ISO 11724:2019
(Main)Solid mineral fuels — Determination of total fluorine in coal, coke and fly ash
Solid mineral fuels — Determination of total fluorine in coal, coke and fly ash
This document specifies a method for the determination of total fluorine in coal, coke and fly ash. From measurement of the total fluorine alone, it is not possible to estimate the amount of fluorine released to the environment by utilization of the coal and subsequent disposal of the ash residue.
Combustibles minéraux solides — Détermination de la teneur totale en fluor dans le charbon, le coke et les cendres
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 11724
Third edition
2019-06
Solid mineral fuels — Determination of
total fluorine in coal, coke and fly ash
Combustibles minéraux solides — Détermination de la teneur totale
en fluor dans le charbon, le coke et les cendres
Reference number
ISO 11724:2019(E)
©
ISO 2019
---------------------- Page: 1 ----------------------
ISO 11724:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 11724:2019(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Sample . 5
7.1 Coal and coke . 5
7.2 Fly ash . 5
8 Procedure. 5
8.1 Number of determinations . 5
8.2 Preparation of test sample . 5
8.3 Blank tests . 5
8.4 Pyrohydrolysis procedure . 5
8.4.1 Apparatus conditioning . 5
8.4.2 Pyrohydrolysis . 5
8.4.3 Pyrohydrolysate processing . 6
8.5 Solution measurement . 6
8.5.1 General. 6
8.5.2 Direct-comparison ISE method . 6
8.5.3 Analyte-addition ISE method . 7
8.5.4 IC method . 7
9 Calculations. 7
9.1 General . 7
9.2 Direct-comparison ISE method . 8
9.3 Analyte-addition ISE method . 9
9.4 IC method . 9
10 Expression of result . 9
11 Precision .10
11.1 Repeatability limit .10
11.2 Reproducibility critical difference .10
12 Test report .10
Bibliography .11
© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 11724:2019(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee
SC 5, Methods of analysis.
This third edition cancels and replaces the second edition (ISO 11724:2016), of which it constitutes a
minor revision. This document incorporates changes related to dated references and other minor items
following its systematic review.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 11724:2019(E)
Solid mineral fuels — Determination of total fluorine in
coal, coke and fly ash
1 Scope
This document specifies a method for the determination of total fluorine in coal, coke and fly ash.
From measurement of the total fluorine alone, it is not possible to estimate the amount of fluorine
released to the environment by utilization of the coal and subsequent disposal of the ash residue.
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 589, Hard coal — Determination of total moisture
ISO 687, Solid mineral fuels — Coke — Determination of moisture in the general analysis test sample
ISO 5068-2, Brown coals and lignites — Determination of moisture content — Part 2: Indirect gravimetric
method for moisture in the analysis sample
ISO 11722, Solid mineral fuels — Hard coal — Determination of moisture in the general analysis test
sample by drying in nitrogen
ISO 13909-4, Hard coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples
ISO 13909-6, Hard coal and coke — Mechanical sampling — Part 6: Coke — Preparation of test samples
3 Terms and definitions
No terms and definitions are defined in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Principle
Mixing of the sample of coal, coke or fly ash with silica, and pyrohydrolysis in a tube furnace at
approximately 1 200 °C in an atmosphere of oxygen and water vapour. Absorption of the volatilized
fluorine compounds in a suitable solution and processing for determination by ion-selective electrode
(ISE) or ion chromatographic (IC) techniques.
5 Reagents
CAUTION — Care shall be exercised when handling reagents, some of which are toxic and
corrosive.
During the analysis, use only reagents of recognized analytical grade and only distilled water, or water
of equivalent purity.
© ISO 2019 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO 11724:2019(E)
5.1 Silica of top size 75 µm, ignited at 1 000 °C for 1 h.
CAUTION — Fine silica is dangerous to health if inhaled.
5.2 Solutions for ISE measurement.
5.2.1 Standard fluorine solution (1 g contains 200 µg of F).
a) For direct-comparison method:
Dissolve 0,221 0 g ± 0,000 2 g of dry (110 °C for 1 h) sodium fluoride in approximately 400 ml of
water contained in a tared plastic bottle, dilute to 500 g ± 0,5 g net with water, and mix.
b) For analyte-addition method:
Dissolve 0,221 0 g ± 0,000 2 g of dry (110 °C for 1 h) sodium fluoride in a tared plastic bottle
containing 150 ml of water and 100 g of buffer (5.2.3). Dilute to 500 g ± 0,5 g net with water and mix.
5.2.2 Absorption solution (0,025 mol/kg NaOH).
Dissolve 2,0 g of sodium hydroxide in about 500 ml of water. Transfer to a tared 2,5 l plastic bottle,
dilute to 2 000 g net with water, and mix.
5.2.3 Buffer (pH 6,5).
Dissolve 10,0 g of potassium nitrate, 5 g of 1,2-cyclohexylenedinitrilotetraacetic acid (CDTA) and 115 g
of ammonium acetate in 350 ml of water. Adjust the pH to 6,5 with glacial acetic acid. Dilute to 500 g net
with water and mix.
5.2.4 Solution for conditioning fluoride ISE.
Weigh 20 g of water, 20 g of absorption solution (5.2.2) and 10 g of buffer (5.2.3) into a polystyrene vial
(6.2). Add approximately 200 mg of standard fluorine solution [of 5.2.1 a) or 5.2.1 b)] and mix.
5.3 Solutions for IC measurement
5.3.1 Absorption solution for IC measurement.
Dissolve 0,300 g of sodium hydrogen carbonate and 1,120 g of sodium carbonate in approximately
500 ml of water and dilute to 2 l.
5.4 Oxygen, compressed.
6 Apparatus
6.1 Vials, made of glass or polystyrene, of capacity 10 ml to 30 ml with tightly fitting snap-on plastic caps.
6.2 Polypropylene bottles or polystyrene vials, tared, of capacity 125 ml, wide necked with linerless
leak-proof screw caps.
6.3 Weighing device: an analytical balance with a resolution of at least 0,1 % relative of the test
portion mass.
6.4 Polyethylene dispensing bottles, for the standard fluorine solution (5.2.1), absorption solution
(5.2.2) and buffer (5.2.3).
2 © ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 11724:2019(E)
6.5 Micropipette, of variable volume, ranging to at least 1 ml.
This is a satisfactory alternative to the 250 ml polyethylene dispensing bottle (6.4) for delivery of small
weighed volumes of standard fluorine solution (5.2.1).
6.6 Apparatus for tube-furnace pyrohydrolysis (see Figure 1).
6.6.1 Steam generator, consisting of the following:
6.6.1.1 Round-bottom flask, 2 l capacity.
6.6.1.2 Heating mantle, 2 l capacity.
6.6.1.3 Y-piece, glass, 10 mm diameter.
6.6.1.4 Oxygen distribution tube, porosity 0.
6.6.1.5 Stopcocks, one three-way and one two-way.
6.6.2 Silica-tube furnace and accessories.
The apparatus consists of
6.6.2.1 Silica tube, made of pure silica (25 mm outer diameter, 20 mm inner diameter), of length
(typically 700 mm) appropriate to the particular furnace used (generally of an approximate length of
400 mm). Preferably, the gas outlet end should be narrowed to a tubule of approximately 7 mm diameter.
NOTE Combustion tubes of alternative refractory compositions do not have adequate thermal stress
characteristics for operation with this method.
6.6.2.2 Silicone stoppers, 20 mm diameter, positioned at inlet end (and outlet, if applicable) of the
silica tube (6.6.2.1).
6.6.2.3 Combustion boats, made of high-alumina unglazed porcelain (approximately
97 mm × 16 mm × 12 mm), preignited at 1 000 °C for 1 h.
6.6.2.4 Silica pusher and T-tube, comprising a silica push rod (5 mm diameter and 500 mm long)
fused at one end to provide a flat disc surface of 10 mm to 12 mm diameter, and having a piece of magnetic
steel affixed to the other end by epoxy resin.
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.