ISO 7692:2025
(Main)Ferrotitanium — Determination of titanium content — Titrimetric method
Ferrotitanium — Determination of titanium content — Titrimetric method
This document specifies a titrimetric method for the determination of the titanium content of ferrotitanium. The method is applicable to titanium contents of a mass fraction between 20,0 % and 80,0 % in ferrotitanium.
Ferro-titane — Dosage du titane — Méthode titrimétrique
General Information
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Standards Content (Sample)
International
Standard
ISO 7692
Second edition
Ferrotitanium — Determination
2025-01
of titanium content —
Titrimetric method
Ferro-titane — Dosage du titane — Méthode titrimétrique
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 3
7 Sample . 5
8 Procedure . 5
8.1 Test portion .5
8.2 Blank test and check test .5
8.3 Determination .6
8.3.1 Decomposition of the test portion .6
8.3.2 Absence of interfering elements .6
8.3.3 Separation of interfering elements .6
8.3.4 Reduction .6
8.3.5 Titration .7
9 Expression of results . 7
10 Precision . 7
10.1 Expression of precision .7
10.2 Calculation of final results .8
11 Test report . 8
Annex A (informative) Original data from the verification test . 9
Annex B (informative) Graphical representation of the precision data.10
Annex C (informative) Flow chart for the acceptance procedure of test results .11
Bibliography .12
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 132, Ferroalloys.
This second edition cancels and replaces the first edition (ISO 7692:1983), which has been technically
revised.
The main changes are as follows:
— in 5.5 (previously in 4.6), hydrofluoric acid has been replaced with fluoboric acid;
— in 5.13 (previously in 4.17), the concentration of titanium standard solution has been changed;
— in 5.13.1 (previously in 4.17.1), the amount of titanium(IV) dioxide has been reduced and the decomposition
of titanium(IV) dioxide has been changed;
— in 5.13.2 (previously in 4.17.2), potassium hexafluorotitanate has been replaced with a titanium sponge
and the preparation has been changed;
— in Clause 6 (previously in Clause 5), polytetrafluoroethylene (PTFE) beakers have been replaced with a
conical flask;
— in Clause 7 (previously in Clause 6), the mesh size of the sieve has been changed;
— the paragraph of the definition of test portion has been changed in 8.1 and the amount of test portion in
8.1 (previously 7.1) has been reduced from 1,0 g to 0,50 g;
— in 8.2.1, (previously in 7.4.1), the method using titanium sponge has been removed;
— in 8.3.1 (previously 7.5.1), the amount of acids has been reduced;
— in 8.3.4 (previously 7.5.3.2), the amount of the aluminium has been reduced from 4,0 g to 3,0 g ± 0,2 g;
— in Clause 9 (previously in Clause 8), the expression of results has been changed;
— in Clause 10, the precision has been added;
iv
— in Clause 11 (previously in Clause 9), the test report has been changed;
— Annex A has been added;
— Annex B has been added;
— Annex C has been added.
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.
v
International Standard ISO 7692:2025(en)
Ferrotitanium — Determination of titanium content —
Titrimetric method
1 Scope
This document specifies a titrimetric method for the determination of the titanium content of ferrotitanium.
The method is applicable to titanium contents of a mass fraction between 20,0 % and 80,0 % in ferrotitanium.
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 3696, Water for analytical laboratory use — Specification and test methods
ISO 3713, Ferroalloys — Sampling and preparation of samples — General rules
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
The test portion shall be dissolved with sulfuric, fluoboric, nitric and hydrochloric acids and the interfering
elements (chromium, vanadium, molybdenum and tin), if present, shall be separated by precipitation of
3+
titanium hydroxide in the presence of hydrogen peroxide. Then, the titanium shall be reduced to Ti by
3+
aluminium metal in an atmosphere of carbon dioxide or nitrogen. Finally, the Ti shall be titrated with
standard volumetric iron(III) ammonium sulfate solution in the presence of thiocyanate as indicator.
5 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
grade 3 water specified in ISO 3696.
5.1 Aluminium, of minimum purity 99,5 %, in the form of foil 0,05 mm thick, and free from titanium.
5.2 Sodium hydrogen carbonate (NaHCO ).
5.3 Nitric acid, with a ρ of 1,38 g/ml to 1,42 g/ml.
5.4 Sulfuric acid, ρ = 1,84 g/ml.
5.5 Hydrochloric acid, with a ρ of 1,16 g/ml to 1,19 g/ml.
5.6 Fluoboric acid, with a mass fraction of 40 % (ρ = 1,39 g/ml).
5.7 Sulfuric acid, ρ = 1,84 g/ml, diluted 1 + 1. Add carefully one volume of the sulfuric acid (5.4) to
one volume of water. Cool while mixing.
5.8 Sulfuric acid, ρ = 1,84 g/ml, diluted 1 + 4. Add carefully one volume of the sulfuric acid (5.4) to
four volumes of water. Cool while mixing.
5.9 Sodium hydroxide (NaOH) solution, of 100 g/l.
5.10 Sodium hydroxide (NaOH) solution, of 20 g/l.
5.11 Hydrogen peroxide (H O ) solution, of a volume fraction of 30 %.
2 2
5.12 Iron(III) sulfate (Fe (SO ) ) solution, of 15 g/l.
2 4 3
5.13 Titanium standard solution, of 1,0 mg/ml, prepared by one of the following methods.
5.13.1 Preparation from titanium(IV) dioxide
Weigh 0,417 2 g ± 0,000 1 g of titanium(IV) dioxide (spectrum pure), which has been previously calcined for
2 h at 800 °C. In a 250 ml dry conical flask, dissolve the titanium(IV) dioxide with 10 g of ammonium sulfate
and 20 ml of sulfuric acid (5.4). Heat the conical flask on a hot-plate until the white sulfuric fumes appear,
then allow to cool. Transfer quantitatively to a 250 ml volumetric flask. After cooling, dilute to the mark
with water and mix.
5.13.2 Preparation from titanium sponge (99,8 % minimum purity)
In a 250 ml polytetrafluoroethylene (PTFE) beaker, dissolve 0,250 0 g ± 0,000 1 g of titanium sponge
(99,8 % minimum purity) with 40 ml of sulfuric acid (5.7) and 5 ml of hydrofluoric acid. Cover the beaker
with a PTFE cover. Oxidize while cold by adding 5 ml of nitric acid (5.3) drop by drop. Heat the PTFE beaker
on a hot-plate until the white sulfuric fumes appear, then allow to cool. Transfer quantitatively to a 250 ml
volumetric flask, after cooling, di
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