1、Designation: D6722 11Standard Test Method forTotal Mercury in Coal and Coal Combustion Residues byDirect Combustion Analysis1This standard is issued under the fixed designation D6722; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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. Scope1.1 These test methods cover procedures to determine thetotal mercury content in a sample of coal or coal com
3、bustionresidue.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system, kidney, and liver damage. Merc
4、ury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury-containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAs website(http:/www.epa.gov/mercury/faq.htm) for additional informa-t
5、ion. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited bystate law.1.4 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 estab
6、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD2013/D2013M Practice for Preparing Coal Samples forAnalysisD3173 Test Method for Moisture in the Analysis
7、 Sample ofCoal and CokeD3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD4621 Guide for Quality Management in an OrganizationThat Samples or Tests Coal and Coke3D7582 Test Methods for Proximate Analysis of Coal andCoke by Macro Thermogravimetric AnalysisIEEE/
8、ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Terminology3.1 For definitions of terms used in this standard, refer toTerminology D121.4. Summary of Test Method4.1 Controlled heating of the analysis sample in oxygen isused to liberate mercury. The sa
9、mple is heated to dryness 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 decompos
10、ition products are carried 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
11、 in the light path ofa single wavelength atomic absorption spectrophotometer.Absorbance peak height or peak area, as a function of mercuryconcentration, is measured at 253.7 nm.1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subco
12、mmittee D05.29 on MajorElements in Ash and Trace Elements of Coal.Current edition approved June 1, 2011. Published June 2011. Originallyapproved in 2001. Last previous edition approved in 2006 as D672201(2006).DOI: 10.1520/D6722-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org
13、, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100
14、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1Mercury and mercury salts can be volatized at low tempera-tures. Precautions against inadvertent mercury loss should be taken whenusing this method.5. Significance and Use5.1 The emission of mercury during coal co
15、mbustion 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 configurations of the instrumentalcomponents that can be used satisfactorily f
16、or 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 detector. The following requirements arespecified for all approved instruments. (No
17、te 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 these functions.6.1.1 The instrument shall be capable of drying the sampleon
18、ce 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.6.1.3 The catalyst in the catalytic tube shall be capable ofcompleting the oxidation
19、of the sample and trapping halogensas well as nitrogen and sulfur oxides. The suggested operatingtemperature of the catalytic tube is 550C.6.1.4 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
20、 furnace capable ofrapidly heating the amalgamator to release all trapped mercury.6.1.6 The instrument shall have a absorption cell withmeasuring cuvettes through which the elemental mercuryreleased from the gold amalgamator flows. The cell shall beheated to avoid any condensation of water or other
21、decompo-sition products.6.1.7 The light source for the atomic absorption processshall be a low pressure mercury lamp.6.1.8 Anarrow bandpass 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
22、various operations of the apparatus, for recording data, andfor reporting results.6.2 Analytical Balance, with a sensitivity of 0.1 mg.6.3 Sample Combustion Boats, made of nickel and conve-nient size suitable for use in the instrument being used.7. Sample7.1 CoalPrepare the analysis sample in accord
23、ance withPractice D2013/D2013M by pulverizing the material to pass a250-m (No. 60) sieve.7.2 Solid Combustion ResidueDry a representative por-tion of the solid residue to constant weight at 110 to 115C.Determine the moisture loss during this drying step if it isdesirable to calculate results to an a
24、s-received basis. Crush thedried portion of the sample to pass a No. 200 (75-m) sieve.Use a mill that minimizes metal contamination. Use portions ofthe -200 mesh material for analysis.7.3 Activated Carbon Sorbent MaterialActivated carbonsorbent material is used in tubes for the absorption of mercury
25、from stack gases. The absorbed mercury is unevenly dispersedin the tubes. The activated carbon material in smaller absorp-tion tubes (100-200 mg) may be analyzed directly withoutfurther preparation. The activated carbon and absorbed mer-cury in larger sorbent tubes must be homogenized before anysamp
26、le subdivision. The procedure given in Appendix A2 isrecommended for the homogenization and subdivision of theactivated carbon sorbent material.47.4 Analyze separate test portions for moisture content inaccordance with Test Methods D3173 or D7582 so thatcalculation to other bases can be made.8. Reag
27、ents8.1 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 limits are issued by a recognizedcertifying agency such as the Nationa
28、l 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 musthave precision values of less than or equal to method repeat-abilit
29、y. 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-oughly before each use.9. Instrument Preparation9.1 Assemble the instr
30、umental 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 appropriate test portion of certified reference mate-rial (CRM), calibra
31、ting 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.4This procedure was developed by the LECO Corporation in St. Joseph, MI. Theprocedure and results from an 11-
32、laboratory interlaboratory study of four analyticalmethods for the analysis of mercury in Appendix K sorbent tubes can be found inthe publication:Evaluation of Methods for Mercury Analysis of Appendix K Sorbent Tubes,EPRI, Palo Alto, CA, Tennessee Valley Authority (TVA), Chattanooga, TN, AEP,Columbu
33、s, OH, Consumers Energy, Jackson, MI, First Energy, Cleveland, OH,LECO Corporation, St. Joseph, MI, Eon U.S., Lexington, KY, Southern Company,Birmingham, AL and TXU Power, Dallas, TX: 2007, 1014565, 110 pD6722 1129.3 CalibrationSelect coal CRMs or other calibratingagents and materials specified by t
34、he 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 bracket the range ofmercury to be tested, with the th
35、ird 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 calibration canresult from contamination of the CR
36、M 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, reference coal, or calibrating agent chosen torepres
37、ent 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 Methods D3173 or D7582. Continue analyz-ing unt
38、il the results from five consecutive determinations fallwithin the repeatability interval of these test methods. Calibratethe instrument according to the manufacturers instructionsusing these values. Analyze, as samples, two CRM referencecoals or calibrating agents that bracket the range of values t
39、o betested. The results obtained for these samples much be withinthe stated precision limits of the CRM, reference coal, orcalibrating agent or the calibration procedure must be repeated.Records for all calibrations must be in accordance with GuideD4621.9.3.3 Periodic Calibration Verification andRec
40、alibrationIn accordance with Guide D4621, 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 calibration procedure repeated.10. Procedure10.1 Ana
41、lyze 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,B = detector response for that analyte,C = unit mass
42、 per detector response established for theanalyte during calibration, andD = mass of test specimen, g.The calculations can be provided automatically by theinstrumental system used for these methods.12. Report12.1 Report results from the mercury determination on anyof the several common bases that di
43、ffer solely with respect tomoisture. Procedures for converting the as-determined concen-trations to the other bases are specified in Practice D3180.13. Precision and Bias13.1 PrecisionThe precision of this test method for thedetermination of mercury in coal, is shown in Table 1. Theprecision charact
44、erized 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 andconsecutive test determinations, carried out on the samesample in the same labora
45、tory 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 value below whichthe absolute difference between two test results, carried
46、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 Materials NIST 1630a,NIST 2692b, and SARM 20 were included in the interlabora-
47、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 3Whenever possible, the analysis of several reference materi-als, spanning the
48、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 Reference Material (CRM). When such amatch is not possible, but a CRM with
49、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 could 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 E691, was conducted in 2000. Eight labs participated.The details of the study and supporting data are given inASTMResearch Report RR: RR:D05-1026 file
