ISO 1953:2025

International
Standard
ISO 1953
Fourth edition
Coal — Size analysis by sieving
2025-10
Charbon — Analyse granulométrique par tamisage
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and Definitions . 1
4 Apparatus . 1
4.1 For all methods .2
4.2 For dry sieving .2
4.3 For wet sieving.2
5 Sampling and preparation . 3
5.1 Sampling .3
5.2 Preparation .3
5.3 Division of the gross sample, other than wet coal of less than 4 mm .4
5.4 Division of the gross sample of wet coal less than 4 mm.4
5.5 Drying of test sample for sizing .4
5.6 Equilibration of test samples dried at enhanced temperature.4
5.7 Equilibration periods .4
6 Procedure . 4
6.1 General .4
6.2 Dry sieving .5
6.2.1 Test sample of maximum particle size greater than 22,4 mm .5
6.2.2 Sample of maximum particle size between 4 mm and 22,4 mm — Manual method .5
6.2.3 Sample of maximum particle size less than 4 mm — Manual method .6
6.2.4 Sample of maximum particle size between 4 mm and 22,4 mm; minus 4 mm —
Mechanical method .7
6.3 Wet sieving .7
7 Expression of results . 8
7.1 Calculation .8
7.2 Graphical presentation .8
8 Test report . 8
Annex A (informative) Guide to sampling .13
Annex B (informative) Example of removal by wet sieving of fine material from a sample having
a maximum particle size less than 4 mm . 14
Annex C (informative)  .15

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
ISO technical committees. Each member body interested in a subject for which a technical committee
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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 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).
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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 27, Coal and coke, Subcommittee SC 1, Coal
preparation: Terminology and performance.
This fourth edition cancels and replaces the third edition (ISO 1953:2015), which has been technically
revised.
The main changes are as follows:
— size analysis of coal greater than 90 mm was removed from Table 1;
— instructions provided for air drying and equilibrating different coals (examples are high rank coal, low
rank coal and lignite). Advice provided for air drying at enhanced temperatures has also been added;
— additional test report items were included;
— Gy’s formula was not suitable to determine minimum masses for sizing at various nominal top sizes and
for precision calculations in Table 1 and has been removed.
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
Introduction
Size analysis involves the separation of a sample of coal into size fractions with defined limits. In the methods
described in this document the results are expressed in terms of the percentage mass of coal remaining
on sieves of different aperture sizes. This information can be of use in several applications, including the
following:
a) determining the size analysis of coals exported and imported internationally;
b) assessing the yields of products from run-of-mine coals;
c) providing design data for coal preparation plants;
d) checking that products from screening plants are within the required limits;
e) assessing the performance of coal-crushing plants;
f) selecting coals for processes and equipment.

v
International Standard ISO 1953:2025(en)
Coal — Size analysis by sieving
1 Scope
This document specifies reference methods for the size analysis of coal by manual sieving (wet or dry), using
test sieves of aperture sizes between 90 mm and 45 μm. A guide to sampling is given in Annex A.
This document is applicable to all coals. It is not applicable to coke.
In the case of pulverized coal which has been ground so that a high proportion passes through the test
sieve of the smallest aperture size, the methods of this document determine only the mass fraction oversize
expressed as a percent.
2 Normative references
The following documents are referred to in the text in such a way that some or all 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 1213-1, Coal and coke — Vocabulary — Part 1: Terms relating to coal preparation
ISO 1213-2, Coal and coke — Vocabulary — Part 2: Terms relating to sampling, testing and analysis
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 13909-2, Coal and coke — Mechanical sampling — Part 2: Sampling of coal from moving streams
ISO 13909-4, Coal and coke — Mechanical sampling — Part 4: Preparation of test samples of coal
ISO 13909-7, Coal and coke — Mechanical sampling — Part 7: Methods for determining the precision of sampling,
sample preparation and testing
ISO 18283, Coal and coke — Manual sampling
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in ISO 1213-1 and ISO 1213-2 apply.
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 Apparatus
The usual laboratory apparatus and the following shall be used.

4.1 For all methods
Test sieves,
a) shall be exclusively round-holed or exclusively square-holed screens in accordance with ISO 3310-1 or
ISO 3310-2;
b) the recommended series of test sieves for general purposes is 125 mm, 90 mm, 75 mm, 63 mm, 50 mm,
45 mm, 31,5 mm, 22,4 mm, 16 mm, 11,2 mm, 8 mm, 5,6 mm, 4 mm, 2 mm and 1 mm nominal aperture
sizes. With square hold-sieves, each side in mm is the recommended series. With round hole sieves, the
diameter of the sieve in mm is the recommended series. If this series is inadequate for the sizing of
graded coals, sieves from the supplementary sizes 100 mm, 80 mm, 40 mm, 25 mm, 20 mm, 12,5 mm,
10 mm and 6,3 mm may be included;
c) for samples in the range 90 mm × 75 mm, single square-hole or round-hole gauges of the required
dimensions may be used for the larger pieces. Sizes greater than 90 mm are not covered by t
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