ISO 12980:2000
(Main)Carbonaceous materials used in the production of aluminium — Green coke and calcined coke for electrodes — Analysis using an X-ray fluorescence method
Carbonaceous materials used in the production of aluminium — Green coke and calcined coke for electrodes — Analysis using an X-ray fluorescence method
This International Standard specifies an X-ray fluorescence method for the determination of elemental impurities in green and calcined petroleum cokes used for the manufacture of anodes. These anodes are used in the production of aluminium.
Produits carbonés utilisés pour la production de l'aluminium — Coke calciné et coke cru pour électrodes — Analyse par fluorescence aux rayons X
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 12980
First edition
2000-04-01
Carbonaceous materials used in
the production of aluminium — Green coke
and calcined coke for electrodes —
Analysis using an X-ray fluorescence
method
Produits carbonés utilisés pour la production de l'aluminium — Coke
calciné et coke cru pour électrodes — Analyse par fluorescence aux
rayons X
Reference number
ISO 12980:2000(E)
©
ISO 2000
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ISO 12980:2000(E)
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ISO 12980:2000(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative reference .1
3 Principle.1
4 Apparatus and materials.2
5 Sampling and test specimen preparation .2
6 Procedure .3
7 Expression of results .8
8 Precision.8
9 Test report .9
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ISO 12980:2000(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 12980 was prepared by Technical Committee ISO/TC 47, Chemistry, Subcommittee
SC 7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminium
industry.
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ISO 12980:2000(E)
Introduction
The determination of the elemental impurities is important for reasons of metal quality and anode consumption.
This International Standard refers only to petroleum coke although the principles described are valid for pitch,
anthracite, graphite or electrode materials. As the sample preparation and/or the mass fraction ranges for these
other materials are quite different it is intended that specific standard methods will be published for each material.
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INTERNATIONAL STANDARD ISO 12980:2000(E)
Carbonaceous materials used in the production of aluminium —
Green coke and calcined coke for electrodes — Analysis using an
X-ray fluorescence method
1 Scope
This International Standard specifies an X-ray fluorescence method for the determination of elemental impurities in
green and calcined petroleum cokes used for the manufacture of anodes. These anodes are used in the production
of aluminium.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these this
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent edition of the normative document indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 6375, Carbonaceous materials for the production of aluminium — Coke for electrodes — Sampling.
3Principle
A pressed tablet of pulverized coke and organic binder is irradiated by X-rays from a target thin window X-ray tube.
The X-ray tubes can be chromium, rhodium or scandium depending on which elements are to be determined.
Irradiation of the test specimen causes ejection and rearrangement of orbital electrons resulting in the emission of
secondary radiation with a characteristic wavelength for each element.
This secondary radiation is reflected, onto the detector system, by a crystal, which is set at a specific angle to the
secondary radiation. Only specific radiation which obeys Bragg's law reaches the detector system.
n� =2d�sin� (1)
where
n is the order of the diffraction;
� is the X-ray wavelength;
d is the interplanar distance in the crystal;
sin � is the angle setting of the crystal.
The intensities of the specific secondary radiation are calculated into mass fractions according to given calibration
curves.
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ISO 12980:2000(E)
4 Apparatus and materials
4.1 X-ray fluorescence spectrometer, equipped with the following crystals: LiF (lithium fluoride, reflecting
200
plane 200), PE (pentaerythiol), PX1 (synthetic W-Si), Ge, TIAP (thallium acid phthalate) and LSM (layered synthetic
microstructure). For instruments equipped with a side window X-ray tube, a scandium tube is advantageous for
light elements. For instruments equipped with an end window X-ray tube, a rhodium tube offers optimum sensitivity.
4.2 Swinging-disc mill, with tungsten-carbide grinding devices.
4.3 Organic binder, suitable for pressed-tablet preparation. The binder shall not contain any of the elements to
be analysed. Suitable binders are 'Hoechst wachs G' or stearic acid.
4.4 Tablet press, capable of providing a 20-tonne load.
4.5 Appropriate sample holders, for example aluminium dishes or brass rings with the dimensions as shown in
Figure 1.
4.6 Detector gas, consisting of 90 % argon and 10 % methane.
4.7 Calibration standards, commercially available and certified covering the range of mass fraction given in
clause 6.5.
4.8 Reference samples (RS), commercially available and certified with appropriate mass fractions for all
elements. (See 6.4.2)
Dimensions in millimetres
Figure 1 — Dimensions of sample holder
5 Sampling and test specimen preparation
5.1 Sampling
Sampling shall be in accordance with the requirements of ISO 6375.
5.2 Test specimen preparation
Crush the sample into sufficiently small particles so as to pass it through a 4 mm sieve. Dry to constant mass at
120 °C. Mill the sample of crushed material into sufficiently small particles so as to pass it through a 63�msieve.
Mix approximately 30 g of this sieved material with approximately 5 g of binder and remill for 20 s. Crush any
remaining lumps with a spatula.
If too many lumps are formed in this mixture, repeat the above procedure with a smaller quantity of binder, for
example 4 g. When a smaller quantity of binder is used, test it to see if the calibration sample and other samples
give pressed tablets strong enough to withstand the procedure. Repeat the above procedure until a suitable
quantity of binder has been added to provide an acceptable mixture for pressing a tablet.
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ISO 12980:2000(E)
Place the material into the selected sample holder.
NOTE Aluminium dishes are preferred, but brass rings ma
...
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