ISO 23202:2006

INTERNATIONAL ISO
STANDARD 23202
First edition
2006-06-01

Aluminium oxide used for the production
of aluminium — Determination of
particles passing a 20 micrometre
aperture sieve
Oxyde d'aluminium utilisé pour la production de l'aluminium —
Détermination de la finesse des particules: mesure du passant
à 20 micromètres




Reference number
ISO 23202:2006(E)
©
ISO 2006

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ISO 23202:2006(E)
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ISO 23202:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Principle. 1
4 Safety . 1
5 Reagents. 1
6 Apparatus . 2
7 Sampling and sample preparation. 3
8 Procedure . 3
9 Calculation and expression of results. 5
10 Precision. 5
11 Quality control. 5
12 Test report . 6
Annex A (informative) Results of test programme . 7
Annex B (normative) Determination of effective aperture of the test sieve. 8
Bibliography . 10

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ISO 23202:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 23202 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary
aluminium.
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ISO 23202:2006(E)
Introduction
This International Standard is based on Australian method, AS 2879.2-2003, Alumina — Determination of
particles passing a 20 micrometre aperture sieve.
The Minus 20 Micron reference material ASCRM 026 was released in December 2003 by SAI Global, along
with a Technical Report on its preparation (TR 2.26-2003, Certified reference materials — Alumina —
Preparation and certification of ASCRM 026). These are available from SAI through their website:
http://www.standards.com.au/

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INTERNATIONAL STANDARD ISO 23202:2006(E)

Aluminium oxide used for the production of aluminium —
Determination of particles passing a 20 micrometre aperture
sieve
1 Scope
This International Standard sets out a wet-sieving procedure for the determination of the percentage by mass
of particles of smelter-grade alumina passing a 20 µm aperture sieve.
This procedure is applicable for aluminas with a −20 µm content up to 4 %.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 802:1976, Aluminium oxide primarily used for the production of aluminium — Preparation and storage of
test samples
ISO 806:2004, Aluminium oxide primarily used for the production of aluminium — Determination of loss of
mass at 300 °C and 1 000 °C
ISO 3310-3, Test sieves — Technical requirements and testing — Part 3: Test sieves of electroformed sheets
3 Principle
A test sample of alumina is sieved on a 20 µm electroformed sieve, using acetone, and the retained material
is determined gravimetrically after drying at 300 °C.
4 Safety
Chemicals used may be hazardous or toxic and reference should be made to the appropriate Material Safety
Data Sheets.
CAUTION — ACETONE PRESENTS A FLAMMABILITY RISK AND SHOULD BE USED IN A SUITABLE
EXTRACTION HOOD.
5 Reagents
5.1 Acetone, analytical reagent grade.
5.2 Desiccant.
Phosphorous pentoxide, activated alumina and molecular sieves have been found to be suitable. Silica gel is
not a suitable desiccant.
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ISO 23202:2006(E)
WARNING — PHOSPHOROUS PENTOXIDE IS A HAZARDOUS MATERIAL AND REFERENCE SHOULD
BE MADE TO THE APPROPRIATE MATERIAL SAFETY DATA SHEET.
5.3 Ethanol or methanol, technical grade.
6 Apparatus
Ordinary laboratory equipment and the following.
6.1 Test sieve, consisting of a frame, nominally of diameter 75 mm to 150 mm, with an electroformed
20 µm aperture mesh constructed and tested in accordance with ISO 3310-3. The aperture shape shall be
round and the sieving medium shall be supported by a suitable grid to provide adequate strength. The
construction materials shall be such that the sieve is resistant to chemical corrosion and no physical damage
shall occur as a result of heating to 110 °C. The mesh shall be attached to the frame of the sieve such that
particles cannot lodge in any part of the joining seam.
NOTE Two suitable mesh sizes are commonly available, 317# and 570#. The open area of the mesh is
approximately 17 % for the 570#, and 3,5 % for the 317#. Thus, the 570# sieve is more efficient but more fragile than the
317# sieve.
6.2 Sieve brush, which is acetone-compatible, of high quality with an unpainted handle and soft bristles.
Any paint on the brush shall be removed.
NOTE 1 Westart Akrilik Filbert #6 or #8 brushes have been found suitable. This information is given for the
convenience of users of this International Standard and does not constitute an endorsement by ISO of the product named.
Equivalent products may be used if they can be shown to lead to the same results.
NOTE 2 A stiff-bristled brush (e.g. hog's bristle) is not suitable, as it may bias the analysis high and may also damage
the sieve mesh.
NOTE 3 A dark-bristled brush is useful, as any alumina particles adhering to the bristles are easily seen.
6.3 Ovens, fitted with mechanical air circulation and capable of being controlled at (300 ± 10) °C.
6.4 Vacuum desiccator, containing an aluminium heat sink, in accordance with ISO 806, and a tray
containing desiccant. A tray containing approximately 250 g of desiccant is suitable.
6.5 Platinum crucibles, of 25 ml capacity and approximate dimensions of 35 mm diameter and 40 mm
depth and fitted with lids. Two crucible and lid sets are required for each determination. The crucible and lid
sets shall be conditioned by placing in an oven maintained at (300 ± 10) °C for 30 min, then cooled and stored
in the heat sink in the desiccator.
6.6 Wash bottle, made of polyethylene and filled with reagent-grade acetone.
6.7 Ultrasonic bath.
6.8 Sample scoop, made of stainless steel or brass with a handle. Nominally this scoop shall take up to
0,5 g of alumina when loaded. (See Figure 1.)
Dimensions in millimetres
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ISO 23202:2006(E)

a
Wall thickness (nominal).
Figure 1 — Typical sampling scoop
7 Sampling and sample preparation
A 50 g test sample shall be prepared from the laboratory sample as specified in ISO 802, taking particular
care to avoid loss of fine particles through dusting. The test sample shall be mixed well by manual or
mechanical tumbling in a sealed container that is not more than 75 % full. After tumbling, let the container rest
to allow fines to settle. Each test portion shall be extracted with the sample scoop (6.8), taking a number of
grabs to make up the required mass. Manual tumbling shall be repeated between extraction of test portions.
A flat-bladed spatula or vibrating spatula should not be used, as segregation may occur.
8 Procedure
8.1 Check the sieve
The sieve shall be checked to ensure that the mesh is not ruptured and that there is not excessive aperture
blinding. When holding the sieve up to a light source, areas of blinding are visible as being darker in
appearance. If more than 30 % of the sieve mesh is blinded, the sieve shall be cleaned as specified in 8.2.
Larger ruptures in the sieve may be seen by visual inspection. To see smaller ruptures, magnification is
required. Inspection using a stereo-microscope
...