Standard Practice for Measuring Sifting Segregation Tendencies of Bulk Solids

SCOPE
1.1 This practice covers an apparatus and procedure for simulating the segregation tendencies of bulk solids by means of the sifting mechanism.
1.2 Temperature- and humidity-sensitive bulk solids may need to be tested at different temperatures and moisture contents, 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 and segregation mechanisms: while sifting is a common segregation mechanism experienced by many bulk solids, other segregation mechanisms not evaluated by this standard might induce segregation in practice.
1.5 The extent to which segregation will occur in an industrial situation is not only a function of the bulk solid and its tendency to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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09-Jul-2003
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ASTM D6940-03 - Standard Practice for Measuring Sifting Segregation Tendencies of Bulk Solids
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D 6940 – 03
Standard Practice for
1
Measuring Sifting Segregation Tendencies of Bulk Solids
This standard is issued under the fixed designation D 6940; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 segregation, n—a process through which blended or
uniform powders or bulk solids become non-uniform, with
1.1 This practice covers an apparatus and procedure for
regions of varying composition, for example, particle size.
simulating the segregation tendencies of bulk solids by means
3.1.3 sifting segregation, n—a mechanism in which finer
of the sifting mechanism.
particles preferentially percolate into a zone within the bulk
1.2 Temperature- and humidity-sensitive bulk solids may
solid.
need to be tested at different temperatures and moisture
3.2 Definitions of Terms Specific to This Standard:
contents, as would happen in an industrial environment.
3.2.1 collection cup, n—a collection cup holds a sample of
1.3 The maximum particle size should be limited to 3 mm,
bulk solid once it is discharged from the apparatus.
to reduce the likelihood of binding the slide gate.
3.2.2 inner hopper, n—the inner hopper is transparent. It
1.4 This standard is not applicable to all bulk solids and
has a steep inner conical section designed to sit within the outer
segregation mechanisms: while sifting is a common segrega-
hopper.
tion mechanism experienced by many bulk solids, other
3.2.3 outer hopper, n—the outer hopper consists of a
segregation mechanisms not evaluated by this standard might
shallow transparent hopper designed to provide funnel flow for
induce segregation in practice.
most bulk solids. It has an attached slide gate/guide cylinder
1.5 The extent to which segregation will occur in an
and support legs.
industrial situation is not only a function of the bulk solid and
3.2.4 representative sample, n—a quantity of the bulk solid
its tendency to segregate, but also the handling equipment (for
to be tested that is representative of that solid in an industrial
example, bin design), process (for example, transfer rates), and
application being studied. Parameters of interest that may
environment.
affect whether or not a sample is representative include:
1.6 This standard does not purport to address all of the
moisture, particle size distribution, raw material variation,
safety concerns, if any, associated with its use. It is the
method of production, aging, chemical composition.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Practice
bility of regulatory limitations prior to use.
4.1 A representative sample of a bulk solid is placed in the
2. Referenced Documents upper hopper of the apparatus.
4.2 The bulk solid is discharged to form a pile within the
2.1 ASTM Standards:
lower hopper, allowing segregation to take place.
D 653 Terminology Relating to Soil, Rock, and Contained
2
4.3 The segregated material is discharged in a funnel flow
Fluids
pattern intended to recover zones of segregated material in a
3. Terminology
known sequence. Samples are collected from the discharge
stream.
3.1 Definitions—Definitions of terms used in this test
4.4 The samples are then available to be tested for differ-
method shall be in accordance with Terminology D 653.
ences relevant to the application, for example, particle size or
3.1.1 funnel flow pattern, n—a flow sequence in a bin or
chemical assay.
hopper characterized by having some bulk solids moving
through stagnant bulk solids. In general, there is no flow along
5. Significance and Use
the hopper walls.
5.1 Sifting segregation can cause horizontal segregation (for
example, center-to-periphery) within bins used to hold and
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This practice is under the jurisdiction of ASTM Committee D18 on Soil and
transport bulk solids. This can affect final product quality in
Rock and is the direct responsibility of Subcommittee D18.24 on Characterization
industrial applications.
and Handling of Powders and Bulk Solids.
Current edition approved July 10, 2003. Published August 2003.
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Annual Book of ASTM Standards, Vol 04.08
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6940–03
5.2 By measuring a bulk solid’s segregation tendency, one 5.3.3 Suffıciently Free Flowing Material—This allows the
can compare results to other bulk solids with known history, or smaller particles to sift through the matrix of larger particles.
determine if the given bulk solid may h
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