Iron ores — Determination of vanadium — Part 1: BPHA spectrophotometric method

ISO 9683-1:2006 specifies a spectrophotometric method using N-benzoyl-phenylhydroxylamine (BPHA) for the determination of the mass fraction of vanadium in iron ores. This method is applicable to mass fractions of vanadium between 0,005 and 0,5 % in natural iron ores, iron ore concentrates and agglomerates, including sinter products.

Minerais de fer — Dosage du vanadium — Partie 1: Méthode spectrophotométrique à la BPHA

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Iron ores — Determination
of vanadium —
Part 1:
BPHA spectrophotometric method
Minerais de fer — Dosage du vanadium —
Partie 1: Méthode spectrophotométrique à la BPHA

Reference number
ISO 9683-1:2006(E)
ISO 2006

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ISO 9683-1:2006(E)
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ii © ISO 2006 – All rights reserved

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ISO 9683-1:2006(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Principle. 1
4 Reagents. 2
5 Apparatus. 3
6 Sampling and samples. 3
6.1 Laboratory sample. 3
6.2 Preparation of predried test samples . 4
7 Procedure. 4
7.1 Number of determinations . 4
7.2 Test portion . 4
7.3 Blank test and check test. 4
7.4 Determination. 4
7.4.1 Decomposition of the test portion . 4
7.4.2 Colour development and extraction . 5
7.4.3 Spectrophotometric measurement . 5
7.4.4 Calibration. 5
8 Expression of results. 6
8.1 Calculation of mass fraction of vanadium . 6
8.2 General treatment of results. 6
8.2.1 Repeatability and permissible tolerance. 6
8.2.2 Determination of analytical result. 7
8.2.3 Between-laboratories precision. 7
8.2.4 Check for trueness . 8
8.2.5 Calculation of final result. 8
8.3 Oxide factor. 9
9 Test report. 9
Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for test
samples. 10
Annex B (informative) Derivation of repeatability and permissible equations . 11
Annex C (informative) Precision data obtained by international analytical trials . 12

© ISO 2006 – All rights reserved iii

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ISO 9683-1:2006(E)
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 9683-1 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 2, Chemical analysis.
This first edition of ISO 9683-1 cancels and replaces ISO 9683:1991, which has been technically revised. It
has been updated to alter the manner in which precision data are presented.
ISO 9683 consists of the following part, under the general title Iron ores — Determination of vanadium:
⎯ Part 1: BPHA spectrophotometric method
The following part is under preparation:
⎯ Part 2: Flame atomic absorption spectrometric method

iv © ISO 2006 – All rights reserved

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Iron ores — Determination of vanadium —
Part 1:
BPHA spectrophotometric method
WARNING — This part of ISO 9683 may involve hazardous materials, operations and equipment. This
part of ISO 9683 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 9683 specifies a spectrophotometric method using N-benzoyl-phenylhydroxylamine (BPHA)
for the determination of the mass fraction of vanadium in iron ores.
This method is applicable to mass fractions of vanadium between 0,005 and 0,5 % in natural iron ores, iron
ore concentrates and agglomerates, including sinter products.
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 648, Laboratory glassware — One-mark pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
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
A test portion is decomposed by fusion with sodium peroxide, and leached with water and sulfuric acid.
Orthophosphoric acid is added to an aliquot and the vanadium is oxidized to the pentavalent state by
potassium permanganate. The excess permanganate is reduced by sodium nitrite in the presence of urea.
A complex is formed by treatment with BPHA and hydrochloric acid, and the complex is extracted with
The absorbance is measured spectrophotometrically at approximately 535 nm.
© ISO 2006 – All rights reserved 1

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ISO 9683-1:2006(E)
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 Iron metal powder, of mass fraction of vanadium < 0,001 %.
4.2 Sodium peroxide, fine powder.
4.3 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 4 + 1.
4.4 Sulfuric acid, ρ 1,84 g/ml, diluted 1 + 4.
4.5 Orthophosphoric acid, ρ 1,7 g/ml, diluted 1 + 1.
4.6 Hydrogen peroxide, 300 g/l solution.
4.7 Sodium nitrite, 3 g/l solution.
4.8 Urea, 250 g/l solution.
4.9 Potassium permanganate, 3,2 g/l solution.
Dissolve 3,2 g of potassium permanganate in 100 ml of water. Boil gently for about 1 h, filter through a
carefully cleaned fine-texture glass filter funnel into a 1 000 ml one-mark volumetric flask, dilute to volume with
water and mix. Store the solution in a brown bottle.
4.10 Sodium tripolyphosphate, 100 g/l solution.
Dissolve 25 g of sodium tripolyphosphate in 170 ml of water, dilute to 250 ml and mix.
4.11 Background solution.
Place 1,300 g of pure iron (4.1) in a zirconium or vitreous carbon crucible (5.1) containing 4,0 g of sodium
peroxide (4.2). Add another 4,0 g of sodium peroxide, mix thoroughly with a glass rod or nickel spatula and
tamp the mixture. Place the crucible for 1 min or 2 min at the entrance of a muffle furnace (5.2), the
temperature of which is regulated at 420 °C ± 10 °C, and then transfer it to the closed furnace for at least 1 h
to effect sintering.
Remove the crucible from the furnace and cool to room temperature. Place the crucible containing the
sintered mass in a dry 400 ml beaker, cover with a watch-glass and, momentarily lifting the cover, add 5 ml of
water around the sinter cake. When the reaction has subsided, add a further 15 ml of water in the same way.
After several minutes, when the reaction has subsided again, empty the crucible into the 400 ml beaker,
rinsing with approximately 10 ml of water. Cautiously pour 30 ml of sulfuric acid (4.4) into the crucible, heat
gently, if necessary, to dissolve any residue, and transfer the solution to the beaker, rinsing with about 10 ml
of water.
Cautiously add 100 ml of sulfuric acid (4.4) and mix with a glass rod. Add 1 to 2 drops of hydrogen peroxide
(4.6) while stirring, until a clear yellow solution is obtained. Boil for about 2 min, cool, transfer to a 200 ml one-
mark volumetric flask, dilute to volume with water and mix.
4.12 Chloroform.
4.13 N-Benzoyl-phenylhydroxylamine (BPHA), 2,5 g/l chloroform solution.
4.14 Vanadium, standard solutions.
4.14.1 Vanadium stock solution, 1 000 µg V/ml.
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ISO 9683-1:2006(E)
Dry several grams of ammonium metavanadate (NH VO ) in an air oven at 100 °C for 1 h and cool to room
4 3
temperature in a desiccator. Weigh, to the nearest 0,000 2 g, 2,296 3 g of the dried product into a 600 ml
beaker, add 400 ml of hot water and heat gently to dissolve. Cool, carefully add 50 ml of sulfuric acid (4.4),
transfer to a 1 000 ml one-mark volumetric flask, quantitatively, dilute to volume with water and mix.
4.14.2 Vanadium standard solution, 50 µg V/ml.
Introduce 5,0 ml of vanadium stock solution (4.14.1) to a 100 ml one-mark volumetric flask containing 70 ml of
water and 5 ml of sulfuric acid (4.4). Cool, dilute to volume with water and mix.
4.15 Calibration solutions.
To each of six 125 ml separating funnels, add 25,0 ml of background solution (4.11) and 7 ml of
orthophosphoric acid (4.5). Using pipettes, add the quantities of vanadium standard solution (4.14.2) and
water as given in Table 1 to the respective separating funnels, and mix by swirling.
Table 1 — Calibration solutions
Vanadium standard Vanadium concentration in the
solution (4.14.2) measured solution
ml ml µg/ml
0 5,0 0
0,5 4,5 0,5
1,0 4,0 1,0
2,0 3,0 2,0
3,5 1,5 3,5
5,0 0 5,0

For colour development and extraction, proceed as directed in 7.4.2, beginning at "Add 0,8 ml of potassium
permanganate solution (4.9) ."
5 Apparatus
Ordinary laboratory apparatus, including one-mark pipettes and one-mark volumetric flasks complying with the
specifications of ISO 648 and ISO 1042, respectively, and the following.
5.1 Zirconium metal or vitreous carbon crucible, of capacity approximately 50 ml.
5.2 Muffle furnace, capable of being regulated at 420 °C ± 10 °C.
5.3 Spectrophotometer.
6 Sampling and samples

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