ISO 16878:2016

INTERNATIONAL ISO
STANDARD 16878
First edition
2016-07-01
Iron ores — Determination of metallic
iron content — Iron(III) chloride
titrimetric method
Minerais de fer — Dosage du fer métallique — Méthode titrimétrique
au chlorure de fer(III)
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

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 Sampling and sample preparation . 3
8 Procedure. 3
8.1 Number of determinations . 3
8.2 Preparation of test portions . 3
8.3 Determination . 3
9 Expression of results . 4
9.1 Calculation of the metallic iron content . 4
9.2 General treatment of result . 4
9.2.1 Repeatability and permissible tolerances . 4
9.2.2 Determination of analytical result . 4
9.2.3 Between-laboratories precision . 4
9.2.4 Check for trueness . 5
9.2.5 Calculation of final result . 6
10 Test report . 6
Annex A (normative) Flowsheet of the procedure for the acceptance of test results .7
Annex B (informative) Derivation of precision statements . 8
Bibliography . 9
Foreword
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The committee responsible for this document is ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 2, Chemical analysis.
This first edition of ISO 16878 cancels and replaces ISO/TS 16878:2010, which has been technically
revised.
iv © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 16878:2016(E)
Iron ores — Determination of metallic iron content —
Iron(III) chloride titrimetric method
CAUTION — This International Standard may involve hazardous operations and equipment. This
International Standard does not purport to address all of the safety issues associated with its use.
It is the responsibility of the user of this International Standard to establish appropriate safety
and health practices and determine the applicability of regulatory limitations prior to its use.
1 Scope
This International Standard specifies a titrimetric method for the determination of the metallic iron
content of reduced iron ores.
This method is applicable to a concentration range of 57,5 % mass fraction to 90,5 % mass fraction of
the metallic iron.
NOTE The term “metallic iron” means those forms of iron not bonded to oxygen or not present as pyrite.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 385, Laboratory glassware — Burettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 10835, Direct reduced iron and hot briquetted iron — Sampling and sample preparation
ISO 11323, Iron ore and direct reduced iron — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11323 apply.
4 Principle
0 +2
Iron present in the oxidation state Fe in the sample is oxidized to Fe by the action of FeCl according
to the following reaction:
03++2
Fe +23Fe → Fe
+2
The Fe is titrated with potassium dichromate solution using the sodium diphenylaminesulfonate
indicator.
5 Reagents
During the analysis, use only reagents of recognized analytical reagent grade and only distilled water
or water of equivalent purity.
5.1 Iron(III) chloride solution.
Add 250 g of iron(III) chloride hexahydrate to a 2 000 ml container holding 600 ml of water and agitate
until it is completely dissolved. Dilute with water to a volume of 1 l.
NOTE For better dissolution of the FeCl , it is recommended to use a warm water bath. The ideal condition is
a complete dissolution of the salt resulting in a translucent solution.
5.2 Sulfuric acid, 1,84 g/ml.
5.3 Phosphoric acid, 1,7 g/ml.
5.4 Solution 15 % sulfuric acid/15 % phosphoric acid mixture.
Add 1 000 ml of water to a 3 000 ml beaker. Place the beaker in a cool place and add slowly with stirring
300 ml of phosphoric acid (5.3). Allow cooling. Add slowly with stirring 300 ml of sulfuric acid (5.2)
and allow cooling. Dilute this mixture to 2 000 ml with stirring. Store the solution in a 2 000 ml high-
density polyethylene bottle or equivalent container.
5.5 Sodium diphenylaminesulfonate.
Dissolve 0,2 g of powdered sodium diphenylaminesulfonate (C H NHC H SO Na) in a sm
...