ISO 2597-2:2019

Iron ores — Determination of total iron content — Part 2: Titrimetric methods after titanium(III) chloride reduction

This document specifies two titrimetric methods, free from mercury pollution, for the determination of total iron content in 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 either dilute potassium dichromate (Method 1) or perchloric acid (Method 2). Both methods are applicable to a concentration range of 30 % mass fraction to 72 % mass fraction of iron in natural iron ores, iron ore concentrates and agglomerates, including sinter products.

Minerais de fer — Dosage du fer total — Partie 2: Méthodes titrimétriques après réduction au chlorure de titane(III)

General Information

• Status: Published
• Publication Date: 02-Apr-2019
• ICS: 73.060.10 - Iron ores
• Technical Committee: ISO/TC 102/SC 2 - Chemical analysis
• Drafting Committee: ISO/TC 102/SC 2 - Chemical analysis
• Current Stage: 6060 - International Standard published
• Due Date: 11-Jul-2019
• Completion Date: 03-Apr-2019

Relations

• Revises: ISO 2597-2:2015 - Iron ores — Determination of total iron content — Part 2: Titrimetric methods after titanium(III) chloride reduction
• Effective Date: 05-Aug-2017

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 2597-2
Third edition
2019-04
Iron ores — Determination of total
iron content —
Part 2:
Titrimetric methods after
titanium(III) chloride reduction
Minerais de fer — Dosage du fer total —
Partie 2: Méthodes titrimétriques après réduction au chlorure de
titane(III)
Reference number
ISO 2597-2:2019(E)
©
ISO 2019

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ISO 2597-2:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
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ii © ISO 2019 – All rights reserved

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ISO 2597-2:2019(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
4.1 Decomposition of the test portion . 2
4.1.1 Acid decomposition . 2
4.1.2 Fusion-filtration . . 2
4.2 Titration of iron . 2
5 Reagents . 2
6 Apparatus . 4
7 Sampling and samples . 4
7.1 Laboratory sample . 4
7.2 Preparation of test samples . 5
7.2.1 General. 5
7.2.2 Ores having significant contents of combined water or oxidizable compounds . 5
7.2.3 Ores outside the scope of 7.2.2 . 5
8 Procedure. 5
8.1 Number of determinations . 5
8.2 Blank test and check test . 5
8.3 Determination of hygroscopic moisture content. 6
8.4 Test portion . 6
8.5 Determination . 6
8.5.1 Decomposition of the test portion . 6
8.5.2 Reduction . 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 .10
9.2.3 Between-laboratories precision .10
9.2.4 Check for trueness .10
9.2.5 Calculation of final result .11
9.2.6 Oxide factors .12
10 Test report .12
Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for
test samples .13
Annex B (normative) Procedure of Japanese weighing method .14
Bibliography .15
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ISO 2597-2:2019(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 102, Iron ore and direct reduced iron,
Subcommittee SC 2, Chemical analysis.
This third edition cancels and replaces the second edition (ISO 2597-2:2015), which has been technically
revised with the following changes:
— the Scope has been reworded to describe the second method using perchloric acid;
— a terms and definitions clause has been added as Clause 3 and the subsequent clauses have been
renumbered accordingly;
— in 4.2 (previously 3.2) a description of the second method using perchloric acid has been added;
— in the second paragraph of 4.1.1 (previously 3.1.1), “water more hydrochloric acid” has been replaced
with “water and hydrochloric acid”;
— in 5.19 (previously 4.19), “5,58” has been replaced with “7,978 1”;
— Clause 5, potassium disulfate (K S O ) has been added as a reagent (5.23);
2 2 7
— in the sixth paragraph of 8.5.1.1 (previously 7.5.1.1), “4.20” has been replaced with “5.23”;
— in the description for V in 9.1 (previously 8.1), “4.13” has been replaced with “5.20”;
1
— in 9.2.4 (previously 8.2.4), Formula (8) and the relevant descriptions have been modified to harmonize
this subclause across all International Standards for which ISO/TC 102/SC 2 is responsible.
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
complete listing of these bodies can be found at www .iso .org/members .html.
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INTERNATIONAL STANDARD ISO 2597-2:2019(E)
Iron ores — Determination of total iron content —
Part 2:
Titrimetric methods after titanium(III) chloride reduction
WARNING — This document may 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.
1 Scope
This document specifies two titrimetric methods, free from mercury pollution, for the determination
of total iron content in 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 either dilute
potassium dichromate (Method 1) or perchloric acid (Method 2).
Both methods are applicable to a concentration range of 30 % mass fraction to 72 % mass fraction of
iron in natural iron ores, 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 385, Laboratory glassware — Burettes
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 80000-1:2009, Quantities and units — Part 1: General
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/
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ISO 2597-2:2019(E)

4 Principle
4.1 Decomposition of the test portion
4.1.1 Acid decomposition
For samples containing not more than 0,05 % mass fraction of vanadium, the test portion is treated
with hydrochloric acid in the presence of tin chloride.
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 combined
with the main iron solution, which is treated with potassium permanganate and evaporated.
4.1.2 Fusion-filtration
For samples containing more than 0,05 % mass fraction of vanadium, the test portion is fused with a
mixture of fluxes, the cold melt is leached with water and the precipitate is filtered, washed in sodium
hydroxide solution, dissolved in hydrochloric acid and evaporated.
4.2 Titration of iron
The major portion of the iron(III) is reduced by tin(II) chloride and the remainder of the iron(III) is
reduced by titanium(III) chloride. The excess reductant is oxidized with either dilute potassium
dichromate solution (Method 1) or dilute perchloric acid (Method 2). The reduced iron 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 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml. (Methods 1 and 2.)
5.2 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 1 + 1. (Methods 1 and 2.)
5.3 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 1 + 12. (Methods 1 and 2.)
5.4 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 2 + 100. (Methods 1 and 2.)
5.5 Hydrofluoric acid, 40 % mass fraction (ρ 1,13 g/ml) or 48 % mass fraction (ρ 1,19 g/ml).
(Methods 1 and 2.)
5.6 Sulfuric acid, ρ 1,84 g/ml. (Methods 1 and 2.)
5.7 Sulfuric acid, ρ 1,84 g/ml, diluted 1 + 1, carefully pour 1 volume of reagent 5.6 into one volume of
cold water. (Methods 1 and 2.)
5.8 Orthophosphoric acid, ρ 1,7 g/ml. (Methods 1 and 2.)
5.9 Perchloric acid, 72 % mass fraction (ρ 1,7 g/ml), diluted 1 + 1. (Method 2.)
5.10 Sulfuric acid–orthophosphoric acid mixture, pour 150 ml of orthophosphoric acid (5.8) into
about 400 ml of water while stirring, add 150 ml of sulfuric acid (5.6), cool in a water bath, dilute with
water to 1 l and mix well. (Methods 1 and 2.)
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ISO 2597-2:2019(E)

5.11 Sodium hydroxide (NaOH), solution, 20 g/l. (Methods 1 and 2.)
5.12 Hydrogen peroxide (H O ), 30 % by volume solution. (Methods 1 and 2.)
2 2
5.13 Hydrogen peroxide (H O ), 30 % by volume solution, diluted 1 + 9. (Method 1.)
2 2
5.14 Tin(II) chloride solution, 100 g/l, dissolve 100 g of crystalline tin(II) chloride (SnCl 2H O) in
2• 2
200 ml of hydrochloric acid (5.1) by heating the solution in a water bath. Cool the solution and dilute
with water to 1 l. This solution should be stored in a brown glass bottle with a small quantity of granular
tin metal. (Methods 1 and 2.)
5.15 Potassium permanganate (KMnO ) solution, 25 g/l. (Methods 1 and 2.)
4
5.16 Potassium dichromate (K Cr O ) solution, 1 g/l. (Method 1.)
2 2 7
5.17 Titanium(III) chloride (TiCl ) solution, 20 g/l, dilute one volume of titanium(III) chloride
3
solution (about 20 % TiCl ) with nine volumes of hydrochloric acid (5.2). (Methods 1 and 2.)
3
Alternatively, dissolve 1,3 g of titanium sponge in about 40 ml of hydrochloric acid (5.1) in a covered
beaker by heating in a water bath. Cool the solution and dilute with water to 200 ml. Prepare fresh
solution as needed.
5.18 Flux mixture, mix one portion of anhydrous sodium carbonate (Na CO ) and two portions of
2 3
sodium peroxide (Na O ). (Methods 1 and 2.)
2 2
5.19 Iron standard solution, 0,1 mol/l. Transfer 7,978 1 g of iron(III) oxide (purity greater than
99,9 % mass fraction) to a 500 ml beaker flask and place a small filter funnel in the neck. Add 75 ml of
hydrochloric acid (5.2) in small increments and heat until dissolved. (Methods 1 and 2.)
Cool, transfer to a 1 000 ml volumetric flask and mix well.
Instead of iron oxide, the use of pure metallic iron with a suitable oxidant is permitted.
To prepare the solution 0,1 mol/l, transfer 5,58 g of pure iron (purity greater than 99,9 % mass fraction)
to a 500 ml Erlenmeyer flask and place a small filter funnel in the neck. Add 75 ml of hydrochloric acid
(5.2) in small increments and heat until dissolved. Cool and oxidize with 5 ml of hydrogen peroxide
(5.13) added in small portions. Heat to boiling and boil to decompose the excess hydrogen peroxide and
to expel chlorine. Cool, transfer to a 1 000 ml volumetric flask and mix well. (Methods 1 and 2.)
1,00 ml of this solution is equivalent to 1,00 ml of the standard potassium dichromate solution (5.20).
5.20 Potassium dichromate (99,9 % minimum purity), standard solution, 0,016 67 mol/l, pulverize
about 6 g of potassium dichromate reagent in an agate mortar, dry at 140 °C to 150 °C for 2 h, and cool to
room temperature in a desiccator. (Methods 1 and 2.)
Transfer 4,903 g of this material to a 300 ml beaker, dissolve in about 100 ml of water, transfer
quantitatively to a 1 000 ml volumetric flask, make up to volume with water after cooling to 20 °C and
mix well. Record the temperature at which this dilution was made (20 °C) on the stock bottle. Measure
the temperature at each use to correct the volume of titrant used.
The volumetric flask should previously be calibrated by weighing the mass of water contained at 20 °C
and converting to volume.
Water used for preparation should previously be equilibrated at room temperature.
A calibrated mercury thermometer, graduated in 0,1 °C divisions and having a marked dipping line,
should be used. Take a sufficient volume of standard solution for dipping the thermometer and transfer
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ISO 2597-2:2019(E)

to a suitable beaker. Measure the temperature of the solution to the nearest 0,1 °C, after dipping for
more than 60 s.
5.21 Indigo carmine [5,5'-disulfonic acid disodium salt (Cl H O N S Na )] solution, 0,1 g/100 ml,
6 8 8 2 2 2
dissolve 0,1 g of indigo carmine in a cold mixture of 50 ml sulfuric acid (5.7) and 50 ml of water.
(Method 1.)
5.22 Sodium diphenylaminesulfonate indicator solution, 0,2 g/100 ml, dissolve 0,2 g of sodium
diphenylaminesulfonate (C H NHC H SO Na) in a small volume of water and dilute to 100 ml. (Method 1
6 5 6 4 3
and Method 2.)
Store the solution in a brown glass bottle.
5.23 Potassium disulfate (K S O ), fine powder. (Methods 1 and 2.)
2 2 7
6 Apparatus
The pipette and volumetric flask specified shall be in accordance with ISO 648 and ISO 1042,
respectively.
Ordinary laboratory apparatus and the following.
6.1 Alumina, zirconium or vitreous carbon crucible, capacity 25 ml to 30 ml, crucibles should be
cleaned before use to avoid contamination with iron.
6.2 Burette, class A, in accordance with ISO 385.
6.3 Weighing bottle, of approximate volume 10 ml and approximate mass 6 g.
6.4 Platinum crucible, capacity 25 ml to 30 ml and having a lid.
6.5 Weighing spatula, of a non-magnetic material or demagnetized stainless steel.
6.6 Muffle furnace, suitable for operation in the range 500 °C to 800 °C.
7 Sampling and samples
7.1 Laboratory sample
For analysis, use a laboratory sample of 100 µm nominal top size that has been taken and prepared
in accordance with ISO 3082. In the case of ores having significant contents of combined water or
oxidizable compounds, use a 160 µm nominal top size.
NOTE A guideline on significant contents of combined water and oxidizable compounds is incorporated in
ISO 7764.
If the determination of total iron relates to a reducibility test, prepare the laboratory
...