ISO 589:2008

Hard coal - Determination of total moisture

ISO 589:2008 describes two methods for determination of the total moisture content of hard coals, a two-stage method and a single-stage method. For either method there is a choice between drying in air and drying in a nitrogen atmosphere. Depending on the coal rank, there may be systematic differences between the results obtained by drying in the different atmospheres on subsamples of a sample. Drying in a nitrogen atmosphere is suitable for all hard coals, while drying in air is only suitable for hard coals not susceptible to oxidation.

Houille — Détermination de l'humidité totale

General Information

• Status: Published
• Publication Date: 27-Oct-2008
• ICS: 73.040 - Coals
• Technical Committee: ISO/TC 27/SC 5 - Methods of analysis
• Drafting Committee: ISO/TC 27/SC 5/WG 1 - Moisture, volatile matter and ash
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Nov-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 589:2003 - Hard coal - Determination of total moisture
• Effective Date: 15-Apr-2008

Overview

ISO 589:2008 - Hard coal - Determination of total moisture specifies laboratory procedures to determine total moisture in hard coals. The standard describes two main approaches: a two-stage (Method A) and a single-stage (Method B) moisture determination, each offering a choice of drying in air or drying in a nitrogen atmosphere. ISO 589:2008 establishes controlled drying temperatures, sample preparation and weighing requirements to produce comparable moisture results for coal quality assessment.

Key topics and technical requirements

• Methods covered
  • Method A (two-stage): first-stage air drying at ambient to 30–40 °C, then residual moisture determination after crushing to 2.8 mm and drying at 105–110 °C.
  • Method B (single-stage): crush to nominal top size (11.2 mm or 10 mm) and dry subsamples at 105–110 °C.
• Atmospheres
  • Nitrogen-flushed ovens: recommended for all hard coals; nitrogen quality: oxygen < 30 µl/L; typical flow ~15× oven volume/hour.
  • Air drying: permitted only for coals not susceptible to oxidation (e.g., many high-rank coals such as anthracites).
• Sampling & sample handling
  • Close linkage with mechanical and manual sampling standards to avoid moisture bias during sampling and transport.
  • Precautions against moisture loss: sealed containers, controlled particle-size reduction (prefer crushers), minimize heat and air exposure during handling.
• Apparatus & precision
  • Weighing trays and dishes with specified loading limits (e.g., ≤1 g/cm²; ≤0.3 g/cm² for dishes), balances to 0.1 g and analytical balances to 1 mg, mills that do not heat samples.
  • Typical test portion for residual-moisture determination: about 10 ± 1 g.

Applications and users

ISO 589:2008 is used by:

• Coal testing laboratories performing quality control and contractual analyses.
• Coal producers and traders for reporting moisture content that affects pricing and transport.
• Power plants and industrial users assessing feedstock quality and combustion characteristics.
• Researchers and standards bodies harmonizing moisture measurement procedures.

Practical benefits:

• Ensures repeatable and comparable moisture determination across labs.
• Reduces systematic bias from oxidation or handling loss.
• Supports accurate coal quality assessment, material accounting and compliance testing.

Related standards

• ISO 11722 - Moisture by drying in nitrogen (general analysis sample)
• ISO 13909 (parts 1–4) - Mechanical sampling and sample preparation
• ISO 18283 - Manual sampling
• ISO 1213-2 - Vocabulary for sampling/testing terms

Using ISO 589:2008 helps maintain reliable, standardized moisture data for hard coal quality control and contractual reporting.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 589
Fourth edition
2008-11-01
Hard coal — Determination of total
moisture
Houille — Détermination de l'humidité totale

Reference number
©
ISO 2008
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2008 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle. 2
5 Reagent. 2
6 Apparatus . 3
7 Sample . 3
8 Procedure . 4
9 Precision. 7
10 Test report . 8
Bibliography . 9

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 589 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 5, Methods
of analysis.
This fourth edition cancels and replaces the third edition (ISO 589:2003), which has been technically revised.
iv © ISO 2008 – All rights reserved

Introduction
Moisture is an important parameter in respect of coal quality.
The moisture content of coal is not an absolute value and conditions for its determination have to be
standardized. It is expected that the results given by the different methods specified here should be
comparable within the limits of the tolerance quoted.
It is always necessary that the determination of the total moisture content of hard coals be considered in close
connection with sampling. Therefore, this International Standard has been prepared in close relationship with
the ISO standards for mechanical sampling ISO 13909 (all parts) and manual sampling ISO 18283.
A major problem with the preparation of test samples for the determination of moisture is the risk of bias due
to inadvertent loss of moisture. This is dependent on the tightness of the sealing of sampling containers, the
level of moisture content in the sample, the ambient conditions, the type of coal and the reduction and division
procedures used. This is described in detail in ISO 13909-4 or ISO 18283.
Depending on the mass, the nominal top size and the facilities available where samples are taken, it is
possible to dry the sample directly after sampling (air-drying), then to reduce the particle size and prepare a
test sample for determination of moisture in the air-dried sample. Alternatively, the whole sample may be
transported to the laboratory and the total moisture determined.
INTERNATIONAL STANDARD ISO 589:2008(E)

Hard coal — Determination of total moisture
1 Scope
This International Standard describes two methods for determination of the total moisture content of hard
coals, a two-stage method and a single-stage method. For either method there is a choice between drying in
air and drying in a nitrogen atmosphere. Depending on the coal rank, there may be systematic differences
between the results obtained by drying in the different atmospheres on subsamples of the same sample.
Drying in a nitrogen atmosphere is suitable for all hard coals, while drying in air is only suitable for hard coals
not susceptible to oxidation.
NOTE The term “not susceptible to oxidation” cannot be defined easily. Usually, high-rank coals such as anthracites
are not oxidized under the conditions described in this International Standard. For all other types of coal, this has to be
verified by experiments.
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 1213-2, Solid mineral fuels — Vocabulary — Part 2: Terms relating to sampling, testing and analysis
ISO 11722, Solid mineral fuels — Hard Coal — Determination of moisture in the general analysis test sample
by drying in nitrogen
ISO 13909-1, Hard coal and coke — Mechanical sampling — Part 1: General introduction
ISO 13909-2, Hard coal and coke — Mechanical sampling — Part 2: Coal — Sampling from moving streams
ISO 13909-3, Hard coal and coke — Mechanical sampling — Part 3: Coal — Sampling from stationary lots
ISO 13909-4:2001, Hard coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test
samples
ISO 18283:2006, Hard coal and coke — Manual sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1213-2 apply.
4 Principle
4.1 Method A — Two-stage methods
4.1.1 Method A 1 — Drying under nitrogen in second stage
The sample is dried in air at ambient temperatures or at elevated temperatures not exceeding 40 °C (first or
free-moisture stage) and the loss in mass recorded. The air-dried sample is crushed to 2,8 mm nominal top
size and subsamples are dried at 105 °C to 110 °C in a nitrogen-flushed oven (second or residual moisture
stage).
NOTE Residual moisture is often called moisture in the air-dried sample.
Provided that the result obtained for the determination of moisture in the analysis sample in accordance with
ISO 11722 can be shown to give the same result as that for the second-stage moisture determination, the
former may be used.
The moisture is calculated from the loss in mass at each of the two stages.
4.1.2 Method A 2 — Drying in air
The sample is dried in air at ambient temperatures or at elevated temperatures not exceeding 40 °C (first or
free-moisture stage) and the loss in mass recorded. The air-dried sample is crushed to 2,8 mm nominal top
size and subsamples are dried in air at 105 °C to 110 °C (second or residual moisture stage).
The moisture is calculated from the loss in mass at each of the two stages.
NOTE This method is suitable only for hard coals not susceptible to oxidation.
4.2 Method B — Single-stage methods
4.2.1 Method B 1 — Drying under nitrogen
The sample is crushed to a nominal top size of either 11,2 mm or, alternatively, 10 mm. A subsample is dried
in a nitrogen-flushed oven at a temperature of 105 °C to 110 °C. The moisture is calculated from the loss in
mass.
4.2.2 Method B 2 — Drying in air
The sample is crushed to a nominal top size of either 11,2 mm or, alternatively, 10 mm. A subsample is dried
in air at a temperature of 105 °C to 110 °C. The moisture is calculated from the loss in mass.
NOTE This method is suitable only for hard coals not susceptible to oxidation.
5 Reagent
Nitrogen, moisture-free, having an oxygen content of less than 30 µl/l.
NOTE Commercially available nitrogen with a water content of less than 5 µl/l does not require further drying.
2 © ISO 2008 – All rights reserved

6 Apparatus
6.1 Method A
6.1.1 Oven, for first-stage moisture determination, capable of being controlled at a temperature of 30 °C to
40 °C, with a sufficiently rapid rate of atmosphere change (e.g. 5 times per hour). The air velocity shall be
such that the sample particles are not dislodged from their tray.
6.1.2 Nitrogen-flushed oven, for second-stage moisture determination, capable of being controlled at a
temperature of 105 °C to 110 °C, with the additional provision for passing a current of dry nitrogen through it
at a flow rate about 15 times the oven volume per hour. The gas velocity shall be such that the sample
particles are not dislodged from their dish.
6.1.3 Oven, for second-stage moisture determination, capable of being controlled at a temperature of
105 °C to 110 °C, with a sufficiently rapid rate of atmosphere change (e.g. 5 times per hour). The air velocity
shall be such that the sample particles are not dislodged from their dish.
6.2 M
...