ISO 10204:2006
(Main)Iron ores — Determination of magnesium — Flame atomic absorption spectrometric method
Iron ores — Determination of magnesium — Flame atomic absorption spectrometric method
ISO 10204:2006 specifies a flame atomic absorption spectrometric method for the determination of the mass fraction of magnesium in iron ores. This method is applicable to mass fractions of magnesium between 0,25 % and 3,5 % in natural iron ores, iron ore concentrates and agglomerates, including sinter products.
Minerais de fer — Dosage du magnésium — Méthode par spectrométrie d'absorption atomique dans la flamme
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 10204
Second edition
2006-06-15
Iron ores — Determination of
magnesium — Flame atomic absorption
spectrometric method
Minerais de fer — Dosage du magnésium — Méthode par
spectrométrie d'absorption atomique dans la flamme
Reference number
ISO 10204:2006(E)
©
ISO 2006
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ISO 10204:2006(E)
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ii © ISO 2006 – All rights reserved
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ISO 10204:2006(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Principle. 1
4 Reagents. 2
5 Apparatus. 2
6 Sampling and samples. 3
6.1 Laboratory sample. 3
6.2 Preparation of predried test samples . 3
7 Procedure. 3
7.1 Number of determinations . 3
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 Treatment of the residue. 4
7.4.3 Preparation of the test solution. 5
7.4.4 Adjustment of the atomic absorption spectrometer . 5
7.4.5 Atomic absorption measurements. 5
8 Expression of results. 6
8.1 Calculation of mass fraction of magnesium . 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 . 7
8.2.5 Calculation of final result. 8
8.3 Oxide factor. 8
9 Test report. 8
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 tolerance equations . 11
Annex C (informative) Precision data obtained by international analytical trials . 12
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ISO 10204:2006(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.
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 10204 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 10204:1992), which has been technically
revised. It has been updated to alter the manner in which precision data are presented.
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INTERNATIONAL STANDARD ISO 10204:2006(E)
Iron ores — Determination of magnesium — Flame atomic
absorption 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 flame atomic absorption spectrometric method for the determination of
the mass fraction of magnesium in iron ores.
This method is applicable to mass fractions of magnesium between 0,25 % and 3,5 % 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 7764, Iron ores — Preparation of predried test samples for chemical analysis
3 Principle
The test portion is decomposed by treatment with hydrochloric acid and a small amount of nitric acid.
The solution is evaporated to dehydrate silica, followed by dilution and filtration.
The residue is ignited and silica is removed by evaporation with hydrofluoric and sulfuric acids. The residue is
fused with sodium carbonate and the cooled melt is dissolved in the filtrate.
The solution is aspirated into the flame of an atomic absorption spectrometer using an air/acetylene burner.
Absorbance values obtained for magnesium are compared with those obtained from the calibration solutions.
NOTE A dinitrogen oxide/acelylene flame may be used for the determination, in which case the sensitivity is
decreased by a factor of about 3.
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ISO 10204:2006(E)
4 Reagents
During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water
of equivalent purity.
4.1 Sodium carbonate (Na CO ), anhydrous.
2 3
4.2 Hydrochloric acid, ρ 1,19 g/ml.
4.3 Hydrochloric acid, ρ 1,19 g/ml, diluted 1 + 9.
4.4 Nitric acid, ρ 1,4 g/ml.
4.5 Hydrofluoric acid, ρ 1,13 g/ml, 40 % (m/m), or ρ 1,185 g/ml, 48 % (m/m).
4.6 Sulfuric acid, ρ 1,84 g/ml, diluted 1 + 1.
4.7 Background solution.
Dissolve 10 g of iron wire [minimum purity 99,9 % (mass fraction), of mass fraction of magnesium less than
0,000 2 %] in 50 ml of hydrochloric acid (4.2) and oxidize by adding nitric acid (4.4) drop by drop. Evaporate
until a syrupy consistency is obtained. Add 20 ml of hydrochloric acid (4.2) and dilute to 200 ml with water.
Dissolve 17 g of sodium carbonate (4.1) in water, add carefully to the iron solution and heat to remove carbon
dioxide. Transfer the cooled solution to a 1 000 ml one-mark volumetric flask, dilute to volume with water and
mix.
4.8 Lanthanum chloride solution.
Dissolve 50 g of lanthanum chloride (LaCl⋅xH O) [of mass fraction of magnesium less than 0,002 %] in 50 ml
3 2
of hydrochloric acid (4.2) and 300 ml of hot water. Cool and dilute to 1 litre.
4.9 Mangnesium standard solution, 15 µg Mg/ml.
Dissolve 0,300 0 g of oxide-free magnesium metal [minimum purity 99,9 % (mass fraction)] by slowly adding
75 ml of hydrochloric acid (4.2), diluted 1 + 3. When dissolved, cool, transfer to a 1 000 ml one-mark
volumetric flask, dilute to volume with water and mix. Transfer 10 ml of this solution to a 200 ml one-mark
volumetric flask, dilute to volume with water and mix.
4.10 Magnesium calibration solutions.
Using pipettes, transfer 2,0 ml; 5,0 ml; 10,0 ml; 20,0 ml; 40,0 ml; and 50,0 ml portions of the magnesium
standard solutions (4.9) to 200 ml volumetric flasks (see next paragraph). Add 6 ml of hydrochloric acid (4.2),
60 ml of background solution (4.7) and 40 ml of lanthanum chloride solution (4.8) to each flask. Dilute all the
solutions to volume with water and mix. Prepare a zero magnesium calibration solution by transferring 60 ml
of the background solution to a 200 ml volumetric flask. Then add 6 ml of hydrochloric acid (4.2) and 40 ml of
lanthanum chloride solution. Dilute all the solutions to volume with water and mix.
The range of magnesium that can be covered may vary from instrument to instrument. Attention should be
paid to the minimum criteria given in 5.3. For instruments having high sensitivity, smaller portions of standard
solution or a more diluted standard solution can be used.
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 Platinum crucible, of minimum capacity 30 ml.
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ISO 10204:2006(E)
5.2 Muffle furnace, capable of maintaining a temperature of approximately 1 100 °C.
5.3 Atomic absorption spectrometer, equipped with an air/acetylene burner.
The atomic absorption spectrometer used in this method shall meet the following criteria:
a) Minimum sensitivity: the absorbance of the most concentrated magnesium calibration solution (4.10) shall
be 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) shall not be 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, shall be less than 1,5 % and 0,5 %, respectively, of the mean value of the absorbance of
the most concentrated calibration 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 may 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 15
Wavelength, nm 285,2
Air flow rate, l/min 22
Acetylene flow rate, l/min 4,2
In systems where the values shown above for gas flow rates do not apply, the ratio of the gas flow rates may still be a
useful guideline.
6 Sampling and samples
6.1 Laboratory sample
For 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.
6.2 Preparation of predried test samples
Thorou
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