ISO/FDIS 20905

FINAL DRAFT
International
Standard
ISO/TC 27/SC 1
Coal preparation — Determination
Secretariat: SA
of dust/moisture relationship for
Voting begins on:
coal
2024-07-17
Préparation du charbon — Détermination de la relation
Voting terminates on:
particules/humidité du charbon
2024-09-11
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
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MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 27/SC 1
Coal preparation — Determination of
Secretariat: SA
dust/moisture relationship for coal
Voting begins on:
Préparation du charbon — Détermination de la relation
particules/humidité du charbon
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2024
IN ADDITION TO THEIR EVALUATION AS
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
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TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
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TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Safety . 1
5 Apparatus and equipment . 2
6 Reagent . 2
7 Sample — Initial . 2
8 Sample preparation — Initial. 3
8.1 Initial total moisture .3
8.2 Moisture adjustment .4
9 Sample preparation — Reagent . 4
10 Dust determination . 5
10.1 Environment and equipment checks .5
10.2 Dust testing .5
11 Calculation . 6
12 Report . 6
13 Precision . 6
Annex A (informative) Worked example . 7
Annex B (informative) Worksheet example . 10
Bibliography .12

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
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 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)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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 27, Coal and Coke, Subcommittee SC 1, Coal
preparation: Terminology and performance.
This second edition cancels and replaces the first edition (ISO 20905:2004), of which it constitutes a minor
revision. The changes compared to the previous edition are as follows:
— the title of ISO/TC 27 was changed from "Solid mineral fuels" to "Coal";
— some terminology was changed to align with ISO rules, for example the terms "percentage", "weight" and
"weighing".
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
The development of the dust/moisture curve provides an indication of the likely response of different
coal types to drying or water addition during mining and handling processes. The dust/moisture curve
provides a good basis for comparing the response of different coal types. Understanding the dust/moisture
characteristics of a coal allows minimized water addition to the product for dust suppression. This in turn
assists in water conservation at mines and other handling facilities, as well as minimizing the total moisture
of the product.
This document describes a reliable measurement of dustiness of coal and extends to cover the relationship
between dust and total moisture utilizing the Rio Tinto Dust Tumbler Test. This test provides a quantitative
measure of the dustiness of a coal that can be used to predict operational dust problems and is also suitable
for the assessment of dust suppression chemicals.
The Rio Tinto Dust Tumbler Test was developed using rotating equipment in a controlled temperature and
humidity environment and uses a stream of air to remove particles which become airborne during the
tumbling process. It is a batch test in which dust particles (−150 µm particles) are collected in a filter bag
of known mass and their mass is determined. From this mass, a dust number, calculated as the mass yield
of dust multiplied by 100 000, is determined for the test total moisture. Only 1 kg of sample is required for
each dust test, but eight sample lots are required to develop the dust/moisture curve for a particular coal,
i.e. approximately 10 kg is required for each coal type.
This dust test can be repeated with subsamples at different coal total moisture levels to develop a dust/
moisture curve. The slope of the curve provides information on how sensitive the dustiness is to changes in
total moisture and a dust number of 10 has been used to provide a comparison between coals.
The test has been successfully used for several years on many coals and other bulk materials. The results
have been correlated with the operating practice. The method has been applied to the evaluation of dust-
control products and the determination of dust-elimination total moisture requirements for coal-handling
systems.
v
FINAL DRAFT International Standard ISO/FDIS 20905:2024(en)
Coal preparation — Determination of dust/moisture
relationship for coal
1 Scope
This document sets out a laboratory procedure for the dust testing of higher rank coals. The procedure
defines a means of evaluating the dust/moisture relationship characteristic of a coal and a dust extinction
moisture (DEM).
NOTE In this document, an experimental dust number of 10 has been used in the example given in Annex A.
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 589, Hard coal — Determination of total moisture
ISO 7886-1, Sterile hypodermic syringes for single use — Part 1: Syringes for manual use
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1
dust
particles of 150 µm or less diameter entrained in an air stream
3.2
dust extinction moisture
DEM
total moisture at which a dust number of 10 is attained on the dust/moisture curve
Note 1 to entry: DEM is a useful point for comparing different coals and the effectiveness of reagents.
4 Safety
The following safety precautions shall be observed:
— To prevent nitrogen build-up within the laboratory, the exhaust tube of the minimum-free-space oven
shall remain clear of obstruction.
— Safety glasses shall be worn at all times.
— The exhaust tube of the minimum-head-space oven shall remain free of obstruction to prevent nitrogen
build-up within the laboratory.

— A dust mask sha
...