1、Designation: D6376 09Standard 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)E11 Specification for Woven Wire Test Sieve Clo
8、th and TestSieves3. Terminology3.1 Definitions:3.1.1 calcined petroleum coke, npetroleum coke that hasbeen thermally treated to drive off the volatile matter and todevelop crystalline structure.3.1.2 green petroleum coke, nsame as raw petroleumcoke.3.1.3 petroleum coke, na solid, carbonaceous residu
9、eproduced 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 compensate forinterferences.3.2.2 analytical sampl
10、e, 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 samples, nsamples of known concentra-tions to
11、be used in the calibration of the X-ray fluorescencespectrometer.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 m1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubr
12、icants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current edition approved Dec. 1, 2009. Published February 2010. Originallyapproved in 1999. Last previous edition approved in 2006 as D637606. DOI:10.1520/D6376-09.2For referenced
13、 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, (ppm)Na
14、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.(No. 200 mesh) sieve. A weighed porti
15、on 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 detected by the wa
16、velength-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 particular X-ray spec
17、trometer.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 various purposes. Thi
18、stest 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 Sulfur contents c
19、an 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 compensate for theseinte
20、rferences.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 each metallic ele
21、ment 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) in less than 1
22、0min, 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 specified in Spec
23、ifi-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 equipped with th
24、e 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 Detector, suitable f
25、or 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, plati-num, rhodium,
26、 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 conform to the sp
27、ecifications 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-10 gas (90 % ar
28、gon, 10 % methane) isused with gas-flow proportional detectors.8.3 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 sam
29、ples of this type are available from several sources.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 LaboratoryChemicals, BDH Ltd.,
30、 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. VanNostrand Co., Inc., NewYork, N
31、Y.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)Titanium 86.13 84.13 LiF (200)Va
32、nadium 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 theelement to be determine
33、d. 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 options, and anyconcentration
34、limit restrictions on your unit.D6376 0929. 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 D4057 and D346 shall be
35、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 by this test met
36、hod 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 be necessary toens
37、ure 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 thereference samples.9.
38、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 concentrations sh
39、all 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 oven at 110 6 10C to
40、 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) sieve depends on
41、 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, grinding, and so f
42、orth) 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 weighings areto be ma
43、de 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 adequate pressure to a
44、chieve 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.)9.3.7 Inspect th
45、e 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 the pellet is to
46、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 % for silicon) are o
47、bserved 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, and preparation
48、 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 counting time bas
49、ed 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 reflect intensity
