ISO 10329:2025

Hard coal - Determination of plastic properties - Constant-torque Gieseler plastometer method

This document specifies a method for obtaining a relative measure of the plastic behaviour of hard coal when heated under prescribed conditions. The method is used to obtain values of the plastic properties of coals and blends used in carbonization and in other situations where determination of plastic behaviour of coals is of practical importance. NOTE The empirical nature of this test requires proper equipment calibration to produce fluidity readings which are a true indication of the relative plastic behaviour of the coal.

Houille — Détermination des propriétés plastiques — Méthode du plastomètre Gieseler à couple constant

General Information

• Status: Published
• Publication Date: 15-May-2025
• ICS: 73.040 - Coals
• Technical Committee: ISO/TC 27/SC 5 - Methods of analysis
• Drafting Committee: ISO/TC 27/SC 5 - Methods of analysis
• Current Stage: 6060 - International Standard published
• Start Date: 16-May-2025
• Due Date: 20-May-2025
• Completion Date: 16-May-2025

Relations

• Revises: ISO 10329:2017 - Coal - Determination of plastic properties - Constant-torque Gieseler plastometer method
• Effective Date: 27-May-2023

Overview

ISO 10329:2025 - Hard coal - Determination of plastic properties - Constant-torque Gieseler plastometer method defines a laboratory procedure to obtain a relative measure of the plastic behaviour (fluidity) of hard coal when heated under prescribed conditions. The method uses a constant-torque Gieseler plastometer to record stirrer rotation (expressed as dd/min) against temperature and yields characteristic plasticity parameters used in carbonization and quality control of coals and blends.

Key topics and technical requirements

• Scope and purpose: Empirical test for relative plastic behaviour of hard coal; applicable to coals and blends important for carbonization.
• Apparatus: Detailed Gieseler plastometer retort design (e.g., crucible internal diameter 21.4 ± 0.1 mm, depth 35.0 ± 0.3 mm), steel stirrer geometry, plastometer head with constant torque drive and 100-division dial (or equivalent electronic readout).
• Constant torque: Brake/clutch adjusted to (101.6 ± 5.0) g·cm (note calibration requirement).
• Heating and bath: Electric furnace with molten solder bath, controlled heating rate (3.0 ± 0.1 °C/min) over ~300 °C to 550 °C; thermocouple placement specified.
• Sample preparation: Representative sampling per ISO 18283 / ISO 13909 series; laboratory sample crushed to pass 4.75 mm, subsampled and reduced to pass 425 µm; final test charge = 5.0 g. Drying limited (≤40 °C) and testing within 8 hours to limit oxidation effects.
• Calibration and quality assurance: Torque checked by string-and-pulley method (or validated transducer). Regular dimension checks on stirrer rabble arms and equipment maintenance emphasized.
• Measured results / terms: dd/min, initial softening temperature, maximum fluidity temperature, maximum fluidity, plastic range, solidification temperature, final fluidity temperature.
• Precision: Method includes sections on repeatability and reproducibility (laboratory comparison required for specific limits).

Practical applications

• Quality control in coke and carbonization plants to assess coal cokeability and blend performance.
• Coal testing and certification laboratories measuring coal fluidity for process optimization.
• Research and development on coal beneficiation, blend formulation, and thermal behaviour.
• Regulatory and procurement specifications where plastic properties influence downstream processing.

Who should use ISO 10329:2025

• Coal and coke producers, carbonization engineers, laboratory managers, QA/QC teams, research institutes, and standards bodies involved in coal testing and material characterization.

Related standards

• ISO 18283 (Manual sampling)
• ISO 13909 series (Coal and coke - Mechanical sampling) These referenced standards govern sampling and sample preparation practices required by ISO 10329:2025.

Keywords: ISO 10329:2025, Gieseler plastometer, hard coal, plastic properties, coal fluidity, constant-torque plastometer, coal testing, carbonization.

Standards Content (Sample)

International
Standard
ISO 10329
Third edition
Hard coal — Determination of
2025-05
plastic properties — Constant-
torque Gieseler plastometer method
Houille — Détermination des propriétés plastiques — Méthode
du plastomètre Gieseler à couple constant
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Calibration . 4
7 Sample . 4
8 Procedure . 4
9 Cleaning of the apparatus .12
10 Calculation and expression of results .12
11 Precision of the method .13
11.1 Repeatability . 13
11.2 Reproducibility . 13

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 5, Methods
of analysis.
This third edition cancels and replaces the second edition (ISO 10329:2017), which has been technically
revised.
The main changes are as follows:
— updated the scope of this document, it is only applicable to hard coal;
— clarified reporting requirements for the various ranges of dd/min.
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
International Standard ISO 10329:2025(en)
Hard coal — Determination of plastic properties — Constant-
torque Gieseler plastometer method
1 Scope
This document specifies a method for obtaining a relative measure of the plastic behaviour of hard coal
when heated under prescribed conditions. The method is used to obtain values of the plastic properties of
coals and blends used in carbonization and in other situations where determination of plastic behaviour of
coals is of practical importance.
NOTE The empirical nature of this test requires proper equipment calibration to produce fluidity readings which
are a true indication of the relative plastic behaviour of the coal.
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 13909-1, Coal and coke — Mechanical sampling — Part 1: General introduction
ISO 13909-2, Coal and coke — Mechanical sampling — Part 2: Sampling of coal from moving streams
ISO 13909-3, Coal and coke — Mechanical sampling — Part 3: Sampling of coal from stationary lots
ISO 13909-4:2016, Hard coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples
ISO 18283, Coal and coke — Manual sampling
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
dial division per minute
dd/min
measure of stirrer rotation rate, as used in the constant-torque Gieseler plastometer method
Note 1 to entry: There are 100 dial divisions for each full 360° rotation of the stirrer. The fluidity result is expressed as
total dial divisions turned by the stirrer in a 1 min time period, i.e. dd/min.
3.2
initial softening temperature
temperature at which dial movement or electronic readout indicates a stirring shaft movement of one dial
division per minute (3.1), with continued indication of movement of at least 1 dd/min thereafter

3.3
maximum fluidity temperature
temperature at which stirring shaft rotation reaches the maximum rate
3.4
plastic range
difference between the initial softening temperature and the solidification temperature
3.5
final fluidity temperature
temperature at which the last 1 dd/min stirrer rotation rate is reached
3.6
solidification temperature
temperature at which the stirring shaft stops
3.7
maximum fluidity
maximum rate of rotation for the stirring shaft in dial divisions per minute (3.1)
3.8
jamming
swelling up of coal into the retort tube during the test
Note 1 to entry: Jamming can produce a lower fluidity result than expected and can only be noted after visual
inspection of the disassembled crucible and retort at the conclusion of the test.
3.9
breaking
free spinning behaviour of coal, either by rotating at maximum motor speed or by abrupt changes in rotation
Note 1 to entry: Breaking occurs as a result of a molten ball of coal forming around the base of the stirrer, and makes
reporting of the true maximum fluidity (3.7) of the coal difficult.
4 Principle
Measurements of the plastic properties of coals are made by applying a constant torque to a stirrer placed in
a crucible into which the coal is charged. The crucible is immersed in a bath and the temperature increased
uniformly. The rotation of the stirrer is recorded in relation to increase in temperature.
5 Apparatus
5.1 Gieseler plastometer retort, composed of the following component parts (see Figure 1).
5.1.1 Retort crucible, cylindrical, with (21,4 ± 0,1) mm inside diameter, and (35,0 ± 0,3) mm in depth
with exterior threads for joining the crucible to the barrel.
The crucible shall have a (2,38 ± 0,02) mm diameter notch with an included angle of 70° in the centre of its
inside base to serve as a seat for the stirrer.
5.1.2 Retort crucible cover, with interior threads for joining the crucible cover to the crucible and
exterior threads for joining the crucible cover to the barrel.
The inside diameter of the hole which accommodates the stirrer shall be (9,5 ± 0,1) mm.
5.1.3 Guide sleeve, provided near the upper end of the stirrer to guide the latter within the barrel with a
clearance of between 0,05 mm and 0,10 mm.

5.1.4 Gas exit hole, provided on the barrel to afford an exit for the volatile products during a test, placed,
for example, at the midpoint of the barrel; as an option, a tube may be fitted if desired.
5.1.5 Barrel, (121,0 ± 2,5) mm long, having an inside diameter of (9,5 ± 0,1) mm.
The top end of the barrel shall be 12,7 mm in inside diameter to a depth sufficient to allow the fitting of a
guide sleeve through which the axle of the stirrer passes when the apparatus is assembled.
5.1.6 Steel stirrer, provided with a straight shaft (3,95 ± 0,05) mm in diameter and equipped with four
rabble arms.
The lower end of the stirrer shall be tapered to a point having an included angle of 60°. The rabble arms on
the stirrer shall be (1,60 ± 0,05) mm in diameter, (6,4 ± 0,05) mm in length, and shall be placed perpendicular
to the shaft at 90° intervals around the shaft and (3,2 ± 0,05) mm apart centre to centre along the shaft. The
middle two rabble arms shall be set at 180° to each other, and likewise, the remaining two arms at 180° to
each other. The lowest rabble arm shall be set to give (1,60 ± 0,05) mm clearance between it and the bottom
of the crucible when the stirrer is in place. The upper end of the stirrer shall be cut to fit into a slot on the
lower end of the axle in the plastometer head.
The rabble arms shall be checked before each test to ensure that they are clean and free from distortion
or other visual damage. It is essential that the dimensions of the rabble arms on the stirrer meet the
requirements in this clause and in Figure 2 and it is important that these dimensions are checked on a
regular basis, e.g. every 50 determinations. If after use, it is found by accurate measurement that any of the
dimensions are outside the spec
...