ISO 12744:2025

Copper, lead, zinc and nickel concentrates - Experimental methods for checking the precision of sampling

This document specifies methods for checking the precision of primary sampling, sample processing, chemical analysis, physical testing and determination of moisture content of copper, lead, zinc and nickel concentrates being carried out in accordance with the methods specified in ISO 12743, expressed in terms of standard deviations.

Concentrés de cuivre, de plomb, de zinc et de nickel — Méthodes expérimentales de contrôle de la fidélité de l'échantillonnage

General Information

• Status: Published
• Publication Date: 09-Mar-2025
• ICS: 73.060.99 - Other metalliferous minerals
• Technical Committee: ISO/TC 183 - Copper, lead, zinc and nickel ores and concentrates
• Drafting Committee: ISO/TC 183 - Copper, lead, zinc and nickel ores and concentrates
• Current Stage: 6060 - International Standard published
• Start Date: 10-Mar-2025
• Due Date: 24-Aug-2025
• Completion Date: 10-Mar-2025

Relations

• Revises: ISO 12744:2006 - Copper, lead, zinc and nickel concentrates - Experimental methods for checking the precision of sampling
• Effective Date: 06-Jun-2022

Overview

ISO 12744:2025 - "Copper, lead, zinc and nickel concentrates - Experimental methods for checking the precision of sampling" specifies standardized experimental procedures to quantify the precision of primary sampling, sample processing, chemical analysis, physical testing and moisture determination for copper, lead, zinc and nickel concentrates. Precision is expressed in terms of standard deviations and is intended for use with sampling procedures in ISO 12743. This third edition updates the evaluation method to use mean squared differences between duplicates, giving a better unbiased estimate of precision.

Key topics and requirements

• Scope: Precision checks for sampling, sample processing, analysis and moisture content determination of sulfide concentrates.
• Interleaved sampling: Pairs of interleaved samples (A and B) formed by diverting alternate increments are the basis for experimental checks.
• Sample numbers: Recommended sampling from more than 20 lots of the same concentrate type for reliable conclusions; minimum increments typically set at 2n (or n divided into two interleaved samples in routine checks).
• Sample processing methods: Three prescribed methods:
  • Method 1: Divide each interleaved sample into two laboratory samples and analyse each in duplicate - allows separate estimation of sampling, processing and analysis precision.
  • Method 2: Unequal division (two from A, one from B) with duplicates - provides separate estimates but with lower precision than Method 1.
  • Method 3: One lab sample from each interleaved sample analysed in duplicate - yields analysis precision and the combined sampling+processing precision.
• Evaluation: Precision calculated from duplicate results using mean squared differences; results reported as estimated standard deviations (sampling S, processing P, analysis A, total T).
• Frequency and conditions: Regular precision checks are recommended, especially after equipment or procedure changes; all determinations run in randomized order by the same analyst on the same day using the same equipment.

Applications and users

ISO 12744:2025 is used for:

• Quality control and verification in assay laboratories and metallurgical labs
• Sampling validation for mining companies, concentrate producers and traders
• Contractual dispute resolution where precise measurement of metal and moisture content is required
• Audit, accreditation and internal QA programs that require documented precision estimates

Typical users: metallurgists, sampling engineers, laboratory managers, quality assurance personnel, and third‑party auditors.

Related standards

• ISO 12743 - Sampling procedures for metal and moisture content (primary reference)
• ISO 10258 - Copper sulfide concentrates - titrimetric determination of copper
• ISO 11441 - Lead sulfide concentrates - determination of lead
• ISO 12739 - (Referenced for analytical methods)

Keywords: ISO 12744:2025, sampling precision, copper concentrates, lead concentrates, zinc concentrates, nickel concentrates, interleaved samples, sample processing, standard deviation, analytical precision.

Standards Content (Sample)

International
Standard
ISO 12744
Third edition
Copper, lead, zinc and nickel
2025-03
concentrates — Experimental
methods for checking the precision
of sampling
Concentrés de cuivre, de plomb, de zinc et de nickel — Méthodes
expérimentales de contrôle de la fidélité de l'échantillonnage
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 General conditions . 2
5.1 General .2
5.2 Number of lots .2
5.3 Number of increments and number of samples .2
5.4 Sample processing and analysis.3
5.5 Frequency of precision checks .3
6 Method of experiment . 3
6.1 Interleaved samples .3
6.2 Sample processing and analysis.4
6.2.1 General .4
6.2.2 Sample processing method 1 .5
6.2.3 Sample processing method 2 .5
6.2.4 Sample processing method 3 .6
7 Evaluation of experimental data . 7
7.1 General .7
7.2 Sample processing method 1 .7
7.3 Sample processing method 2 .8
7.4 Sample processing method 3 .10
8 Assessment of results and action .11
8.1 General .11
8.2 Sampling .11
8.3 Sample processing .11
8.4 Analysis .11
9 Recording of data .11
Annex A (informative) Recording of sampling data .12
Bibliography .16

iii
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
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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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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Any trade name used in this document is information given for the convenience of users and does not
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO’s adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 183, Copper, lead, zinc and nickel ores and
concentrates.
This third edition cancels and replaces the second edition (ISO 12744:2006), which has been technically
revised.
The main changes are as follows:
— the precisions of sampling, sample preparation and measurement are now estimated from the mean
squared differences between duplicates rather than simply the mean differences, which provides a
better unbiased estimate of precision.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 12744:2025(en)
Copper, lead, zinc and nickel concentrates — Experimental
methods for checking the precision of sampling
WARNING — This document can involve hazardous materials, operations and equipment. It is the
responsibility of the user of this document to establish appropriate health and safety practices and
determine the applicability of regulatory limitations prior to use.
1 Scope
This document specifies methods for checking the precision of primary sampling, sample processing,
chemical analysis, physical testing and determination of moisture content of copper, lead, zinc and nickel
concentrates being carried out in accordance with the methods specified in ISO 12743, expressed in terms of
standard deviations.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 10258, Copper sulfide concentrates — Determination of copper content — Titrimetric methods
ISO 11441, Lead sulfide concentrates — Determination of lead content — Back titration of EDTA after
precipitation of lead sulfate
ISO 12743, Copper, lead, zinc and nickel concentrates — Sampling procedures for determination of metal and
moisture content
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 Symbols
k number of lots
n number of increments
R absolute difference between duplicates for interleaved samples A and B
R absolute difference between means for divided interleaved samples A and A , and B and B
2 1 2 1 2
R absolute difference between means for interleaved sample A and interleaved sample B
s estimated value of standard deviation, σ

2 2
s estimated variance from R
1 1
2 2
s estimated variance from R
2 2
2 2
s estimated variance from R
3 3
s estimated standard deviation of analysis
A
s estimated standard deviation of sample processing
P
s estimated standard deviation of sampling
S
s estimated standard deviation of sampling and sample processing
SP
s estimated total standard deviation of sampling, sample processing and analysis
T
x first duplicate result for interleaved sample, where i = 1 and 2 and indicates interleaved sample A or B
i1
x second duplicate result for interleaved sample, where i = 1 and 2 and indicates interleaved sample
i2
A or B
x first duplicate result for interleaved sample, where i = 1 and 2 and indicates interleaved sample A
ij1
or B, and j = 1 or 2 and indicates laboratory samples A or A , and B or B
1 2 1 2
x second duplicate result for sample, where i = 1 and 2 and indicates interleaved sample A or B, and
ij2
j = 1 or 2 and indicates laboratory samples A or A , and B or B
1 2 1 2
x
mean value of duplicate results
mean of mean value of duplicate results
x
mean of x values, and grand mean for sample processing method 3
x
grand mean of all results for sample processing methods 1 and 2
x
5 General conditions
5.1 General
The determination of precision of primary sampling is based on collecting pairs of interleaved samples from
each lot. If sample processing and measurement are also carried out in duplicate, it is possible to determine
the precision of sample processing and analysis.
5.2 Number of lots
It is recommended that pairs of interleaved samples should be collected from more than 20 lots of the same
type of concentrate, in order to reach a reliable conclusion. The lot size shall be chosen to ensure that more
than 20 lots are available for the precision determination.
5.3 Number of increments and number of samples
The minimum number of increments for checking precision should preferably be twice the number
determined in accordance with ISO 12743. Hence, if the number of increments required for routine sampling
is n and one lot sample is constituted, the minimum number of increments should be 2n, and two interleaved
samples shall be constituted.
Alternatively, if the precision is being checked as part of routine sampling, n increments may be taken and
two interleaved samples constituted, each comprising n/2 increments. The sampling precision thus obtained
shall be divided by 2 to obtain the sampling precision for lot samples comprising n increments.
5.4 Sample processing and analysis
Sample processing shall be carried out in accordance with ISO 12743. The analysis of samples shall be
carried out according to the methods specified in the relevant International Standards, such as ISO 10258,
ISO 11441 and ISO 12739.
5.5 Frequency of precision checks
It is recommended that, even after a precision check has been conducted, further checks should be carried
out at regular intervals. Precision checks should also be carried out when there is a change in equipment.
Because of the large amount of work involved in checking precision, it is recommended that checks should
be carried out as a part of routine sampling and analysis.
6 Method of experiment
6.1 Interleaved samples
Each alternate primary increment shall be diverted so that pairs of interleaved samples A and B are formed.
The number of divided increments per primary increment should be the same as for routine sampling. An
example of a sampling plan for producing pairs of interleaved samples A and B is shown in Figure 1.

Figure 1 — Example of a plan for interleaved duplicate sampling
6.2 Sample processing and analysis
6.2.1 General
The pairs of interleaved samples A and B taken in accordance with 6.1 shall be divided separately and subjected
to method 1, method 2 or method 3 sample processing and analysis as described in 6.2.2, 6.2.3 or 6.2.4.

6.2.2 Sample processing method 1
The two interleaved samples A and B shall be divided separately to prepare four laboratory samples: A , A ,
1 2
B and B . These laboratory samples shall each be analysed in duplicate, and the duplicates designated as
1 2
follows:
— x and x for sample A ;
111 112 1
— x and x for sample A ;
121 122 2
— x and x for sample B ;
211 212 1
— x and x for sample B .
221 222 2
See Figure 2.
The eight determinations shall be run in random order, by the same analyst on the same day using
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