under the fixed designation D 6376; the number immediately following the designation indicates th
2、e year oforiginal adoption or, 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.1. Scope*1.1 This test method covers the X-ray fluorescence s
3、pectro-metric determination of total sulfur and trace metals in samplesof raw or calcined petroleum coke. Elements determined usingthis test method are listed in Table 1.1.2 Detection limits, sensitivity, and optimal element rangeswill vary with matrices, spectrometer type, analyzing crystal,and oth
4、er instrument conditions and parameters.1.3 All analytes are determined as the element and reportedas such. These include all elements listed in Table 1. This testmethod may be applicable to additional elements or concen-tration ranges if sufficient standards are available to produceproper calibrati
5、on equations.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 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
6、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 346 Practice for Collection and Preparation of CokeSamples for Laboratory AnalysisD 1552 Test Method for Sulfur in Petroleum Product
7、s(High-Temperature Method)D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 5056 Test Method for Trace Metals in Petroleum Coke byAtomic AbsorptionD 5600 Test Method for Trace Metals in Petroleum Coke byInductively Coupled Plasma Atomic Emission Spectrom-etry (ICP-AES)E11 Speci
8、fication for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 Definitions:3.1.1 calcined petroleum coke, nraw petroleum coke thathas been thermally treated to drive off the volatile matter andto develop crystalline structure.3.1.2 green petroleum coke, nsame as raw petroleumcoke.3.1.3 petr
9、oleum coke, na solid, carbonaceous residueproduced by thermal decomposition of heavy petroleum frac-tions or cracked stocks, or both3.1.4 raw petroleum coke, npetroleum coke that has notbeen calcined.3.2 Definitions of Terms Specific to This Standard:3.2.1 alpha, ncorrection factor used to compensat
10、e forinterferences.3.2.2 analytical sample, na representative fraction takenfrom a larger mass of petroleum coke and reduced by grindingto pass a 75 m (No. 200 mesh) sieve.3.2.3 pellet, na blend of dried sample and binder milledtogether and then formed into a pellet by pressure.3.2.4 reference sampl
11、es, nsamples of known concentra-tions to be used in the calibration of the X-ray fluorescencespectrometer.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Cok
12、e and Carbon Material.Current edition approved July 1, 2006. Published July 2006. Originally approvedin 1999. Last previous edition approved in 2005 as D 637605.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
13、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.TABLE 1 Applicable Concentration RangesElement Concentration Range, (ppm)Na 50500Al 50500Si 20500S, % 0.107.0Ca 20500Ti 10200V 202000Mn 10200Fe 201000Ni 205001*A Summary of Changes section appears at
14、the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 A representative sample of petroleum coke is dried toconstant mass at 110 6 10C and then crushed to pass a 75 m(No. 200 mesh) sieve.
15、 A weighed portion of this analyticalsample is mixed with stearic acid, or other suitable binder, andthen milled and compressed into a small, smooth pellet suitablefor analysis. The pellet is irradiated by an X-ray beam. Thecharacteristic X rays of the elements analyzed are excited,separated, and de
16、tected by the wavelength-dispersive X-rayspectrometer. These measured X-ray intensities are convertedto elemental concentration through the use of a calibrationequation derived from analyses of standard materials. Thiscalibration equation defines the sensitivity and backgroundassociated with a parti
17、cular X-ray spectrometer.4.2 The K-alpha spectral lines are used for all of theelements determined by this test method.5. Significance and Use5.1 The presence and concentration of sulfur and variousmetallic elements in a petroleum coke are major factorsdetermining the suitability of a coke for vario
18、us purposes. Thistest method provides rapid means for measuring sulfur andcommercially important metallic elements in coke samples.5.2 This test method provides a guide for determiningconformance to material specifications for use by buyers andsellers in a commercial transfer of petroleum coke.5.3 S
19、ulfur contents can be used to evaluate the potentialformation of sulfur oxides (SOx), a source of atmosphericpollution.6. Interferences6.1 Review all potential spectral interferences for the ele-ments listed in Table 2. Follow your manufacturers operatingguide to develop and apply alphas to compensa
20、te for theseinterferences.6.2 Compensate for inter-element effects by using alphas aspart of the regression procedure provided with spectrometersoftware.6.3 Changes in the sulfur concentration in the sample affectsanalyte X-ray intensities. Therefore, determine the magnitudeof the sulfur effect on e
21、ach metallic element and apply inappropriate correction.7. Apparatus7.1 Balance, capable of weighing 50 6 0.01 g.7.2 Hydraulic Press, capable of exerting a force of not lessthan 276 MPa (40 000 psi).7.3 Mill or Grinder, capable of reducing 20 g of petroleumcoke to a sample passing 75 m (No. 200 mesh
22、) in less than 10min, without introducing contamination.7.4 Mixer/Mill, for blending sample and binder.7.5 Pellet Cup, Aluminum (optional), tapered to holdpressed pellets.7.6 Pelletizing Die, for forming pellets of a diameter suit-able for use in the spectrometer.7.7 Sieves, 75 m (No. 200 mesh) as s
23、pecified in Specifi-cation E11.7.8 Drying Oven, capable of maintaining a minimum tem-perature of 110 6 10C.7.9 X-ray Spectrometer, equipped for soft X-ray detectionof the K-alpha spectral lines for all of the elements determinedby this test method. For increased sensitivity, this instrumentshall be
24、equipped with the following:7.9.1 Analyzing CrystalsThis choice is made based on theelement to be determined. The crystal selected should yieldoptimal sensitivity with minimum interferences. The samecrystal shall be used for both standards and unknowns. SeeTable 2 for recommended crystals.7.9.2 Dete
25、ctor, suitable for the determination of elements inquestion. Choices include gas-flow proportional, sealed pro-portional, and scintillation detectors.7.9.3 Optical Path, in a vacuum.7.9.4 Pulse-Height Analyzer, or other means of energydiscrimination.7.9.5 Suitable X-ray TubeChromium, molybdenum, pla
26、ti-num, rhodium, or tungsten target and dual targets have beenfound suitable. The scandium tube is very advantageous forlight elements.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall c
27、onform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Societywhere such specifications are available.3,4Other grades may beused, provided they are of sufficiently high purity to permit usewithout diminishing the accuracy of the determination.8.2 Detector GasP
28、10 gas (90 % argon, 10 % methane) isused with gas-flow proportional detectors.3Reagent 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 Labo
29、ratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4For the testing of reagents not listed by the American Chemical Society, seeReagent Chemicals and Standards, by Joseph Rosin, D. VanNost
30、rand Co., Inc., NewYork, NY.TABLE 2 Suitable Instrument Operating ConditionsElement2Q Angle,DegreesABackground,DegreesAAnalyzingCrystalASodium 25.05 26.75, 24.35 Multilayer, 2d ;50Aluminum 145.13 143.13 PETSilicon 144.95 147.05, 142.85 InSbSulfur 110.68 113.18 GeCalcium 113.08 116.00 LiF (200)Titani
31、um 86.13 84.13 LiF (200)Vanadium 76.93 78.93 LiF (200)Manganese 62.97 60.97 LiF (200)Iron 57.52 59.02 LiF (200)Nickel 48.66 49.92, 47.40 LiF (200)AThe wavelength angles and analyzing crystals listed are suitable due to theirsensitivity and general industry acceptance.These choices are made based on
32、theelement to be determined. Other instrument operating conditions can be used, butan attempt should always be made to use only those conditions yielding optimalsensitivity with minimum interferences. The instrument manufacturer should beconsulted for recommendations on optimal targets, crystal opti
33、ons, and anyconcentration limit restrictions on your unit.D63760628.3 Pellet Binder MaterialStearic acid, or other suitablebinder, providing no spectral interferences shall be used.8.4 Reference Samples, of petroleum coke bracketing theelement ranges of the analytical samples. Commercial refer-ence
34、samples of this type are available from several sources.9. Sampling and Preparation of Test Specimens9.1 Basic AssumptionsAll petroleum coke samples exam-ined using this test method shall be analytical samples repre-sentative of a green or calcined coke production lot orshipment. Practices D 4057 an
35、d D 346 shall be followed. Theanalytical sample shall pass a 75 m (No. 200 mesh) sieve andshall be of sufficient quantity to provide sample for all testingand analyses planned for the particular lot of petroleum coke.To provide for possible replicate determinations of the sulfurand metallic contents
36、 by this test method and for a retainsample, an analytical sample shall be 50 g or more for this testalone.NOTE 1Results are particle dependent, and erroneous data may becollected if analytical samples contain particles varying significantly insize from those in reference samples. Measurements may b
37、e necessary toensure the equivalence of analytical samples and reference samples. Themost difficult problems occur when there are coarse petroleum cokesamples and finely ground reference samples. In this case, it is best togrind the analytical samples, achieving a size distribution similar to theref
38、erence samples.9.2 Types of Samples:9.2.1 Reference SamplesThese samples shall be similar tothe analytical samples in composition and physical properties.A wide range of concentrations is required for inter-elementeffect detection when regression software is used to analyzereference data. Elemental
39、concentrations shall bracket thevalues expected in the analytical samples.9.2.2 Analytical SamplesSamples whose sulfur and me-tallic contents are to be determined.9.3 Typical Preparation of Standards and Test Specimens:9.3.1 Dry a sufficient portion of the analytical sample toconstant mass in an ove
40、n at 110 6 10C to obtain at least 5 g.9.3.2 Weigh 5 6 0.01 g of the dried analytical sample.9.3.3 Add 1 6 0.01 g of binder and mill for a minimum of20 s. Binder/coke ratio shall remain constant for samples andstandards.9.3.3.1 Suitable grinding times to produce particles passinga 75 m (No. 200 mesh)
41、 sieve depends on the type of grinderused and coke variations. Further grinding time impactselement intensities. It is important that grinding time bethoroughly investigated and optimized.NOTE 2It is essential that the same sample preparation procedure(including sample mass, binder mass and ratio, g
42、rinding, and so forth) befollowed precisely for all analytical and reference samples. Even a smallchange in procedure requires making all new reference samples match thechanged procedure. All reference samples and analytical samples usedwith them shall be prepared in exactly the same manner.All weig
43、hings areto be made to the nearest 0.01 g.9.3.4 Place the pellet cup in the die mounted on thehydraulic press. Transfer sufficient ground mix to this cup toproduce a pile of maximum height above the cup lip. Handpack with a flat spatula until the ground mix is level with thecup lip.9.3.5 Apply adequ
44、ate pressure to achieve a stable pellet.Allow adequate time to reach a pressure of approximately 276MPa (40 000 psi) and hold for a minimum of 5 s.9.3.6 Release the pressures slowly, and remove the pelletfrom the die. (WarningRelease the pressure slowly to avoidpossible damage to the pressure gauge.
45、)9.3.7 Inspect the pellet surface to ensure that it is smoothand free of cracks. The cylindrical pellets should be 3 to 7 mmthick.9.3.8 When the pellet is too thin, repeat 9.3.2-9.3.7 usingabout 20 % more ground mix.9.3.9 Clean the outside surface of the pellet cup, using aclean cloth or tissue. If
46、the pellet is to be stored, it is importantto properly identify it and store it in a dry place.9.3.10 Unused test specimens prepared and stored as aboveare generally stable for years. Reference sample pellets can beused daily for establishing instrument conditions. If changesgreater than 3 % (10 % f
47、or silicon) are observed for thecalculated concentrations for any element in a used pellet, thereference sample pellets shall be prepared again. If deviationspersist, recalibrate the instrument.10. Preparation of Apparatus10.1 Follow manufacturers instructions for the initial as-sembly, conditioning
48、 and preparation of the XRF unit.10.2 Follow the manufacturers control setting and opera-tion instructions.10.3 Peak and Background Intensity MeasurementsA de-cision on counting time is made after analyzing all requiredreference samples and after the sensitivity is known. A sug-gested strategy for
49、counting time based on reference samples isas follows:10.3.1 Counting time is derived from:Relative error, % 5 100/Tt!3 1/Rp!2 Rb! (1)where:Tt= the total counting time for the peak and the back-ground. Ttcan be calculated as all other terms, eitherknown or measured,Rp= the count rate for the peak, andRb= the count rate for the background.10.3.2 The partitioning of counting time based on the peakand background is estimated from:Tp/Tb5 Rp/Rb!(2)where:Tp= the peak count time,Tb= the background count time, andRpand Rb= values used to ref
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