ISO 13292:1997

SLOVENSKI STANDARD
SIST ISO 13292:2000
01-junij-2000
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Copper, lead and zinc sulfide concentrates -- Experimental methods for checking the
bias of sampling
Concentrés sulfurés de cuivre, de plomb et de zinc -- Méthodes expérimentales de
contrôle de l'erreur systématique d'échantillonnage
Ta slovenski standard je istoveten z: ISO 13292:1997
ICS:
73.060.99 Druge rude Other metalliferous minerals
SIST ISO 13292:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 13292:2000

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SIST ISO 13292:2000
INTERNATIONAL ISO
STANDARD 13292
First edition
1997-11-15
Copper, lead and zinc sulfide
concentrates — Experimental methods for
checking the bias of sampling
Concentrés sulfurés de cuivre, de plomb et de zinc — Méthodes
expérimentales de contrôle de l'erreur systématique d'échantillonnage
Reference number
A
ISO 13292:1997(E)

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SIST ISO 13292:2000
ISO 13292:1997(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.
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.
International Standard ISO 13292 was prepared by Technical Committee
ISO/TC 183, Copper, lead and zinc ores and concentrates.
Annexes A and B of this International Standard are for information only.
©  ISO 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet central@iso.ch
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
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SIST ISO 13292:2000
©
INTERNATIONAL STANDARD  ISO ISO 13292:1997(E)
Copper, lead and zinc sulfide concentrates — Experimental
methods for checking the bias of sampling
1 Scope
This International Standard specifies methods for checking whether there is any bias in the sampling of copper, lead
and zinc sulfide concentrates, where the sampling is carried out in accordance with the methods specified in ISO
12743. These methods can also be used for checking whether there is any bias in sample processing and for
checking possible significant differences in the analyses of exchange samples and lot samples taken at different
places, e.g., at loading and discharge points. Numerical examples are given in annex A.
2 Normative reference
The following standards contains provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the edition indicated was valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
1)
ISO 12743:— , Copper, lead and zinc sulfide concentrates — Sampling procedures for determination of metal and
moisture content.
3 General requirements and recommendations
The procedures specified in this International Standard are applicable to paired data only. The results obtained from
the method to be checked for bias (referred to as Method B) are compared with the results for a reference method
(referred to as Method A), which is considered to produce unbiased results from technical and empirical viewpoints.
If there is no significant difference between the results obtained using Method B and Method A, then Method B may
be adopted as a routine method.
While the procedures specified in clause 5 are principally designed for checking bias against a reference method,
separate measurements of quality characteristics, e.g., at loading (Method A) and discharge (Method B), or
analyses of exchange samples may also be compared to check whether there is a statistically significant difference
between the results.
Mechanical sampling systems or manual sampling methods are tested for bias by comparing the test results for final
system or manually collected samples (Method B) with test results for reference increments collected from a
stopped conveyor belt (Method A). Analytical methods or test procedures are checked against certified reference
materials.

1)  To be published.
1

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SIST ISO 13292:2000
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ISO 13292:1997(E) ISO
The standard method of taking reference increments from a stopped conveyor belt presents operational difficulties,
even if the handling system is capable of being restarted with a fully loaded belt. The main problems are losses in
production tonnage and the difficulty experienced in sequence starting the handling system. During a ship loading or
unloading operation, this can cause delays in the turnaround time of the ship.
Alternative reference methods, which are also expensive, divert the ore flow onto a transfer conveyor belt to
produce a material bed section identical to that from the main belt on which the mechanical primary sampler
(Method B) is installed. Stopped belt sampling is then carried out on the transfer belt to collect reference increments
(Method A). The transfer conveyor belt should be of sufficient length to allow establishment of a material bed
section which is not influenced by any longitudinal segregation introduced by the diversion plate. The primary
sampler and the point of diversion to the transfer belt should be as close as possible.
Sampling and sample processing procedures are more prone to bias than analytical techniques and test methods.
As system samples and reference increments are progressively reduced in mass and particle size, subsamples and
test samples become increasingly vulnerable to sample loss and contamination. Therefore, systematic errors occur
more frequently during sample processing than during sampling, so different stages of the sample processing
procedure may require testing for bias.
When testing for bias, the number of paired sets of measurements (data sets) shall be not less than 20. The number
of data sets required depends on the variance of the differences between the two methods and on the value of the
bias, δ, to be detected.
Any chemical or physical characteristic may be used to check whether any bias is present, e.g., copper, lead, zinc
or moisture content. Bias may not always be present for just one parameter. Therefore several parameters,
preferably including all those which are likely to be of interest, should be examined to determine whether bias exists.
Characteristics to be tested for the presence of bias need to be decided before the test work begins.
It is recommended that increments for Method A and Method B be taken from closely adjacent portions of the
concentrate, and that sample processing and analysis be carried out on each increment individually. This is likely to
reduce the number of data sets required to detect a given bias.
Even after a bias check has been conducted, further checks should be carried out at regular intervals. Bias checks
should also be carried out when sampling equipment is changed.
4 Sampling and sample processing methods
4.1 Sampling
4.1.1  General
The method to be checked (Method B) shall be compared with a designated reference method (Method A) using the
same type of concentrate. As specified in clause 3, at least 20 pairs of samples shall be collected following the
procedures detailed in ISO 12743.
4.1.2  Checking bias in mechanical sampling
Method A: Reference increments are taken by stopped-belt sampling.
Method B: System increments are taken from a moving stream with a mechanical sampler.
4.1.3  Checking bias between sampling at different locations
Method A: Increments are taken from a moving stream with a mechanical sampler at a loading location.
Method B: Increments are taken from a moving stream with a mechanical sampler at a discharge location.
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SIST ISO 13292:2000
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ISO ISO 13292:1997(E)
4.2 Sample processing
The procedure for constituting pairs of samples and carrying out the subsequent sample processing and analysis
shall be as follows:
a) Constitute two samples (sample A and sample B), consisting of one or a number of individual increments
obtained in accordance with Method A and Method B.
b) Subject sample A and sample B to similar sample processing and analysis procedures, as specified in ISO
12743 and other relevant International Standards, to obtain sets of measurements for the characteristics of
interest.
5 Analysis of experimental data
5.1 Statistical basis
It is helpful at this point to review the definitions of Type I and Type II risks in bias testing. Consider the null
hypothesis, H , that there is no positive or negative bias in Method B compared with Method A. The alternative
0
hypothesis, H , is that there is either positive or neg
...