1、Designation: D 6722 01 (Reapproved 2006)Standard Test Method forTotal Mercury in Coal and Coal Combustion Residues byDirect Combustion Analysis1This standard is issued under the fixed designation D 6722; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he 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. Scope1.1 These test methods cover procedures to determine thetotal mercury content in a sampl
3、e of coal or coal combustionresidue.1.2 The values stated in SI units are regarded as thestandard.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
4、 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 121 Terminology of Coal and CokeD 2013 Practice for Preparing Coal Samples for AnalysisD 3173 Test Method for Moisture in theAnalysis Sample ofCoal and CokeD 3180 Practice
5、for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD 4621 Guide for Quality Management in an OrganizationThat Samples or Tests Coal and CokeD 5142 Test Methods for Proximate Analysis of the Analy-sis Sample of Coal and Coke by Instrumental ProceduresIEEE/ASTM SI 10 Standard f
6、or Use of the InternationalSystem of Units (SI): The Modern Metric System3. Terminology3.1 For definitions of terms used in this standard, refer toTerminology D 121.4. Summary of Test Method4.1 Controlled heating of the analysis sample in oxygen isused to liberate mercury. The sample is heated to dr
7、yness in theinstrument and then thermally and chemically decomposed.The decomposition products are carried by flowing oxygen tothe catalytic section of the furnace, where oxidation is com-pleted and halogens as well as nitrogen and sulfur oxides aretrapped. The remaining decomposition products are c
8、arried toa gold amalgamator that selectively traps mercury. After thesystem is flushed with oxygen to remove any remainingdecomposition products, the amalgamator is rapidly heated,releasing mercury vapor. Flowing oxygen carries the mercuryvapor through absorbance cells positioned in the light path o
9、fsingle wavelength atomic absorption spectrophotometer. Ab-sorbance peak height or peak area, as a function of mercuryconcentration, is measured at 253.7 nm.NOTE 1Mercury and mercury salts can be volatized at low tempera-tures. Precautions against inadvertent mercury loss should be taken whenusing t
10、his method.5. Significance and Use5.1 The emission of mercury during coal combustion can bean environmental concern.5.2 When representative test portions are analyzed accord-ing to this procedure, the total mercury is representative ofconcentrations in the sample.6. Apparatus6.1 There are several co
11、nfigurations of the instrumentalcomponents that can be used satisfactorily for this test method.Functionally, the instrument shall have the following compo-nents: drying compartment, decomposition tube, catalyst tube,gold amalgamator, amalgamator furnace, measuring cuvettes,mercury lamp, and detecto
12、r. The following requirements arespecified for all approved instruments. (Note 2).NOTE 2The approval of an instrument with respect to these functionsis paramount to this test method, since such approval tacitly providesapproval of both the materials and the procedures used with the system toprovide
13、these functions.6.1.1 The instrument shall be capable of drying the sampleonce it is weighed and introduced.6.1.2 The instrument shall have a decomposition tube whichshall be operated at a temperature high enough to completelydecompose the sample. The suggested operating temperature is800C.1This tes
14、t method is under the jurisdiction of 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 April 1, 2006. Published April 2006. Originallyapproved in 2001. Last previous edition approved
15、 in 2001 as D672201.2For 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.1Copyright ASTM International, 100 Barr H
16、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.3 The catalyst in the catalytic tube shall be capable ofcompleting the oxidation of the sample and trapping halogensas well as nitrogen and sulfur oxides. The suggested operatingtemperature of the catalytic tube is 550C.6.
17、1.4 The instrument shall contain a gold amalgamator fixedto an inert material and shall be capable of trapping allmercury.6.1.5 The amalgamator shall contain a furnace capable ofrapidly heating the amalgamator to release all trapped mercury.6.1.6 The instrument shall have a absorption cell withmeasu
18、ring cuvettes through which the elemental mercuryreleased from the gold amalgamator flows. The cell shall beheated to avoid any condensation of water or other decompo-sition products.6.1.7 The light source for the atomic absorption processshall be a low pressure mercury lamp.6.1.8 A narrow bandpass
19、interference filter or monochroma-tor, capable of isolating the 253.65 nm mercury line, shall beused.6.1.9 The system may contain a computer for controllingthe various operations of the apparatus, for recording data, andfor reporting results.6.2 Analytical Balance, with a sensitivity of 0.1 mg.6.3 S
20、ample Combustion Boats, made of nickel and conve-nient size suitable for use in the instrument being used.7. Sample7.1 Prepare the analysis sample of coal in accordance withMethod D 2013 by pulverizing the material to pass a 250-mm(No. 60) sieve.7.2 Analyze separate test portions for moisture conten
21、t inaccordance with Test Method D 3173 or Test Methods D 5142.8. Reagents8.1 OxygenHigh purity oxygen, as specified by the instru-ment manufacturer, shall be used.8.2 Certified Reference Materials (CRMs)Use CertifiedReference Material (CRM) coals with dry-basis mercury val-ues for which confidence l
22、imits are issued by a recognizedcertifying agency such as the National Institute of Standardsand Technology (NIST). It is recommended that the user verifythe value with the certifying agency before using the CRM coalfor quality control purposes.8.3 All CRMs, reference coals, or calibrating agents mu
23、sthave precision values of less than or equal to method repeat-ability. Such CRMS, reference coals, or calibrating agents mustbe stable with respect to moisture and be pulverized to pass100 % through a 250 m (No. 60) USAStandard Sieve. CRMs,reference coals, or calibrating agents must be mixed thor-o
24、ughly before each use.9. Instrument Preparation9.1 Assemble the instrumental system in accordance withthe manufacturers instructions. Follow the instrument manu-facturers recommended procedure to optimize the perfor-mance of the instrument.9.2 Adjustment of Response of Measurement SystemWeigh an app
25、ropriate test portion of certified reference mate-rial (CRM), calibrating agent, or reference coal. Analyze thetest portion (see 9.1). Repeat this procedure. Adjust instrumentresponse, as recommended by the manufacturer, until theabsence of drift is indicated.9.3 CalibrationSelect coal CRMs or other
26、 calibratingagents and materials specified by the manufacturer that havecertified mercury values in the range of samples to be analyzed.Three such CRMs or calibrating agents are recommended foreach range of mercury values to be tested. When possible, twoof the CRMs or calibrating agents shall bracke
27、t the range ofmercury to be tested, with the third falling within the range.9.3.1 All coal CRMs should be in accordance with 8.2 andshall be supplied by or have traceability to an internationallyrecognized certifying organization.WarningAn indicatedproblem with linearity of the instrument during cal
28、ibration canresult from contamination of the CRM or calibrating agent asthe container becomes depleted. It is therefore recommendedthat the CRM or calibrating agent be discarded when less thanfive grams remain in the container.9.3.2 Calibration ProcedureAnalyze, as samples, por-tions of a CRM, refer
29、ence coal, or calibrating agent chosen torepresent the level of mercury in the samples to be tested. Usethe “as-determined” mercury values for calibration. Thesevalues must have been calculated previously from the certified“dry basis” mercury values and residual moisture determinedusing either Test
30、Methods D 3173 or D 5142. Continue ana-lyzing until the results from five consecutive determinationsfall within the repeatability interval of these test methods.Calibrate the instrument according to the manufacturers in-structions using these values. Analyze, as samples, two CRMreference coals or ca
31、librating agents that bracket the range ofvalues to be tested. The results obtained for these samplesmuch be within the stated precision limits of the CRM,reference coal, or calibrating agent or the calibration proceduremust be repeated. Records for all calibrations must be inaccordance with Guide D
32、 4621.9.3.3 Periodic Calibration Verification andRecalibrationIn accordance with Guide D 4621, analyze acontrol sample on a periodic basis. Results obtained for thecontrol sample must be within established limits, or all resultsobtained since the last successful control check must berejected and the
33、 calibration procedure repeated.10. Procedure10.1 Analyze a test specimen of the analysis sample inaccordance with the manufacturers instructions.11. Calculation11.1 Calculate the concentration of mercury, on the appro-priate sample basis, as follows:A 5B 3 C!D3 100 (1)where:A = mg/Kg of the analyte
34、,B = detector response for that analyte,C = unit mass per detector response established for theanalyte during calibration, andD 6722 01 (2006)2D = mass of test specimen, g.The calculations can be provided automatically by theinstrumental system used for these methods.12. Report12.1 Report results fr
35、om the mercury determination on anyof the several common bases that differ solely with respect tomoisture. Procedures for converting the as-determined concen-trations to the other bases are specified in Practice D 3180.13. Precision and Bias13.1 PrecisionThe precision of this test method for thedete
36、rmination of mercury in coal, is shown in Table 1. Theprecision characterized by the repeatability (Sr, r) and repro-ducibility (SR, R) is described in Table A1.1 in Annex A1.13.1.1 Repeatability Limit (r)The value below which theabsolute difference between two test results of separate andconsecutiv
37、e test determinations, carried out on the samesample in the same laboratory by the same operator using thesame apparatus on samples taken at random from a singlequantity of homogeneous material, may be expected to occurwith a probability of approximately 95 %.13.1.2 Reproducibility Limit (R)The valu
38、e below whichthe absolute difference between two test results, carried out indifferent laboratories using samples taken at random from asingle quantity of material that is as homogeneous as possible,may be expected to occur with a probability of approximately95 %.13.2 BiasCertified Reference Materia
39、ls NIST 1630a,NIST 2692b, and SARM 20 were included in the interlabora-tory study to ascertain possible bias between reference materialvalues and those determined by this method. A comparison ofthe NIST and SARM values and those obtained in theinterlaboratory study are given in Table 2.NOTE 3Wheneve
40、r possible, the analysis of several reference materi-als, spanning the concentration range of interest, is the most meaningfulway to investigate measurement bias. When a matrix match is possible theuncertainty in sample measurements can be equated to that observed inmeasurement of the Certified Refe
41、rence Material (CRM). When such amatch is not possible, but a CRM with a related matrix is available, the testsample uncertainty may be related to those observed when measuring theCRM. Different methods of measurement of a property may not becapable of equal repeatability. Accordingly, instances cou
42、ld arise wherethe method of measurement has greater variability than that or those usedin certification of the CRM.13.3 An interlaboratory study, designed consistent withPractice E 691, was conducted in 2000. Eight labs participated.The details of the study and supporting data are given inASTMResear
43、ch Report RR:D-5 1026 filed at ASTM headquarters.ANNEX(Mandatory Information)A1. PRECISION STATISTICSA1.1 The precision of this test method, characterized byrepeatability (Sr, r) and reproducibility (SR, R) has beendetermined for the following materials as listed in Table A1.1.A1.2 Repeatability Sta
44、ndard Deviation (Sr)The standarddeviation of test results obtained under repeatability condi-tions.A1.3 Reproducibility Standard Deviation (SR)The stan-dard deviation of test results obtained under reproducibilityconditions.TABLE 1 Concentration Range and Limits for Repeatability andReproducibility
45、for Mercury in CoalConcentrationRange, ppmRepeatability LimitrReproducibility LimitRHg 0.017 0.5860.008 + 0.06 x0.007 + 0.13 xTABLE 2 Comparison of Certified Values for NIST 1630a, NIST2692b, and SARM 20 with Interlaboratory Study Values for TotalMercury in CoalReferenceCRM LevelRR Value,ppmCRM Valu
46、e,ppmBias,ppmSignificant(95% Confidence)NIST 1630a 0.0912 0.0938 0.0026 noNIST 2692b 0.124 0.1333 0.0093 yesSARM 20 0.25 0.25 0 noD 6722 01 (2006)3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users o
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48、e years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical c
49、ommittee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.as
