ISO 11535:2006

INTERNATIONAL ISO
STANDARD 11535
Second edition
2006-12-15
Iron ores — Determination of various
elements — Inductively coupled plasma
atomic emission spectrometric method
Minerais de fer — Dosage de divers éléments — Méthode par
spectrométrie d'émission atomique avec plasma induit par haute
fréquence
Reference number
©
ISO 2006
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©  ISO 2006
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ii © ISO 2006 – All rights reserved

Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Principle. 2
4 Reagents. 2
5 Apparatus . 4
6 Sampling and samples. 4
6.1 Laboratory sample. 4
6.2 Preparation of predried test samples . 5
7 Procedure . 5
7.1 Number of determinations . 5
7.2 Test portion . 5
7.3 Blank test and check test. 5
7.4 Determination. 5
7.4.1 Decomposition of the test portion . 5
7.4.2 Adjustment of spectrometer. 6
7.4.3 Measurements. 7
8 Calculation of results . 7
8.1 Calibration graph . 7
8.2 Correction of spectral interference. 7
8.3 Standardization of calibration graph (drift correction). 9
8.4 General treatment of results. 10
8.4.1 Repeatability and permissible tolerances.10
8.4.2 Determination of analytical result. 10
8.4.3 Check for trueness . 11
8.4.4 Calculation of final result. 11
8.5 Oxide factors . 12
9 Test report . 12
Annex A (informative) Suggested calibration solutions . 13
Annex B (normative) Plasma-spectrometer performance tests. 15
Annex C (normative) Flowsheet of the procedure for the acceptance of analytical values for test
samples. 18
Annex D (informative) Derivation of repeatability and permissible tolerance equations . 19
Annex E (informative) Precision data obtained by international analytical trials. 20

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 11535 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 11535:1998), which has been technically
revised. It has been updated to alter the manner in which the precision data are presented.

iv © ISO 2006 – All rights reserved

INTERNATIONAL STANDARD ISO 11535:2006(E)

Iron ores — Determination of various elements — Inductively
coupled plasma atomic emission spectrometric method
WARNING — This International Standard may involve hazardous materials, operations and equipment.
This International Standard does not purport to address all of the safety problems associated with its
use. It is the responsibility of the user of this International Standard to establish appropriate health and
safety practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies a method for the determination of aluminium, calcium, phosphorus,
magnesium, manganese, silicon and titanium in iron ores by inductively coupled plasma atomic emission
spectrometry (ICP-AES).
This method is applicable to the mass-fraction ranges given in Table 1, in natural iron ores, iron ore concentrates
and agglomerates, including sinter products.
Table 1 — Mass-fraction ranges
Element Range of mass fractions
%
Al 0,07 to 3,30
Ca 0,012 to 6,80
Mg 0,008 to 1,90
Mn 0,012 to 1,70
P 0,011 to 1,60
Si 0,44 to 9,40
Ti 0,018 to 0,17
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
The test portion is decomposed by fusion in a sodium carbonate/sodium tetraborate flux and the cooled melt
is dissolved in hydrochloric acid.
The solution is diluted to volume and measured on an ICP spectrometer. Final results are read from a
calibration graph prepared using standard solutions.
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 oxide (Fe O ), of minimum purity 99,99 % (mass fraction).
2 3
4.2 Sodium carbonate (Na CO ), anhydrous.
2 3
To produce final impurity levels in a solution below the detection limits determined or suggested in the
performance test, a high-quality grade is required.
4.3 Sodium tetraborate (Na B O ), anhydrous.
2 4 7
The same purity criteria as for the sodium carbonate are required.
4.4 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml.
The same purity criteria as for the sodium carbonate are required.
4.5 Hydrochloric acid, ρ 1,16 g/ml to 1,19 g/ml, diluted 1 + 1.
Add 500 ml of hydrochloric acid (4.4) to 500 ml of water and mix.
4.6 Nitric acid, ρ 1,4 g/ml.
The same purity criteria as for the sodium carbonate are required.
4.7 Stock solutions.
4.7.1 Phosphorus, 1 000 µg/ml.
Dry approximately 10 g of potassium dihydrogen orthophosphate (KH PO ) at 110 °C until a constant mass is
2 4
reached, and cool in a desiccator. Dissolve 4,393 6 g in about 200 ml of water in a 1 000 ml one-mark
volumetric flask. When the dissolution is complete, dilute to volume with water and mix.
4.7.2 Manganese, 1 000 µg/ml.
Dissolve 1,000 0 g of high-purity manganese metal in 20 ml of hydrochloric acid (4.5) in a covered tall-form
beaker while heating. When dissolution is complete, cool, transfer to a 1 000 ml one-mark volumetric flask,
dilute to volume with water and mix.
4.7.3 Magnesium, 1 000 µg/ml.
Dissolve 1,000 0 g of high-purity magnesium metal in 20 ml of hydrochloric acid (4.5) in a covered tall-form
beaker while heating. When dissolution is complete, cool, transfer to a 1 000 ml one-mark volumetric flask,
dilute to volume with water and mix.
2 © ISO 2006 – All rights reserved

4.7.4 Silicon, 1 000 µg/ml.
Accurately weigh 2,139 3 g of pure silicon oxide (finely ground, previously heated at 1 000 °C for 45 min) into
a platinum crucible (5.2). Mix with 5 g of sodium carbonate (4.2), and melt in a furnace at 1 000 °C for 15 min.
Dissolve the melt in 100 ml of warm water and transfer to a 1 000 ml one-mark volumetric flask; increase the
volume to approximately 500 ml with water, add 20 ml of hydrochloric acid (4.5), dilute to volume with water
and mix. Store in a polyethylene flask.
4.7.5 Aluminium, 1 000 µg/ml.
Dissolve 1,000 0 g of high-purity aluminium metal in 20 ml of hydrochloric acid (4.5) in a covered tall-form
beaker. Add about 4 drops of nitric acid (4.6). When dissolution is complete, add about 20 ml of water and heat
to liberate oxides of nitrogen. Cool and transfer to a 1 000 ml one-mark volumetric flask, dilute to volume with
water and mix.
4.7.6 Titanium, 1 000 µg/ml.
Dissolve 1,000 0 g of high-purity titanium metal in 100 ml of hydrochloric acid (4.5) in a covered tall-form
beaker while heating. When dissolution is complete, cool, transfer to a 1 000 ml one-mark volumetric flask,
dilute to volume with hydrochloric acid (4.5) and mix.
4.7.7 Calcium, 1 000 µg/ml.
Dry approximately 10 g of calcium carbonate (CaCO ) at 110 °C until a constant mass is reached, and cool in
a desiccator. Dissolve 2,497 2 g in 20 ml of hydrochloric acid (4.5) in a covered tall-form beaker while heating.
When dissolution is complete, cool, transfer to a 1 000 ml one-mark volumetric flask, dilute to volume with
water and mix.
4.8 Calibration and reference solutions
Calibration solutions are defined as the solutions required for plotting the calibration graphs of the elements
analysed. Their concentration ranges in solution, expressed in micrograms per millilitre, are determined with
reference to the performance parameter values and the linearity response of the instrument. A minimum of
10 solutions is necessary to cover the mass-fraction ranges given in Table 1. For te
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