ISO/TR 18336:2016

TECHNICAL ISO/TR
REPORT 18336
First edition
2016-02-15
Guidelines for good XRF laboratory
practice for the iron ore industry
Lignes directrices de bonnes pratiques de laboratoire de
spectrométrie de fluorescence de rayons X pour l’industrie du
minerais de fer
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Reagents . 1
3 Apparatus . 2
4 Fused glass beads . 5
4.1 General . 5
4.2 Storage . 5
4.3 Disc making precision . 5
4.4 Bead distortion (curvature and flatness) . 6
5 Quality control . 6
5.1 Selection of QC samples and frequency of preparation . 6
5.2 Analysis of QC and analytical samples . 7
5.3 Control charts . 7
5.4 Participation in proficiency test programs . 8
Annex A (informative) Results for flux loss on ignition testing . 9
Annex B (informative) Procedure to check disc making precision .10
Annex C (informative) Method to determine relationship between height and concentration.11
Annex D (informative) Production of a height adjustable cup .12
Annex E (informative) Bead measurement apparatus .13
Annex F (informative) Flow sheet for fused bead quality .14
Annex G (informative) Microsoft Excel program for calculating disc precision .15
Annex H (informative) Data input screen for calculating disc precision .19
Annex I (informative) Loss of accuracy with no loss of precision .20
Annex J (informative) Loss of accuracy with loss of precision .22
Annex K (informative) Loss of accuracy and precision — Loss of bead making precision .23
Annex L (informative) Results for spectrometer precision test .25
Annex M (informative) Drift correction .26
Bibliography .27
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 2, Chemical analysis.
iv © ISO 2016 – All rights reserved

Introduction
This Technical Report is intended for use in conjunction with other International Standards for the
chemical analysis of iron ores. Although it was written for a high through-put iron ore laboratory,
the procedures described can be modified to suit other industry or laboratory requirements. Some
laboratories may find the recommended frequency of testing recommended by this Technical Report
to be excessive for their situation or the precision required by them. In this case, the operator may use
their informed discretion to adapt the recommendations of the guidelines to their situation.
TECHNICAL REPORT ISO/TR 18336:2016(E)
Guidelines for good XRF laboratory practice for the iron
ore industry
1 Scope
This Technical Report specifies recommended quality control procedures for XRF laboratories
operating within the iron ore industry.
2 Reagents
All reagents (including fusion fluxes and calibration reagents) should be purchased from reputable
suppliers and should meet the minimum requirements for purity as listed in ISO 9516-1. All reagents
should have a batch number and, where available, a certificate of analysis. Details of purchased reagents
(supplier, amount purchased, quality, and batch number) should be recorded. These records should
include what the reagents are used for. For batches of flux, the records should indicate which samples
were analysed with a particular batch.
2.1 Fusion flux
As the levels of contamination may vary from batch to batch of flux, the purity of fusion fluxes should
be checked prior to use. This can be achieved by fusing duplicate beads of pure silica and iron with
the new flux, and analysing these along with beads prepared using a previously tested (certified) flux.
Background concentrations should not exceed 10 ppm to 20 ppm (as compared to a certified batch of
flux) for each of the following oxides Mn O , SnO , V O , Cr O , Co O , NiO, CuO, ZnO, As O , PbO, BaO,
3 4 2 2 5 2 3 3 4 2 3
Na O and Cl and the sum of the positive differences should not exceed 40 ppm to 50 ppm.
The concentrations of the oxides should not exceed 0,01 % for each of the following oxides Fe O , SiO ,
2 3 2
CaO, Al O , TiO , MgO, K O and P O , (the absolute sum of the differences should not exceed 0,02 %),
2 3 2 2 2 5
while backgrounds should not differ by more than 0,01 %. Sulfur (reported as SO ) can frequently vary
by 0,05 %. Where flux does not conform to specifications, a second duplicate set of beads (made with old
and new flux) should be prepared by a different operator on the same day, or by the same operator on a
different day. If the material fails to meet the minimum specifications, the supplier of non-conforming
flux should be contacted and a replacement batch obtained and tested.
Where non-significant deviations are observed for major and trace elements between flux batches,
these beads can be used to update calibration intercepts. In all cases, records of calibration prior and
after amendment should be kept.
Prior to calibration amendment, the concentration levels of all previously analysed blank beads (prior
to calibration amendment) should be plotted, and trends noted. If consecutive sets of duplicate beads
show consistent positive concentration increases, previous beads should be refused and re-run, and the
trends confirmed or negated.
Where laboratories elect to use additive fluxes (oxidizing, release agents or internal standard
compounds), the homogeneity of the flux should be tested, assessed and compared against the quoted
quality or against a flux batch that is known to be homogenous. Testing methods include direct
measurement of added analytes, or indirect measurement of a quality parameter (ignition loss). An
example of flux testing results can be found in Annex A.
As calibrations would have been amended, trends will be seen as negative values progressing towards
a more positive result. If past expected trends cannot be replicated, the XRF instrument (calibration,
monitor) should be inspected. If previously seen trends are repeated, flux suppliers should be contacted,
and the problem discussed.
2.2 Calibration reagents
Reagents used for XRF recalibration should be checked in a similar manner to that used to check flux
(by preparing both the old reagent and the new reagent in the same type of flux). Here the level of
contaminants should not exceed those reported on the reagent supplier’s certificate of analysis. Please
note that it is common for reagent suppliers to report reagent purity based on an “as difference” basis.
Consequently, a 99,999 % reagent may have only been analysed for a single contaminant whose content
is less than 1 ppm. However, this reagent may contain other contaminants which have not been analysed
whose concentration may be significant.
Alternatively, if no in-house high purity reagent is available, small quantities of analysed reagents may
be obtained from reputable laboratories. In addition, where reagents are suspected of contamination,
they can be externally analysed.
3 Apparatus
All equipment used to prepare and measure fused glass beads should be checked on a regular basis in
accordance with the schedule set out in Table 1. The frequencies defined in Table 1 are those required by
a high through-put iron ore laboratory. As this Technical Report is a guideline rather than a prescriptive
standard, laboratories with lesser demands can modify the figures accordingly.
3.1 Bead preparation equipment
All equipment used for the production of fused glass beads (such as balances, fusion ware, fusion
furnaces and sample drying equipment) should be installed, maintained and operated in accordance to
the manufacturer’s recommendations. The external surfaces of all fusion furnaces should be inspected
at the commencement of each shift for excessive dust and glass fragments or glass spills. If any spillage
is detected it should be cleaned up before further use. On a weekly basis, or if spillage has occurred,
fusion furnaces should be allowed to cool and the interior should be inspected for faults (broken or
loose furnace
...