ISO 4443:2022

INTERNATIONAL ISO
STANDARD 4443
First edition
2022-01
Cryolite primarily used for the
production of aluminium —
Determination of elements —
Wavelength-dispersive X-ray
fluorescence spectrometric method
using pressed powder tablets
Cryolithe principalement utilisée pour la production de
l'aluminium — Dosage des éléments — Méthode par spectrométrie
de fluorescence des rayons X à dispersion de longueur d'onde utilisant
des pastilles de poudre pressée
Reference number
ISO 4443:2022(E)
© ISO 2022

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ISO 4443:2022(E)
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© ISO 2022
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Published in Switzerland
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ISO 4443:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 1
6 Apparatus . 2
7 Test procedure .2
7.1 Test specimen preparation . 2
7.2 Test tablet preparation . 2
7.3 X-ray fluorescence spectrometer application . 2
7.3.1 Instrumental conditions . 2
7.3.2 Calibration and calibration reference materials . 3
7.3.3 Verification of the calibration . 3
7.4 Monitoring of the sample for correction of instrumental drift . 3
7.5 Analyses, calculation and expression of results . 4
8 Precision . 4
8.1 General . 4
8.2 Repeatability . 4
8.3 Reproducibility . 4
9 Test report . 5
Annex A (informative) Conversion table . 6
Annex B (informative) Example of how to use Table 2 using sulfur (SO ) .7
4
Bibliography . 8
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ISO 4443:2022(E)
Foreword
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This document was prepared by Technical Committee ISO/TC 226, Materials for the production of
primary aluminium.
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ISO 4443:2022(E)
Introduction
In the production of aluminium, cryolite is used as a flux in order to lower the melting points of
aluminium smelting baths and increase the conductivity of the electrolyte. This use is critical during
the start-up and normal operation stages of electrolysis cells.
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INTERNATIONAL STANDARD ISO 4443:2022(E)
Cryolite primarily used for the production of aluminium —
Determination of elements — Wavelength-dispersive X-ray
fluorescence spectrometric method using pressed powder
tablets
1 Scope
This document specifies a wavelength-dispersive X-ray fluorescence spectrometric (XRF) method for
the determination of cryolite (Na AlF ) from the content of fluorine to the content of trace elements.
3 6
The calibration reference materials are not specified in this method.
The method is applicable to cryolite, which is primarily used for the production of aluminium. Annex A
provides conversion factors for converting elements to compounds. The validity and precision of test
results for concentrations outside these ranges has not been determined.
The concentration range of fluorine (given as F) is from 510 g/kg to 560 g/kg. The concentration range
of aluminium (given as Al) is from 120 g/kg to 150 g/kg. The concentration range of sodium (given as
Na) is from 270 g/kg to 330 g/kg. The concentration range of silicon (given as SiO ) is from the lowest
2
limit of detection (LLD) to 4,0 g/kg. The concentration range of iron (given as Fe O ) is from LLD to
2 3
0,37 g/kg. The concentration range of sulfur (given as SO ) is from LLD to 5,0 g/kg. The concentration
4
range of phosphorus (given as P O ) is from LLD to 0,40 g/kg. The concentration range of calcium
2 5
(given as CaO) is from LLD to 0,80 g/kg.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
A representative sample of cryolite is milled. A test portion is packed and pressed on a powder tablet
press to make the test tablets.
The test tablets are analysed on an X-ray fluorescence spectrometer instrument that has been calibrated
using a series of cryolite reference materials covering the required concentration range of the elements
to be determined.
5 Reagents and materials
5.1 Acetone or ethyl alcohol, analytical pure, used as dispersing agent.
5.2 Boric acid, analytical pure.
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ISO 4443:2022(E)
6 Apparatus
6.1 Wavelength-dispersive X-ray fluorescence spectrometer (XRF), with vacuum path and
equipped with crystals required as shown in Table 1.
6.2 Vibratory disc mill, with tray, ring and puck made of non-contaminating material. Tungsten-
car
...