ISO 15633:2017

INTERNATIONAL ISO
STANDARD 15633
Third edition
2017-07
Iron ores — Determination of
nickel — Flame atomic absorption
spectrometric method
Minerais de fer — Dosage du nickel — Méthode par spectrométrie
d’absorption atomique dans la flamme
Reference number
ISO 15633:2017(E)
©
ISO 2017

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ISO 15633:2017(E)

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© ISO 2017, Published in Switzerland
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ISO 15633:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 2
7 Sampling and samples . 3
7.1 Laboratory sample . 3
7.2 Preparation of predried test samples . 3
8 Procedure. 4
8.1 Number of determinations . 4
8.2 Test portion . 4
8.3 Blank test and check test . 4
8.4 Determination . 4
8.4.1 Decomposition of the test portion . 4
8.4.2 Removal of iron . 5
8.4.3 Treatment of the residue . 5
8.4.4 Preparation of the calibration solutions . 5
8.4.5 Adjustment of the atomic absorption spectrometer. 6
8.4.6 Atomic absorption measurements . 6
9 Expression of results . 6
9.1 Calculation of nickel content . 6
9.2 General treatment of results . 7
9.2.1 Repeatability and permissible tolerance . 7
9.2.2 Determination of analytical result . 7
9.2.3 Between-laboratories precision . 7
9.2.4 Check for trueness . 8
9.2.5 Calculation of final result . 9
9.3 Oxide factor . 9
10 Test report . 9
Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for
test samples .11
Annex B (informative) Derivation of repeatability and permissible tolerance formulae .12
Annex C (informative) Precision data obtained by international analytical trial .13
Bibliography .14
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ISO 15633:2017(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).
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URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 02, Chemical analysis.
This third edition cancels and replaces the second edition (ISO 15633:2015), of which it constitutes a
minor revision with the following changes:
— in Clause 1 “0,1 %” has been replaced by “0,10 %”;
— in 7.1 “<160 μm” has been replaced by “−160 μm”;
— in 8.2 a new sentence has been included to make reference to ISO 2596;
— in the titles of 9.1, Table B.1 and Figure C.1 “sulfur” has been replaced by “nickel”;
— in 9.2.4 Formula (8) and the relevant descriptions have been modified to harmonize this subclause
across all documents for which ISO/TC 102/SC 2 is responsible.
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ISO 15633:2017(E)

Introduction
The objective of a proposed revision of ISO 9685:1991 was to extend the lower limit for a flame atomic
absorption spectrometric method determination of both chromium and nickel in iron ores down to
0,001 %. However, due to bias, the method for nickel could not be approved for referee purposes.
The 22nd meeting of ISO/TC 102/SC 2 decided to progress this document as a non-referee method.
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INTERNATIONAL STANDARD ISO 15633:2017(E)
Iron ores — Determination of nickel — Flame atomic
absorption spectrometric method
WARNING — This document might 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
prior to use.
1 Scope
This document specifies a flame atomic absorption spectrometric method for the determination of the
nickel mass fraction of iron ores.
This method is applicable to mass fractions of nickel between 0,001 % and 0,10 % in natural iron ores,
iron ore concentrates and agglomerates including sinter products.
This method is not appropriate for referee purposes.
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 3696, Water for analytical laboratory use — Specification and test methods
ISO 7764, Iron ores — Preparation of predried test samples for chemical analysis
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:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Principle
The test portion of iron ore is decomposed by treatment with hydrochloric and nitric acids.
The major portion of iron in the filtrate is removed by extraction with 4-methylpentan-2-one.
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ISO 15633:2017(E)

The insoluble residue is ignited and silicon dioxide is removed by evaporation with hydrofluoric and
sulfuric acids. The residue is fused with a mixture of sodium carbonate and sodium tetraborate, and
then dissolved with hydrochloric acid and combined with the main solution.
5 Reagents
During the analysis, use only reagents of recognized analytical grade and only water that conforms to
Grade 2 of ISO 3696.
5.1 Sodium carbonate (Na CO ), anhydrous powder.
2 3
5.2 Sodium tetraborate (Na B O ), anhydrous powder.
2 4 7
5.3 Lithium tetraborate (Li B O ), anhydrous powder.
2 4 7
5.4 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml.
5.5 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 2 + 1.
5.6 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 1 + 1.
5.7 Hydrochloric acid, ρ = 1,16 g/ml to 1,19 g/ml, diluted 2 + 100.
5.8 Nitric acid, ρ = 1,4 g/ml.
5.9 Nitric acid, ρ = 1,4 g/ml, diluted 1 + 1.
5.10 Hydrofluoric acid, ρ = 1,13 g/ml, 40 % (mass fraction) or ρ = 1,19 g/ml, 48 % (mass fraction).
5.11 Sulfuric acid, ρ = 1,84 g/ml.
5.12 Sulfuric acid, ρ = 1,84 g/ml, diluted 1 + 1.
5.13 4-methylpentan-2-one, (methyl isobutyl ketone, MIBK).
5.14 Nickel standard solution A, 100 µg Ni/ml.
Dissolve 0,100 0 g of nickel metal [purity > 99,9 % (mass fraction)] (see Note of 5.15) in 30 ml of nitric
acid (5.9). After cooling, transfer quantitatively to a 1 000 ml one-mark volumetric flask, dilute to
volume with water and mix.
5.15 Nickel standard solution B, 10 µg Ni/ml.
Transfer 100,0 ml of nickel standard solution A (5.14) to a 1 000 ml one-mark volumetric flask. Dilute to
volume with water and mix.
NOTE The purity of the metals stated on the certificates does not generally take into account the presence of
absorbed gases such as oxygen, carbon monoxide, etc.
6 Apparatus
Ordinary laboratory apparatus including one-mark pipettes and one-mark volumetric flasks complying
with the specifications of ISO 648, ISO 1042 and the following.
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ISO 15633:2017(E)

6.1 Platinum crucible, of minimum capacity 25 ml.
6.2 Muffle furnace.
6.3 Atomic absorption spectrometer, equipped with an air-acetylene burner.
WARNING — Follow the manufacturer’s instructions for igniting and extinguishing the air-
acetylene flame to avoid possible explosion hazards. Wear tinted safety glasses whenever the
burner is in operation.
The atomic absorption spectrometer used in this method shall meet the following criteria.
a) Minimum sensitivity: the absorbance of the most concentrated calibration solution (see 8.4.4) is at
least 0,3.
b) Graph linearity: the slope of the calibration graph covering the top 20 % of the concentration range
(expressed as a change in absorbance) is not less than 0,7 of the value of the slope for the bottom
20 % of the concentration range determined in the same way.
c) Minimum stability: the standard deviation of the absorbance of the most concentrated calibration
solution and that of the zero calibration solution each being calculated from a sufficient number
of repetitive measurements are less than 1,5 % and 0,5 %, respectively of the mean value of the
absorbance of the most concentrated solution.
The use of a strip-chart recorder and/or digital readout device is recommended to evaluate criteria a),
b) and c) and for all subsequent measurements.
NOTE Instrument parameters vary with each instrument. The following parameters were successfully used
in several laboratories and they can be used as guidelines. An air-acetylene flame was used.
Hollow-cathode lamp, mA 10
Wavelength, nm 232,0
Air flow rate, l/min 10
Acetylene flow rate, l/min 2,5
In systems where the values shown above for gas flow rates do not apply, the ratio of the gas flow rates can still
be a useful guideline.
7 Sampling and samples
7.1 Laboratory sample
For analysis, use a laboratory sample of −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 −160 μm.
NOTE A guideline on significant contents of combined water and oxidizable compounds is incorporated in
ISO 7764.
Ensure that the sample has not been pulverized in a nickel/chromium pot.
7.2 Preparation of predried test samples
Thoroughly mix the laboratory sample and, taking multiple increments, extract a test sample in
such a manner that it is representative of the entire contents of the container. Dry the test sample at
105 °C ± 2 °C as specified in ISO 7764. This is the predried test sample.
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ISO 15633:2017(E)

8 Procedure
8.1 Number of determinations
Carry out the analysis at least in duplicate, in accordance with Annex A and independently on one
predried test sample.
NOTE The expression “independently”
...