ISO 2926:2013

INTERNATIONAL ISO
STANDARD 2926
Third edition
2013-09-01
Aluminium oxide used for the
production of primary aluminium —
Particle size analysis for the range
45 µm to 150 µm — Method using
electroformed sieves
Oxyde d’aluminium utilisé pour la production d’aluminium
primaire — Analyse granulométrique dans la gamme 45 µm à 150
µm — Méthode par emploi de tamis électroformés
Reference number
©
ISO 2013
© ISO 2013
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ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Apparatus . 1
5 Procedure. 2
5.1 Sample preparation . 2
5.2 Preparation of test sieves . 2
5.3 Determination . 2
6 Calculation of results . 3
7 Test report . 3
8 Precision . 4
Annex A (informative) Example of calculation of size analysis . 5
Annex B (informative) Determination and use of effective aperture . 6
Annex C (informative) Results of interlaboratory test programme . 7
Annex D (informative) Ultrasonic cleaning of sieves
........................................................................................................................... 9
Bibliography .10
Foreword
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The committee responsible for this document is ISO/TC 226, Materials for the production of primary aluminium.
This third edition cancels and replaces the second edition (ISO 2926:2005), which has been technically
revised to reflect modern industry practice. The major changes are:
— recommended effective aperture tolerance limits have been added;
— sieves are cleaned by brushing rather than using an ultrasonic bath;
— the mass of sample to be sieved is 50 g;
iv © ISO 2013 – All rights reserved

Introduction
This International Standard is based on AS 2879.6-1995 prepared by Standards Australia.
INTERNATIONAL STANDARD ISO 2926:2013(E)
Aluminium oxide used for the production of primary
aluminium — Particle size analysis for the range 45 µm to
150 µm — Method using electroformed sieves
1 Scope
This International Standard specifies a dry sieve method using electroformed sieves for determining the
mass distribution of the particle sizes in aluminium oxide used for the production of primary aluminium.
This method is applicable to calcined aluminium oxide containing a maximum of 20 % mass fraction of
particles having a mean diameter exceeding 150 µm, and containing a maximum of 15 % mass fraction
of particles having a mean diameter less than 45 µm.
This method is not applicable to the use of woven wire sieves.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 3310-3, Test sieves — Technical requirements and testing — Part 3: Test sieves of electroformed sheets
3 Principle
A test portion of the crude sample is sieved mechanically through electroformed sieves.
Each of the separate fractions is weighed on the sieve, and a cumulative mass of material retained on
each sieve aperture size is calculated.
4 Apparatus
4.1 Test sieves, each including a sieving medium (screen) and a frame.
The frames shall be cylindrical, having nominal diameters of 200 mm and heights between 50 mm and
75 mm. A lid and a bottom receiver shall be included. The sieves, lid and bottom receiver shall be capable
1)
of being fitted together tightly to form a series of test sieves .
The screens shall be constructed of smooth electroformed sheet having square openings. The aperture
tolerances shall be in accordance with ISO 3310-3.
The sieve apertures shall have nominal sizes of 150 µm, 106 µm, 75 µm, 53 µm and 45 µm. Refer to
Annex B for effective aperture determination and tolerance limits.
1) Certified electroformed sieves manufactured by Precision Eforming of Cortland, New York, USA, are examples of
suitable products available commercially. This information is given for the convenience of users of this International
Standard and does not constitute an endorsement by ISO of these products.
4.2 Mechanical sieve shaker, capable of clamping the sieves mounted inside each other together with
the top lid and bottom receiver to form a vertical assembly.
2)
The apparatus shall impart to the sieve assembly a simultaneous horizontal rotary motion and a
vertical tapping action resulting from the fall of a hammer. This combined action shall cause sufficient
displacement of the aluminium oxide particles to prevent aggregation but not cause any deformation
of the sieving screen or any size reduction of the aluminium oxide particles through shock or abrasion.
4.3 Laboratory top pan balance, capable of weighing the sieves to the nearest 0,01 g.
The balance may be fitted with a lightweight frame mounted on the weighing pan to enable direct
weighing of test sieves and receiver.
4.4 Brush, fine bristled, soft, a few centimetres wide.
5 Procedure
5.1 Sample preparation
Split the sample into test portions by riffling or rotary sample division until the required mass is obtained.
Weigh the final split to the nearest 0,01 g. The mass (m ) of the final split should fall in the range 45 to 55 g.
5.2 Preparation of test sieves
Prepare the test sieves as follows.
a) Clean each test sieve (4.1) in turn by inverting it over a suitable container, brushing the mesh to
remove trapped particles and tapping the sieve frame lightly to remove any adhering particles.
b) Inspect each sieve to ensure that the mesh is not ruptured and there is not excessive aperture
binding. Upon holding the sieve up to a light source, areas of blinding are visible as being darker in
appearance. If more than 10 % of the sieve mesh is blinded the sieve is not sufficiently clean to use.
Larger ruptures in the sieve may be seen by visual inspection. To see smaller ruptures magnification
is required. Inspection using a stereo microscope is recommended; scan the entire mesh area and
the edges to check for ruptures.
NOTE 1 Ruptures of the mesh can be successfully repaired using silver solder or hardening synthetic resin.
When a repair is performed, check the repaired area under magnification to ensure the rupture is covered and
that the solder is bonded to the mesh.
NOTE 2 Other options for cleaning sieves are given in Annex D.
5.3 Determination
Determine the size distribution as follows.
a) Weigh each sieve (masses m ) on the top pan balance (4.3) to the nearest 0,01 g. Similarly, weigh the
bottom receiver.
b) Assemble the test sieves (4.1) on the mechanical sieve shaker (4.2) in order of increasing aperture
size from bottom to top, starting with the bottom receiver.
c) Spread the test portion (5.1) on the top-most sieve. Close with the tightly fitting lid and install the
positioning cover. Lower the hammer onto the cover.
2) RO-TAP Testing sieve shakers, (W. S. Tyler Inc., Mentor, Ohio, U.S.A.), operated in accordance with the
manufacturer’s recommended settings, are examples of suitable products available commercially. This information
is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO
of these products.
2 © ISO 2013 – All rights reserved

d) Switch on the mechanical sieve shaker and allow it to operate for 30 min.
e) Remove the sieve stack, and weigh each sieve and its contents to the nearest 0,01 g (masses m ).
f) Similarly weigh the bottom receiver and contents.
6 Calculation of results
Calculate the results as follows:
a) Calculate the masses of each retained sample from the following equation:
m = m – m (1)
3 2 1
where
m is the mass of retained sample, in grams;
m is the mass of test sieve plus retained sample, in grams;
m is the mass of test sieve, in grams.
In the case of the sample collected in the bottom receiver, m is the mass of the bottom receiver and m
1 2
is the mass of the bottom receiver plus contents.
b) Calculate the cumulative mass m for each sieve size.
c) Calculate the mass recovered m , using the following equation:
mm= (2)
53∑
where m is the mass of sieve contents for each sieve and the bottom receiver.
If the mass m exceeds the mass of the original test portion (m ) by more than 0,5 g, or if m is less than
5 0 5
m , then another test portion should be analysed. Due to absorption of moisture during the test, some
increase in mass is normal. Any loss in mass is most likely caused by physical loss of sample.
d) Calculate, to two decimal places, the cumulative per cent final mass m for each sieve aperture size,
using the following equation:
m
m =×100
m
e) Prepare a table of values of m corresponding to each successive nominal aperture size. Report each
value of m to one decimal place.
NOTE 1 It can be useful to plot a cumulative distribu
...