ISO 7404-5:1994
(Main)Methods for the petrographic analysis of bituminous coal and anthracite — Part 5: Method of determining microscopically the reflectance of vitrinite
Methods for the petrographic analysis of bituminous coal and anthracite — Part 5: Method of determining microscopically the reflectance of vitrinite
Cancels and replaces the first edition (1984). Specifies the method for determining microscopically the maximum and random reflectance in oil of polished surfaces of the vitrinite component of coals. Applicable to either coals from single seams or coal blends covering the whole range of bituminous coal and anthracite.
Méthodes d'analyse pétrographique des charbons bitumineux et de l'anthracite — Partie 5: Détermination au microscope du pouvoir réflecteur de la vitrinite
Metode petrografskih analiz bituminoznega premoga in anatracita - 5. del: Določanje odsevnosti vitrinita z mikroskopom
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INTERNATIONAL
ISO
STANDARD 7404-5
Second edition
1994-10-01
Methods for the petrographic analysis of
bitutninous coal and anthracite -
Part 5:
Method of determining microscopically the
reflectance of vitrinite
Methodes d ’analyse petrographique des charbons bitumineux et de
I ‘an thracite -
Partie 5: Determination au microscope du pouvoir rkflecteur de Ia vitrinite
Reference number
ISO 7404-5:1994(E)
---------------------- Page: 1 ----------------------
ISO 7404-5: 1994(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. Esch 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.
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.
International Standard ISO 7404-5 was prepared by Technical Committee
lSO/TC 27, Solid mineral fuels.
This second edition cancels and replaces the first edition
(1 SO 7404-5: 1984), which has been technically revised.
ISO 7404 consists of the following Parts, under the general title Methods
for the petrographic analysis of bituminous coal and anthracite:
- Part 7: Vocabulary
- Part 2: Method of preparing coal samples
- Part 3: Method of determining maceral group composition
- Part 4: Method of determining microlithotype, carbominerite and
minerite composition
microscopically the reflectance of
- Part 5: Method of determining
vitrinite
Annex A of this part of ISO 7404 is for information only.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 2 ----------------------
0 ISO
ISO 7404-5: 1994(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 no-
menclature and analytical methods and has published an extensive hand-
book describing in detail the characteristics of a wide range of coals. The
text of this part of ISO 7404 agrees substantially with the 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.
Petrographic analyses sf a Single coal provide information about the rank,
the maceral and microlithotype compositions and the distribution of min-
erals in the coal. The reflectance of vitrinite is a useful measure of coal
rank and the distribution of the reflectance of vitrinite in a coal blend, to-
gether with a maceral group analysis, tan provide information about some
important Chemical and technological properties of the blend.
ISO 7404 is concerned with the methods of petrographic analysis cur-
rently employed in characterizing bituminous coal and anthracite in the
context of their technological use. lt establishes a System for petrographic
analysis and comprises five Parts, as follows:
Part 1: Vocabulary.
Part 2: Method of preparing coal samples.
Part 3: Method of determining maceral group composition.
Part 4: Method of determining microlithotype, ca rbomi nerite and
minerite composition.
Part 5: Method of determining mi croscopically the reflectance of
vitrinite.
For information on the nomenclature and analysis of brown coals and
lignites, reference should be made to the International Handbook of Coal
Petrograph+l] published by the ICCP.
The properties of a given coal are determined by the proportions and as-
sociations of the macerals and minerals present (see ISO 7404-3[21) and
by the rank of the coal. One property that normally tan be used as an in-
dicator of rank, independent of the petrographic composition, is the
reflectance of the vitrinite of the coal which increases progressively with
increasing degree of coalification.
The reflectances of the submacerals of vitrinite differ even in a Single coal
seam and therefore the value of the reflectance obtained depends on the
choice of the submacerals used for measurement. Reflectance measure-
ments are made on one or more of the submacerals of vitrinite, and in
reporting the results it is necessary to specify on which submacerals the
. . .
Ill
---------------------- Page: 3 ----------------------
ISO 7404-5: 1994(E) 0 ISO
measurements were made and in what Proportion. Consequently, a vital
step in the measurement of vitrinite reflectance is the identification of
vitrinite and its various submacerals. For this purpose, ISO 7404-1 and the
ICCP handbook should be consulted.
The reflectance value obtained also depends on whether maximum or
random reflectance measurements are made so that the type of
measurement has to be specified.
All of these analysis procedures are applicable to Single coal seams or to
blends providing that enough measurements are made in compliance with
an unbiased sampling procedure on a representative Sample.
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD 0 ISO
Iso 74o4-~:~994(E)
Methods for the petrographic analysis of bituminous
coal and anthracite -
Part 5:
Method of determining microscopically the reflectance of
vitrinite
ISO 7404-1 :1994, Methods for the petrographic
1 Scope
analysis of bituminous coal and anthracite - Part 1:
Vocabulary.
This part of ISO 7404 specifies the method for deter-
mining microscopically the maximum and random
ISO 7404-2:1985, Methods for the petrographic
reflectance in oil of polished surfaces of the vitrinite
analysis of bituminous coal and anthracite - Part 2:
component of coals. The method is applicable to ei-
Method of preparing coal samples.
ther coals from Single seams or coal blends covering
the whole range of bituminous coal and anthracite.
By itself, this method is unsuitable for determining the
3 Definitions
proportion of components in a blend, particularly
when the components have dissimilar measurable
For the purposes of this part of ISO 7404, the defi-
vitrinite contents.
nitions given in ISO 7404-1 apply.
The method necessitates the identification of vitrinite
by the Operator. Reflectance measurements on
4 Principle
vitrinite obtained by interpreting the results of a com-
puterized automated System of microscopic analysis
Light, with a wavelength of 546 nm, reflected at near
are outside the scope of this part of ISO 7404.
normal incidence from a specified area of well-
polished vitrinite, measured under oil immersion using
a photomultiplier (or similar device), is compared with
light reflected under identical conditions from a num-
ber of Standards of known reflectance. Because dif-
ferent vitrinite particles within a Single coal seam
2 Normative references
invariably differ slightly from one another in Optical
properties, enough readings on different particles are
The following Standards contain provisions which,
taken to ensure that the results are representative.
through reference in this text, constitute provisions
of this part of ISO 7404. At the time of publication, the
editions indicated were valid. All Standards are subject
5 Materials
to revision, and Parties to agreements based on this
part of ISO 7404 are encouraged to investigate the
possibility of applying the most recent editions of the
5.1 Immersion Oil, of a non-drying, non-corrosive
Standards indicated below. Members of IEC and ISO
type, with a refractive index of 1,518 0 + 0,000 4 at
maintain registers of currently valid International
23 “C and a wavelengttdnof 546 nm andkith a tem-
Standards. perature coefficient - dt of less than 0,000 5 K- ‘.
1
---------------------- Page: 5 ----------------------
0 ISO
ISO 7404-5: 1994(E)
NQTES
- Reflectance Standards in common use
Table 1
-
1 Oil from a bottle which was first opened more than a
year previously should not be used unless the refractive
Reflectance in
index has been checked.
immersion oil
Refractive
Designation of 1.518 at
index
2 The oil should not contain polychlorinated biphenyls or
546 nm (see
other toxic components.
5.1)
%
-
5.2 Calibration Standards
Optical glasses 1,70 to 1,97 0,32 to 1,66
Spinel 1,73 0,42
1,77
Leucosapphire 0,59
5.2.1 Reflectance Standards, consisting of polished
Yttrium aluminium
surfaces of materials that
1,84 0,92
garnet (YAG)
a) are isotropic (or basal sections of uniaxial min-
Gadolinium gallium
1,98
1,73
erals);
garnet (3G)
Diamond 2,42 5,28
b) are durable and resistant to corrosion;
Silicon carbide 2,66 7,50
have constant reflectance over a long period;
Cl
Where the refractive index is not known, or where it
are free from in clusions, grain boundaries, dis-
d)
is suspected that the surface properties may not ex-
continuities, internal flaws and fractures;
actly match the nominal bulk properties, determine
the reflectance by careful comparison with a Standard
e) have negligibly low absorptance.
of known reflectance (see note 4).
To avoid significant amounts of light other than that
NOTES
reflected from the top surface returning to the objec-
3 For measuring a coal reflectance of about 1,O %, stan-
tive, the body of the Standard shall be either deeper
dards with reflectances of approximately 0,6 %, 1,O % and
than 5 mm or wedge-shaped. The lower surface shall
1,6 % should be used.
be matt if it makes an angle of less than IO” with the
upper polished surface.
4 Standards need careful cleaning to avoid scratching the
polished surface. Tarnishing may also occur with some
The sides shall be shielded from external light.
Standard materials, particularly glasses. When the surface
becomes scratched, or when comparison with the other
The reflectance of the Standards shall be in the region
Standards Shows that the reflectance value has changed,
of the reflectance of the coal to be measured. Use at
polishing is necessary.
least three such Standards with weil-spaced
reflectances (see note 3).
5.2.2 Zero Standard
lf a coal with a reflectance greater than 2,0 % is to
be measured, use one or more additional Standards
NOTE 5 A suitable non-reflecting Standard consists of a
with reflectance greater than 2,0 %.
coal or opaque resin block with a hole about 5 mm in di-
ameter and 5 mm deep, drilled in its upper surface and filled
Table 1 gives mean values of refractive index and of
with immersion Oil. Alternatively, Optical glasses of
reflectance for reflectance Standards in common use.
refractive index lower than that of the immersion oil may
Determine exactly the reflectance of any Optical glass
be used.
Standard by using a comparable Standard or by means
of a determination of the refractive index.
Where the refractive index, IZ, and (if significant) the
6 Apparatus
absorptance, CX, of the Standard material are known for
a wavelength of 546 nm, calculate the reflectance, R,
as a percentage using the equation
6.1 Binocular reflected light microscope with
(n - 1,518)* + n2a2 x 1oo
Photometer.
’ = (n + 1,518)’ + n2a2
NOTE 6 The reference letters refer to figure 1.
---------------------- Page: 6 ----------------------
0 ISO
ISO 7404-5: 1994(E)
6.1.1 Light Source (A). adequate blackening to absorb stray light.
c)
Any light Source with a stable output may be used; a NOTE IO Subject to the above precautions, part of the
light beam may be diverted to the eyepieces or to a tele-
quartz halogen lamp with a rating of 100 W is rec-
Vision Camera for continuous Observation during reflectance
ommended.
measurement.
6.1.2 Polarizer (E) (optional): A sheet or prism
polarizer.
6.1.8 Filter(s) (0), with a peak transmittance in the
range of 546 nm + 5 nm and a half-peak
6.1.3 Light-controlling apertures, consisting of
transmittance band of less than 30 nm.
two variable diaphragms, one of which is focused on
the back focal plane of the objective [illuminator ap- NOTE 11 The filters should be inserted into the light path
immediately before the photomultiplier.
erture (C)] and the other on the surface of the speci-
men [field stop (F)]. lt shall be possible to centre both
diaphragms on the Optical axis of the microscope
6.1.9 Photomultiplier tube (P), fitted in a housing
System. The Optical Parts of a typical reflectance
attached to the microscope, permitting the light
measuring microscope are shown in figure 1.
passing through the measuring aperture and filter to
fall onto the photomultiplier window.
NOTE 7 The com ponent Parts may not always be in the
same uence.
seq
NOTES
6.1.4 Vertical illuminator, Berek prism, simple
12 The photomultiplier tube should be of a type rec-
coated glass plate or Smith illuminator (a combined ommended for low light-level applications, and should have
adequate sensitivity at 546 nm with low dark current. It
mirror and glass plate). Typical light paths are shown
should have a linear response over the range of the
in figure 2.
measurement and the output should be stable over periods
of up to 1 h.
6.1.5 Objective (I), Strain-free objective, designed
for use with polarized light and an immersion oil of
13 A 50 mm dia meter straight t be with an end window
refractive index 1,518, with a magnification of be-
and conta ining 11 dynodes is freq ently used.
tween x 25 and x 60 and a low value for the parasitic
reflection (see 8.2.3).
6.1.10 Microscope Stage (K), fitted with a mech-
anical Stage capable of advancing the specimen by
NOTE 8 The diameter of the objective should be as large
as possible. A larger objective gives increased light inten-
0,5 mm Steps in the X and Y directions and provided
sity, thereby reducing the Signal amplification and hence the
with a means for making small adjusting movements.
electronie noise; it also makes it possible to work with a
For maximum reflectance, the Stage shall be capable
smaller measuring aperture.
of being rotated through 360” perpendicular to the
Optical axis, and being centred by adjusting either the
6.1.6 Eyepieces (L), Two viewing eyepieces, one
Stage or the objective.
of which is fitted with crosslines which may be
scaled, such that the total magnification given by the
objective, eyepiece and tube factor (if any) is between
6.2 Stabilized d.c. power supply unit for the light
x 250 and x 750.
Source.
NOTE 9 A th ird eyepiece (M) may be necessary in the
The following characteristics have been found to be
light path leadin g to the photomultiplier.
satisfactory:
6.1.7 Microscope tube, with the following features:
a) a lamp output of between 90 % and 95 % of rated
output;
a) measuring aperture (N) which restricts the light
reaching the photomultiplier to that reflected from
b) an output Variation of less than 0,02 % for a sup-
an area of the specimen (J) less than 80 Pm* and
ply Variation of 10 %;
which tan be aligned with the crosslines in the
c) a ripple content at full load of less than 0,07 %
viewing eyepiece;
peak to peak;
b) a means of optically isolating the viewing eye-
less than
pieces if they permit the entry of extraneous light d) a temperature coefficient of
during measurement; 0,05 % K- ‘.
---------------------- Page: 7 ----------------------
ISO 7404=5:1994(E)
A Lamp
B Coll8ctor lens
Illuminator aperture
C
Heat filter
D
Polarizer
E
F Field stop
G Field-stop focusing lens
H Vertical illuminator
P
1 Obj8CtiV8
Specimen
J
K Stage
Vi8Wing 8y8-pi8C8S
L
Third eye-piece
M
N Measuring aperture
0 546 nm interference filter
P Photomultiplier tube
. .
G
C DEF
\tP- '
Figure 1 - Optical Parts of a typical reflectance measuring microscope
4
---------------------- Page: 8 ----------------------
ISO 7404-5: 1994(E)
Camp filament
Collector lens
Illuminator aperture (Position of filament image)
Field stop
Field-stop focusing lens
Berek prism
Back focal plane of objective (Position of images of the
filament and the illuminator aperture)
0 bjective
Sutface of specimen (Position of image of field stop)
a) Berek prism vertical illuminator
Thin glass reflector
-0
Coated glass plate
0
0 E D E
G G ----h,Ai,AJ---
--7-h, ,A-r--
c
H
t
L?sL
1 I
b) Gfass plate illuminator c) Smith Ctluminatoa
Figure 2 - Types of vertical illuminators
---------------------- Page: 9 ----------------------
0 ISO
ISO 7404-5:1994( E)
6.3 Stabilized d.c. voltage power supply unit for
7 Preparation of coal Sample
the photomultiplier tube.
Prepare and polish a particulate block as described in
The following characteristics have been found to be
ISO 7404-2.
satisfactory:
a) an output Variation of less than 0,05 % for a 8 Procedure
IO % Variation in supply voltage;
8.1 Setting up the apparatus
b) a ripple content at full load of less than 0,07 %
peak to peak;
NOTE 17 In 8.1.3 and 8.1.4 letters in parentheses relate
to the key in figure ‘l.
temperature coefficient of less than
c) a
0,05 % K- ‘;
8.1 .l Starting procedure
d) a Change in load from zero to full rated load that
Ensure that the room temperature remains within the
Causes less than 0,l % Variation in output voltage.
range 18 “C to 28 “C. Switch on the lamp, power
supplies and other electrical Parts of the apparatus.
NOTE 14 If the mains voltage at peak periods is expected
Set the power supply to the photomultiplier to within
to fall below 90 % of the normal rated value, a suitably rated
stabilizing autotransformer should be connected between the voltage range recommended by the manufacturer
the mains power Point and the two stabilized power sup-
of the particular photomultiplier tube. Allow about
plies (see 6.2 and 6.3).
30 min to elapse for stability of the apparatus to be
attained Prior to making any measurements.
8.1.2 Adjusting the microscope for random or
6.4 Display, comprising one of the following de-
maximum measurements
wces:
If random reflectance measurements are to be made,
a)
...
SLOVENSKI STANDARD
SIST ISO 7404-5:1998
01-februar-1998
0HWRGHSHWURJUDIVNLKDQDOL]ELWXPLQR]QHJDSUHPRJDLQDQDWUDFLWDGHO
'RORþDQMHRGVHYQRVWLYLWULQLWD]PLNURVNRSRP
Methods for the petrographic analysis of bituminous coal and anthracite -- Part 5: Method
of determining microscopically the reflectance of vitrinite
Méthodes d'analyse pétrographique des charbons bitumineux et de l'anthracite -- Partie
5: Détermination au microscope du pouvoir réflecteur de la vitrinite
Ta slovenski standard je istoveten z: ISO 7404-5:1994
ICS:
73.040 Premogi Coals
SIST ISO 7404-5:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 7404-5:1998
---------------------- Page: 2 ----------------------
SIST ISO 7404-5:1998
INTERNATIONAL
ISO
STANDARD 7404-5
Second edition
1994-10-01
Methods for the petrographic analysis of
bitutninous coal and anthracite -
Part 5:
Method of determining microscopically the
reflectance of vitrinite
Methodes d ’analyse petrographique des charbons bitumineux et de
I ‘an thracite -
Partie 5: Determination au microscope du pouvoir rkflecteur de Ia vitrinite
Reference number
ISO 7404-5:1994(E)
---------------------- Page: 3 ----------------------
SIST ISO 7404-5:1998
ISO 7404-5: 1994(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. Esch 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.
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.
International Standard ISO 7404-5 was prepared by Technical Committee
lSO/TC 27, Solid mineral fuels.
This second edition cancels and replaces the first edition
(1 SO 7404-5: 1984), which has been technically revised.
ISO 7404 consists of the following Parts, under the general title Methods
for the petrographic analysis of bituminous coal and anthracite:
- Part 7: Vocabulary
- Part 2: Method of preparing coal samples
- Part 3: Method of determining maceral group composition
- Part 4: Method of determining microlithotype, carbominerite and
minerite composition
microscopically the reflectance of
- Part 5: Method of determining
vitrinite
Annex A of this part of ISO 7404 is for information only.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 4 ----------------------
SIST ISO 7404-5:1998
0 ISO
ISO 7404-5: 1994(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 no-
menclature and analytical methods and has published an extensive hand-
book describing in detail the characteristics of a wide range of coals. The
text of this part of ISO 7404 agrees substantially with the 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.
Petrographic analyses sf a Single coal provide information about the rank,
the maceral and microlithotype compositions and the distribution of min-
erals in the coal. The reflectance of vitrinite is a useful measure of coal
rank and the distribution of the reflectance of vitrinite in a coal blend, to-
gether with a maceral group analysis, tan provide information about some
important Chemical and technological properties of the blend.
ISO 7404 is concerned with the methods of petrographic analysis cur-
rently employed in characterizing bituminous coal and anthracite in the
context of their technological use. lt establishes a System for petrographic
analysis and comprises five Parts, as follows:
Part 1: Vocabulary.
Part 2: Method of preparing coal samples.
Part 3: Method of determining maceral group composition.
Part 4: Method of determining microlithotype, ca rbomi nerite and
minerite composition.
Part 5: Method of determining mi croscopically the reflectance of
vitrinite.
For information on the nomenclature and analysis of brown coals and
lignites, reference should be made to the International Handbook of Coal
Petrograph+l] published by the ICCP.
The properties of a given coal are determined by the proportions and as-
sociations of the macerals and minerals present (see ISO 7404-3[21) and
by the rank of the coal. One property that normally tan be used as an in-
dicator of rank, independent of the petrographic composition, is the
reflectance of the vitrinite of the coal which increases progressively with
increasing degree of coalification.
The reflectances of the submacerals of vitrinite differ even in a Single coal
seam and therefore the value of the reflectance obtained depends on the
choice of the submacerals used for measurement. Reflectance measure-
ments are made on one or more of the submacerals of vitrinite, and in
reporting the results it is necessary to specify on which submacerals the
. . .
Ill
---------------------- Page: 5 ----------------------
SIST ISO 7404-5:1998
ISO 7404-5: 1994(E) 0 ISO
measurements were made and in what Proportion. Consequently, a vital
step in the measurement of vitrinite reflectance is the identification of
vitrinite and its various submacerals. For this purpose, ISO 7404-1 and the
ICCP handbook should be consulted.
The reflectance value obtained also depends on whether maximum or
random reflectance measurements are made so that the type of
measurement has to be specified.
All of these analysis procedures are applicable to Single coal seams or to
blends providing that enough measurements are made in compliance with
an unbiased sampling procedure on a representative Sample.
---------------------- Page: 6 ----------------------
SIST ISO 7404-5:1998
INTERNATIONAL STANDARD 0 ISO
Iso 74o4-~:~994(E)
Methods for the petrographic analysis of bituminous
coal and anthracite -
Part 5:
Method of determining microscopically the reflectance of
vitrinite
ISO 7404-1 :1994, Methods for the petrographic
1 Scope
analysis of bituminous coal and anthracite - Part 1:
Vocabulary.
This part of ISO 7404 specifies the method for deter-
mining microscopically the maximum and random
ISO 7404-2:1985, Methods for the petrographic
reflectance in oil of polished surfaces of the vitrinite
analysis of bituminous coal and anthracite - Part 2:
component of coals. The method is applicable to ei-
Method of preparing coal samples.
ther coals from Single seams or coal blends covering
the whole range of bituminous coal and anthracite.
By itself, this method is unsuitable for determining the
3 Definitions
proportion of components in a blend, particularly
when the components have dissimilar measurable
For the purposes of this part of ISO 7404, the defi-
vitrinite contents.
nitions given in ISO 7404-1 apply.
The method necessitates the identification of vitrinite
by the Operator. Reflectance measurements on
4 Principle
vitrinite obtained by interpreting the results of a com-
puterized automated System of microscopic analysis
Light, with a wavelength of 546 nm, reflected at near
are outside the scope of this part of ISO 7404.
normal incidence from a specified area of well-
polished vitrinite, measured under oil immersion using
a photomultiplier (or similar device), is compared with
light reflected under identical conditions from a num-
ber of Standards of known reflectance. Because dif-
ferent vitrinite particles within a Single coal seam
2 Normative references
invariably differ slightly from one another in Optical
properties, enough readings on different particles are
The following Standards contain provisions which,
taken to ensure that the results are representative.
through reference in this text, constitute provisions
of this part of ISO 7404. At the time of publication, the
editions indicated were valid. All Standards are subject
5 Materials
to revision, and Parties to agreements based on this
part of ISO 7404 are encouraged to investigate the
possibility of applying the most recent editions of the
5.1 Immersion Oil, of a non-drying, non-corrosive
Standards indicated below. Members of IEC and ISO
type, with a refractive index of 1,518 0 + 0,000 4 at
maintain registers of currently valid International
23 “C and a wavelengttdnof 546 nm andkith a tem-
Standards. perature coefficient - dt of less than 0,000 5 K- ‘.
1
---------------------- Page: 7 ----------------------
SIST ISO 7404-5:1998
0 ISO
ISO 7404-5: 1994(E)
NQTES
- Reflectance Standards in common use
Table 1
-
1 Oil from a bottle which was first opened more than a
year previously should not be used unless the refractive
Reflectance in
index has been checked.
immersion oil
Refractive
Designation of 1.518 at
index
2 The oil should not contain polychlorinated biphenyls or
546 nm (see
other toxic components.
5.1)
%
-
5.2 Calibration Standards
Optical glasses 1,70 to 1,97 0,32 to 1,66
Spinel 1,73 0,42
1,77
Leucosapphire 0,59
5.2.1 Reflectance Standards, consisting of polished
Yttrium aluminium
surfaces of materials that
1,84 0,92
garnet (YAG)
a) are isotropic (or basal sections of uniaxial min-
Gadolinium gallium
1,98
1,73
erals);
garnet (3G)
Diamond 2,42 5,28
b) are durable and resistant to corrosion;
Silicon carbide 2,66 7,50
have constant reflectance over a long period;
Cl
Where the refractive index is not known, or where it
are free from in clusions, grain boundaries, dis-
d)
is suspected that the surface properties may not ex-
continuities, internal flaws and fractures;
actly match the nominal bulk properties, determine
the reflectance by careful comparison with a Standard
e) have negligibly low absorptance.
of known reflectance (see note 4).
To avoid significant amounts of light other than that
NOTES
reflected from the top surface returning to the objec-
3 For measuring a coal reflectance of about 1,O %, stan-
tive, the body of the Standard shall be either deeper
dards with reflectances of approximately 0,6 %, 1,O % and
than 5 mm or wedge-shaped. The lower surface shall
1,6 % should be used.
be matt if it makes an angle of less than IO” with the
upper polished surface.
4 Standards need careful cleaning to avoid scratching the
polished surface. Tarnishing may also occur with some
The sides shall be shielded from external light.
Standard materials, particularly glasses. When the surface
becomes scratched, or when comparison with the other
The reflectance of the Standards shall be in the region
Standards Shows that the reflectance value has changed,
of the reflectance of the coal to be measured. Use at
polishing is necessary.
least three such Standards with weil-spaced
reflectances (see note 3).
5.2.2 Zero Standard
lf a coal with a reflectance greater than 2,0 % is to
be measured, use one or more additional Standards
NOTE 5 A suitable non-reflecting Standard consists of a
with reflectance greater than 2,0 %.
coal or opaque resin block with a hole about 5 mm in di-
ameter and 5 mm deep, drilled in its upper surface and filled
Table 1 gives mean values of refractive index and of
with immersion Oil. Alternatively, Optical glasses of
reflectance for reflectance Standards in common use.
refractive index lower than that of the immersion oil may
Determine exactly the reflectance of any Optical glass
be used.
Standard by using a comparable Standard or by means
of a determination of the refractive index.
Where the refractive index, IZ, and (if significant) the
6 Apparatus
absorptance, CX, of the Standard material are known for
a wavelength of 546 nm, calculate the reflectance, R,
as a percentage using the equation
6.1 Binocular reflected light microscope with
(n - 1,518)* + n2a2 x 1oo
Photometer.
’ = (n + 1,518)’ + n2a2
NOTE 6 The reference letters refer to figure 1.
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SIST ISO 7404-5:1998
0 ISO
ISO 7404-5: 1994(E)
6.1.1 Light Source (A). adequate blackening to absorb stray light.
c)
Any light Source with a stable output may be used; a NOTE IO Subject to the above precautions, part of the
light beam may be diverted to the eyepieces or to a tele-
quartz halogen lamp with a rating of 100 W is rec-
Vision Camera for continuous Observation during reflectance
ommended.
measurement.
6.1.2 Polarizer (E) (optional): A sheet or prism
polarizer.
6.1.8 Filter(s) (0), with a peak transmittance in the
range of 546 nm + 5 nm and a half-peak
6.1.3 Light-controlling apertures, consisting of
transmittance band of less than 30 nm.
two variable diaphragms, one of which is focused on
the back focal plane of the objective [illuminator ap- NOTE 11 The filters should be inserted into the light path
immediately before the photomultiplier.
erture (C)] and the other on the surface of the speci-
men [field stop (F)]. lt shall be possible to centre both
diaphragms on the Optical axis of the microscope
6.1.9 Photomultiplier tube (P), fitted in a housing
System. The Optical Parts of a typical reflectance
attached to the microscope, permitting the light
measuring microscope are shown in figure 1.
passing through the measuring aperture and filter to
fall onto the photomultiplier window.
NOTE 7 The com ponent Parts may not always be in the
same uence.
seq
NOTES
6.1.4 Vertical illuminator, Berek prism, simple
12 The photomultiplier tube should be of a type rec-
coated glass plate or Smith illuminator (a combined ommended for low light-level applications, and should have
adequate sensitivity at 546 nm with low dark current. It
mirror and glass plate). Typical light paths are shown
should have a linear response over the range of the
in figure 2.
measurement and the output should be stable over periods
of up to 1 h.
6.1.5 Objective (I), Strain-free objective, designed
for use with polarized light and an immersion oil of
13 A 50 mm dia meter straight t be with an end window
refractive index 1,518, with a magnification of be-
and conta ining 11 dynodes is freq ently used.
tween x 25 and x 60 and a low value for the parasitic
reflection (see 8.2.3).
6.1.10 Microscope Stage (K), fitted with a mech-
anical Stage capable of advancing the specimen by
NOTE 8 The diameter of the objective should be as large
as possible. A larger objective gives increased light inten-
0,5 mm Steps in the X and Y directions and provided
sity, thereby reducing the Signal amplification and hence the
with a means for making small adjusting movements.
electronie noise; it also makes it possible to work with a
For maximum reflectance, the Stage shall be capable
smaller measuring aperture.
of being rotated through 360” perpendicular to the
Optical axis, and being centred by adjusting either the
6.1.6 Eyepieces (L), Two viewing eyepieces, one
Stage or the objective.
of which is fitted with crosslines which may be
scaled, such that the total magnification given by the
objective, eyepiece and tube factor (if any) is between
6.2 Stabilized d.c. power supply unit for the light
x 250 and x 750.
Source.
NOTE 9 A th ird eyepiece (M) may be necessary in the
The following characteristics have been found to be
light path leadin g to the photomultiplier.
satisfactory:
6.1.7 Microscope tube, with the following features:
a) a lamp output of between 90 % and 95 % of rated
output;
a) measuring aperture (N) which restricts the light
reaching the photomultiplier to that reflected from
b) an output Variation of less than 0,02 % for a sup-
an area of the specimen (J) less than 80 Pm* and
ply Variation of 10 %;
which tan be aligned with the crosslines in the
c) a ripple content at full load of less than 0,07 %
viewing eyepiece;
peak to peak;
b) a means of optically isolating the viewing eye-
less than
pieces if they permit the entry of extraneous light d) a temperature coefficient of
during measurement; 0,05 % K- ‘.
---------------------- Page: 9 ----------------------
SIST ISO 7404-5:1998
ISO 7404=5:1994(E)
A Lamp
B Coll8ctor lens
Illuminator aperture
C
Heat filter
D
Polarizer
E
F Field stop
G Field-stop focusing lens
H Vertical illuminator
P
1 Obj8CtiV8
Specimen
J
K Stage
Vi8Wing 8y8-pi8C8S
L
Third eye-piece
M
N Measuring aperture
0 546 nm interference filter
P Photomultiplier tube
. .
G
C DEF
\tP- '
Figure 1 - Optical Parts of a typical reflectance measuring microscope
4
---------------------- Page: 10 ----------------------
SIST ISO 7404-5:1998
ISO 7404-5: 1994(E)
Camp filament
Collector lens
Illuminator aperture (Position of filament image)
Field stop
Field-stop focusing lens
Berek prism
Back focal plane of objective (Position of images of the
filament and the illuminator aperture)
0 bjective
Sutface of specimen (Position of image of field stop)
a) Berek prism vertical illuminator
Thin glass reflector
-0
Coated glass plate
0
0 E D E
G G ----h,Ai,AJ---
--7-h, ,A-r--
c
H
t
L?sL
1 I
b) Gfass plate illuminator c) Smith Ctluminatoa
Figure 2 - Types of vertical illuminators
---------------------- Page: 11 ----------------------
SIST ISO 7404-5:1998
0 ISO
ISO 7404-5:1994( E)
6.3 Stabilized d.c. voltage power supply unit for
7 Preparation of coal Sample
the photomultiplier tube.
Prepare and polish a particulate block as described in
The following characteristics have been found to be
ISO 7404-2.
satisfactory:
a) an output Variation of less than 0,05 % for a 8 Procedure
IO % Variation in supply voltage;
8.1 Setting up the apparatus
b) a ripple content at full load of less than 0,07 %
peak to peak;
NOTE 17 In 8.1.3 and 8.1.4 letters in parentheses relate
to the key in figure ‘l.
temperature coefficient of less than
c) a
0,05 % K- ‘;
8.1 .l Starting procedure
d) a Change in load from zero to full rated load that
Ensure that the room temperature remains within the
Causes less than 0,l % Variation in output voltage.
range 18 “C to 28 “C. Switch on the lamp, power
supp
...
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