ISO/TS 4689-1:2023

Iron ores — Determination of sulfur content — Part 1: Barium sulfate gravimetric method

This document specifies a barium sulfate gravimetric method for the determination of the sulfur content of iron ores. This method is applicable to a concentration range of a mass fraction of sulfur from 0,01 % to 3,9 % in natural iron ores, iron ore concentrates and agglomerates including sinter products.

Minerais de fer — Dosage du soufre — Partie 1: Méthode gravimétrique au sulfate de baryum

General Information

• Status: Published
• Publication Date: 13-Mar-2023
• ICS: 73.060.10 - Iron ores
• Technical Committee: ISO/TC 102/SC 2 - Chemical analysis
• Drafting Committee: ISO/TC 102/SC 2 - Chemical analysis
• Current Stage: 6060 - International Standard published
• Start Date: 14-Mar-2023
• Due Date: 13-Mar-2023
• Completion Date: 14-Mar-2023

Relations

• Revises: ISO 4689:1986 - Iron ores — Determination of sulfur content — Barium sulfate gravimetric method
• Effective Date: 18-Oct-2014

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 4689-1
First edition
2023-03
Iron ores — Determination of sulfur
content —
Part 1:
Barium sulfate gravimetric method
Minerais de fer — Dosage du soufre —
Partie 1: Méthode gravimétrique au sulfate de baryum
Reference number
ISO/TS 4689-1:2023(E)
© ISO 2023

---------------------- Page: 1 ----------------------
ISO/TS 4689-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 4689-1:2023(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 test samples . 3
7.2.1 General . 3
7.2.2 Ores having significant contents of combined water or oxidizable
compounds . 3
7.2.3 Ores outside the scope of 7.2.2 . 3
8 Procedure .3
8.1 Number of determinations . 3
8.2 Blank test and check test . 3
8.3 Test portion . 4
8.4 Determination . 4
8.4.1 Decomposition of the test portion . 4
8.4.2 Separation . 4
8.4.3 Precipitation of barium sulfate . 5
8.4.4 Weighing . 5
9 Expression of results . 5
9.1 Calculation of sulfur content . 5
9.2 General treatment of results . 6
9.2.1 Repeatability and permissible tolerance . 6
9.2.2 Check for trueness . 6
9.2.3 Calculation of final result . 7
10 Test report . 8
Annex A (normative) Flow sheet of the procedure for the acceptance of analytical values
for test samples . 9
Annex B (informative) Derivation of repeatability and permissible tolerance equations .10
Annex C (informative) Precision data obtained by interlaboratory analytical trial .11
Annex D (informative) Filter device diagram .12
Bibliography .13
iii
© ISO 2023 – All rights reserved

---------------------- Page: 3 ----------------------
ISO/TS 4689-1:2023(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 (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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 102, Iron Ores, Subcommittee SC 02,
Chemical analysis.
This first edition of ISO/TS 4689-1 cancels and replaces the first edition of ISO 4689:1986, which has
been technically revised.
The main changes are as follows:
— the decomposition method of samples has been changed from the original acid dissolution and
alkali melting method to soda-zinc oxide semi melting method.
A list of all parts in the ISO 4689 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
  © ISO 2023 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 4689-1:2023(E)
Introduction
In this document, a new way of melting the samples for determination of sulfur content by barium
sulfate gravimetric method is specified as follows.
— Samples are semi-molten with sodium carbonate and zinc oxide.
— The sulfate ions are leached by electromagnetic stirring and separated from the iron and other
interference elements such as lead, antimony, bismuth, tin, silicon, titanium, etc.
This method is also suitable for complex natural and artificial sample analysis.
This document consists of Part 1 of the ISO 4689 series, Iron ores — Determination of sulfur content.
v
© ISO 2023 – All rights reserved

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4689-1:2023(E)
Iron ores — Determination of sulfur content —
Part 1:
Barium sulfate gravimetric method
1 Scope
This document specifies a barium sulfate gravimetric method for the determination of the sulfur
content of iron ores.
This method is applicable to a concentration range of a mass fraction of sulfur from 0,01 % to 3,9 % 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 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 7764, Iron ores — Preparation of predried test samples for chemical analysis
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
The analysis principle is as follows:
a) decomposition of a test portion by treatment with a soda-zinc oxide flux mixture to a semi-molten
state;
b) water leaching of sulfate ion with electro-magnetic stirring and filtration of the insoluble residue;
c) transformation of sulfate ion to barium sulfate through adjustment of the acidity and addition of
barium chloride solution;
d) filtration of barium sulfate and gravimetric determination;
e) removal of the interference of Cr, Sn, P through hydrogen peroxide, citric acid and calcium
carbonate.
1
© ISO 2023 – All rights reserved

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ISO/TS 4689-1:2023(E)
5 Reagents
During the analysis, use only reagents of recognized analytical grade and only distilled water or water
of equivalent purity.
5.1 Sodium carbonate-zinc oxide mixed flux, grind Na CO to −100 mesh, blend Na CO and ZnO
2 3 2 3
by 3:2 (mass ratio).
5.2 Calcium carbonate.
5.3 Hydrofluoric acid, ρ 1,15 g/ml.
5.4 Hydrochloric acid solution, mix ρ = 1,15 g/ml hydrochloric acid and distilled water by 1:1
(volume ratio).
5.5 Sulfuric acid solution, mix ρ = 1,84 g/ml sulfuric acid and distilled water by 1:1 (volume ratio).
5.6 Hydrogen peroxide, 30 % (mass fraction).
5.7 Ethanol (ethyl).
5.8 Citric acid solution, 50 % (mass fraction).
5.9 Sodium carbonate (Na CO ), 20 g/l solution.
2 3
5.10 Silver nitrate, 10 g/l solution.
5.11 Methyl orange, 1 g/l solution.
5.12 Barium chloride (BaCl ·2H O), 100 g/l solution.
2 2
Dissolve 100 g of crystalline barium chloride dihydrate (BaCl ·2H O) in 1 l of water, cover and heat to
2 2
boiling point. Keep warm on a water bath for a minimum of 2 h and allow cooling to room temperature
overnight. Store the solution in a plastic bottle and, before each use, filter the required volume through
a close-texture filter paper.
5.13 Hydrochloric acid wash solution, containing barium chloride. Filter 10 ml of barium chloride
solution (5.12) through a close-texture filter paper, add 40 ml hydrochloric acid (5.4), dilute to about
1 000 ml.
6 Apparatus
The usual laboratory apparatu
...

ISO/TS 4689-1:2023(E)
ISO TC 102/SC 02
ISO/DTS 4689-1
ISO TC 102/SC 02
Secretariat: SA
Date: 2022-04-252023-01-06

Iron ores — Determination of sulfur content — Part 1: Barium sulfate gravimetric method
Minerais de fer — Dosage du soufre — Partie 1: Méthode gravimétrique au sulfate de baryum

Draft Technical
Specification

Warning for WDs and CDs
This document is not an ISO International Standard. It is distributed for review and comment. It is subject to
change without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.

---------------------- Page: 1 ----------------------
ISO DTS/TS 4689-1:2022(E)
COPYRIGHT PROTECTED DOCUMENT

© ISO 20XX2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no
part of this publication may be reproduced or utilized otherwise in any form or by any means,
electronic or mechanical, including photocopying, or posting on the internet or an intranet, without
prior written permission. Permission can be requested from either ISO at the address below or
ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland

© ISO 20## – All rights reserved i
© ISO 2023 – All rights reserved i

---------------------- Page: 2 ----------------------
ISO/TS 4689-1:2023(E)
Contents
Foreword . iii
Introduction . 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 test samples . 3
6.2.1 General . 3
6.2.2 Ores having significant contents of combined water or oxidizable compounds . 3
6.2.3 Ores outside the scope of 6.2.2 . 3
7 Procedure . 4
7.1 Number of determinations . 4
7.2 Blank test and check test . 4
7.3 Test portion . 4
7.4 Determination . 4
7.4.1 Decomposition of the test portion . 4
7.4.2 Separation . 5
7.4.3 Precipitation of barium sulfate . 5
7.4.4 Weighing . 5
8 Expression of results . 6
8.1 Calculation of sulfur content . 6
8.2 General treatment of results . 6
8.2.1 Repeatability and permissible tolerance . 6
8.2.2 Check for trueness . 7
8.2.3 Calculation of final result . 8
9 Test report . 8
Annex A (informative) Flow sheet of the procedure for the acceptance of analytical values
for test samples . 9
Annex B (informative) Derivation of repeatability and permissible tolerance equations . 10
Annex C (informative) Precision data obtained by interlaboratory analytical trial . 11
Annex D (informative) Filter device diagram . 12
ii © ISO 20## – All rights reserved
ii © ISO 2023 – All rights reserved

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ISO/TS 4689-1:2023(E)

© ISO 20## – All rights reserved iii
© ISO 2023 – All rights reserved iii

---------------------- Page: 4 ----------------------
ISO/TS 4689-1:2023(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 (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).
Field Code Changed
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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 102, Iron Ores, Subcommittee SC 02,
Chemical analysis.
This second edition cancels and replaces the first edition (ISO 4689:1986), which has been technically
revised.
The main change ischanges are as follows:
— The decomposition method of samples washas been changed from the original acid dissolution and
alkali melting method to soda-zinc oxide semi melting method.
A list of all parts in the ISO 4689 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv © ISO 20## – All rights reserved
iv © ISO 2023 – All rights reserved

---------------------- Page: 5 ----------------------
ISO/TS 4689-1:2023(E)
Introduction
In this revisiondocument, a new way of melting the samples for determination of sulfur content by barium
sulfate gravimetric method is specified as follows:
— Samples are semi-molten with sodium carbonate and zinc oxide;.
— The sulfate ions are leached by electromagnetic stirring and separated from the iron and other
interference elements such as lead, antimony, bismuth, tin, silicon, titanium, etc.
This method is also suitable for complex natural and artificial sample analysis.
This revision will formdocument consists of Part 1 of the ISO 4689 series, Iron ores — Determination of
sulfur content.
© ISO 20## – All rights reserved v
© ISO 2023 – All rights reserved v

---------------------- Page: 6 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4689-1:2023(E)

Iron ores — Determination of sulfur content — Part 1: Barium
sulfate gravimetric method
1 Scope
This document specifies a barium sulfate gravimetric method for the determination of the sulfur content
of iron ores.
This method is applicable to a concentration range of a mass fraction of sulfur from 0,01 % to 3,9 % 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 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 7764, Iron ores — Preparation of predried test samples for chemical analysis
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Principle
The analysis principle is as follows.
a) Decomposition of a test portion by treatment with a soda-zinc oxide flux mixture to a semi-molten
state.
b) Water leaching of sulfate ion with electro-magnetic stirring and filtration of the insoluble residue.
c) Transformation of sulfate ion to barium sulfate through adjustment of the acidity and addition of
barium chloride solution. Filtration of barium sulfate and gravimetric determination.
© ISO 2023 – All rights reserved 1

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ISO/TS 4689-1:2023(E)
d) Filtration of barium sulfate and gravimetric determination.
e) Removal of the interference of Cr, Sn, P through hydrogen peroxide, citric acid and calcium carbonate.
5 Reagents
During the analysis, use only reagents of recognized analytical grade reagents and only distilled water or
water of equivalent purity.
5.1 Sodium carbonate-zinc oxide mixed flux, grind Na CO to −100 mesh, blend Na CO and ZnO by
2 3 2 3
3:2 (mass ratio)).
5.2 Calcium carbonate.
5.3 Hydrofluoric acid, ρ 1.,15 g/ml.
5.4 Hydrochloric acid solution, mix ρ=1.,15 g/ml hydrochloric acid and distilled water by 1:1 (volume
ratio)).
5.5 Sulfuric acid solution, mix ρ=1.,84 g/ml sulfuric acid and distilled water by 1:1 (volume ratio)).
5.6 Hydrogen peroxide, 30 % (mass fraction)).
5.7 Ethanol (ethyl)).
5.8 Citric acid solution, 50 % (mass fraction)).
5.9 Sodium carbonate (Na2CO3), 20 g/l solution.
5.10 Silver nitrate, 10 g/l solution.
5.11 Methyl orange, 1 g/l solution.
5.12 Barium chloride (BaCl2·2H2O), 100 g/l solution.
Dissolve 100 g of crystalline barium chloride dihydrate (BaCl2·2H2O) in 1 l of water, cover and heat to
boiling point. Keep warm on a water bath for a minimum of 2 h and allow cooling to room temperature
overnight. Store the solution in a plastic bottle and, before each use, filter the required volume through a
close-texture filter paper.
5.13 Hydrochloric acid wash solution, containing barium chloride. Filter 10 ml of barium chloride
solution (5.12) through a close-texture filter paper, add 40 ml hydrochloric acid (5.4), dilute to about
1, 000 ml.
6 Apparatus
The usual laboratory apparatus and, in particular, the following shall be used.

2 © ISO 20## – All rights reserved
2 © ISO 2023 – All rights reserved

---------------------- Page: 8 ----------------------
ISO/TS 4689-1:2023(E)
6.1 Glass plate suction funnel, 150 ml.
An example of a figure is given in Annex D-, Figure D.1.
6.2 Water filtration membrane, 0.,2 μm.
6.3 Sand core filter, 300 ml.
An example of a figure is given in Annex D-, Figure D.2.
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 with 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.
7.2 Preparation of test samples
7.2.1 General
Depending on the ore type, proceed in accordance with either 7.2.2 or 7.2.3.
7.2.2 Ores having significant contents of combined water or oxidizable compounds
Prepare an air-equilibrated test sample in accordance with ISO 2596 with the following types of ore:
a) Processed ores containing metallic iron;.
b) Natural or processed ores in which the sulfur content is higher than 0, 2 % mass fraction;.
c) Natural or processed ores in which the content of combined water is higher than 2, 5 % mass
fraction.
7.2.3 Ores outside the scope of 7.2.2
Prepare a predried test sample as follows.
Thoroughly mix the laboratory sample and, taking multiple increments, extract a test sample in such a
manner that it is representative of the whole contents of the container. Dry the test sample at 105 ± ± 2
℃ as specified °C in accordance with ISO 7764.
© ISO 20## – All rights reserved 3
© ISO 2023 – All rights reserved 3

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ISO/TS 4689-1:2023(E)
8 Procedure
8.1 Number of determinations
Carry out the analysis at least in duplicate in accordance with Annex A, independently, on one test
sample.
NOTE The expression “independently” means that the second and any subsequent result is not affected by the
previous result(s). For this particular analytical method, this condition implies that the repetition of the procedure
is carried out
...

TECHNICAL ISO/TS
SPECIFICATION 4689-1
First edition
Iron ores — Determination of sulfur
content —
Part 1:
Barium sulfate gravimetric method
Minerais de fer — Dosage du soufre —
Partie 1: Méthode gravimétrique au sulfate de baryum
PROOF/ÉPREUVE
Reference number
ISO/TS 4689-1:2023(E)
© ISO 2023

---------------------- Page: 1 ----------------------
ISO/TS 4689-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
PROOF/ÉPREUVE © ISO 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TS 4689-1:2023(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 test samples . 3
7.2.1 General . 3
7.2.2 Ores having significant contents of combined water or oxidizable
compounds . 3
7.2.3 Ores outside the scope of 7.2.2 . 3
8 Procedure .3
8.1 Number of determinations . 3
8.2 Blank test and check test . 3
8.3 Test portion . 4
8.4 Determination . 4
8.4.1 Decomposition of the test portion . 4
8.4.2 Separation . 4
8.4.3 Precipitation of barium sulfate . 5
8.4.4 Weighing . 5
9 Expression of results . 5
9.1 Calculation of sulfur content . 5
9.2 General treatment of results . 6
9.2.1 Repeatability and permissible tolerance . 6
9.2.2 Check for trueness . 6
9.2.3 Calculation of final result . 7
10 Test report . 8
Annex A (normative) Flow sheet of the procedure for the acceptance of analytical values
for test samples . 9
Annex B (informative) Derivation of repeatability and permissible tolerance equations .10
Annex C (informative) Precision data obtained by interlaboratory analytical trial .11
Annex D (informative) Filter device diagram .12
Bibliography .13
iii
© ISO 2023 – All rights reserved PROOF/ÉPREUVE

---------------------- Page: 3 ----------------------
ISO/TS 4689-1:2023(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 (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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 102, Iron Ores, Subcommittee SC 02,
Chemical analysis.
This second edition cancels and replaces the first edition (ISO 4689:1986), which has been technically
revised.
The main changes are as follows:
— The decomposition method of samples has been changed from the original acid dissolution and
alkali melting method to soda-zinc oxide semi melting method.
A list of all parts in the ISO 4689 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
PROOF/ÉPREUVE © ISO 2023 – All rights reserved

---------------------- Page: 4 ----------------------
ISO/TS 4689-1:2023(E)
Introduction
In this document, a new way of melting the samples for determination of sulfur content by barium
sulfate gravimetric method is specified as follows:
— Samples are semi-molten with sodium carbonate and zinc oxide.
— The sulfate ions are leached by electromagnetic stirring and separated from the iron and other
interference elements such as lead, antimony, bismuth, tin, silicon, titanium, etc.
This method is also suitable for complex natural and artificial sample analysis.
This document consists of Part 1 of the ISO 4689 series, Iron ores — Determination of sulfur content.
v
© ISO 2023 – All rights reserved PROOF/ÉPREUVE

---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 4689-1:2023(E)
Iron ores — Determination of sulfur content —
Part 1:
Barium sulfate gravimetric method
1 Scope
This document specifies a barium sulfate gravimetric method for the determination of the sulfur
content of iron ores.
This method is applicable to a concentration range of a mass fraction of sulfur from 0,01 % to 3,9 % 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 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 7764, Iron ores — Preparation of predried test samples for chemical analysis
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
The analysis principle is as follows.
a) Decomposition of a test portion by treatment with a soda-zinc oxide flux mixture to a semi-molten
state.
b) Water leaching of sulfate ion with electro-magnetic stirring and filtration of the insoluble residue.
c) Transformation of sulfate ion to barium sulfate through adjustment of the acidity and addition of
barium chloride solution.
d) Filtration of barium sulfate and gravimetric determination.
e) Removal of the interference of Cr, Sn, P through hydrogen peroxide, citric acid and calcium
carbonate.
1
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ISO/TS 4689-1:2023(E)
5 Reagents
During the analysis, use only reagents of recognized analytical grade and only distilled water or water
of equivalent purity.
5.1 Sodium carbonate-zinc oxide mixed flux, grind Na CO to −100 mesh, blend Na CO and ZnO
2 3 2 3
by 3:2 (mass ratio).
5.2 Calcium carbonate.
5.3 Hydrofluoric acid, ρ 1,15 g/ml.
5.4 Hydrochloric acid solution, mix ρ=1,15 g/ml hydrochloric acid and distilled water by 1:1
(volume ratio).
5.5 Sulfuric acid solution, mix ρ=1,84 g/ml sulfuric acid and distilled water by 1:1 (volume ratio).
5.6 Hydrogen peroxide, 30 % (mass fraction).
5.7 Ethanol (ethyl).
5.8 Citric acid solution, 50 % (mass fraction).
5.9 Sodium carbonate (Na CO ), 20 g/l solution.
2 3
5.10 Silver nitrate, 10 g/l solution.
5.11 Methyl orange, 1 g/l solution.
5.12 Barium chloride (BaCl ·2H O), 100 g/l solution.
2 2
Dissolve 100 g of crystalline barium chloride dihydrate (BaCl ·2H O) in 1 l of water, cover and heat to
2 2
boiling point. Keep warm on a water bath for a minimum of 2 h and allow cooling to room temperature
overnight. Store the solution in a plastic bottle and, before each use, filter the required volume through
a close-texture filter paper.
5.13 Hydrochloric acid wash solution, containing barium chloride. Filter 10 ml of barium chloride
solution (5.12) through a close-texture filter paper, add 40 ml hydrochloric acid (5.4), dilute to about
1 000 ml.
6 Apparatus
The usual laboratory apparatus and, in particular
...