ASTM_D_6940_-_10.pdf

Designation:D694010Standard Practice forMeasuring Sifting Segregation Tendencies of Bulk Solids1This standard is issued under the fixed designation D6940;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.Scope*1.1 This practice covers an apparatus and procedure forsimulating the segregation tendencies of bulk solids by meansof the sifting mechanism.1.2 Temperature-and humidity-sensitive bulk solids mayneed to be tested at different temperatures and moisturecontents,as would happen in an industrial environment.1.3 The maximum particle size should be limited to 3 mm,to reduce the likelihood of binding the slide gate.1.4 This standard is not applicable to all bulk solids andsegregation mechanisms:while sifting is a common segrega-tion mechanism experienced by many bulk solids,othersegregation mechanisms not evaluated by this standard mightinduce segregation in practice.Practice D6941 covers anothercommon mechanism:fluidization.1.5 The extent to which segregation will occur in anindustrial situation is not only a function of the bulk solid andits tendency to segregate,but also the handling equipment(forexample,bin design),process(for example,transfer rates),andenvironment.1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 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:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture)Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6941 Practice for Measuring Fluidization Segregation Ten-dencies of Powders3.Terminology3.1 Definitions:3.1.1 For common definitions of terms in this standard,referto Terminology D653.3.1.2 funnel flow pattern,na flow sequence in a bin orhopper characterized by having some bulk solids movingthrough stagnant bulk solids.In general,there is no flow alongthe hopper walls.3.1.3 segregation,na process through which blended oruniform powders or bulk solids become non-uniform,withregions of varying composition,for example,particle size.3.1.4 sifting segregation,na mechanism in which finerparticles preferentially percolate into a zone within the bulksolid.3.2 Definitions of Terms Specific to This Standard:3.2.1 collection cup,na collection cup holds a specimenof bulk solid once it is discharged from the apparatus.3.2.2 inner hopper,nthe inner hopper is transparent.It hasa steep inner conical section designed to sit within the outerhopper.3.2.3 outer hopper,nthe outer hopper consists of a shal-low transparent hopper designed to provide funnel flow formost bulk solids.It has an attached slide gate/guide cylinderand support legs.3.2.4 representative sample,na quantity of the bulk solidto be tested that is representative of that solid in an industrialapplication being studied.Parameters of interest that mayaffect whether or not a sample is representative include,but arenot limited to:moisture,particle size distribution,raw materialvariation,method of production,aging,chemical composition.4.Summary of Practice4.1 A representative sample of a bulk solid is placed in theupper hopper of the apparatus.1This practice is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.24 on Characterizationand Handling of Powders and Bulk Solids.Current edition approved July 1,2010.Published August 2010.Originallyapproved in 2003.Last previous edition approved in 2004 as D694004.DOI:10.1520/D6940-10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandardsvolume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2 The bulk solid is discharged to form a pile within thelower hopper,allowing segregation to take place.4.3 The segregated material is discharged in a funnel flowpattern intended to recover zones of segregated material in aknown sequence.Specimens are collected from the dischargestream.4.4 The specimens are then available to be tested fordifferences relevant to the application,for example,particlesize or chemical assay.5.Significance an