1、Designation: D6376 10Standard Test Method forDetermination of Trace Metals in Petroleum Coke byWavelength Dispersive X-ray Fluorescence Spectroscopy1This standard is issued under the fixed designation D6376; 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the X-ray fluorescence spectro-metric determination of t
3、otal 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 other instrument conditions and par
4、ameters.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 calibration equations.1.4 The values stat
5、ed in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 establish appro-priate safety and
6、 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D346 Practice for Collection and Preparation of CokeSamples for Laboratory AnalysisD1552 Test Method for Sulfur in Petroleum Products(High-Temperature Method)D4057 Pra
7、ctice for Manual Sampling of Petroleum andPetroleum ProductsD5056 Test Method for Trace Metals in Petroleum Coke byAtomic AbsorptionD5600 Test Method for Trace Metals in Petroleum Coke byInductively Coupled Plasma Atomic Emission Spectrom-etry (ICP-AES)D6969 Practice for Preparation of Calcined Petr
8、oleum CokeSamples for AnalysisD6970 Practice for Collection of Calcined Petroleum CokeSamples for AnalysisE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Terminology3.1 Definitions:3.1.1 calcined petroleum coke, npetroleum coke that hasbeen thermally treated to drive off the volat
9、ile matter and todevelop crystalline structure.3.1.2 green petroleum coke, nsame as raw petroleumcoke.3.1.3 petroleum 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 notbe
10、en calcined.3.2 Definitions of Terms Specific to This Standard:3.2.1 alpha, ncorrection factor used to compensate 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
11、 blend of dried sample and binder milledtogether and then formed into a pellet by pressure.3.2.4 reference samples, 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 Prod
12、ucts and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current edition approved July 1, 2010. Published July 2010. Originally approvedin 1999. Last previous edition approved in 2009 as D637609. DOI: 10.1520/D6376-10.2For
13、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.TABLE 1 Applicable Concentration RangesElement Concentration Range
14、, (ppm)Na 50500Al 50500Si 20500S, % 0.107.0Ca 20500Ti 10200V 202000Mn 10200Fe 201000Ni 205001*A Summary of Changes section appears at 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.
15、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. A weighed portion of this analyticalsample is mixed with stearic acid, or other suitable binder, andthen milled and compressed into a small, smooth pellet suitablefo
16、r analysis. The pellet is irradiated by an X-ray beam. Thecharacteristic X rays of the elements analyzed are excited,separated, and detected by the wavelength-dispersive X-rayspectrometer. These measured X-ray intensities are convertedto elemental concentration through the use of a calibrationequati
17、on derived from analyses of standard materials. Thiscalibration equation defines the sensitivity and backgroundassociated with a particular 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 con
18、centration of sulfur and variousmetallic elements in a petroleum coke are major factorsdetermining the suitability of a coke for various purposes. Thistest method provides rapid means for measuring sulfur andcommercially important metallic elements in coke samples.5.2 This test method provides a gui
19、de for determiningconformance to material specifications for use by buyers andsellers in a commercial transfer of petroleum coke.5.3 Sulfur contents can be used to evaluate the potentialformation of sulfur oxides (SOx), a source of atmosphericpollution.6. Interferences6.1 Review all potential spectr
20、al interferences for the ele-ments listed in Table 2. Follow your manufacturers operatingguide to develop and apply alphas to compensate for theseinterferences.6.2 Compensate for inter-element effects by using alphas aspart of the regression procedure provided with spectrometersoftware.6.3 Changes i
21、n the sulfur concentration in the sample affectsanalyte X-ray intensities. Therefore, determine the magnitudeof the sulfur effect on each 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 n
22、ot 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) 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 pel
23、lets.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 specified 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
24、 the K-alpha spectral lines for all of the elements determinedby this test method. For increased sensitivity, this instrumentshall be equipped with the following:7.9.1 Analyzing CrystalsThis choice is made based on theelement to be determined. The crystal selected should yieldoptimal sensitivity wit
25、h minimum interferences. The samecrystal shall be used for both standards and unknowns. SeeTable 2 for recommended crystals.7.9.2 Detector, suitable for the determination of elements inquestion. Choices include gas-flow proportional, sealed pro-portional, and scintillation detectors.7.9.3 Optical Pa
26、th, in a vacuum.7.9.4 Pulse-Height Analyzer, or other means of energydiscrimination.7.9.5 Suitable X-ray TubeChromium, molybdenum, plati-num, rhodium, or tungsten target and dual targets have beenfound suitable. The scandium tube is very advantageous forlight elements.8. Reagents and Materials8.1 Pu
27、rity 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 Societywhere such specifications are available.3,4Other grades may beus
28、ed, provided they are of sufficiently high purity to permit usewithout diminishing the accuracy of the determination.8.2 Detector GasP-10 gas (90 % argon, 10 % methane) isused with gas-flow proportional detectors.3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society
29、, 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.4Fo
30、r the testing of reagents not listed by the American Chemical Society, seeReagent Chemicals and Standards, by Joseph Rosin, D. VanNostrand Co., Inc., NewYork, NY.TABLE 2 Suitable Instrument Operating ConditionsElement2Q Angle,DegreesABackground,DegreesAAnalyzingCrystalASodium 25.05 26.75, 24.35 Mult
31、ilayer, 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)Titanium 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 angl
32、es and analyzing crystals listed are suitable due to theirsensitivity and general industry acceptance.These choices are made based on theelement to be determined. Other instrument operating conditions can be used, butan attempt should always be made to use only those conditions yielding optimalsensi
33、tivity with minimum interferences. The instrument manufacturer should beconsulted for recommendations on optimal targets, crystal options, and anyconcentration limit restrictions on your unit.D6376 1028.3 Pellet Binder MaterialStearic acid, or other suitablebinder, providing no spectral interference
34、s shall be used.8.4 Reference Samples, of petroleum coke bracketing theelement ranges of the analytical samples. Commercial refer-ence 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
35、this test method shall be analytical samples repre-sentative of a green or calcined coke production lot orshipment. Practices D4057, D346, D6969, and D6970 shall befollowed. The analytical sample shall pass a 75 m (No. 200mesh) sieve and shall be of sufficient quantity to providesample for all testi
36、ng and analyses planned for the particular lotof petroleum coke. To provide for possible replicate determi-nations of the sulfur and metallic contents by this test methodand for a retain sample, an analytical sample shall be 50 g ormore for this test alone.NOTE 1Results are particle dependent, and e
37、rroneous data may becollected if analytical samples contain particles varying significantly insize from those in reference samples. Measurements may be necessary toensure the equivalence of analytical samples and reference samples. Themost difficult problems occur when there are coarse petroleum cok
38、esamples and finely ground reference samples. In this case, it is best togrind the analytical samples, achieving a size distribution similar to thereference samples.9.2 Types of Samples:9.2.1 Reference SamplesThese samples shall be similar tothe analytical samples in composition and physical propert
39、ies.A wide range of concentrations is required for inter-elementeffect detection when regression software is used to analyzereference data. Elemental concentrations shall bracket thevalues expected in the analytical samples.9.2.2 Analytical SamplesSamples whose sulfur and me-tallic contents are to b
40、e 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 oven 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
41、 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) sieve depends on the type of grinderused and coke variations. Further grinding time impactselement intensities. It is important that grinding time be
42、thoroughly investigated and optimized.NOTE 2It is essential that the same sample preparation procedure(including sample mass, binder mass and ratio, grinding, and so forth) befollowed precisely for all analytical and reference samples. Even a smallchange in procedure requires making all new referenc
43、e samples match thechanged procedure. All reference samples and analytical samples usedwith them shall be prepared in exactly the same manner.All weighings 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
44、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 adequate 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
45、.6 Release the pressures slowly, and remove the pelletfrom the die. (WarningRelease the pressure slowly to avoidpossible damage to the pressure gauge.)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 pelle
46、t 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 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 abo
47、veare generally stable for years. Reference sample pellets can beused daily for establishing instrument conditions. If changesgreater than 3 % (10 % for silicon) are observed for thecalculated concentrations for any element in a used pellet, thereference sample pellets shall be prepared again. If de
48、viationspersist, recalibrate the instrument.10. Preparation of Apparatus10.1 Follow manufacturers instructions for the initial as-sembly, conditioning, and preparation of the XRF unit.10.2 Follow the manufacturers control setting and opera-tion instructions.10.3 Peak and Background Intensity Measure
49、mentsA de-cision on counting time is made after analyzing all requiredreference samples and after the sensitivity is known. A sug-gested strategy for 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
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