ASTM_E_2296_-_03_2013.pdf

Designation:E229603(Reapproved 2013)Standard Practice forSilver Corrections in Metal Bearing Ores,Concentrates,andRelated Metallurgical Materials by Fire Assay Slag Recyclingand Cupel Proof Gravimetry1This standard is issued under the fixed designation E2296;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,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 This practice covers the silver loss correction,utilizingslag recycling and cupellation of proof silver during the fireassay of metal bearing ores,concentrates,and related metal-lurgical materials.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 practices and determine the applica-bility of regulatory limitations prior to use.(See Practices E50and ISO 35:1989.)2.Referenced Documents2.1 ASTM Standards:2E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE50 Practices for Apparatus,Reagents,and Safety Consid-erations for Chemical Analysis of Metals,Ores,andRelated MaterialsE135 Terminology Relating to Analytical Chemistry forMetals,Ores,and Related MaterialsE882 Guide for Accountability and Quality Control in theChemical Analysis Laboratory2.2 ISO Documents:3ISO 35:1989 Certification of Reference MaterialsGeneraland Statistical PrinciplesISO 10378:1994 CopperSulfideConcentratesDetermination of Gold and Silver ContentsFire AssayGravimetric and Atomic Absorption SpectrometricMethod3.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,refer to Terminology E135.4.Summary of Practice4.1 In the process of fire assay fusion,the slag is retainedfrom the initial fusion and reprocessed through the fusionprocedure.The resulting lead button is combined with thepreliminary lead button during cupellation.Proof silver iscarried through the cupellation procedure to determine thesilver losses.(See ISO 10378:1994,Bugbee,4and Smith5.)5.Significance and Use5.1 This practice is primarily intended to be used for thecorrection of silver loss in the fire assay process.Silvercontents are determined by fire assay for the purpose ofmetallurgical exchange between buyer and seller.It is assumedthat all who use this practice will be trained analysts capable ofperforming skillfully and safely.It is expected that work willbe performed in a properly equipped laboratory under appro-priate quality control practices such as those described inGuide E882.6.Apparatus6.1 Assay Furnace,capable of temperatures up to 1100 C,accurate to 6 5 C with draft controls.6.2 Analytical Balance,capable of weighing to 0.001 mg.6.3 Hammer,blacksmith type.6.4 Hammering Block,flat steel or iron.1This practice is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals,Ores,and Related Materials and is the direct responsibility ofSubcommittee E01.02 on Ores,Concentrates,and Related Metallurgical Materials.Current edition approved Oct.1,2013.Published October 2013.Originallyapproved in 2003.Last previous edition approved in 2008 as E2296 03(2008)1.DOI:10.1520/E2296-03R13.2For 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.3Available from International Organization for Standardization(ISO),1,ch.dela Voie-Creuse,CP 56,CH-1211 Geneva 20,Switzerland,http:/www.iso.org.4Bugbee,E.E.,A Textbook of Fire Assaying,Third Ed.,John Wiley and Sons,Inc.,Hoboken,NJ,1946.5Smith,E.A.,The Sampling and Assay of the Precious Metals,Second Ed.,Charles Griffin and Co.,Ltd.,1947.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.6Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Borax,sodium tetraborate(Na2B4O7),technical grade.7.3 Crucibles,standard fire assay clay.7.4 Cupels,magnesite(MgCO3)or bone ash,size deter-mined by lead button weight.NOTE1Cupel size is determined by the weight of the lead button.Cupels must be large enough to hold all the molten lead from the primaryfire assay fusion and slag re-fusion.7.5 Lead Foil(99.99%pu