1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 6043-2.4:2000 ISO 1298
2、0:2000 ICS 71.100.10; 75.160.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Methods of sampling and test for carbonaceous materials used in aluminium manufacture Part 2: Electrode coke Section 2.4: Analysis by X-ray flourescence spectroscopyThis British Standard, having be
3、en prepared under the direction of the Sector Committee for Materials and Chemicals, was published under the authority of the Standards Committee and comes into effect on 15 August 2000 BSI 08-2000 ISBN 0 580 36316 3 BS 6043-2.4:2000 Amendments issued since publication Amd. No. Date Comments Nationa
4、l foreword This British Standard reproduces verbatim ISO 12980:2000 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CII/24, Raw materials for the aluminium industry, which has the responsibility to: aid enquirers to understa
5、nd the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on thi
6、s committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using t
7、he “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity fro
8、m legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 9 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.Referencenumber ISO12980
9、:2000(E) INTERNATIONAL STANDARD ISO 12980 Firstedition 2000-04-01 Carbonaceousmaterialsusedin theproductionofaluminiumGreencoke andcalcinedcokeforelectrodes AnalysisusinganX-rayfluorescence method Produits carbons utiliss pour la production de laluminium Coke calcin et coke cru pour lectrodes Analys
10、e par fluorescence aux rayons XISO12980:2000(E) ii ISO12980:2000(E)iii Contents Page Foreword.iv Introduction.v 1 Scope1 2 Normativereference1 3 Principle1 4 Apparatusandmaterials.2 5 Samplingandtestspecimenpreparation.2 6 Procedure.3 7 Expressionofresults8 8 Precision.8 9 Testreport9ISO12980:2000(E
11、) iv Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISO memberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnical committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishe
12、dhas therighttoberepresentedonthatcommittee.Internationalorganizations,governmentalandnon-governmental,in liaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnical Commission(IEC)onallmattersofelectrotechnicalstandardization. InternationalStandardsaredraftedinac
13、cordancewiththerulesgivenintheISO/IECDirectives,Part3. DraftInternationalStandardsadoptedbythetechnicalcommitteesarecirculatedtothememberbodiesforvoting. PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote. Attentionisdrawntothepossibilitythatsomeoftheelemen
14、tsofthisInternationalStandardmaybethesubjectof patentrights.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights. InternationalStandardISO12980waspreparedbyTechnicalCommitteeISO/TC47, Chemistry, Subcommittee SC7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonace
15、ous products for the aluminium industry.ISO12980:2000(E)v Introduction Thedeterminationoftheelementalimpuritiesisimportantforreasonsofmetalqualityandanodeconsumption. ThisInternationalStandardrefersonlytopetroleumcokealthoughtheprinciplesdescribedarevalidforpitch, anthracite,graphiteorelectrodemater
16、ials.Asthesamplepreparationand/orthemassfractionrangesforthese othermaterialsarequitedifferentitisintendedthatspecificstandardmethodswillbepublishedforeachmaterial.INTERNATIONALSTANDARD ISO12980:2000(E)1 Carbonaceousmaterialsusedintheproductionofaluminium GreencokeandcalcinedcokeforelectrodesAnalysi
17、susingan X-rayfluorescencemethod 1 Scope ThisInternationalStandardspecifiesanX-rayfluorescencemethodforthedeterminationofelementalimpuritiesin greenandcalcinedpetroleumcokesusedforthemanufactureofanodes.Theseanodesareusedintheproduction ofaluminium. 2 Normativereference Thefollowingnormativedocument
18、containsprovisionswhich,throughreferenceinthistext,constituteprovisionsof thisInternationalStandard.Fordatedreferences,subsequentamendmentsto,orrevisionsof,anyofthesethis publicationsdonotapply.However,partiestoagreementsbasedonthisInternationalStandardareencouragedto investigatethepossibilityofappl
19、yingthemostrecenteditionofthenormativedocumentindicatedbelow.For undatedreferences,thelatesteditionofthenormativedocumentreferredtoapplies.MembersofISOandIEC maintainregistersofcurrentlyvalidInternationalStandards. ISO6375, Carbonaceous materials for the production of aluminium Coke for electrodes S
20、ampling. 3Principle ApressedtabletofpulverizedcokeandorganicbinderisirradiatedbyX-raysfromatargetthinwindowX-raytube. TheX-raytubescanbechromium,rhodiumorscandiumdependingonwhichelementsaretobedetermined. Irradiationofthetestspecimencausesejectionandrearrangementoforbitalelectronsresultingintheemiss
21、ionof secondaryradiationwithacharacteristicwavelengthforeachelement. Thissecondaryradiationisreflected,ontothedetectorsystem,byacrystal,whichissetataspecificangletothe secondaryradiation.OnlyspecificradiationwhichobeysBraggslawreachesthedetectorsystem. n =2d sin (1) where n istheorderofthediffractio
22、n; istheX-raywavelength; d istheinterplanardistanceinthecrystal; sin istheanglesettingofthecrystal. Theintensitiesofthespecificsecondaryradiationarecalculatedintomassfractionsaccordingtogivencalibration curves.ISO12980:2000(E) 2 4 Apparatusandmaterials 4.1 X-rayfluorescencespectrometer,equippedwitht
23、hefollowingcrystals:LiF 200 (lithiumfluoride,reflecting plane200),PE(pentaerythiol),PX1(syntheticW-Si),Ge,TIAP(thalliumacidphthalate)andLSM(layeredsynthetic microstructure).ForinstrumentsequippedwithasidewindowX-raytube,ascandiumtubeisadvantageousfor lightelements.Forinstrumentsequippedwithanendwind
24、owX-raytube,arhodiumtubeoffersoptimumsensitivity. 4.2 Swinging-discmill,withtungsten-carbidegrindingdevices. 4.3 Organicbinder,suitableforpressed-tabletpreparation.Thebindershallnotcontainanyoftheelementsto beanalysed.SuitablebindersareHoechstwachsGorstearicacid. 4.4 Tabletpress,capableofprovidinga2
25、0-tonneload. 4.5 Appropriatesampleholders,forexamplealuminiumdishesorbrassringswiththedimensionsasshownin Figure1. 4.6 Detectorgas,consistingof90%argonand10%methane. 4.7 Calibrationstandards,commerciallyavailableandcertifiedcoveringtherangeofmassfractiongivenin clause6.5. 4.8 Referencesamples(RS),co
26、mmerciallyavailableandcertifiedwithappropriatemassfractionsforall elements.(See6.4.2) Dimensionsinmillimetres Figure1Dimensionsofsampleholder 5 Samplingandtestspecimenpreparation 5.1 Sampling SamplingshallbeinaccordancewiththerequirementsofISO6375. 5.2 Testspecimenpreparation Crushthesampleintosuffi
27、cientlysmallparticlessoastopassitthrougha4mmsieve.Drytoconstantmassat 120C.Millthesampleofcrushedmaterialintosufficientlysmallparticlessoastopassitthrougha63 msieve. Mixapproximately30gofthissievedmaterialwithapproximately5gofbinderandremillfor20s.Crushany remaininglumpswithaspatula. Iftoomanylumpsa
28、reformedinthismixture,repeattheaboveprocedurewithasmallerquantityofbinder,for example4g.Whenasmallerquantityofbinderisused,testittoseeifthecalibrationsampleandothersamples givepressedtabletsstrongenoughtowithstandtheprocedure.Repeattheaboveprocedureuntilasuitable quantityofbinderhasbeenaddedtoprovid
29、eanacceptablemixtureforpressingatablet.ISO12980:2000(E)3 Placethematerialintotheselectedsampleholder. NOTE Aluminiumdishesarepreferred,butbrassringsmayalsobeused. Placethefilledsampleholderinthepressandpressat20tfor20s. Forthebestresults,thetestspecimenshouldbeatleast4mmthick. 6 Procedure 6.1 Measur
30、ementconditions Themeasurementconditionsareapparatus-dependentbuttheindicationsinTable1canserveasguidelines. Normallynolineoverlappingwillbeexperiencediftheseconditionsareusedforthemeasurementofpetroleum coke. Table1Typicalmeasurementconditionsforthedifferentelements Element line Na K Al K Si K S K
31、Ca K V K Fe K Ni K Crystal LSM a or PX1 PEorPX1 PEorPX1 PEorGe LiF 200 LiF 200 LiF 200 LiF 200 Counter F b F F FFFFF Exposure, totaltime,s 100 20 20 10 10 20 30 20 Collimator coarse coarse coarse medium fine fine fine fine kV 40 40 40 40 40 40 60 60 mA 60 60 60 60 60 60 40 40 Angle 28 PE:145,1 PX1:1
32、9,5 PE:109,2 PX1:16,6 PE:75,8 PX1:110,9 113,1 76,9 57,5 48,7 Offsetangle c 2 1 1 1 F=flowcounter a Layeredsyntheticmicrostructurewith2dvaluearound5nm. b A1 mor2 mflowcounterwindowisrequired. c Backgroundmeasurementangles( offsetangles). 6.2 Intensitiesandbackgroundcorrections ThenetpeakintensityI,ex
33、pressedasthenumberofcountspersecond,oftheelementofinterestiscalculatedas thedifferencebetweenthemeasuredpeakintensityoftheelementandthebackgroundintensityatthepeakangle inaccordancewithequations(4)and(5).SeeFigure2. I=I p I b (2) where I p isthecountrate,expressedasthenumberofcountspersecond,attheel
34、ementposition(2 ); I b isthebackgroundcountrate,expressedasthenumberofcountspersecond,attheelementposition (2 );ISO12980:2000(E) 4 and I=I p C 1 I b1 C 2 I b2 (3) where I b1 iscountrate,expressedasthenumberofcountspersecond,atthenegative( offsetangleofthe backgroundposition; I b2 iscountrate,express
35、edasthenumberofcountspersecond,atthepositive( offsetangleofthe backgroundposition; C d dd 1 2 12 C d dd 2 1 12 where d 2 isthedifferencebetweenthepositive( offsetangleofthebackgroundpositionand2 ; d 1 isthedifferencenegative( offsetangleofthebackgroundpositionand2 ; togivethenetcountrateI. Figure2In
36、tensitiesandbackgroundcorrectionsISO12980:2000(E)5 6.3 Countingtime Theminimumcountingtimeisthetimenecessarytoachieveanetcountingerror(2 % ) net whichislessthanthe desiredprecisionforthemeasurement. Assumethatthepartofthecountingerrorintherepeatability( 4 )ofthismethodisabout50%. Chooseareferencemat
37、erialhavinganelementmassfractioninthemiddleoftherangegivenin6.5.1.Measure thecountingrate.Calculatetheminimumcountingtimeforeachelementbyusingequation(4). t= 100 2 1 % pb F H G G I K J J II 2 (4) Where t isthetotalcountingtimeforthepeaksandbackground; I p ismeasuredpeakintensity,expressedasthenumber
38、ofcountspersecond; I b isthebackgroundintensity,expressedasthenumberofcountspersecond; 2 % istherelativetargetedprecision,expressedasapercentage,atthe95%probabilitylevel. ForNa,take2%astherelativetargetedprecisionfor2 % .Forotherelements,take1%for2 % . Thisequationrequiresthatthedistributionofthecou
39、ntingtimeatpeakandbackgroundfollowtheequationbelow: t t I I p b p b = (5) where t p isthecountingtimeforthepeak; t b isthecountingtimeforthebackground. NOTE Additionalcheckssuchasmonitorsamplesarerecommended,andwilldependontheageandstateofthe equipment.Adescriptionisgivenin6.4.1. 6.4 Driftdetectionb
40、yuseofamonitorsample 6.4.1 Driftdetection Anydriftinthenetcountratecanbedetectedbyusingamonitorstandardduringthecalibrationprocedureand duringthemeasurementofunknownsamples. Calculatethedriftfactorf d foreachelementbytheratio f I I d = 1 n (6) where I 1 istheintensityofmonitorstandardduringthecalibr
41、ationprocedure; I n istheintensityofmonitorstandardwhenunknownsamplesaremeasured.ISO12980:2000(E) 6 Ifthedriftfactordoesnotliewithintherepeatabilityrange(see7.1)thisindicatesthatamajorchange,orproblem hasoccurredintheX-rayequipment.ChecktheX-rayequipment,rectifyasnecessaryandrecalibrate. 6.4.2 Selec
42、tionandpreparationofmonitorstandards Amonitorstandardcanbepreparedasdescribedbelowor,alternatively,useareferencesample(RS),with appropriatemassfractionsforallelements. Monitorstandardscanbepreparedincopperdishes,withdimensionsaccordingtotheactualsampleholderas showninFigure1. Selectappropriatecompon
43、entsforthemonitorsample,weighthemintothedesiredproportions,mixthemcarefully andfusethemat1200Cina(Pt+5%Au)-crucible(atypicalrecipeisgiveninTable2). Allowtocool,crushthemeltandmeltagain.Repeatthisprocedureoncemore,thenfinelygrindthemeltinthe swinging-discmill.Placethepowderinathinlayerinthecopperdish
44、andheatonagasburneruntiltheenamel softensandadherestothecopper.Repeatthisprocedureuntilalayerof0,5mminthecopperdishiscreated.A typicalrecipeformonitorstandardsisshowninTable2.Asuitableamountis5g. Table2Typicalmonitorrecipe S V Ni Na Ca Al Fe Si Li 2 B 4 O 7 90% K 2 SO 4 8% V 2 O 5 0,3% NiO 0,3% Na 2
45、 CO 3 0,2% CaO 0,2% Al 2 O 3 0,2% Fe 2 O 3 0,3% SiO 2 0,3% Itispreferablethatthemonitorstandardgivessomewhathigherintensitiesthanthetestsamples. Thebestresultsareobtainedwhenthemassfractionsofthedifferentelementsarechoseninsuchawaythatthe monitorintensitiesare10timesto20timesthemeanintensitiesmeasur
46、edonthecalibrationstandards. Takethemonitorsample,asdescribedabove,ortheappropriatereferencesamplethatistobeusedasamonitor, andprepareaccordingto5.2. Aftercalibration,inordertodetermineitsnominalmassfraction,testthehomogeneityofthemonitorstandard. IftheactualvalueofthemonitorRSliesoutsidetherepeatab
47、ilityrange(see7.1)whenanalysingunknown samples,analyseanewRS.Iftheresultsstillexceedthetolerancemassfraction,recalibratetheequipment. 6.5 Calibration 6.5.1 Referencematerialselection ThecertifiedreferencematerialsareselectedinordertocovertherangeofimpuritiesgiveninTable3. Table3Massfractionrangeofth
48、ereferencematerials Elements S % V g/g Ni g/g Na g/g Ca g/g Al g/g Fe g/g Si g/g Massfraction range 0,5to5 20to500 20to500 20to200 20to200 20to500 20to500 20to500ISO12980:2000(E)7 Certifiedcalibrationstandardsshallhavebeencertifiedbyinterlaboratorytestinginaccordancewithwetchemical methods. Preparet
49、hesereferencematerialsinaccordancewith5.2. Sulfurisresponsibleforanabsorptioneffect;thereforereferencematerialsshowinghighandlowelementalmass fractionsandwithhighandlowsulfurcontentshallbeavailabletocorrectforthiseffect. 6.5.2 Calculationofthecalibrationline Inthecalibrationgraph(seeanexampleinFigure3)thenetcountrate(I)orthecountrateratio(monitorsample) isgivenonthey-axis,whilethechemicalmassfraction(w)isgivenonthex-axis.Thecalibrationlineisfixedb
