ASTM D6376-99
(Test Method)Standard Test Method for Determination of Trace Metals in Petroleum Coke by Wavelength Dispersive X-Ray Fluorescence Spectroscopy
Standard Test Method for Determination of Trace Metals in Petroleum Coke by Wavelength Dispersive X-Ray Fluorescence Spectroscopy
SCOPE
1.1 This test method covers the X-ray fluorescence spectrometric determination of total sulfur and trace metals in samples of raw or calcined petroleum coke. Elements determined using this test method are listed in Table 1.
1.2 Detection limits, sensitivity, and optimal element ranges will vary with matrices, spectrometer type, analyzing crystal, and other instrument conditions and parameters.
1.3 All analytes are determined as the element and reported as such. These include all elements listed in Table 1. This test method may be applicable to additional elements or concentration ranges if sufficient standards are available to produce proper calibration equations.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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AnAmerican National Standard
Designation:D6376–99
Standard Test Method for
Determination of Trace Metals in Petroleum Coke by
Wavelength Dispersive X-ray Fluorescence Spectroscopy
This standard is issued under the fixed designation D6376; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
TABLE 1 Applicable Concentration Ranges
1. Scope
Concentration Range,
1.1 This test method covers the X-ray fluorescence spectro-
Element
(ppm)
metricdeterminationoftotalsulfurandtracemetalsinsamples
Na 50 – 500
of raw or calcined petroleum coke. Elements determined using
Al 50 – 500
this test method are listed in Table 1.
Si 20 – 500
S, % 0.10 – 7.0
1.2 Detectionlimits,sensitivity,andoptimalelementranges
Ca 20 – 500
will vary with matrices, spectrometer type, analyzing crystal,
Ti 10 – 200
and other instrument conditions and parameters.
V 20 – 2000
Mn 10 – 200
1.3 All analytes are determined as the element and reported
Fe 20 – 1000
as such. These include all elements listed in Table 1. This test
Ni 20 – 500
method may be applicable to additional elements or concen-
tration ranges if sufficient standards are available to produce
proper calibration equations.
E11 Specification for Wire Cloth and Sieves for Testing
1.4 The values stated in SI units are to be regarded as the
Purposes
standard. The values given in parentheses are for information
only.
3. Terminology
1.5 This test method does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 Alpha—correction factor used to compensate for in-
responsibility of the user of this standard to establish appro-
terferences.
priate safety and health practices and determine the applica-
3.1.2 analytical sample—for the purposes of this test
bility of regulatory limitations prior to use.
method, a representative fraction taken from a larger mass of
petroleum coke and reduced by grinding to pass a 75 µm (No.
2. Referenced Documents
200 mesh) sieve.
2.1 ASTM Standards:
3.1.3 calcined petroleum coke—raw petroleum coke that
D346 Practice for Collection and Preparation of Coke
has been thermally treated to drive off the volatile matter and
Samples for Laboratory Analysis
to develop crystalline structure.
D1552 Test Method for Sulfur in Petroleum Products
3.1.4 green petroleum coke—sameasrawpetroleumcoke;a
(High-Temperature Method)
solid, carbonaceous residue produced by thermal decomposi-
D4057 Practice for Manual Sampling of Petroleum and
tion of heavy petroleum fractions or cracked stocks, or both.
Petroleum Products
3.1.5 pellet—a blend of dried sample and binder milled
D5056 TestMethodforTraceMetalsinPetroleumCokeby
together and then formed into a pellet by pressure.
Atomic Absorption
3.1.6 petroleum coke—a solid, carbonaceous residue pro-
D5600 TestMethodforTraceMetalsinPetroleumCokeby
duced by thermal decomposition of heavy petroleum fractions
InductivelyCoupledPlasmaEmissionSpectrometry(ICP-
or cracked stocks, or both
AES)
3.1.7 raw petroleum coke—petroleum coke that has not
been calcined.
3.1.8 reference samples—for the purposes of this test
This test method is under the jurisdiction of ASTM Committee D02 on
method, samples of known concentrations to be used in the
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee
D02.05.0D on Petroleum Coke. calibration of the X-ray fluorescence spectrometer.
Current edition approved Jan. 10, 1999. Published March 1999.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4. Summary of Test Method
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.1 A representative sample of petroleum coke is dried to
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. constantmassat110 610°Candthencrushedtopassa75µm
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
D6376–99
(No. 200 mesh) sieve. A weighed portion of this analytical 7.2 Hydraulic Press, capable of exerting a force of not less
sample is mixed with stearic acid, or other suitable binder, and than 276 MPa (40 000 psi).
thenmilledandcompressedintoasmall,smoothpelletsuitable 7.3 Mill or Grinder, capable of reducing 20 g of petroleum
for analysis. The pellet is irradiated by an X-ray beam. The coketoasamplepassing75µm(No.200mesh)inlessthan10
characteristic X rays of the elements analyzed are excited, min, without introducing contamination.
separated, and detected by the wavelength-dispersive X-ray 7.4 Mixer/Mill, for blending sample and binder.
spectrometer. These measured X-ray intensities are converted 7.5 Pellet Cup, Aluminum (optional), tapered to hold
to elemental concentration through the use of a calibration pressed pellets.
equation derived from analyses of standard materials. This 7.6 Pelletizing Die, for forming pellets of a diameter suit-
calibration equation defines the sensitivity and background able for use in the spectrometer.
associated with a particular X-ray spectrometer. 7.7 Sieves, 75 µm (No. 200 mesh) as specified in Specifi-
4.2 The K-alpha spectral lines are used for all of the cation E11.
elements determined by this test method. 7.8 Drying Oven, capable of maintaining a minimum tem-
perature of 110 6 10°C.
5. Significance and Use
7.9 X-ray Spectrometer, equipped for soft X-ray detection
5.1 The presence and concentration of sulfur and various
of the K-alpha spectral lines for all of the elements determined
metallic elements in a petroleum coke are major factors
by this test method. For increased sensitivity, this instrument
determiningthesuitabilityofacokeforvariouspurposes.This
shall be equipped with the following:
test method provides rapid means for measuring sulfur and
7.9.1 Analyzing Crystals—Thischoiceismadebasedonthe
commercially important metallic elements in coke samples.
element to be determined. The crystal selected should yield
5.2 This test method provides a guide for determining
optimal sensitivity with minimum interferences. The same
conformance to material specifications for use by buyers and
crystal shall be used for both standards and unknowns. See
sellers in a commercial transfer of petroleum coke.
Table 2 for recommended crystals.
5.3 Sulfur contents can be used to evaluate the potential
7.9.2 Detector,suitableforthedeterminationofelementsin
formation of sulfur oxides (SO ), a source of atmospheric
question. Choices include gas-flow proportional, sealed pro-
x
pollution.
portional, and scintillation detectors.
7.9.3 Optical path, in a vacuum.
6. Interferences
7.9.4 Pulse-height Analyzer, or other means of energy
6.1 Review all potential spectral interferences for the ele-
discrimination.
ments listed in Table 2. Follow your manufacturer’s operating
7.9.5 Suitable X-ray Tube—Chromium,molybdenum,plati-
guide to develop and apply alphas to compensate for these
num, rhodium, or tungsten target and dual targets have been
interferences.
found suitable. The scandium tube is very advantageous for
6.2 Compensate for inter-element effects by using alphas as
light elements.
part of the regression procedure provided with spectrometer
software.
8. Reagents and Materials
6.3 Changesinthesulfurconcentrationinthesampleaffects
8.1 Purity of Reagents—Reagent grade chemicals shall be
analyte X-ray intensities. Therefore, determine the magnitude
used in all tests. Unless otherwise indicated, it is intended that
of the sulfur effect on each metallic element and apply in
all reagents shall conform to the specifications of the Commit-
appropriate correction.
tee onAnalytical Reagents of theAmerican Chemical Society
3,4
wheresuchspecificationsareavailable. Othergradesmaybe
7. Apparatus
used,providedtheyareofsufficientlyhighpuritytopermituse
7.1 Balance, capable of weighing 50 6 0.01 g.
without diminishing the accuracy of the determination.
8.2 Detector Gas—P-10gas(90%argon,10%methane)is
TABLE 2 Suitable Instrument Operating Conditions
used with gas-flow proportional detectors.
2Q Angle, Background, Analyzing
Element
8.3 Pellet Binder Material—Stearic acid, or other suitable
A A A
Degrees Degrees Crystal
binder, providing no spectral interferences shall be used.
Sodium 25.05 26.75, 24.35 Multilayer, 2d ;50Å
8.4 Reference Samples, of petroleum coke bracketing the
Aluminum 145.13 143.13 PET
Silicon 144.95 147.05, 142.85 InSb
element ranges of the analytical samples. Commercial refer-
Sulfur 110.68 113.18 Ge
ence samples of this type are available from several sources.
Calcium 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) Reagent Chemicals, American Chemical Society Specifications, American
Nickel 48.66 49.92, 47.40 LiF (200) Chemical Society, Washington, DC. For suggestions on the testing of reagents not
A listed by the American Chemical Society, see Analar Standards for Laboratory
The wavelength angles and analyzing crystals listed are suitable due to their
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
sensitivityandgeneralindustryacceptance.Thesechoicesaremadebasedonthe
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
elementtobedetermined.Otherinstrumentoperatingconditionscanbeused,but
MD.
an attempt should always be made to use only those conditions yielding optimal
For the testing of reagents not listed by the American Chemical Society, see
sensitivity with minimum
...
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