ISO 7404-3:2009

INTERNATIONAL ISO
STANDARD 7404-3
Third edition
2009-10-01


Methods for the petrographic analysis of
coals —
Part 3:
Method of determining maceral group
composition
Méthodes d'analyse pétrographique des charbons —
Partie 3: Détermination de la composition en groupes de macéraux




Reference number
ISO 7404-3:2009(E)
©
ISO 2009

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ISO 7404-3:2009(E)
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ii © ISO 2009 – All rights reserved

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ISO 7404-3:2009(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Principle .1
5 Reagents and materials .1
6 Apparatus.2
7 Preparation of coal sample .2
8 Procedure.2
9 Expression of results.3
10 Precision .4
11 Test report.5
Annex A (informative) Sub-division of maceral groups.6
Bibliography.7

© ISO 2009 – All rights reserved iii

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ISO 7404-3:2009(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.
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 7404-3 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels.
This third edition cancels and replaces the second edition (ISO 7404-3:1994), which has been technically
revised.
ISO 7404 consists of the following parts, under the general title Methods for the petrographic analysis of coals:
1)
⎯ Part 1: Vocabulary
⎯ Part 2: Methods of preparing coal samples
⎯ Part 3: Method of determining maceral group composition
1)
⎯ Part 4: Method of determining microlithotype, carbominerite and minerite composition
⎯ Part 5: Method of determining microscopically the reflectance of vitrinite


1) Parts 1 and 4 of this International Standard will be available under the original title, Methods for the petrographic
analysis of bituminous coal and anthracite, until the revisions of these documents have reached the stage at which they
are publicly available.
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ISO 7404-3:2009(E)
Introduction
Petrographic analyses have been recognized internationally as important in the context of the genesis, vertical
and lateral variation, continuity, metamorphism and usage of coal. The International Committee for Coal and
Organic Petrology (ICCP) has made recommendations concerning nomenclature and analytical methods and
has published an extensive handbook, describing the characteristics of a wide range of coals. The ICCP also
runs an accreditation program for maceral group analysis. The text of this part of ISO 7404 agrees with text of
the handbook and incorporates many useful comments made by members of the ICCP and by member
bodies of ISO/TC 27, Solid mineral fuels.
ISO 11760, Classification of coals, uses the maceral group composition as one of three parameters to classify
coal; the other parameters are vitrinite reflectance and ash yield, respectively, for rank and grade.
Petrographic analyses of a single coal provide information about the rank, the maceral and microlithotype
compositions and the distribution of minerals in the coal. The reflectance of vitrinite (or huminite) is a useful
measure of coal rank and the distribution of the reflectance of vitrinite (or huminite) in a coal blend, together
with a maceral group analysis, can provide information about some important chemical and technological
properties of the blend.
ISO 7404 (all parts) is concerned with the methods of petrographic analysis currently employed in
characterizing coal in the context of its technological use. It establishes a system for petrographic analysis.
For information on the nomenclature and analysis of brown coals and lignites, reference should be made to
the International Handbook of Coal Petrography published by ICCP.
Macerals are microscopically recognizable organic constituents of coal, and can be grouped together into
three maceral groups: vitrinite (or huminite in lower rank coal), liptinite and inertinite.
Maceral groups and their subdivisions are listed in Annex A and described in detail in ISO 7404-1. The
properties of a given coal are determined by the proportions and associations of the macerals and minerals
present and by the rank of the coal. The method of determining maceral group composition described in this
part of ISO 7404 applies to determinations made in reflected white light; the additional use of fluorescence
microscopy is recommended when analysing lower rank coals.
In addition to the macerals, it is possible to identify certain minerals in coal; these can either be determined as
separate categories or be ignored. As some of the minerals cannot be satisfactorily determined under the
microscope, an estimate of the total mineral matter content can be obtained from the ash.
Annex A of this part of ISO 7404 is for information only.
© ISO 2009 – All rights reserved v

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INTERNATIONAL STANDARD ISO 7404-3:2009(E)

Methods for the petrographic analysis of coals —
Part 3:
Method of determining maceral group composition
1 Scope
This part of ISO 7404 specifies a method for determining the proportions of the maceral groups (and the
minerals, if desired) in coals. It is concerned only with determinations made on polished particulate blocks
using incident white light. For lower-rank coals, the additional use of the fluorescence mode is necessary to
identify liptinites.
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 7404-1, Methods for the petrographic analysis of bituminous coal and anthracite — Part 1: Vocabulary
ISO 7404-2, Methods for the petrographic analysis of coals — Part 2: Method of preparing coal samples
ISO 11760, Classification of coals
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7404-1 apply.
4 Principle
A representative sample of coal is used to prepare a particulate block as described in ISO 7404-2. This is
examined using a reflected light microscope and the macerals are identified under an immersion medium by
their relative reflectance, colour, size and morphology. Their proportions are determined by a point-count
proc
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