ISO/TS 11725:2002

SLOVENSKI STANDARD
SIST ISO/TS 11725:2003
01-junij-2003
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Solid mineral fuels -- Determination of nitrogen -- Semi-micro gasification method
Combustibles minéraux solides -- Détermination de la teneur en azote -- Méthode semi-
micrométrique par gazéification
Ta slovenski standard je istoveten z: ISO/TS 11725:2002
ICS:
75.160.10 Trda goriva Solid fuels
SIST ISO/TS 11725:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO/TS 11725:2003

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SIST ISO/TS 11725:2003

TECHNICAL ISO/TS
SPECIFICATION 11725
First edition
2002-08-01

Solid mineral fuels — Determination of
nitrogen — Semi-micro gasification method
Combustibles minéraux solides — Détermination de la teneur en azote —
Méthode semi-micrométrique par gazéification




Reference number
ISO/TS 11725:2002(E)
©
ISO 2002

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SIST ISO/TS 11725:2003
ISO/TS 11725:2002(E)
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ii © ISO 2002 – All rights reserved

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SIST ISO/TS 11725:2003
ISO/TS 11725:2002(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references.1
3 Principle.1
4 Reagents.2
5 Apparatus .2
6 Preparation of the test sample .6
7 Procedure .6
8 Blank test.7
9 Expression of results .8
10 Precision.8
11 Test report .8
Annex A (informative) Derivation of factors used in calculations in this Technical Specification .9
Bibliography.10

© ISO 2002 – All rights reserved iii

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SIST ISO/TS 11725:2003
ISO/TS 11725:2002(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
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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 3.
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.
In other circumstances, particularly when there is an urgent market requirement for such documents, a technical
committee may decide to publish other types of normative document:
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an
ISO working group and is accepted for publication if it is approved by more than 50 % of the members of the
parent committee casting a vote;
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a
vote.
An ISO/PAS or ISO/TS is reviewed after three years with a view to deciding whether it should be confirmed for a
further three years, revised to become an International Standard, or withdrawn. In the case of a confirmed ISO/PAS
or ISO/TS, it is reviewed again after six years at which time it has to be either transposed into an International
Standard or withdrawn.
Attention is drawn to the possibility that some of the elements of this Technical Specification may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TS 11725 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 5,
Methods of analysis.
Annex A of this Technical Specification is for information only.

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SIST ISO/TS 11725:2003
ISO/TS 11725:2002(E)
Introduction
A method for the determination of nitrogen in coals, ISO 333, has been in use for many years, but experience has
shown that it is unsuitable for cokes and some high carbon content coals and chars which require long reaction
times with the potential loss of nitrogen from the system before completion of the test. The method described in this
Technical Specification, based on JIS M 8813, addresses that shortcoming and is applicable to all solid fuels.
It has been prepared as a Technical Specification since there is at present little experience with the method outside
Japan, where it was developed and tested.
© ISO 2002 – All rights reserved v

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SIST ISO/TS 11725:2003

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SIST ISO/TS 11725:2003
TECHNICAL SPECIFICATION ISO/TS 11725:2002(E)

Solid mineral fuels — Determination of nitrogen — Semi-micro
gasification method
1 Scope
This Technical Specification specifies a method of determining the nitrogen content of hard coals, brown coals and
lignites, cokes and chars by a semi-micro gasification method.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this Technical Specification. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this Technical Specification are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 331, Coal — Determination of moisture in the analysis sample — Direct gravimetric method
ISO 687, Coke — Determination of moisture in the general analysis test sample
ISO 1015, Brown coals and lignites — Determination of moisture content — Direct volumetric method
ISO 1988, Hard coal — Sampling
ISO 2309, Coke — Sampling
ISO 5068, Brown coals and lignites — Determination of moisture content — Indirect gravimetric method
ISO 5069-2, Brown coals and lignites — Principles of sampling — Part 2: Sample preparation for determination of
moisture content and for general analysis
ISO 9411-1, Solid mineral fuels — Mechanical sampling from moving streams — Part 1: Coal
ISO 9411-2, Solid mineral fuels — Mechanical sampling from moving streams — Part 2: Coke
3 Principle
A known mass of the sample is mixed with a flux and pyrolyzed at temperatures up to 1 000 °C in a silica tube
through which steam is passing. Ammonia, which is formed from the nitrogen present, is absorbed in boric acid
solution and determined by titration with sulfuric acid.
© ISO 2002 – All rights reserved 1

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SIST ISO/TS 11725:2003
ISO/TS 11725:2002(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.
4.1 Boric acid solution, saturated
Dissolve 60 g of boric acid in 1 l of hot water, cool and allow to stand for three days before decanting the clear
solution.
4.2 Sodium hydroxide, 250 g/l solution
Dissolve 250 g of sodium hydroxide in water and dilute to 1 l; mix thoroughly.
4.3 Ammonia, approximately 0,17 g/l solution
Dissolve 0,535 g of ammonium chloride in 30 ml of water. Transfer the solution to a steam distillation apparatus as
described in 5.4. Transfer 4 ml of the boric acid (4.1) to the receiver. Add 150 ml of the sodium hydroxide solution
(4.2) to the distillation flask and pass steam through the apparatus whilst maintaining the temperature at
approximately 125 °C.
When approximately 250 ml of distillate have been collected, cease the distillation. Dilute the distillate to 1 l with
water and mix well.
4.4 Helium, purity > 99,8 %
4.5 Soda-lime, powdered
Granular soda-lime (NaOH solution absorbed on CaO) may be crushed using a porcelain pestle and mortar.
4.6 Activated alumina, neutral, pore size approximately 9 nm
4.7 Silica fibre, diameter 1 µm to 5 µm
4.8 Sulfuric acid, standard volumetric solution, concentration c(H SO ) = 0,005 mol/l
2 4
4.9 Mixed indicator solution
 solution A — dissolve 0,125 g of 2-(4-dimethylaminophenylazo) benzoic acid, sodium salt (methyl red), in
100 ml of water.
 solution B — dissolve 0,083 g of 3,7-bis(dimethylamino)phenothiazine-5-ylium chloride (methylene blue), in
100 ml of water. Store in a dark glass bottle.
Mix equal volumes of solutions A and B. Store in a dark glass bottle. Discard the mixed solution after 1 week.
4.10 Graphite, powdered, spectroscopy electrode purity
5 Apparatus
5.1 Analytical balance, capable of weighing to 0,1 mg
5.2 Graduated glassware, conforming to the requirements for Grade “A” in the International Standards
prepared by ISO/TC 48, “Laboratory glassware and related apparatus”
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SIST ISO/TS 11725:2003
ISO/TS 11725:2002(E)
5.3 Gasification apparatus
See Figure 1.
Dimensions in millimetres

Key
1 Water 6 Boat
2 Peristaltic pump 7 Pyrolysis tube
3 Steam-raising surfac
...