ASTM_D_3684_-_01.pdf

Designation:D 3684 01Standard Test Method forTotal Mercury in Coal by the Oxygen BombCombustion/Atomic Absorption Method1This standard is issued under the fixed designation D 3684;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 describes a procedure for the analysisof total mercury in coal.1.2 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.Specific precau-tionary statements are given in 8.3.1.1.3 The values stated in SI units(IEEE/ASTM SI 10)shallbe regarded as the standard.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 2013 Method of Preparing Coal Samples for Analysis3D 3173 Test Method for Moisture in theAnalysis Sample ofCoal and Coke3D 3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different Bases3D 5142 Test Methods for the Proximate Analysis of theAnalysis Sample of Coal and Coke by InstrumentalProcedures3E 144 Practice for Safe Use of Oxygen CombustionBombs4IEEE/ASTM SI 10 Standard for Use of International Sys-tem of Units(SI):The Modern Metric System43.Summary of Test Method3.1 Total mercury is determined in this test method bycombusting a weighed sample in an oxygen bomb with dilutenitric acid absorbing the mercury vapors.The bomb is rinsedinto a reduction vessel with dilute nitric acid,and the mercuryis determined by the flameless cold vapor atomic absorptiontechnique.NOTE1Mercury and mercury salts can be volatilized at low tempera-tures.Precautions against inadvertent mercury loss should be taken whenusing this method.4.Significance and Use4.1 The possible emission of mercury that may be found incoal from coal combustion is an environmental concern.4.2 When test portions are burned according to this proce-dure,the total mercury is quantitatively retained and is repre-sentative of concentrations in the whole coal.5.Apparatus5.1 Combustion BombThe combustion bomb shall beconstructed of materials that are not affected by the combustionprocess or products.The bomb must be designed so that allliquid combustion products can be completely recovered bywashing the inner surfaces.There must be no gas leakageduring the test.The bomb must be capable of withstanding ahydrostatic pressure test to gage pressure of 20 MPa(approxi-mately 3000 psig)at room temperature without stressing any ofthe parts beyond the elastic limit.5.2 Water BathA container shall be large enough to holdthe combustion bomb,and enough cooling water shall be usedto dissipate the heat generated during the combustion process.The container should be designed to allow a constant flow ofwater around the combustion bomb.5.3 Combustion CruciblesSamples shall be burned in anopen crucible of platinum,quartz,or acceptable base-metalalloy.5.4 Firing Wire,100 mm of either No.34 B&S(0.160-mm)nickel-chromium alloy,No.34 B&S iron,or No.38 B&S(0.101-mm)gage platinum wire.5.5 Firing CircuitA 6-to 16-V alternating or directcurrent is required for ignition purposes with an ammeter orpilot light in the circuit to indicate when current is flowing.Astepdown transformer connected to an alternating currentlighting circuit or batteries may be used.The ignition circuitswitch shall be of the momentary double-contact type,nor-mally open,except when held closed by the operator.Theswitch should be depressed only long enough to fire the charge.5.6 Analytical Balance,with a sensitivity of 0.1 mg.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 October 10,2001.Published December 2001.Origi-nally published as D 3684 78.Last previous edition D 3684 94(2000).2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 05.06.4Annual Book of ASTM Standards,Vol 14.04.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.7 Atomic Absorption Spectrophotometer,with a flamelesscold-vapor mercury analysis system comprised of either aclosed recirculating system or an open one-pass system.5.8 Reduction Vessels,biochemical oxygen demand(BOD)bottles,300-mL capacity.6.Reagents6.1 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.5Other grades may beused,provided it is first