SIST ISO 925:1998

SLOVENSKI STANDARD
SIST ISO 925:1998
01-maj-1998
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Solid mineral fuels -- Determination of carbonate carbon content -- Gravimetric method
Combustibles minéraux solides -- Dosage du carbone sous forme de carbonate --
Méthode gravimétrique
Ta slovenski standard je istoveten z: ISO 925:1997
ICS:
75.160.10 Trda goriva Solid fuels
SIST ISO 925:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 925:1998

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SIST ISO 925:1998
IS0
INTERNATIONAL
925
STANDARD
Third edition
1997-05-01
Solid mineral fuels - Determination
of carbonate carbon content -
Gravimetric method
- Dosage du carbone sous forme
Combustibles minkraux solides
- Mthode gravimgtrique
de carbonate
Reference number
IS0 925: 1997(E)

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SIST ISO 925:1998
IS0 925: 1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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-
in liaison with ISO, also take part in the work. IS0
governmental,
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 IS0 925 was prepared by Technical Committee
ISO/TC 27, So/id mineral fuels, Subcommittee SC 5, Methods of analysis.
This third edition cancels and replaces the second edition (IS0 925:1980),
which has been technically revised.
Annex A of this International Standard is for information only.
0 IS0 1997
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 the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii

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SIST ISO 925:1998
IS0 925: 1997(E)
INTERNATIONAL STANDARD @ IS0
- Determination of carbonate carbon
Solid mineral fuels
Gravimetric method
content -
1 Scope
This International Standard specifies a gravimetric method of determining the carbon in the mineral carbonates
associated with solid mineral fuels.
NOTE - The result obtained will include any carbon from atmospheric carbon dioxide absorbed by the fuel.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 331 :I 983, Coal - Determination of moisture in the analysis sample - Direct gravimetric method.
Determination of moisture in the analysis sample.
IS0 687:1974, Coke -
IS0 1015: 1992, Brown coals and /ignites - Determination of moisture content - Direct volumetric method.
Calculation of analyses to different bases.
IS0 1170:1977, Coal and coke -
IS0 1988:1975, Hard coal - Sampling.
IS0 2309:1980, Coke - Sampling.
IS0 5068:1983, Brown coals and /ignites - Determination of moisture content - Indirect gra vime tric method.
IS0 5069-2:1983, Brown coals and /ignites - Principles of sampling - Part 2: Sample preparation for determination
of moisture content and for general analysis.
IS0 9411-I : 1994, So/id mineral fuels - Mechanical sampling from moving streams - Part I: Coal.
- Mechanical sampling from moving streams - Part 2: Coke.
IS0 9411-2:1993, So/id mineral fuels
3 Principle
A known mass of sample is treated with hydrochloric acid, which reacts with the carbonates present to liberate
carbon dioxide. The carbon dioxide resulting from the decomposition of the carbonates is absorbed and weighed.

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SIST ISO 925:1998
@ IS0
IS0 925: 1997(E)
4 Reagents
WARNING - Care should be exercised when handling reagents, many of which are toxic and corrosive.
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled
water, or water of equivalent purity.
Distilled water may be freed from carbon dioxide by boiling gently for 15 min.
NOTE -
4.1 Hydrochloric acid, approximately 3 mol/l.
4.2 Hydrogen sulfide absorbent
Any of the following:
a) copper phosphate, granular, particle size I,2 mm to 0,7 mm;
NOTE 1 Copper(H) phosphate granules may be prepared as follows:
Mix copper phosphate powdered reagent to a stiff paste with 1 % starch solution. Press through a sheet of metal,
perforated with apertures of approximately 1 mm diameter. Dry the extruded material at 110 OC. Sieve to recover the
desired size fraction.
b) copper sulfate, deposited on a supporting base of ground pumice;
NOTE 2 A suitable absorbent, based on copper sulfate, may be prepared as follows:
Prepare pumice by crushing and sieving to obtain the 2,8 mm to 0,7 mm fraction. Transfer approximately 60 g of the
prepared pumice to an evaporating basin, covering with a saturated solution of copper sulfate, evaporate to
dryness with constant stirring, and heat at 150 OC to 160 “C for 3 h to 4 h. Cool in a desiccator and store in a glass-
stoppered bottle.
silver sulfate, granular.
C)
4.3 Magnesium perchlorate, anhydrous, particle size I,2 mm to 0,7 mm.
WARNING - Due regard must be taken of local regulations when disposing of exhausted magnesium
perchlorate. It is essential that regeneration of magnesium perchlorate is not attempted, owing to the risk
of explosion.
4.4 Sodium hydroxide, on an inert base, preferably of coarse grading, for example I,7 mm to I,2 mm, and
preferably of the self-indicating type.
4.5 Wetting agent, suitable for use in acid solution.
NOTE - A liquid wetting agent at a concentration of 100 ml/l or ethanol [95 % (V/V)] are suitable.
4.6 Check test reagent
Either of the following:
a) anhydrous sodium carbonate;
b) anhydrous calcium carbonate.
2

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SIST ISO 925:1998
@ IS0 IS0 925: 1997(E)
5 Apparatus
5.1 Analytical balance, capable of weighing to the nearest 0,l mg.
5.2 Graduated glassware, conforming to the requirements for Grade A in the International Standards prepared
by ISOrlC 48, Laboratory glassware and related apparatus.
5.3 Purification tube, consisting of an absorption tube ’) containing sodium hydroxide on an inert base (4.4).
5.4 Reaction flask assembly, comprising a 300 ml round-bottomed flask fitted with a tap funnel, a double-surface
condenser and a bulbed tube.
5.5 Absorption train, consisting of three absorption tubes a), b) and c)l) packed respectively as follows:
a) magnesium perchlorate (4.3) to dry the gas;
absorbent (4.2) followed by a protective layer of magnesium perchlorate (4.3). The connection
hydrogen sulfide
W
from this tube to tube c) shall be fitted at its outlet end with a stopcock or othe r means of closure;
c) sodium hydroxide on an inert base (4.4), to absorb carbon dioxide generated in the reaction flask, followed by a
protective layer of magnesium perchlorate (4.3) to absorb water produced in the reaction between carbon
dioxide and sodium hydroxide. This tube shall be fitted with stopcocks or other means of closure at the inlet and
outlet ends.
5.6 Air circulation equipment
mI/min
A suction pump, capable of drawing air at a rate of 50 through the apparatus, connected through a flowmeter
to a tee-piece fitted with a stopcock (the air vent).
5.7 Heating source, for the reaction flask.
Either an electric heating mantle to accommodate a 300 ml flask or a small ga
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