ISO 10835:2007

INTERNATIONAL ISO
STANDARD 10835
Second edition
2007-02-15

Direct reduced iron and hot briquetted
iron — Sampling and sample preparation
Minerais de fer préréduits et fer briqueté à chaud — Échantillonnage et
préparation des échantillons




Reference number
ISO 10835:2007(E)
©
ISO 2007

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ISO 10835:2007(E)
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ISO 10835:2007(E)
Contents Page
Foreword. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
4 General considerations for sampling and sample preparation . 3
4.1 Basic requirements. 3
4.2 Establishing a sampling scheme . 4
4.3 System verification. 5
5 Fundamentals of sampling and sample preparation . 5
5.1 Minimization of bias. 5
5.1.1 General. 5
5.1.2 Minimization of particle-size degradation . 5
5.1.3 Extraction of increments. 5
5.1.4 Increment mass. 6
5.2 Overall precision. 7
5.3 Quality variation. 9
5.4 Sampling precision and number of primary increments. 9
5.4.1 Mass-basis sampling. 9
5.4.2 Time-basis sampling. 9
5.5 Precision of sample preparation and overall precision. 11
5.5.1 General. 11
5.5.2 Preparation and measurement of gross sample . 11
5.5.3 Preparation and measurement of partial samples . 11
5.5.4 Preparation and measurement of each increment . 11
6 Methods of sampling. 12
6.1 Mass-basis sampling. 12
6.1.1 Mass of increment . 12
6.1.2 Quality variation. 13
6.1.3 Number of primary increments . 13
6.1.4 Sampling interval. 13
6.1.5 Methods of taking increments. 13
6.2 Time-basis sampling . 14
6.2.1 Mass of increment . 14
6.2.2 Quality variation. 14
6.2.3 Number of increments. 14
6.2.4 Sampling interval. 14
6.2.5 Methods of taking increments. 14
6.3 Stratified random sampling within fixed mass or time intervals . 15
6.3.1 General. 15
6.3.2 Fixed mass intervals. 15
6.3.3 Fixed time intervals. 15
7 Sampling from moving streams . 15
7.1 General. 15
7.2 Safety of operations . 16
7.3 Robustness of sampling installation. 16
7.4 Versatility of sampling system . 16
7.5 Primary samplers. 16
7.5.1 Location. 16
7.5.2 Types of primary sampler . 17
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ISO 10835:2007(E)
7.5.3 General design criteria for primary cutters . 17
7.5.4 Cutter aperture of primary sampler. 21
7.5.5 Cutter speed of primary sampler. 21
7.6 Secondary and subsequent samplers . 22
7.7 On-line sample preparation. 22
7.7.1 Arrangement for sample preparation. 22
7.7.2 Crushers. 22
7.7.3 Dividers. 22
7.7.4 Dryers. 27
7.8 Checking precision and bias . 27
7.9 Cleaning and maintenance. 27
7.10 Example of a flowsheet . 27
8 Sampling from stationary situations. 29
9 Stopped-belt reference sampling . 29
10 Sample preparation. 30
10.1 Fundamentals. 30
10.1.1 General. 30
10.1.2 Crushing and grinding. 30
10.1.3 Mixing. 30
10.1.4 Sample division. 30
10.1.5 Mass of divided sample. 31
10.1.6 Split use and multiple use of sample. 33
10.2 Method of constituting partial samples or a gross sample . 33
10.2.1 General. 33
10.2.2 Method of constitution for mass-basis sampling. 33
10.2.3 Method of constitution for time-basis sampling. 34
10.3 Mechanical methods of division. 34
10.3.1 Mechanical increment division. 34
10.3.2 Other mechanical-division methods . 35
10.4 Manual methods of division. 35
10.4.1 Manual increment division. 35
10.4.2 Fractional shoveling. 38
10.4.3 Manual riffle division method . 39
10.5 Preparation of test sample for physical testing. 40
10.6 Preparation of test sample for moisture determination. 40
10.7 Preparation of test sample for chemical analysis .41
10.7.1 Mass and particle size . 41
10.7.2 Preparation to – 250 µm. 41
10.7.3 Final preparation to – 160 µm . 42
10.7.4 Distribution of samples for chemical analysis. 42
10.8 Example of sample-preparation process. 43
11 Packing and marking of sample . 43
Annex A (informative) Inspection of mechanical sampling systems. 45
Annex B (normative) Equation for number of increments . 49
Annex C (normative) Riffle dividers. 52
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ISO 10835:2007(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
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.
ISO 10835 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 1, Sampling.
This second edition cancels and replaces the first edition (ISO 10835:1995), which has been technically
revised.

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INTERNATIONAL STANDARD ISO 10835:2007(E)

Direct reduced iron and hot briquetted iron — Sampling
and sample preparation
WARNING — This International Standard may involve hazardous materials, operations and equipment,
and does not purport to address all of the safety issues associated with its use. It is the responsibility
of the user of this standard to establish appropriate health and safety practices and determine the
applicability of regulatory limitations prior to use.
1 Scope
This International Standard gives
a) the underlying theory,
b) the basic principles for sampling and preparation of samples, and
c) the basic requirements for the design, installation and operation of sampling systems,
for mechanical sampling, manual sampling and preparation of samples taken from a lot under transfer, to
determine the chemical composition, moisture content and physical properties of the lot.
The methods specified in this International Standard are applicable to both the loading and discharging of
direct reduced iron (DRI) and hot briquetted iron (HBI), by means of belt conveyors and other ore handling
equipment to which a mechanical sampler may be installed or where stopped-belt sampling may safely be
conducted. In this International Standard, DRI includes both reduced pellets and reduced lump ores.
CAUTION — Direct reduced iron (DRI) and, in some cases, hot briquetted iron (HBI), for example, with
low density or high fines content, may react with water and air to produce hydrogen and heat. The
heat produced may cause ignition. Therefore, due consideration shall be given to the safety of
operators by respecting applicable regulations or international codes.
2 Normative references
The following referenced documents are indispensable for the application 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 565:1990, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal
sizes of openings
ISO 3084:1998, Iron ores — Experimental methods for evaluation of quality variation
ISO 3085:2002, Iron ores — Experimental methods for checking the precision of sampling, sample
preparation and mesasurement
ISO 3086:1998, Iron ores — Experimental methods for checking the bias of sampling
ISO 3087:1998, Iron ores — Determination of moisture content of a lot
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ISO 10835:2007(E)
ISO 3534-1:2006, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in
probability
ISO 4701:1999, Iron ores — Determination of size distribution by sieving
ISO 11323:2002, Iron ores and direct reduced iron — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11323 and the following apply.
3.1
lot
discrete and defined quantity of DRI or HBI for which quality characteristics are to be assessed
3.2
increment
quantity of DRI or HBI collected in a single operation of a sampling device
3.3
sample
relatively small quantity of DRI or HBI, taken from a lot so as to be representative in respect of the quality
characteristics to be assessed
3.4
partial sample
sample consisting of less than the complete number of increments needed for a gross sample
3.5
gross sample
sample comprising all increments, entirely representative of all quality characteristics of a lot
3.6
test sample
sample prepared to meet all specific conditions for a test
3.7
test portion
part of a test sample that is actually and entirely subjected to the specific test
3.8
stratified sampling
sampling of a lot carried out by taking increments from systematically specified positions and in appropriate
proportions from identified parts called strata
NOTE Examples of strata, based on time, mass or space, include production periods (e.g. 5 min), production masses
(e.g. 1 000 t), holds in vessels, wagons in a train, or containers.
3.9
systematic sampling
selection of increments at regular intervals from a lot
3.10
mass-basis sampling
sampling carried out so that increments are taken at equal mass intervals, increments being, as near as
possible, of uniform mass
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ISO 10835:2007(E)
3.11
time-basis sampling
sampling carried out so that increments are taken from free-falling streams, or from conveyors, at uniform time
intervals, the mass of each increment being proportional to the mass flow rate at the instant of taking the
increment
3.12
proportional sample division
division of samples or increments such that the mass of each retained divided portion is a fixed proportion of
the mass being divided
3.13
constant-mass division
division of samples or increments such that the retained divided portions are of almost uniform mass,
irrespective of variations in mass of the samples or increments being divided
NOTE This method is required for sampling on a mass basis. “Almost uniform” means that variations in mass are
less than 20 % in terms of the coefficient of variation.
3.14
split use of sample
separate use of parts of a sample, as test samples for separate determinations of quality characteristics
3.15
multiple use of sample
use of a sample in its entirety for the determination of one quality characteristic, followed by the use of the
same sample in its entirety for the determination of one or more other quality characteristics
3.16
nominal top size of DRI
smallest aperture size, within the range of the R20 Series (in ISO 565, square opening), such that no more
than 5 % by mass of the DRI is retained on the sieve
3.17
nominal top size of HBI
prior to crushing, the largest average dimension of HBI briquettes, or, after crushing, the smallest aperture
size, within the range of the R20 Series (in ISO 565, square opening), such that no more than 5 % by mass of
the HBI is retained on the sieve
4 General considerations for sampling and sample preparation
4.1 Basic requirements
The basic requirement for a correct sampling scheme is that all of the DRI or HBI in the lot has an equal
opportunity of being selected and becoming part of the partial sample or gross sample for analysis. Any
deviation from this basic requirement can result in an unacceptable loss of accuracy and precision. An
incorrect sampling scheme cannot be relied on to provide representative samples.
The best sampling location to satisfy the above requirement is at a transfer point between conveyor belts.
Here, the full cross-section of the DRI or HBI stream can be conveniently intercepted at regular intervals,
enabling representative samples to be obtained. Alternatively, samples may be taken from a stopped
conveyor belt, provided a full cross-section of DRI or HBI of adequate length is taken from the conveyor (see
Clause 9).
In situ sampling of ships, stockpiles, wagons, containers and bunkers is not permitted, because there is no
suitable sampling device that can be driven down to the bottom and then extract the full column of DRI or HBI.
Consequently, all parts of the lot do not have an equal opportunity of being sampled. The only effective
procedure is sampling from a conveyor belt when the DRI or HBI is being conveyed to or from the ship,
stockpile, container or bunker.
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ISO 10835:2007(E)
Sampling shall be carried out by systematic sampling or stratified random sampling either on a mass basis
(see 6.1 or 6.3.2) or on a time basis (see 6.2 or 6.3.3). However, if periodic variations in quality or quantity are
present, sampling shall be restricted to stratified random sampling within fixed mass or time intervals (see
6.3.2 or 6.3.3).
The methods used for sampling and sample preparation depend on the final choice of the sampling scheme,
and on the steps necessary to minimize possible biases and obtain acceptable overall precision.
Moisture samples shall be processed as soon as possible and test portions weighed immediately. If this is not
possible, samples shall be stored in impervious airtight containers with a minimum of free air space to
minimize any change in moisture content, but should be prepared without delay.
4.2 Establishing a sampling scheme
The procedure for establishing a sampling scheme is as follows:
a) identify the lot to be sampled and the quality characteristics to be determined;
b) ascertain the nominal top size;
c) determine the mass of increment considering the nominal top size, the DRI- or HBI-handling equipment
and the device for taking increments;
d) specify the precision required;
e) ascertain the quality variation, σ , of the lot in accordance with ISO 3084, or, if this is not possible,
W
assume a “large” quality variation as specified in 5.3;
f) determine the minimum number of primary increments, n , to be taken from the lot for systematic or
1
stratified random sampling;
g) determine the sampling interval, in tonnes, for mass-basis sampling, or in minutes for time-basis sampling;
h) determine the sampling location and the method of taking increments;
i) take increments having almost uniform mass for mass-basis sampling or having a mass proportional to
the flow rate of the stream at the time of sampling for time-basis sampling; Increments are to be taken at
the intervals determined in item g) during the entire period of handling the lot;
j) determine whether the sample is for split use or multiple use;
k) establish the method of combining increments into a gross sample or partial samples;
l) establish the sample-preparation procedure, including division, crushing, mixing and drying;
m) dry the samples, if necessary, except for the moisture sample;
n) crush the samples, if necessary, except for the size sample and some physical testing samples;
o) divide samples according to the minimum mass of divided sample for a given nominal top size, employing
constant mass or proportional division for mass-basis sampling, or proportional division for time-basis
sampling;
p) prepare the test sample.
Sample containers for DRI and crushed HBI shall be suitable for storing and transporting the material in very
well-protected conditions. Samples shall be stored in airtight containers and shall not be left unprotected from
the atmosphere at any stage.
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ISO 10835:2007(E)
4.3 System verification
Stopped-belt sampling is the reference method for collecting samples against which mechanical and manual
sampling procedures may be compared to establish that they are unbiased in accordance with the procedures
specified in ISO 3086. However, before any bias tests are conducted, sampling and sample-preparation
systems shall first be inspected to confirm that they conform to the correct design principles specified in this
International Standard. Inspections shall also include an examination of whether any loading, unloading or
reclaiming procedures could produce periodic variations in quality, in phase with the taking of increments, e.g.
size distribution. When such cyclic variations occur, the source of the variations shall be investigated to
determine the practicability of eliminating the variations. If this is not possible, stratified random sampling shall
be carried out (see 6.3).
An example of a suitable inspection procedure and checklist is provided in Annex A. This will quickly reveal
any serious deficiencies in the sampling or sample-preparation system and may avoid the need for expensive
bias testing. Consequently, sampling systems shall be designed and constructed in a manner that facilitates a
regular verification of correct operation.
Regular checks of quality variation and precision shall also be carried out in accordance with ISO 3084 and
ISO 3085 to monitor variations in quality variation and to verify the precision of sampling, sample preparation
and analysis. This is particularly important for new products or new sampling systems, or when signif
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