ISO 587:2020

INTERNATIONAL ISO
STANDARD 587
Third edition
2020-08
Coal and coke — Determination of
chlorine using Eschka mixture
Charbon et coke — Dosage du chlore à l'aide du mélange Eschka
Reference number
©
ISO 2020
© ISO 2020
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
5.1 For all methods . 2
5.2 For the Volhard and ISE methods . 2
5.3 For the Volhard method only . 2
5.4 For the Mohr method only . 2
6 Apparatus . 2
7 Preparation of the test sample . 3
8 Procedure. 3
8.1 Combustion . 3
8.2 Completion . 3
8.2.1 Volhard method . 3
8.2.2 Mohr method . 4
8.2.3 ISE method . 4
8.3 Blank test . 4
9 Expression of results . 5
9.1 Volhard method . 5
9.2 Mohr titration . 5
9.3 ISE method . 5
9.4 All methods . 6
10 Precision . 6
10.1 Repeatability limit . 6
10.2 Reproducibility limit . 6
11 Test report . 6
Annex A (informative) Derivation of factors used in calculations in this International Standard .7
Foreword
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This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 5,
Methods of analysis.
This fourth edition cancels and replaces the third edition (ISO 587:1997), of which it constitutes a minor
revision. The changes compared to the previous edition are as follows:
— updating of referenced documents;
— adding of the provision of terms and definitions.
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iv © ISO 2020 – All rights reserved

INTERNATIONAL STANDARD ISO 587:2020(E)
Coal and coke — Determination of chlorine using Eschka
mixture
1 Scope
This document specifies a method of determining the chlorine content of hard coal, brown coals and
lignites, and coke using Eschka mixture.
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 687, Solid mineral fuels — Coke — Determination of moisture in the general analysis test sample
ISO 1170, Coal and coke — Calculation of analyses to different bases
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 18283, Hard coal and coke — Manual sampling
3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Principle
A known mass of sample is ignited in intimate contact with Eschka mixture in an oxidizing atmosphere
to remove combustible matter and to convert the chlorine to alkaline chlorides. These are extracted
with nitric acid or water and determined by either the Volhard or the Mohr method, or by potentiometric
titration using an Ion Selective Electrode (ISE).
5 Reagents
WARNING — Care should be exercised when handling reagents, many of which are toxic and
corrosive.
During analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
distilled water, or water of equivalent purity.
5.1 For all methods
5.1.1 Eschka mixture.
Mix two parts by mass of light, calcined magnesium oxide with one part of anhydrous sodium or
potassium carbonate. The mixture shall entirely pass a test sieve of 0,212 mm nominal aperture.
5.1.2 Nitric acid, concentrated, chlorine-free, mass fraction approximately 70 %.
5.2 For the Volhard and ISE methods
5.2.1 Silver nitrate, standard volumetric solution, c(AgNO ) = 0,025 mol/l.
Heat crushed, crystalline silver nitrate at 125 °C for two to three hours. Dissolve 4,247 g in water and
dilute to 1 l. Store in an amber glass bottle.
5.3 For the Volhard method only
5.3.1 3,5,5-Trimethylhexan-1-ol.
5.3.2 n-Hexan-1-ol.
5.3.3 Potassium thiocyanate, standard volumetric solution, c(KSCN) ≈ 0,025 mol/l.
Dissolve 2,4 g of potassium thiocyanate in water and dilute to 1 l. Titrate against the silver nitrate
solution (5.2.1) and calculate the exact equivalence.
5.3.4 Iron (III) alum (ammonium iron (III) sulfate) indicator, saturated solution.
Saturate 100 ml of water with approximately 125 g of iron (III) alum [(NH ) SO ⋅Fe (SO ) ⋅24H O] and
4 2 4 2 4 3 2
add sufficient nitric acid (5.1.2) to remove the brown colour.
5.4 For the Mohr method only
5.4.1 Silver nitrate, standard volumetric solution, c(AgNO ) = 0,050 mol/l.
Weigh 8,494 g of silver nitrate, dried as in (5.2.1), dissolve in water and dilute to 1 l. Store in an amber
glass bottle.
5.4.2 Potassium chromate, indicator solution.
Dissolve 5 g of potassium chromate in 100 ml of water.
6 Apparatus
6.1 Analytical balance, capable of weighing to the nearest 0,1 mg.
6.2 Graduated glassware, conforming to the requirements for Grade A in the International Standards
prepared by ISO/TC 48.
6.3 Electrically heated muffle furnace, capable of being maintained at a temperature of
675 °C ± 25 °C, with adequate ventilation.
6.4 Crucible, of platinum, silica or glazed porcelain, of capacity approximately 25 ml.
2 © ISO 2020 – All rights reserved

6.5 Flat plate, 6 mm thick, of silica or other suitable refractory material, which fits easily into the
muffle furnace (6.3).
6.6 Potentiometric titration assembly, equipped with a chloride ion selective electrode and double
junction reference electrode.
7 Preparation of the test sample
The sample shall be the general analysis test sample, prepared to a nominal top size of 212 μm by the
preparation procedures specified in ISO 13909-4 or ISO 18283.
The sample should be brought in moisture equilibrium with the laboratory atmosphere by exposure in
a thin layer on a tray. Exposure time shall be kept to a minimum.
The sample shall be thoroughly mixed for at least 1 min immediately before analysis, preferably by
mechanical means.
If the results are to be calculated other than on an "air-dried" basis (see Clause 9), then, after weighing
the test portion, determine the moisture content using a further portion of the test sample by the
method specified in ISO 687, ISO 5068-2 or ISO 11722.
8 Procedure
8.1
...