ISO 11790:2017
(Main)Copper, lead, zinc and nickel concentrates — Guidelines for the inspection of mechanical sampling systems
Copper, lead, zinc and nickel concentrates — Guidelines for the inspection of mechanical sampling systems
ISO 11790:2017 sets out recommended practices for the inspection of mechanical sampling systems. It serves as a reference for conformance with applicable International Standards for copper, lead, zinc and nickel concentrates. ISO 11790:2017 covers general considerations, including precision, quality variation, bias, establishment of inspection systems and inspection procedures.
Concentrés de cuivre, de plomb, de zinc et de nickel — Lignes directrices pour le contrôle des systèmes mécaniques d'échantillonnage
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INTERNATIONAL ISO
STANDARD 11790
Second edition
2017-06
Copper, lead, zinc and nickel
concentrates — Guidelines for the
inspection of mechanical sampling
systems
Concentrés de cuivre, de plomb, de zinc et de nickel —
Lignes directrices pour le contrôle des systèmes mécaniques
d’échantillonnage
Reference number
ISO 11790:2017(E)
©
ISO 2017
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ISO 11790:2017(E)
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ISO 11790:2017(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General consideration . 2
4.1 Precision . 2
4.2 Quality variation . 2
4.3 Bias . 2
4.4 Operation of the sampling system . 2
5 Establishment of inspection system . 3
5.1 General . 3
5.2 Audits . 3
5.3 Mechanical inspections. 4
5.4 Operational inspections . 4
6 Procedures . 4
6.1 Audits . 4
6.2 Mechanical inspections. 5
6.3 Operational inspections . 6
6.4 Control charts . 6
6.4.1 General. 6
6.4.2 Sampling ratio . 6
6.4.3 Extraction ratio . 7
6.5 Sampling records .10
6.6 Operator’s inspection report .10
Annex A (informative) Example of a sampling checklist for copper ore .11
Annex B (informative) Example of sampling plant operator’s inspection report on a shift basis .14
Annex C (informative) Example of sampling-system operations inspection summary .17
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ISO 11790:2017(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.
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).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 183, Copper, lead, zinc and nickel ores and
concentrates.
This second edition cancels and replaces the 2010 edition (ISO 11790:2010), of which it constitutes
a minor revision. The main change is the deletion of reference to ISO 20212, which has not yet been
published.
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INTERNATIONAL STANDARD ISO 11790:2017(E)
Copper, lead, zinc and nickel concentrates — Guidelines for
the inspection of mechanical sampling systems
WARNING — This document may 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 any other limitations prior to use.
1 Scope
This document sets out recommended practices for the inspection of mechanical sampling systems. It
serves as a reference for conformance with applicable International Standards for copper, lead, zinc and
nickel concentrates.
This document covers general considerations, including precision, quality variation, bias, establishment
of inspection systems and inspection procedures.
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 12743, Copper, lead, zinc and nickel concentrates — Sampling procedures for determination of metal
and moisture content
ISO 12744, Copper, lead, zinc and nickel concentrates — Experimental methods for checking the precision
of sampling
ISO 13292, Copper, lead, zinc and nickel concentrates — Experimental methods for checking the bias of
sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12743, ISO 12744 and
ISO 13292 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
audit
critical review of a mechanical sampling system, undertaken by a suitably qualified person not directly
involved in the operation of that system, which measures its compliance with stipulated operating
specifications
3.2
mechanical inspection
comparative record of observations and measurements of physical parameters against design criteria,
and records of subsequent changes or improvements undertaken by a suitably qualified person not
involved in the day-to-day operation of the system
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ISO 11790:2017(E)
3.3
operational inspection
record of observations and inspections undertaken by the system operator before, during and after the
sampling of a lot
Note 1 to entry: The operator is the person taking the sample.
4 General consideration
4.1 Precision
Precision checks are recommended for each material type sampled by the system. If there is a
significant change in material type or a new material type is introduced, a precision check should be
carried out. The test should outline the precision of sampling, preparation and analysis of each material
type sampled by the system. These tests shall be in accordance with ISO 12744.
4.2 Quality variation
2
The variance between increments, s , is a measure of the heterogeneity of the lot and is the variance of
b
2
the quality characteristics of increments taken from the lot. The value of s shall be measured
b
experimentally for each material type for each handling plant under normal operating conditions, in
accordance with ISO 12743.
The entire material-handling system up to the mechanical sampling system should be examined to
determine whether any unloading, storage or reclaiming procedures produce a cyclical pattern which
could cause the increment collection to get in phase with the sequence of material variability. Variations
in the physical characteristics, such as particle-size distribution, surface moisture, extraneous matter
and oversized material, could become cyclical and could even be in phase with mass-based or time-
based increment collection. Where such cyclical variations occur in the material stream, the source
of the variations should be investigated to determine the practicability of eliminating the variations.
If there is no practical way to eliminate the variations, the interval between primary cuts should be
adjusted so that the collection of increments is not in phase with the cyclic variation. Alternatively,
stratified random sampling may be used.
4.3 Bias
After commissioning and auditing of a new system or any major engineering modifications of an
existing system, a bias test should be carried out in accordance with ISO 13292 to confirm the correct
operation of the system. In multi-material-type facilities, it is recommended that the material having
the highest variability be chosen for the bias test.
It is recommended that, on a regular basis, further bias sample pairs be taken to confirm that the initial
bias result is still relevant. If a significant change is made to the sampling system, or a new material
having more difficult sampling characteristics is introduced, the need for a new bias test should be
considered.
NOTE Provided that the mechanical sampling system satisfies the criteria outlined in ISO 12743, bias tests
are not mandatory. However, quality-assurance principles at individual plants might require bias tests.
4.4 Operation of the sampling system
The mechanical sampling system should be started at some time in advance of the start of conveying the
material to be sampled, so that any foreign substances (including water) are purged. Where hydraulic
drives are used, sufficient time should be allowed for the hydraulic oil and the associated system to
attain temperature equilibrium. It is recommended, particularly in multi-material-type sampling
systems, that one primary cut be allowed to pass through the mechanical system as a conditioner
before sampling commences.
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ISO 11790:2017(E)
It is recommended that the operator review any sampling-system records maintained by the previous
operator. These records should include such things as quantities of material handled and sampled, and
notations as to system malfunctions, stoppages, blockages or other deficiencies. The operator should
use a suitable checklist, such as the example in Annex A. It is recommended that the operator complete
all items on a suitable checklist designed for the particular system. For large multi-user systems, an
operator’s inspection report, such as the example in Annex B, should be developed.
Sufficient suitably designed inspection points should be available to observe that the falling-stream and
cross-belt cutters cut the full stream of material, and cutter apertures can be inspected for blockages
and blinding.
5 Establishment of inspection system
5.1 General
To ensure reliable operation, it is recommended that a sampling checklist (Annex A) and operator’s
sampling record (Annex B) be developed with input from the following sources:
a) original design criteria and records of any subsequent changes or improvements;
b) sampling equipment operating and maintenance manuals;
c) management responsible for the system;
d) personnel operating or maintaining the system;
e) for a new system, the designers and commissioning personnel.
The general method for establishing these procedures is as follows.
1) Refer to ISO 12743 to ascertain the correct sampling scheme.
2) Refer to the equipment supplier’s operating and maintenance manuals to ascertain correct
procedures for operation and intervals for routine maintenance. The manuals can provide useful
information on the basis of the system design. Information such as conveyor rates, conveyor speeds
and material parameters (particularly sizing and variability) are significant data and should
always be kept in mind when changes are contemplated.
3) Examine existing sampling and maintenance records for an extended period. This information will
provide guidance for operators to ensure that the required level of inspection and maintenance
is carried out to ensure reliable operation, and will possibly alert operators to any inappropriate
maintenance or modifications that may have been made to the equipment.
4) Seek the personal experience of maintenance, operational and sampling personnel with respect to
the sampling system. This information, together with that obtained from the above, will enable an
appropriate operator’s manual, operator’s sampling record and system checklist to be prepared.
5.2 Audits
A scheme for regular audits of the sampling system should be established. Reference should be made
to the original operating parameters and equipment supplier’s design data, as well as any records of
any subsequent changes or improvements, in order to establish conformance with current applicable
International Standards. Annex A provides a typical reference list.
NOTE 1 Correct operation of all new systems needs to be confirmed by an audit following the commissioning
stage before being accepted as operational.
NOTE 2 The design and operation of the system need to be confirmed by an audit prior to any bias test.
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ISO 11790:2017(E)
5.3 Mechanical inspections
A scheme for routine inspections of the sampling system by operators should be established, similar to
the example in Annex A. The frequency and detail of inspections will be determined by factors such as,
but not limited to, reliability of the system, handling characteristics of the sampled material, frequency
of use of the system and purpose of sampling (e.g. process control compared to large multi-user port
facilities).
5.4 Operational inspections
Operational procedures and inspections should be established and carried out immediately before,
during and immediately after operation of the sampling system for a given lot or sub-lot, similar to the
example in Annex A. These procedures and inspections will be less extensive than those undertaken
as audits or mechanical inspections, as given in 5.2 and 5.3, respectively. They should be designed
to be simple inspections of the integrity of the sampling process. For large multi-user facilities, it is
recommended that a system of operational reports be developed and an example of such a report is
provided in Annex B.
6 Procedures
6.1 Audits
When assessing the conformance of a mechanical sampling system, an auditor should refer to Annex A,
the relevant parts of ISO 12743 and the design flow chart of the particular system being evaluated. It is
recommended that an audit be carried out at least once per year by a suitably qualified person who is
not directly involved in the operation and management of that particular sampling system.
It is essential that reference be made to the original operational parameters upon which the sampling
system was designed, as well as records of any changes or improvements. Operational conditions, such
as conveyor capacity, belt speed or material top size, could have been altered without due regard to the
impact on the operation and conformity of the sampling system.
Common examples of such alterations and their potential consequences are as follows.
a) An increase in the capacity of a conveyor could result in an excessive primary increment mass that
will no longer be entirely contained by the primary sample cutter.
b) A change in conveyor speed could affect the trajectory of material at a transfer point which could
result in a part of the material stream being missed by the sample cutter.
c) A change in nominal top size of the concentrate could result in the original cutter aperture no
longer being large enough (i.e. three times the nominal top size of the material being sampled) to
conform to ISO 12743.
Items that should be covered as a minimum are as follows.
1) Safety requirements of site.
2) Original and current operating parameters.
3) Selection of appropriate sampling procedure.
4) General condition of the equipment, including build-up of material or blockages in chutes, cutters
and sample loss or sample contamination.
5) Comparison of design and actual increment masses for all cutters at several flow rates on the
product belt, up to the maximum.
6) Condition of cutters, cutter apertures and cutter lips. Check for foreign material, such as wood,
rags, stones and material that may be blinding the cutter apertures.
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ISO 11790:2017(E)
7) Conformance to ISO 12743, in particular:
i) minimizing bias;
ii) correct design and operation of sample cutters;
iii) the number of primary increments and sub-lots required;
iv) the methods of taking primary increments and division of gross samples, partial samples and
increments.
8) Ongoing precision monitoring using ISO 12744.
9) Crusher condition (inspect jaw plates, rolls and screens for wear and blinding).
10) Nominal top size of feed and
...
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