ISO 2597-1:2006

INTERNATIONAL ISO
STANDARD 2597-1
Second edition
2006-05-01
Iron ores — Determination of total iron
content —
Part 1:
Titrimetric method after tin(II) chloride
reduction
Minerais de fer — Dosage du fer total —
Partie 1: Méthode titrimétrique après réduction au chlorure d'étain(II)

Reference number
©
ISO 2006
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ii © ISO 2006 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Principle. 2
4 Reagents. 2
5 Apparatus . 3
6 Sampling and samples. 4
6.1 Laboratory sample. 4
6.2 Preparation of test samples. 4
6.2.1 Ores having significant contents of combined water or oxidizable compounds . 4
6.2.2 Ores outside the scope of 6.2.1. 4
7 Procedure . 4
7.1 Number of determinations . 4
7.2 Test portion . 5
7.3 Determination of hygroscopic moisture content . 5
7.4 Blank test and check test. 5
7.5 Determination. 5
7.5.1 Decomposition of the test portion . 5
7.5.2 Reduction . 6
7.5.3 Titration. 7
7.5.4 Blank test. 7
8 Expression of results . 7
8.1 Calculation of total iron content. 7
8.2 General treatment of results. 8
8.2.1 Repeatability and permissible tolerance. 8
8.2.2 Determination of analytical result. 8
8.2.3 Between-laboratories precision . 8
8.2.4 Check for trueness . 9
8.2.5 Calculation of final result. 10
8.3 Oxide factors in percent. 10
9 Test report . 10
Annex A (normative) Flowsheet for the procedure for the acceptance of analytical values for test
samples. 11
Annex B (informative) Derivation of precision statements. 12
Annex C (informative) Decontamination of the waste solutions from the analysis . 13

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 2597-1 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 2, Chemical analysis.
This second edition cancels and replaces the first edition (ISO 2597-1:1994), which has been editorially
revised.
ISO 2597 consists of the following parts, under the general title Iron ores — Determination of total iron
content:
⎯ Part 1: Titrimetric method after tin(II) chloride reduction
⎯ Part 2: Titrimetric method after titanium(III) chloride reduction
⎯ Part 3: Calculation method
iv © ISO 2006 – All rights reserved

Introduction
This part of ISO 2597 has been updated to correct errors in the presentation of statistical information in the
previous edition.
This is considered to be an editorial revision.

INTERNATIONAL STANDARD ISO 2597-1:2006(E)

Iron ores — Determination of total iron content —
Part 1:
Titrimetric method after tin(II) chloride reduction
WARNING — This part of ISO 2597 may involve hazardous materials, operations and equipment. This
part of ISO 2597 does not purport to address all of the safety issues associated with its use. It is the
responsibility of the user to establish appropriate health and safety practices and determine the
applicability of regulatory limitations prior to use.
1 Scope
This part of ISO 2597 specifies a titrimetric method for the determination of the total iron content of iron ores,
using potassium dichromate after reduction of the trivalent iron by tin(II) chloride.
The method is applicable to total iron contents between 30 % (mass fraction) and 72 % (mass fraction) in
natural iron ores, iron ore concentrates and agglomerates, including sinter products.
NOTE An equivalent International Standard that does not use mercury(II) chloride is ISO 9507:1990, Iron ores —
Determination of total iron content — Titanium(III) chloride reduction methods.
A suggested procedure for removal of mercury from the waste solutions before discharge to effluent drains is
given in Annex C.
2 Normative references
The following referenced documents are indispensable for the application 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 — One-mark 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 3696, Water for analytical laboratory use — Specification and test methods
ISO 7764, Iron ores — Preparation of predried test samples for chemical analysis
3 Principle
The test portion is decomposed by one of the following methods:
a) For samples containing not more than 0,05 % (mass fraction) vanadium, 0,1 % (mass fraction)
molybdenum or 0,1 % (mass fraction) copper: treatment with hydrochloric acid, the residue being filtered
off and ignited, treatment with hydrofluoric and sulfuric acids to remove silica, and fusion with potassium
pyrosulfate.
The melt is dissolved in hydrochloric acid, iron is precipitated with ammonia solution, the precipitate is
re-dissolved in hydrochloric acid and this solution is added to the main solution.
b) For samples containing more than 0,05 % (mass fraction) vanadium: fusion with alkali, the melt being
leached with water and filtered, the filtrate being discarded. The residue is dissolved in hydrochloric acid.
Trivalent iron in the solution is reduced using tin(II) chloride. Excess reductant is oxidized with mercury(II)
chloride.
The reduced iron is titrated with potassium dichromate solution, using sodium diphenylaminesulfonate as the
indicator.
4 Reagents
During the analysis, use only reagents of recognized analytical grade, and only water that complies with
grade 2 of ISO 3696.
4.1 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml.
4.2 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 1 + 1.
4.3 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 1 + 2.
4.4 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 1 + 10.
4.5 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 1 + 50.
4.6 Sulfuric acid, ρ = 1,84 g/ml.
4.7 Sulfuric acid, ρ = 1,84 g/ml, diluted 1 + 1.
4.8 Hydrofluoric acid, ρ = 1,13 g/ml, [40 % (mass fraction)], or ρ = 1,19 g/ml, [48 % (mass fraction)].
4.9 Orthophosphoric acid, ρ = 1,7 g/ml.
4.10 Ammonia solution, ρ = 0,90 g/ml.
4.11 Sodium carbonate (Na CO ), anhydrous powder.
2 3
Heat for 30 min at 500 °C, or confirm that the water content is not more than 1 % (mass fraction) (by heating a
test portion for 30 min at 500 °C and measuring the loss in mass).
4.12 Sodium peroxide (Na O ), dry powder.
2 2
Store this reagent in a dry environment and do not use after it has begun to agglomerate.
4.13 Potassium pyrosulfate (K S O ), fine powder.
2 2 7
2 © ISO 2006 – All rights reserved

4.14 Sulfuric acid-orthophosphoric acid mixture.
Cautiously pour 150 ml of sulfuric acid (4.6) into about 300 ml of water while stirring, cool in a water bath or
running water, add 150 ml of orthophosphoric acid (4.9) and dilute to 1 litre with water.
4.15 Sodium hydroxide, 20 g/l solution.
4.16 Tin(II) chloride, 100 g/l solution.
Dissolve 100 g of crystalline tin(II) chloride dihydrate (SnCl ·2H O) in 200 ml of hydrochloric acid (4.1) by
2 2
heating the solution in a water bath.
Cool the solution and dilute to 1 litre with water.
Store this solution in a brown glass bottle with the addition of a small quantity of granular or mossy tin metal.
NOTE The tin(II) chloride solution may be prepared in 250 ml lots.
4.17 Mercury(II) chloride (HgCl ), 50 g/l solution.
4.18 Potassium permanganate (KMnO ), 30 g/l solution.
4.19 Iron standard solution, 0,1 mol/l.
Weigh, to the nearest 0,002 g, 5,58 g of pure iron [minimum purity 99,9 % (mass fraction)] into a 500 ml
conical flask and place a small filter funnel in the neck. Add 75 ml of hydrochloric acid (4.2) in small
increments and heat until the iron has dissolved. Cool and oxidize with 5 ml of hydrogen peroxide [30 %
(volume fraction)] added in small portions. Heat to boiling and boil to decompose the excess hydrogen
peroxide and to remove chlorine. Transfer to a 1 000 ml one-mark volumetric flask, dilute to volume with water
and mix.
1,00 ml of this solution is equivalent to 1,00 ml of potassium dichromate standard volumetric solution.
4.20 Potassium dichromate, standard volumetric solution, c(K Cr O ) = 0,016 67 mol/l.
2 2 7
Pulverize about 6 g of potassium dichromate standard reagent [minimum purity 99,9 % (mass fraction)] in an
agate mortar, dry in an air bath at 140 °C to 150 °C for 2 h, and cool to room temperature in a desiccator.
Dissolve 4,904 g of this dried and pulverized potassium dichromate in water and dilute the solution to exactly
1 000 ml.
Record, on the stock bottle, the temperature at which this dilution was made (t ).
4.21 Sodium diphenylaminesulfonate, solution.
Dissolve 0,2 g of powdered sodium diphenylaminesulfonate (C H NHC H SO Na) in a small volume of water
6 5 6 4 3
and dilute to 100 ml.
Store this solution in a brown glass bottle.
5 Apparatus
Ordinary laboratory apparatus, including burettes, one-mark pipettes and one-mark volumetric flasks
complying with the specifications of ISO 385, ISO 648 or ISO 1042, respectively (unless otherwise indicated),
and the following.
5.1 Zirconium, vitreous carbon or alkali-resistant sintered alumina crucibles, of capacity 25 ml to
30 ml.
5.2 Platinum crucibles, of capacity 25 ml to 30 ml.
5.3 Porcelain crucibles, of capacity 25 ml to 30 ml.
5.4 Weighing spatula, of non-magnetic material or demagnetized stainless steel.
5.5 Muffle furnace, capable of being maintained at between 500 °C ± 10 °C and 800 °C ± 10 °C.
6 Sampling and samples
6.1 Laboratory sample
For the analysis, use a laboratory sample of minus 100 µm particle size which 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 particle size of minus 160 µm.
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 sample by crushing and
pulverizing, to less than 100 µm particle size, the whole of one of the reducibility test portions which has been
reserved for chemical analysis. In the case of ores having significant contents of combined water or oxidizable
compounds, use a particle size of minus 160 µm.
6.2 Preparation of test samples
Depending on the ore type, proceed in accordance with either 6.2.1 or 6.2.2.
6.2.1 Ores having significant contents of combined water or oxidizable compounds
Prepare an air-equilibrated test sample, in accordance with ISO 2596, with the following types of ores:
a) natural or processed ores in which the content of combined water is higher than 2,5 % (mass fraction);
b) processed ores containing metallic iron;
c) natural or processed ores in which the sulfur content is higher than 0,2 % (mass fraction).
6.2.2 Ores outside the scope of 6.2.1
Prepare a predried test sample as follows.
Thoroughly mix the laboratory sample and, taking multiple increments, extract a test sample in such a way
that it is representative of the whole contents of the container. Dry the test sample at 105 °C ± 2 °C, as
specified in ISO 7764. (This is the predried test sample.)
7 Procedure
7.1 Number of determinations
Carry out the analysis at least in duplicate in accordance with Annex A, independently, on one test
sample (6.2).
NOTE The expression “independently” means that the second and any subsequent result is not affected by the
previous result(s). For this particular analytical method, this condition implies that the repetition of the procedure is carried
out either by the same operator at a different time, or by a different operator, including appropriate recalibration in either
case.
4 © ISO 2006 – All rights reserved

7.2 Test portion
Taki
...