1、A Referencenumbe r ISO15249:1998 (E) INTERNATIONAL STANDARD ISO 15249 Firstedition 19981215 ZincsulfideconcentratesDetermination ofgoldcontentAciddissolution/solvent extraction/flameatomicabsorption spectrometricmethod ConcentrssulfursdezincDosagedelorMthodepardissolution acide,extractionlaidedunsol
2、vantetspectromtriedabsorption atomiquedanslaflammeISO15249:1998(E) ISO1998 Allrightsreserved.Unlessotherwisespecified,nopartofthispublicationmaybereproducedorutilizedinanyformorbyan ymeans,electronic ormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromthepublisher. Internati
3、onalOrganizationforStandardization Casepostale56 CH1211Genve20 Switzerland Internet isoiso.ch PrintedinSwitzerland ii Contents Page 1Scope 1 2Normativereferences . .1 3Principle 1 4Reagents. 1 5Apparatus .3 6Sample . .3 7Procedure .3 8Expressionofresults 5 9Precision .5 10Testreport . .7 AnnexA (nor
4、mative) Procedureforthepreparationanddeterminationofthemassofapredried testportion . .8 AnnexB (normative) Flowsheetoftheprocedurefortheacceptanceofanalyticalvaluesfortestsamples .10 AnnexC (informative) Derivationofprecisionequations .11 AnnexD (informative) Bibliography 16ISO ISO15249:1998(E) iii
5、Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISO memberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnical committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhas
6、therighttoberepresentedonthatcommittee.Internationalorganizations,governmentalandnongovernmental,in liaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnical Commission(IEC)onallmattersofelectrotechnicalstandardization. DraftInternationalStandardsadoptedbythetec
7、hnicalcommitteesarecirculatedtothememberbodiesforvoting. PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote. InternationalStandardISO15249waspreparedbyTechnicalCommiteeISO/TC183, Copper,leadandzincores. AnnexesAandBformanintegralpartofthisInternationalStand
8、ard.AnnexesCandDareforinformationonly.INTERNATIONALSTANDARD ISO ISO15249:1998(E) 1 ZincsulfideconcentratesDeterminationofgoldcontent Aciddissolution/solventextraction/flameatomicabsorption spectrometricmethod 1Scope ThisInternationalStandardspecifiesanaciddecomposition,solventextraction,flameatomica
9、bsorptionspectrometric procedureforthedeterminationofgoldinzincsulfideconcentrates. Themethodisapplicabletothedeterminationofgoldinzincconcentratescontainingupto60%( m/m)zincintheform ofzincblendeandrelatedmaterials. Themethodisapplicabletogoldcontentsfrom0,5g/tto12g/t. 2Normative references Thefoll
10、owingstandardscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthis InternationalStandard.Atthetimeofpublication,theeditionsindicatedwerevalid.Allstandardsaresubjecttorevision, andpartiestoagreementsbasedonthisInternationalStandardareencouragedtoinvestigatethepossibilityof app
11、lyingthemostrecenteditionsofthestandardsindicatedbelow.MembersofIECandISOmaintainregistersof currentlyvalidInternationalStandards. ISO3851:1984, LaboratoryglasswareBurettesPart1:Generalrequirements. ISO648:1977, LaboratoryglasswareOnemarkpipettes. ISO1042:1998, LaboratoryglasswareOnemarkvolumetricfl
12、asks. ISO3696:1987, WaterforanalyticallaboratoryuseSpecificationandtestmethods . ISO4787:1984, LaboratoryglasswareVolumetricglasswareMethodsforuseandtestingofcapacity . ISO9599:1991, Copper,leadandzincsulfideconcentratesDeterminationofhygroscopicmoistureintheanalysis sampleGravimetricmethod . 3Princ
13、iple Roastingoftheconcentrateat450 Cand600 Ctoremovearsenicandsulfur,followedbydecompositioninbromine aquaregiahydrofluoricacid.ExtractionofthegoldintoDIBKcontainingAliquat336fromanaquaregiamediumand determinationbyflameatomicabsorptionspectrometricat242,8nm. 4Reagents Duringtheanalysis,useonlyreage
14、ntsofrecognizedanalyticalgradeandwaterthatcomplieswithgrade2of ISO3696. 4.1 Gold metal,minimum99,99%purity.ISO15249:1998(E) ISO 2 4.2 Nitricacid, ( r 20 1,42g/ml). 4.3 Hydrochloricacid, ( r 20 1,16g/mlto1,19g/ml). 4.4 Aquaregia Mixthreepartshydrochloricacid(4.3)andonepartnitricacid(4.2)withthreepart
15、sofwater.Preparefreshlyas required. 4.5 Bromineliquid, 99,5% m/m. 4.6 Hydrofluoricacid ( r 20 1,19g/ml). WARNINGEvenwhendiluted,hydrofluoricacidisextremelydangerousandharmfultotheeyesand skin:rubberglovesandgogglesshouldbewornwhenusingthisacid.Hydrofluoricacidattacksglassware. Careshouldbetakentomin
16、imizethetimeofacidcontactwithglassware.Useonlyinamechanically ventilatedfumecupboard. 4.7 Diisobutylketone ( r 20 0,81g/ml). 4.8 Aliquat336 (methyltrioctylammoniumchloride). 4.9 1 %Aliquat336indiisobutylketone Add1mlofAliquat336(4.8)to99mlofdiisobutylketone(4.7)andmixthoroughly. 4.10 Goldstandardsol
17、utions NOTE Standardsolutionsshouldbepreparedatthesameambienttemperatureasthatatwhichthedeterminationsareto beconducted. 4.10.1 Goldstandardsolution (1000 m g/ml). Weigh0,1000gofgoldmetal(4.1)intoa50mlbeaker,add10mlaquaregia(4.4),coverandheattodissolvethe gold.Washandremovethecover,andevaporatetonea
18、rdryness(donotallowtogotodrynessotherwisegoldwill precipitate).Cool,add5mlofhydrochloricacid(4.3)andtransferthesolutionquantitativelytoa100mlvolumetric flask,dilutetovolumewithwaterandmixthoroughly. 4.10.2 Goldstandardsolution (100 m g/ml). Pipette10mlofgoldstandardsolution(4.10.1)intoa100mlvolumetr
19、icflask,add5mlofhydrochloricacid(4.3),dilute tovolumewithwaterandmixthoroughly. 4.10.3 Goldstandardsolution (10 m g/ml). Pipette10mlofgoldstandardsolution(4.10.2)intoa100mlvolumetricflask,add5mlofhydrochloricacid(4.3), dilutetovolumewithwaterandmixthoroughly. Thissolutionshallbefreshlyprepared. 4.11
20、 Calibrationsolutions NOTE Calibrationsolutionsshouldbepreparedatthesameambienttemperatureasthatatwhichthedeterminationsare tobeconducted. Toeachofseven125mlseparatingfunnelsadd75mlofwaterand20mlofaquaregia(4.4).Addfromaburette(5.2) 0ml,1ml,2ml,3ml,4ml,5mland6mlofgoldstandardsolution(4.10.3).Treatth
21、esesolutionsusingtheextraction proceduregivenin7.4. Thesestandardscontain0 m g,10 m g,20 m g,30 m g,40 m g,50 m gand60 m gofgold.ISO ISO15249:1998(E) 3 5Apparatus Ordinarylaboratoryequipmentplusthefollowing. 5.1 Volumetricglassware, ofclassAcomplyingwithISO3851,ISO648andISO1042andusedinaccordance wi
22、thISO4787. 5.2 Burette,Agrade,10mlcapacitycapableofbeingreadto0,02ml. 5.3 Mufflefurnace,capableofgivinganadequatezoneofuniformtemperaturebetween450 Cand600 C.A ventilatedfurnaceispreferred. 5.4 Crucibles, porcelain,havingadepthof10mmto15mmandadiameterof60mmto75mm. 5.5 Atomicabsorptionspectrometer(AA
23、S), equippedwithbackgroundcorrectionandaglassbead,ratherthan aflowspoiler,inthespraychamber.Scaleexpansionandaflowadjustablenebulizerarerecommended. 5.6 Centrifuge, capableofholdingatleast15mltubesandrevolvingat0,833s 1 (3000rpm). 5.7 Centrifugetubes, 15mlvolumewithcaps.Polypropyleneissuitable. 5.8
24、Separatingfunnels, of125mlcapacity.BorosilicateglasswithPTFEstopcocksarerecommended. 6Sample 6.1Test sample PrepareanairequilibratedtestsampleinaccordancewithISO9599. NOTE Atestsampleisnotrequiredifpredriedtestportionsaretobeused(seeannexA). 6.2Test portion Takingmultipleincrements,extractatestporti
25、onfromthetestsampleinsuchamannerthatitisrepresentativeof thewholecontentsofthedishortray.Weigh,tothenearest0,1mg,approximately5gofthetestsample.Atthe sametimeasthetestportionisweighed,weightestportionsforthelevelofhygroscopicmoistureinaccordance withISO9599. Alternatively,themethodspecifiedinannexAm
26、aybeusedtopreparepredriedtestportionsdirectlyfromthe laboratorysample. 7Procedure 7.1 Numberofdeterminations Carryoutthedeterminationsatleastinduplicate,andasfaraspossibleunderrepeatabilityconditions,oneachtest sample. NOTE Repeatabilityconditionsexistwheremutuallyindependenttestresultsareobtainedwi
27、ththesamemethodon identicaltestmaterialinthesamelaboratorybythesameoperatorusingthesameequipmentwithinshortintervalsoftime. 7.2Blank test Carryoutablanktestinparallelwiththeanalysisusingallreagentsspecifiedinthedeterminationbutomittingthe testportion.Thepurposeoftheblanktestinthismethodistochecktheq
28、ualityofthereagents.Ifasignificantblank valueisobtainedasaresultoftheblanktest,checkallreagentsandrectifytheproblem.ISO15249:1998(E) ISO 4 7.3 Decompositionoftestportion Transferthetestportiontoaporcelaincrucibleandplaceinthemufflefurnace(5.3)at450 Candheatfor2h. Raisethemufflefurnacetemperatureto60
29、0 Candcontinueheatingfor1h. Removethecruciblefromthefurnace,cool,andtransfertheroastedtestportiontoa250mlconicalbeaker. Add10mlofwater,swirltoformaslurryandadd2mlofbromine(4.5)andmix.Coverwithawatchglass,swirltomix andallowtostandatroomtemperaturefor15min. Add15mlofhydrochloricacid(4.3)anddigestonah
30、otplateat90 Cuntilfumesofbromineareexpelled.Continuethe digestionfor30min.Removefromthehotplateandcool. Removethewatchglassandrinsetheundersidewithaminimumofwater,collectingthewashingsintheconical beaker.Carefullyadd10mlofnitricacid(4.2)and1mlofhydrofluoricacid(4.6).Returnthebeakertothehotplate andg
31、entlyevaporatetoneardryness. NOTE Donotallowthedigestionmixturetogotodryness,asgoldwillbelost. Rinsethesidesofthebeakerwithaminimumofwater,add20mlofaquaregia(4.4),coverwiththewatchglass, returntothehotplateandheatgentlyfor10min.Removefromthehotplateandcool. 7.4Extraction Transferthetestsolutiontoa12
32、5mlseparatingfunnel(5.8),addsufficientwatertomakethevolumeto100mland swirltomix. Add8mlof1%Aliquatindiisobutylketone(4.9),stopperandshakefor1min.Allowthephasestoseparateand slowlyrunofftheloweraqueouslayeruntilabout4mlofaqueousmaterialremain.Transferthese,withtheorganic layer,toa15mlcentrifugetube(5
33、.7).Centrifugeuntilaclearorganiclayerisobtained. 7.5 Determinationofgold Determinethegoldcontentintheorganiclayerbyflameatomicabsorptionspectrometryusingcalibrationsolutions (4.11).Asaguide,thefollowingatomicabsorptionconditionsarerecommended;however,theinstrumentshouldbe optimizedtogivemaximumsensi
34、tivityandasnearaspracticaltoalinearrelationshipbetweenabsorbanceand concentration. flame:airacetyleneoxidizing wavelength:242,8nm lampcurrent:4mA backgroundcorrector:on aspirationrate:aspiratediisobutylketoneaswastesolution;adjust(reduce)flowratetogiveanoxidizing flame integrationtime:3s numberofint
35、egrations:5 NOTE Theorganicusedforextraction,diisobutylketone(4.7)shouldbeaspiratedbetweeneachstandardsolutionand betweeneachtestsolutionduringthedetermination. Performthreemeasurementsoneachstandardsolution.Calculatetothreesignificantfiguresthemeanabsorbance foreachstandardsolution,providedthatther
36、angeofvaluesdoesnotexceed0,003absorbanceunits.Ifthisrange isexceeded,repeatthecalibrations. Thetestsolutionsshouldbetreatedinthesamemanner.Plotacalibrationgraphofabsorbanceversusconcentration ofgoldintheorganiclayer.ISO ISO15249:1998(E) 5 8 Expressionofresults Thegoldcontentofthetestportion w Au ,ex
37、pressedingramspertonne,isgivenbythefollowingequation: w= C m H Au - 100 100 .(1) where C isthegoldcontentoftheorganiclayerinmicrograms; m isthemassoftestportioningrams; H isthehygroscopicmoisturecontentasapercentageofthetestportion(inthecaseofapredriedtest portionbeingused, H=0). 9Precision 9.1 Expr
38、essionofprecision Theprecisionofthisanalyticalmethodisexpressedbythefollowingequations: s r =0,0372 X +0,0042 .(2) s L =0,0822 X +0,1002 .(3) where X isthemeancontentofgold,ingramspertonne,inthesample; s r isthewithinlaboratorystandarddeviation,ingramsofgoldpertonne; s L isthebetweenlaboratoriesstan
39、darddeviation,ingramsofgoldpertonne. SeeannexC. 9.2 Methodforobtainingthefinalresult SeeannexB. Calculatethefollowingquantitiesfromtheduplicateresults X 1 and X 2 andprocessaccordingtotheflowchartin annexB: Meanofduplicates X =( X 1 + X 2 )/2 .(4) Withinlaboratorystandarddeviation s r =0,0372 X +0,0
40、042 .(5) Repeatabilitylimit r=2,8 s r .(6) 9.3 Precisionbetweenlaboratories Theprecisionbetweenlaboratoriesisusedtodeterminetheagreementbetweentheresultsreportedbytwo(or more)laboratories.Itisassumedthatalllaboratorieshavefollowedthesameprocedure.ISO15249:1998(E) ISO 6 Calculatethefollowingquantitie
41、s. Meanoffinalresults m 1,2 =( m 1 + m 2 )/2 .(7) Betweenlaboratoriesstandarddeviation s L =0,0822 m 1,2 +0,1002 .(8) Withinlaboratorystandarddeviation s r =0,0372 m 1,2 +0,0042 .(9) PermissibledifferenceP, s + s / = 28 2 () L 2 r 2 .(10) RangeE=- mm 12 .(11) where m 1 isthefinalresult,ingramsofgold
42、pertonne,reportedbylaboratory1; m 2 isthefinalresult,ingramsofgoldpertonne,reportedbylaboratory2. If Eisequaltoorlessthan P,thefinalresultsareinagreement. 9.4 Checkoftrueness Thetruenessoftheanalyticalmethodcanbecheckedbyapplyingittoacertifiedreferencematerial(CRM).The procedureisthesameasthatdescribedinclause7.Whentheprecisionhasbeenconf
