Iron ores — Determination of magnesium — Flame atomic absorption spectrometric method

ISO 10204:2017 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 0,010 % and 2,00 % 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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Status
Published
Publication Date
18-Jul-2017
Current Stage
9020 - International Standard under periodical review
Due Date
15-Jul-2022
Completion Date
15-Jul-2022
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INTERNATIONAL ISO
STANDARD 10204
Fourth edition
2017-07
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 10204:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 10204:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

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ii © ISO 2017 – All rights reserved
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ISO 10204:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus ..................................................................................................................................................................................................................... 3

7 Sampling and samples .................................................................................................................................................................................... 4

7.1 Laboratory sample ............................................................................................................................................................................... 4

7.2 Preparation of test samples ......................................................................................................................................................... 4

7.2.1 General...................................................................................................................................................................................... 4

7.2.2 Method specified in ISO 2596 ............................................................................................................................... 4

7.2.3 Method specified in ISO 7764 ............................................................................................................................... 4

8 Procedure..................................................................................................................................................................................................................... 4

8.1 Number of determinations ........................................................................................................................................................... 4

8.2 Test portion ................................................................................................................................................................................................ 4

8.3 Blank test and check test ................................................................................................................................................................ 5

8.3.1 Blank test ................................................................................................................................................................................ 5

8.3.2 Check test ............................................................................................................................................................................... 5

8.4 Determination ......................................................................................................................................................................................... 5

8.4.1 Decomposition of the test portion .................................................................................................................... 5

8.4.2 Treatment of the residue .......................................................................................................................................... 5

8.4.3 Preparation of the test solution .......................................................................................................................... 6

8.4.4 Adjustment of the atomic absorption spectrometer......................................................................... 6

8.4.5 Atomic absorption measurements ................................................................................................................... 7

9 Expression of results ........................................................................................................................................................................................ 7

9.1 Calculation of mass fraction of magnesium ................................................................................................................... 7

9.2 General treatment of results ....................................................................................................................................................... 7

9.2.1 Repeatability and permissible tolerance .................................................................................................... 7

9.2.2 Determination of analytical result .................................................................................................................... 8

9.2.3 Between-laboratories precision ......................................................................................................................... 8

9.2.4 Check for trueness .......................................................................................................................................................... 8

9.2.5 Calculation of final result .......................................................................................................................................... 9

9.3 Oxide factor ................................................................................................................................................................................................ 9

10 Test report ................................................................................................................................................................................................................10

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 trials ...........................................13

Bibliography .............................................................................................................................................................................................................................14

© ISO 2017 – All rights reserved iii
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ISO 10204:2017(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).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO’s adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

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 2, Chemical analysis.

This fourth edition cancels and replaces the third edition (ISO 10204:2015), of which it constitutes a

minor revision with the following changes:

— in 7.2, reference to ISO 2596 has been incorporated and 7.2 has been rearranged in a more appropriate

layout/format;
— in 8.2, reference to ISO 2596 has been incorporated;
— “predried” has been deleted where it is inappropriate in 8.1, 8.2, and 8.3.2;
— in Table 1, some minor changes have been made;

— in 9.2.4, Formula (7) and relevant descriptions have been modified to harmonize this subclause

across all documents for which ISO/TC 102/SC 2 is responsible.
iv © ISO 2017 – All rights reserved
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INTERNATIONAL STANDARD ISO 10204:2017(E)
Iron ores — Determination of magnesium — 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 and determine the applicability of any limitations prior to use.
1 Scope

This document 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 0,010 % and 2,00 % in natural iron

ores, iron ore concentrates, and agglomerates, including sinter products.
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 9516-1:2003, Iron ores — Determination of various elements by X-ray fluorescence spectrometry —

Part 1: Comprehensive procedure
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 is decomposed by the treatment with hydrochloric acid and a small amount of nitric

acid, and then 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.

© ISO 2017 – All rights reserved 1
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ISO 10204:2017(E)

The solution obtained is aspirated into the flame of an atomic absorption spectrometer using an air-

acetylene burner.

The absorbance values obtained for magnesium are compared with those obtained from calibration

solutions.

NOTE A dinitrogen oxide/acetylene flame can be used for the determination, in which case, the sensitivity is

decreased by a factor of about 3.
5 Reagents

During the analysis, use only reagents of recognized analytical grade and only water that complies with

Grade 2 of ISO 3696.
5.1 Sodium carbonate, (Na CO ), anhydrous.
2 3
5.2 Hydrochloric acid, ρ 1,19 g/ml.
5.3 Hydrochloric acid, ρ 1,19 g/ml, diluted 1 + 9.
5.4 Nitric acid, ρ 1,4 g/ml.

5.5 Hydrofluoric acid, ρ 1,13 g/ml, 40 % (mass fraction) or ρ 1,185 g/ml, 48 % (mass fraction).

5.6 Sulfuric acid, ρ 1,84 g/ml, diluted 1 + 1.

5.7 Pure iron, minimum purity 99,9 % (mass fraction), of mass fraction of magnesium less than

0,0002 %.
5.8 Background solution.

Dissolve 5,0 g pure iron (5.7) in 50 ml of hydrochloric acid (5.2) and oxidize by adding nitric acid (5.4)

drop by drop. Evaporate until a syrupy consistency is obtained. Add 20 ml of hydrochloric acid (5.2)

and dilute to 200 ml with water. Dissolve 17 g of sodium carbonate (5.1) 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.
5.9 Lanthanum chloride solution.

Dissolve 50 g of lanthanum chloride (LaCl ·7H O) (of mass fraction of magnesium less than 0,002 %) in

3 2

50 ml of hydrochloric acid (5.2) and 300 ml of hot water. Cool and dilute to 1 l.

5.10 Magnesium standard solution, 25 μg Mg/ml.

Dissolve 0,500 0 g of oxide-free magnesium metal [minimum purity 99,9 % (mass fraction)] or 0,829 2 g

of analytical grade magnesium oxide (dried and weighed in accordance with ISO 9516-1:2003, 4.9) by

slowly adding 75 ml of hydrochloric acid (5.2), 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.
5.11 Magnesium calibration solutions.

Using pipettes, transfer 2,0 ml, 5,0 ml, 10,0 ml, 15,0 ml, and 20,0 ml portions of magnesium standard

solution (5.10) to 200 ml volumetric flasks (see next paragraph). Add 6 ml of hydrochloric acid (5.2),

60 ml of background solution (5.8), and 40 ml of lanthanum chloride solution (5.9) to each flask.

Dilute the solution to volume with water and mix. Prepare a zero magnesium calibration solution

2 © ISO 2017 – All rights reserved
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ISO 10204:2017(E)

by transferring 60 ml of background solution (5.8) to a 200 ml volumetric flask. Then add 6 ml of

hydrochloric acid (5.2) and 40 ml of lanthanum chloride solution (5.9). Dilute the solution to volume

with water and mix.

The range of magnesium that can be covered can vary from instrument to instrument. Attention should

be paid to the minimum criteria given in 6.3. For instruments having high sensitivity, smaller portions

of standard solution or a more diluted standard solution can be used.
6 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.

6.1 Platinum crucible with a lid, of minimum capacity 30 ml.

6.2 Muffle furnace, capable of maintaining a temperature of approximately 1 100 °C.

6.3 Atomic absorption spectrometer, equipped with an air-acetylene burner.

WARNING — Follow the manufacturer’s instructions for igniting and extinguishing the

dinitrogen oxide/acetylene flame to avoid possible explosion hazards. Wear tinted safety glasses

whenever the flame is burning.

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

(see 5.11) shall be at least 0,3.

b) Graph linearity: the ratio between the slope of the calibration graph covering the top 20 % of the

concentration range (expressed as a change in absorbance) and the value of the slope for the bottom

20 % of the concentration range determined in the same way shall not be less than 0,7.

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
...

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