ISO/TS 2597-4:2019

TECHNICAL ISO/TS
SPECIFICATION 2597-4
First edition
2019-09
Iron ores — Determination of total
iron content —
Part 4:
Potentiometric titration method
Minerais de fer — Dosage du fer total —
Partie 4: Méthode potentiométrique de titration
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 3
7 Sampling and samples . 4
7.1 Laboratory sample . 4
7.2 Preparation of test samples . 4
7.2.1 General. 4
7.2.2 Method specified in ISO 7764 . 4
7.2.3 Method specified in ISO 2596 . 5
8 Procedure. 5
8.1 Number of determinations . 5
8.2 Test portion . 5
8.3 Blank test and check test . 5
8.4 Determination of hygroscopic moisture content. 5
8.5 Determination . 5
8.5.1 Decomposition of the test portion . 5
8.5.2 Reduction . 6
8.5.3 Titration. 7
8.5.4 Blank test . 7
9 Expression of results . 8
9.1 Calculation of total iron content . 8
9.2 General treatment of results . 9
9.2.1 Repeatability and permissible tolerance . 9
9.2.2 Determination of analytical result . 9
9.2.3 Between-laboratories precision . 9
9.2.4 Check for trueness .10
9.2.5 Calculation of final result .11
9.2.6 Oxide factors .11
10 Test report .11
Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for
test sample .13
Annex B (informative) Volumetric titration cell and structure of instrument as follows .14
Annex C (informative) Types of detecting electrode .16
Annex D (informative) Derivation of precision statements .18
Annex E (informative) Computer program for end point of titration .19
Bibliography .22
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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This document was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 2, Chemical analysis.
A list of all parts in the ISO 2597 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2019 – All rights reserved

TECHNICAL SPECIFICATION ISO/TS 2597-4:2019(E)
Iron ores — Determination of total iron content —
Part 4:
Potentiometric titration method
WARNING — This document can involve hazardous materials, operations and equipment. This
document does not purport to address all of the safety problems associated with its use. It is the
responsibility of the user of this document to establish appropriate health and safety practices
and determine the applicability of regulatory limitations prior to use.
1 Scope
This document specifies a potentiometric titration method for the determination of total iron content
of iron ores, using potassium dichromate as titrant after reduction of the iron(III) by tin(II) chloride
and titanium(III) chloride. The excess reductant is then oxidized by potassium dichromate solution.
This method is applicable to total iron contents between a mass fraction of 29,04 % and a mass fraction
of 72,02 % in natural iron ores and iron ore concentrates and agglomerates including sinter products.
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 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 2596, Iron ores — Determination of hygroscopic moisture in analytical samples — Gravimetric, Karl
Fischer and mass-loss methods
ISO 3082, Iron ores — Sampling and sample preparation procedures
ISO 7764, Iron ores — Preparation of predried test samples for chemical analysis
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
For samples containing not more than a mass fraction of 0,1 % of vanadium, copper or manganese, the
test portion is treated with hydrochloric acid in the presence of tin chloride and the residue is filtered,
ignited and treated with hydrofluoric and sulfuric acids. The mixture is fused with potassium disulfate
and the cold melt is dissolved in water and hydrochloric acid and neutralized with ammonia solution.
The precipitate is filtered, washed with water, dissolved with hydrochloric acid and combined with
the main iron solution, which is treated with potassium permanganate and evaporated. Finally, after
the combined solution is treated with correlative reagents, the total iron in solution is titrated by a
potentiometric titrator.
5 Reagents
During the analysis, use only reagents of recognized analytical grade, and only distilled water or water
of equivalent purity.
5.1 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml.
5.2 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 1 + 1.
5.3 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 2 + 100.
5.4 Hydrofluoric acid, a mass fraction of 40 % (ρ 1,13 g/ml) or a mass fraction of 48 % (ρ 1,19 g/ml).
5.5 Sulfuric acid, ρ 1,84 g/ml.
5.6 Sulfuric acid, ρ 1,84 g/ml, diluted 1 + 1.
Carefully pour 1 volume of reagent (5.5) into 1 volume of cold water.
5.7 Orthophosphoric acid, ρ 1,7 g/ml.
5.8 Sulfuric acid-orthophosphoric acid mixture.
Pour 150 ml of orthophosphoric acid (5.7) into about 400 ml of water while stirring, add 150 ml of
sulfuric acid (5.5), cool in a water bath,
...