ISO 11760:2018

INTERNATIONAL ISO
STANDARD 11760
Second edition
2018-11
Classification of coals
Classification des charbons
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Classification .3
4.1 General . 3
4.2 Rank — Primary categories . 3
4.3 Rank — Sub-categories . 4
4.4 Petrographic (maceral group) composition . 5
4.5 Ash yield . 6
5 Nature of the coal sample .6
6 Descriptive classification terminology .7
7 Analytical tolerances .7
8 Graphic representation . 8
Bibliography .9
Foreword
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This document was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC
5, Methods of analysis.
This second edition cancels and replaces the first edition (ISO 11760:2005), of which it constitutes a
minor revision.
The main changes compared to the previous edition are as follows:
— replacement of AS 2434-1 with ISO 1018 in Table 1.
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iv © ISO 2018 – All rights reserved

Introduction
Coals occur worldwide and vary significantly in their physical and chemical characteristics for a variety
of reasons, both with respect to the organic coal substance and to the associated mineral matter that is
always present to varying extents. Coals are an important source of energy, as well as being essential for
the production of metallurgical cokes, and are widely used as feedstock for other industrial processes
such as in the production of gaseous fuels and synthesis gas. Hence, a wide range of procedures has
been developed by the International Organization for Standardization (ISO) for the analysis and testing
of coals. These ISO procedures are variously designated as being applicable to “hard coals”, “brown
coals” and “lignite”, “bituminous coals” and “anthracite”. There are, however, no ISO definitions that
specify the boundaries that apply to these descriptive terms, which all relate to the geological maturity
(rank) of the coals. Further, there is no simple system for the classification of coals that can provide,
on a comparative basis, an indication of coal characteristics on a worldwide basis. This ISO standard
provides a basis for addressing both these issues.
The classification is not intended to be used for commercial purposes because the assessment and
selection of coals for a specific purpose require detailed information that enables the likely performance
of a coal in a particular application to be anticipated. The wide-ranging list of ISO analyses and tests
provides that information.
The development of this ISO standard has been guided by the recently published “International Classification
[14]
of in-Seam Coals” . The ISO standard, however, represents a simplified version that incorporates some
significant modifications made for reasons given in the classification details that follow.
INTERNATIONAL STANDARD ISO 11760:2018(E)
Classification of coals
1 Scope
This document describes a simple classification system for coals providing
— guidance on the selection of the appropriate ISO standard procedures for the analyses and testing
of coals,
— international comparison of coals in terms of some key characteristics,
— descriptive categorization of coals.
The system is applicable to coals of all ranks, but care is required in relation to the classification of
some types of coal.
The system can be applied to a wide range of representative coal samples, provided their exact nature
is stated. Such samples include bore-core seam sections and composite samples, raw (as-mined) coal,
washed coal, blends of coals of similar rank and selected, specified size fractions.
The system provides a broad framework within which coals can be assessed. The selection of coals for
a specific use requires detailed information that enables the likely performance of a coal in a particular
application to be anticipated. The wide-ranging list of ISO analyses and test procedures for coals serve
this purpose. The selection of the appropriate procedures to be used in assessing a coal depends on the
intended use.
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 1213-2, Solid mineral fuels — Vocabulary — Part 2: Terms relating to sampling, testing and analysis
ISO 7404-1, Methods for the petrographic analysis of coals — Part 1: Vocabulary
ISO 7404-5, Methods for the petrographic analysis of coals — Part 5: Method of determining microscopically
the reflectance of vitrinite
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1213-2, ISO 7404-1 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
coal
carbonaceous sedimentary rock largely derived from plant remains with an associated mineral content
corresponding to an ash yield less than, or equal to, 50 % by mass (dry basis)
Note 1 to entry: In the geological coalification sequence, the transformation from peat to coal is defined as
occurring when the total in-situ moisture content has decreased to 75 % by mass. The upper limit for undisturbed
coal seams in the normal coalification process leading to semi-graphite is defined as corresponding to a mean
random vitrinite reflectance, R , of 6,0 % or, preferably, a mean maximum vitrinite reflectance, R , of 8 %,
r v,max
determined in accordance with ISO 7404-5. The upper limit, R , for disturbed, contact altered, coals can
v,max
exceed 10 %; see Table 1, Note 2.
3.2
vitrinite
group of macerals with a grey colour (as observed with reflected light under a microscope) and with a
reflectance generally between that of the associated darker liptinite and lighter inertinite over the rank
range in which the three respective maceral groups can be readily recognized
Note 1 to entry: In the upper range of medium rank, vitrinite reflectance can be less than that of liptinite (where
liptinite is recognizable) whilst at very high rank (R > 4,0 %), the maximum reflectance of both liptinite and
r
vitrinite may exceed that of inertinite.
Note 2 to entry: In medium and high rank coals, vitrinite reflectance measurements should preferably be taken
on telovitrinite or, in its absence, on the whole of the vitrinite population. Within low-rank coals, vitrinite
reflectance measurements shall be measured on the submaceral ulminite B, or preferably on Eu-ulminite, if
present. Eu-ulminite consists of gelified plant tissues with the cell structures weakly visible in reflected white
light. Ulminite B is the more highly reflecting part of ulminite; see Reference [9].
3.3
inertinite
maceral group that is composed of particles having a reflectance in low and medium-rank coals that
is higher than that of the macerals of the vitrinite and liptinite groups, but is lower than that of the
corresponding vitrinite in very high-rank coals
Note 1 to entry: The reflectance of inertinite macerals begins to be exceeded by that of the macerals of the
vitrinite group when the vitrinite and inertinite reflectance, R , has reached about 4 %; see Reference [8].
r
3.4
liptinite
maceral group that includes sporinite, cutinite, suberinite, resinite, liptodetrinite and alginite
Note 1 to entry: At low ranks, the reflectance of liptinite macerals is lower than that of vitrinite but converges
with that of vitrinite at medium rank B to A. Liptinite macerals show stronger primary autofluorescence relative
to that of macerals from the other maceral groups up to medium rank B.
3.5
lignite
brown coal
coal having a mean random vitrinite reflectance, R , less than 0,4 %
r
Note 1 to entry: The terms “brown coal” and “lignite” are frequently used as alternatives but the latter is the
[10]
term now preferred by the International Commission for Coal and Organic Petrology .
3.6
sub-bituminous coal
coal having a mean random vitrinite reflectance, R , equal to or greater than 0,4 % but less than 0,5 %
r
2 © ISO 2018 – All rights reserved

3.7
bituminous coal
coal, synonymous with medium-rank coal, having a mean random vitrinite reflectance, R , equal to or
r
greater than 0,5 %, but less than 2,0 %
3.8
anthracite
coal, synonymous with high-rank coal, having a mean random vitrinite reflectance, R , equal to or
r
...