ASTM_D_1757_-_03.pdf

Designation:D 1757 03Standard Test Method forSulfate Sulfur in Ash from Coal and Coke1This standard is issued under the fixed designation D 1757;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method pertains to the determination of sulfatesulfur in coal or coke ash.1.2 The values stated in SI units(Practice E 380)shall beregarded as the standard.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.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 2795 Test Methods for Analysis of Coal and Coke Ash3D 3174 Test Method forAsh in theAnalysis Sample of Coaland Coke from Coal3D 3177 Test Methods for Total Sulfur in the AnalysisSample of Coal and Coke3D 3682 Test Method for Major and Minor Elements inCombustion Residues from Coal Utilization Processes3D 4326 Test Method for Major and Minor Elements in Coaland Coke Ash by X-Ray Fluorescence3E 380 Practice for Use of the International System of Units(SI)(the Modernized Metric System)42.2British Standard:BS 1016,Part 14 Analysis of Coal Ash and Coke Ash53.Summary of Test Methods3.1 Test Method AModified British MethodA specifiedquantity of ash is digested in boiling dilute hydrochloric acidsolution to which bromine water is added to convert sulfite thatmay be present to the sulfate form.After neutralization andprecipitation of iron with ammonium hydroxide,the mixture isfiltered and sulfate in the filtrate is determined gravimetricallyas barium sulfate(BaSO4).3.2 Test Method BEschka MixtureA specified quantityof ash and Eschka mixture are ignited together in air.Thesulfates are dissolved in hot water and separated from undis-solved ash residue and magnesium oxide by filtration.Sulfatein the filtrate is determined gravimetrically as barium sulfate(BaSO4).4.Significance and Use4.1 Laboratory furnace temperature and furnace ventilationhave an influence on SO3retention in laboratory ash.Conse-quently,sulfur in ash as determined in the laboratory cannot beassumed to be equivalent to sulfur present in the mineral matterin coal or to the retention of sulfur in ash produced under theconditions of commercial utilization.4.2 The sulfate sulfur determined by these test methods canbe used to calculate the sulfur trioxide portion of ash so that theash content or ash composition can be reported on a sulfurtrioxide free basis.5.Interferences5.1 Barium in coal ashes can result in incomplete recoveryof sulfate sulfur.5.2 High iron content can be encountered in coal and cokeash and can introduce error if,during the sulfate precipitation,the iron is either partially adsorbed by the BaSO4precipitate orcoprecipitated as iron sulfate.6.Apparatus6.1 Muffle Furnace,electric,capable of maintaining a tem-perature of 800 6 25C for igniting barium sulfate.6.2 Crucibles or Capsules,porcelain,platinum,alundum,orsilica of 10 to 15-mL capacity,for igniting BaSO4.1This test 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 10,2003.Published July 2003.Originallyapproved in 1960.Last previous edition approved in 2000 as D 1757 96(2000).2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 05.06.4Annual Book of ASTM Standards,Vol 14.04.5Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.7.Purity of Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.67.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type IV of Specification D 1193.8.Analysis Sample8.1 The analysis sample shall be prepared in accordancewith the section on Preparation of Coal Ash and Coke Ash inone of the following Test Methods:D 2795,D 3174,D 3682,or D 4326.8.2 Prior to analysis re-ignite at the original conditions asufficient quantity of thoroughly mixed analysis sample for aperiod of not less than 1 h.8.3 For purposes of comparison of results between labora-tories the analysis sample shall be taken from a commonanalysis sample prepared according to the conditions specifiedin 8.1 an