ISO 4701:2017
(Main)Iron ores and direct reduced iron — Determination of size distribution by sieving
Iron ores and direct reduced iron — Determination of size distribution by sieving
ISO 4701:2017 specifies the methods to be employed for determination of size distributions by sieving of iron ore and direct reduced iron (excluding briquetted iron), utilizing sieves having aperture sizes of 36 µm or larger. The size distribution is expressed in terms of mass and percentage mass, passed or retained on selected sieves. The purpose of this document is to provide a basis for any testing of iron ore and direct reduced iron involving size determination for use by contracting parties in the sale and purchase of these materials. When this document is used for comparative purposes, the concerned parties will agree on the selection of the detailed method to be employed in order to eliminate sources of subsequent controversy.
Minerais de fer et minerais de fer préréduits — Détermination de la granulométrie par tamisage
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 4701
Fourth edition
2017-11
Iron ores and direct reduced iron —
Determination of size distribution by
sieving
Minerais de fer et minerais de fer préréduits — Détermination de la
granulométrie par tamisage
Reference number
ISO 4701:2017(E)
©
ISO 2017
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ISO 4701:2017(E)
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ISO 4701:2017(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles and planning . 2
4.1 General . 2
4.2 Purpose of the analysis . 2
4.3 Impact of ore and DRI properties . 2
4.3.1 Effect of moisture content. 2
4.3.2 Degradation of material . 3
4.3.3 Magnetic ores . 3
4.4 Nature of sample . 4
4.5 Choice of sieving method . 4
4.6 Maximum particle size permitted on a sieve . 4
4.7 Specified loading of sieves . 5
4.7.1 General. 5
4.7.2 Batch sieving with a single sieve or nest of sieves . 5
4.7.3 Loading of continuous sieving machines . 6
4.8 Sieving time . 6
4.8.1 General. 6
4.8.2 End point ruling . 7
4.8.3 Retention time for continuous sieving machines . 7
5 Apparatus . 7
5.1 Sieve media . 7
5.1.1 Shape of aperture . 7
5.1.2 Size of aperture . 7
5.1.3 Construction of sieve media . 7
5.1.4 Sieve frames for hand or mechanical nest sieving . 7
5.2 Sieving machines . 7
5.3 Accessories for wet sieving . 8
5.4 Drying equipment . 9
5.5 Equipment for the determination of mass . 9
6 Samples . 9
6.1 Derivation of size sample . 9
6.2 Mass of test sample(s) for sieving . 9
6.2.1 General. 9
6.2.2 Minimum mass . 9
7 Procedures .10
7.1 Drying .10
7.2 Division .10
7.3 Preparation and maintenance of sieves for test or nest sieving . .11
7.4 Sieving .11
7.4.1 General.11
7.4.2 Hand placing on individual sieves .11
7.4.3 Hand sieving in the −40 mm to +1 mm range .11
7.4.4 Hand sieving in the −1 mm range.12
7.4.5 Mechanical batch sieving .13
7.4.6 Wet sieving of coarse and fine samples .13
7.4.7 Continuous machine sieving .14
7.5 Determination of mass .14
7.5.1 General.14
7.5.2 Wet sieving — Determination of mass of solids-content in washings .15
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ISO 4701:2017(E)
7.6 Determination of sieving end point .15
7.6.1 Dry sieving .15
7.6.2 Wet sieving .16
8 Verification .16
8.1 General .16
8.2 Checking of division .16
8.3 Verification of sieve media .16
8.4 Verification of sieving machines .16
8.5 Verification of weighing devices .16
9 Results .16
9.1 Evaluation of results .16
9.2 Calculation and expression of results.17
9.3 Repeatability and acceptance of results .18
10 Test report and working log .19
11 Precision .19
11.1 Overall precision, β . .19
SPM
11.2 Precision of preparation and measurement, β .19
PM
Annex A (informative) Steps for establishing operating conditions .21
Annex B (normative) Scheme of sample preparation and sieving procedure .22
Annex C (normative) Maximum mass to be retained at completion of batch sieving .23
Annex D (informative) Size apertures in R20 and R40/3 series .25
Annex E (informative) Typical batch sieving apparatus .26
Annex F (informative) Desirable features of mechanical sieving machines .27
Annex G (normative) Procedure for determining the minimum mass of sample used for sieving .30
Annex H (normative) Flowsheet of the procedure for the acceptance of analytical values for
test portions .33
Annex I (informative) Additional information .34
Annex J (normative) Determination of the average particle size (APS) .36
Bibliography .37
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ISO 4701:2017(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: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 1, Sampling.
This fourth edition cancels and replaces the third edition (ISO 4701:2008), which has been technically
revised. It also incorporates the amendment ISO 4701:2008/Cor.1:2010. The following changes have
been made:
— in Tables 3 and 6, the specification size subtitles and mean values have been updated in accordance
with ISO 4701:2008/Cor.1:2010;
— in Table 3, class > 340 and modified class from > 270 to 270 to 340 have been included;
— in 7.4.3 c), the amplitude of hand sieving in the −40 mm to +1 mm range, from 120 mm to 95 mm has
been changed;
— in 7.4.4, the use of a smooth platform for hand sieving in the −1 mm range has been included;
— in 7.6.1.2, the time of sieving from 1 min to 10 s for the –40 mm to +1 mm range for the determination
of sieving end point has been changed;
— Formula (G.1) has been corrected to harmonize the units.
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INTERNATIONAL STANDARD ISO 4701:2017(E)
Iron ores and direct reduced iron — Determination of size
distribution by sieving
1 Scope
This document specifies the methods to be employed for determination of size distributions by sieving
of iron ore and direct reduced iron (excluding briquetted iron), utilizing sieves having aperture sizes
of 36 µm or larger. The size distribution is expressed in terms of mass and percentage mass, passed or
retained on selected sieves. The purpose of this document is to provide a basis for any testing of iron
ore and direct reduced iron involving size determination for use by contracting parties in the sale and
purchase of these materials.
When this document is used for comparative purposes, the concerned parties will agree on the selection
of the detailed method to be employed in order to eliminate sources of subsequent controversy.
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 565, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal sizes
of openings
ISO 2591-1, Test sieving — Part 1: Methods using test sieves of woven wire cloth and perforated metal plate
ISO 3082, Iron ores — Sampling and sample preparation procedures
ISO 3085, Iron ores — Experimental methods for checking the precision of sampling, sample preparation
and measurement
ISO 3086, Iron ores — Experimental methods for checking the bias of sampling
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3310-2, Test sieves — Technical requirements and testing — Part 2: Test sieves of perforated metal plate
ISO 3852, Iron ores for blast furnace and direct reduction feedstocks — Determination of bulk density
ISO 10835:2007, Direct reduced iron and hot briquetted iron — Sampling and sample preparation
ISO 11323, Iron ore and direct reduced iron — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11323 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
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ISO 4701:2017(E)
4 Principles and planning
4.1 General
The determination of size distribution of iron ores and direct reduced iron (DRI) may be carried out
on a “dry” or “natural” (or “as-received”) basis. Before a particle size determination is carried out, it is
necessary to plan the entire sequence of procedures to be followed.
The basis for determination and the sequence of procedures will depend on the following:
a) the purpose of the size analysis;
b) the properties of the iron ore and DRI to be evaluated;
c) the form in which the iron ore and DRI is received, e.g. gross sample, increments or partial samples;
d) the apparatus available.
A typical decision tree to determine the sequence of procedures necessary to perform size analysis is
shown in Figure 1. The guidelines for practical application of this document are provided in Annex A.
General principles of sieving are given in ISO 2591-1.
4.2 Purpose of the analysis
The principal purposes of particle size determination are as follows.
a) To measure the mass and calculate the percentage mass of an ore or DRI passing or retained on one
or more specification sieves.
The choice of sieve aperture sizes shall be determined by the specification size(s) required together
with the necessity for introducing intermediate aperture sizes to satisfy the maximum particle size
and sieve loading constraints. See 4.6 and 4.7.
b) To generate an overall size distribution curve.
The choice of sieve apertures will depend on the resolution required for the curve and the need to
satisfy sieve loading constraints.
4.3 Impact of ore and DRI properties
4.3.1 Effect of moisture content
The effect of the moisture content of the size sample on sample division and sieving should be assessed
before the commencement of the size determination procedure.
When it is difficult to conduct sample division due to sample being adhesive or excessively wet, the
sample shall be dried to constant mass in accordance with 7.1.
Partial drying of a sample for the purpose of size distribution analysis is not acceptable, as residual
moisture might affect the effective separation of the individual size fractions.
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ISO 4701:2017(E)
Figure 1 — Typical decision tree for selecting size determination procedure
4.3.2 Degradation of material
Certain iron ores, particularly lump ore, and DRI can be subject to significant degradation during the
sampling and size analysis sequences. Furthermore, different sampling and size analysis processes
can cause degradation of ores and DRI to different extents. Consequently this could lead to significant
variation in results for the same lot.
It is therefore essential that any degradation should be minimized through the correct design of
handling, sampling and size analysis systems.
Sampling systems should be designed in accordance with the guidelines set out in ISO 3082 and
ISO 10835.
4.3.3 Magnetic ores
For iron ores with pronounced magnetic properties and DRI that has been handled by magnets, it is
desirable to ensure that the size sample be demagnetized or that the sieves are non-magnetic.
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ISO 4701:2017(E)
4.4 Nature of sample
The sample may be received in the form of a gross sample, several partial samples or increments.
The procedures for sampling of iron ores and direct reduced iron (see ISO 3082 and ISO 10835) will
generally provide quantities of material in excess of the requirements for sieving.
If it is undesirable to sieve the entire mass, division of the following is permissible:
a) gross sample;
b) partial samples;
c) increments;
d) fractions obtained during sieving.
Methods governing the division and the mass of sample to be sieved are provided in Clause 6.
4.5 Choice of sieving method
4.5.1 Two different sieving methods are available to perform particle size analysis (see Annex I):
a) dry sieving, i.e. sieving without the application of water;
b) wet sieving, i.e. sieving with a sufficient application of water to ensure the passage of undersize
particles through the sieve apertures.
A table summarizing the sample preparation and sieving procedure is given in Annex B.
4.5.2 The results of these methods could be different. No specific preference is given in this document
for either method when sieving iron ore samples. For DRI, dry sieving is recommended.
4.5.3 The choice of sieving method (see 4.5.5) for each part of a size determination shall be made
on the basis of attaining the defined precision of testing (see 11.1). Details on the procedure shall be
recorded in the working log.
4.5.4 If a combination of any of the sieving methods is employed for different parts of the same overall
size distribution, the changeover from dry to wet sieving shall be clearly indicated on the report sheet
(see Clause 10).
4.5.5 The following factors should be taken into account when making the choice of sieving method.
a) For dry sieving on a natural basis sample, the moisture content of the charge shall be sufficiently
low so as not to introduce any bias beyond acceptable limits.
b) Wet sieving should be used
1) if there is a tendency for a significant proportion of fine particles to adhere to the larger ones,
or if the ore has a tendency to cake on drying, or
2) if the fine particles of iron ore tend to become charged with static electricity during the sieving
operation and adhere tenaciously to the sieve.
4.6 Maximum particle size permitted on a sieve
0,7
To avoid damage to sieves, the maximum particle size in any charge shall not exceed 10 W , where W
is the sieve aperture size, in millimetres.
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ISO 4701:2017(E)
Examples of the relationship between maximum particle size and sieve aperture size are given in
Table 1.
Table 1 — Maximum particle size permitted on a sieve
Sieve aperture size Approximate size of
W largest particle
25 mm 95 mm
11,2 mm 55 mm
4 mm 26 mm
1 mm 10 mm
250 μm 3,8 mm
45 μm 1,2 mm
36 μm 1,0 mm
4.7 Specified loading of sieves
4.7.1 General
The loading of a sieve or nest of sieves or continuous sieving machine shall be limited as prescribed in
4.7.2 and 4.7.3, and requires previous information about the size distribution of the sample to be sieved.
4.7.2 Batch sieving with a single sieve or nest of sieves
4.7.2.1 General
The mass of sample that may be loaded onto any sieve is limited by the conditions covering the mass
to be retained and by the need to avoid undue degradation. It could be necessary to sieve a sample
in several portions. The results shall be combined. The maximum mass retained shall not exceed the
values tabulated in Annex C or as determined in 4.7.2.2 or 4.7.2.3.
The maximum loading is defined as that corresponding to the maximum mass retained but shall not
exceed twice the maximum mass retained.
4.7.2.2 Apertures > 4 mm
The loading of the sieve shall be such that the maximum mass of sample retained on any sieve at the
completion of sieving shall be in accordance with Formulae (1) and (2) or the visual rule c).
a) Apertures ≥ 22,4 mm
mW=+0,,005 0 0004 ρ A (1)
()
b
b) For apertures < 22,4 mm and ≥ 4 mm
mW=0,0007 ρ A (2)
b
where
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ISO 4701:2017(E)
m is the maximum mass to be retained on the sieve, in kilograms;
W is the sieve aperture size, in millimetres;
ρ is the bulk density of the sample, in kilograms per cubic metre, determined in accordance with
b
ISO 3852;
A is the area of the sieve, in square metres.
The formulae apply only if the open area of the sieve (incomplete apertures are regarded as
blanked-off areas) exceeds 40 %. For open areas of less than 40 %, the values of m shall be reduced
pro rata.
c) Alternative visual rule
On completion of sieving, the particles spread out as a single layer shall cover not more than three-
quarters of the floor area of the sieve.
4.7.2.3 Apertures < 4 mm
For sieves in the < 4 mm range, the maximum mass of sample retained shall be as given in Annex C.
4.7.3 Loading of continuous sieving machines
In the case of continuous sieving machines, the rate of feed shal
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