SIST ISO 4689-2:2017

Iron ores - Determination of sulfur content - Part 2: Combustion/titration method

ISO 4689-2:2017 specifies a combustion/titration method for the determination of the sulfur content of iron ores.
This method is applicable to sulfur contents between 0,002 % (mass fraction) and 0,25 % (mass fraction) in natural iron ores, iron ore concentrates, and agglomerates, including sinter products. The results are not affected by the presence of fluoride.

Minerais de fer - Dosage du soufre - Partie 2: Méthode par combustion et titration

Železove rude - Določevanje žvepla - 2. del: Metoda s sežiganjem/titracijo

Ta dokument določa metodo s sežiganjem/titracijo za določevanje vsebnosti žvepla v železovih rudah.
Ta metoda se uporablja za vsebnosti žvepla od 0,002 % (masni delež) do 0,25 % (masni delež) v naravnih železovih rudah, koncentratih železove rude in aglomeratih, vključno s sintranimi izdelki. Prisotnost fluorida ne vpliva na rezultate.

General Information

• Status: Published
• Publication Date: 27-Mar-2017
• ICS: 73.060.10 - Iron ores
• Technical Committee: I12 - Imaginarni 12 Imaginarni TC za ISO področje - vzdrževani privzeti ISO standardi
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 20-Mar-2017
• Due Date: 25-May-2017
• Completion Date: 28-Mar-2017
• Ref Project: ISO 4689-2:2017 - Iron ores - Determination of sulfur content - Part 2: Combustion/titration method

Relations

• Replaces: SIST ISO 4689-2:2016 - Iron ores - Determination of sulfur content - Part 2: Combustion/titration method
• Effective Date: 01-May-2017

Overview

ISO 4689-2:2017 specifies a validated combustion/titration method for the determination of sulfur content in iron ores. The procedure applies to natural iron ores, iron ore concentrates and agglomerates (including sinter products) with sulfur contents from 0.002 % to 0.25 % (mass fraction). Results are not affected by fluoride. The standard defines sample preparation, reagents, apparatus, test procedure, calculation, precision and reporting requirements for reliable sulfur analysis.

Key topics and technical requirements

• Principle: Sample is mixed with tungsten(VI) oxide (WO3) and combusted at 1 200 °C ± 25 °C in a resistance furnace using nitrogen as carrier gas. Evolved SO2 is absorbed in dilute hydrochloric acid containing starch and potassium iodide (KI) and titrated continuously with a standard potassium iodate (KIO3) solution.
• Applicable range: 0.002 % – 0.25 % S (mass fraction).
• Test portion mass:
  • 0.002–0.100 % S → 1.0 g test portion
  • 0.100–0.25 % S → 0.5 g test portion
• Reagents & solutions: analytical-grade reagents; KIO3 standard (0.001042 mol/L) where 1 mL = 0.10 mg S. Use tungsten oxide, tin(II) chloride (if chlorides present), Mg(ClO4)2 and NaOH-coated silica in drying train.
• Apparatus essentials: resistance furnace, refractory combustion tube/boat or cartridge, drying tower, flowmeter, multi-hole bubbler and burette (or micro-syringe/piston burette for very low S < 0.005 %).
• Chloride handling: when chloride is present or suspected, pass combustion gases through a tin(II) chloride absorption tube to remove chlorine before SO2 absorption.
• Quality control: include blank tests and parallel analysis of a certified reference material; carry out at least duplicate independent determinations. The standard provides repeatability, between-laboratory precision and procedures for acceptance of analytical values.
• Safety: warns about hazardous operations and materials; users must establish appropriate health and safety practices.

Applications and users

ISO 4689-2:2017 is used by:

• Mining and iron ore laboratories for QA/QC of raw ore, concentrates and sinter.
• Metallurgical and pelletizing plants monitoring sulfur for process control.
• Certification and reference-material laboratories validating analytical results.
• Regulatory bodies and trade labs where standardized sulfur measurement is required for commercial specifications.

Keywords: ISO 4689-2:2017, iron ores, sulfur determination, combustion/titration method, sulfur analysis, iron ore concentrates, sinter products, analytical method.

Related standards

• ISO 4689 series (other parts, e.g., combustion/infrared method)
• ISO 3082 (sampling and sample preparation)
• ISO 7764 (preparation of predried test samples)
• ISO 2596 (hygroscopic moisture)
• ISO Guide 35 (reference materials)
• ISO 385 / ISO 648 / ISO 1042 (laboratory glassware)

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2017
1DGRPHãþD
SIST ISO 4689-2:2016
äHOH]RYHUXGH'RORþHYDQMHåYHSODGHO0HWRGDVVHåLJDQMHPWLWUDFLMR
Iron ores - Determination of sulfur content - Part 2: Combustion/titration method
Minerais de fer - Dosage du soufre - Partie 2: Méthode par combustion et titration
Ta slovenski standard je istoveten z: ISO 4689-2:2017
ICS:
73.060.10 Železove rude Iron ores
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 4689-2
Third edition
2017-03
Iron ores — Determination of sulfur
content —
Part 2:
Combustion/titration method
Minerais de fer — Dosage du soufre —
Partie 2: Méthode par combustion et titration
Reference number
©
ISO 2017
© 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
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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved

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 . 5
7.1 Laboratory sample . 5
7.2 Preparation of predried test samples . 5
8 Procedure. 5
8.1 Number of determinations . 5
8.2 Test portion . 5
8.3 Blank test and check test . 5
8.4 Determination . 6
9 Expression of results . 7
9.1 Calculation of sulfur content . 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
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 equations .12
Annex C (informative) Precision data obtained by international analytical trial .13
Bibliography .14
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 third edition cancels and replaces the second edition (ISO 4689-2:2015), which constitutes a minor
revision with the following changes:
— 6.7: first line, after “approximately”, insert “10 g”;
— 9.2.4: modify Formula (7) and the relevant descriptions, to harmonize this subclause across all
standards for which ISO/TC 102/SC 2 is responsible.
A list of all parts in the ISO 4689 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
This document was originally published as ISO 4690:1986. Under a policy of rationalization of the
numbering system used in ISO/TC 102, it has been decided to re-designate this document as ISO 4689-2.
It was further decided to introduce a combustion/infrared method, numbered ISO 4689-3.
When next revised, ISO 4689:1986 will be re-designated as ISO 4689-1.
INTERNATIONAL STANDARD ISO 4689-2:2017(E)
Iron ores — Determination of sulfur content —
Part 2:
Combustion/titration method
WARNING — This document may 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 regulatory limitations prior to use.
1 Scope
This document specifies a combustion/titration method for the determination of the sulfur content of
iron ores.
This method is applicable to sulfur contents between 0,002 % (mass fraction) and 0,25 % (mass
fraction) in natural iron ores, iron ore concentrates, and agglomerates, including sinter products. The
results are not affected by the presence of fluoride.
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 385, Laboratory glassware — Burettes
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 7764, Iron ores — Preparation of predried test samples for chemical analysis
ISO Guide 35, Reference materials — General and statistical principles for certification
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 sample is mixed with tungsten(VI) oxide and heated at 1 200 °C in a resistance furnace, using
nitrogen as a carrier gas.
The evolved sulfur dioxide is absorbed in dilute hydrochloric acid solution containing starch and
potassium iodide, and the solution is titrated continuously during evolution with a standard volumetric
solution of potassium iodate.
5 Reagents
During analysis, use only reagents of recognized analytical grade, and only distilled water or water of
equivalent purity.
5.1 Magnesium perchlorate, Mg(ClO ) , anhydrous, free flowing, particle size 0,5 mm to 2 mm.
4 2
5.2 Tungsten(VI) oxide, (WO ).
5.3 Tin(II) chloride, SnCl ·2H O, particle size 0,5 mm to 2 mm.
2 2
5.4 Sodium hydroxide coated silica, particle size 0,5 mm to 2 mm.
5.5 Hydrochloric acid, ρ, 1,16 g/ml to 1,19 g/ml, diluted 1 + 66.
5.6 Potassium iodide, KI, 3 % (mass fraction) solution.
5.7 Starch, 2 % (mass fraction) solution.
Make a suspension of 2,0 g of starch in 10 ml of water, add to 50 ml of boiling water and stir. Cool, dilute
to 100 ml and mix.
Prepare this solution immediately prior to use.
5.8 Potassium iodate, KIO , standard volumetric solution, 0,001 042 mol/l.
The potassium iodate should be previously dried for 2 h at 130 °C.
Weigh, to the nearest 0,000 2 g, 0,223 g of dried potassium iodate and dissolve in water. Cool, transfer
to a 1 l volumetric flask, dilute to volume and mix.
1 ml of this standard volumetric solution is equivalent to 0,10 mg of sulfur.
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, as well as the following. See Figure 1.
6.1 Nitrogen supply.
6.2 Drying tower, containing sodium hydroxide coated silica (5.4) and magnesium perchlorate (5.1).
6.3 Flowmeter, graduated from 0 to 1 l/min.
6.4 Resistance furnace, capable of maintaining a temperature of 1 200 °C ± 25 °C.
6.5 Refractory combustion tube, capable of withstanding a temperature of 1 200 °C ± 25 °C.
2 © ISO 2017 – All rights reserved

6.6 Refractory combustion boat, with loose-fitting lid, or a suitable refractory combustion boat
capable of accommodating a porous cartridge, as shown in Figure 2 a) or b) respectively.
The following dimensions can be used as guidelines.
Combustion boat Cartridge
Length 80 mm Length 50 mm
Width 13 mm Internal diameter 15 mm
Depth 9 mm
6.7 Tin(II) chloride absorption tube, of narrow glass tubing containing approximately 10 g of solid
tin(II) chloride (5.3), suitably plugged with inert wool to prevent the reagent being blown into the
absorption vessel.
A U-tube is suitable. Where necessary, this is inserted in the train at the exit of the combustion tube at
point X in Figure 1.
If the sample is known or thought to contain chloride, e.g. in the form of sodium chloride, chlorapatite,
or scapolite, the chlorine formed during combustion of the sample should be removed by passing the gas
stream through solid tin(II) chloride in a suitable tube or vessel (6.7) prior to absorption and titration.
If numerous samples having chloride contents >1 (mass fraction) are to be analysed, it is advisable to
determine the absorption capacity of the tin(II) chloride in order to be able to judge the most suitable
interval for reagent replacement. In such cases, a larger absorption vessel may be preferred.
The tin(II) chloride absorption tube should also be fitt
...

INTERNATIONAL ISO
STANDARD 4689-2
Third edition
2017-03
Iron ores — Determination of sulfur
content —
Part 2:
Combustion/titration method
Minerais de fer — Dosage du soufre —
Partie 2: Méthode par combustion et titration
Reference number
©
ISO 2017
© 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
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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved

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 . 5
7.1 Laboratory sample . 5
7.2 Preparation of predried test samples . 5
8 Procedure. 5
8.1 Number of determinations . 5
8.2 Test portion . 5
8.3 Blank test and check test . 5
8.4 Determination . 6
9 Expression of results . 7
9.1 Calculation of sulfur content . 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
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 equations .12
Annex C (informative) Precision data obtained by international analytical trial .13
Bibliography .14
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 third edition cancels and replaces the second edition (ISO 4689-2:2015), which constitutes a minor
revision with the following changes:
— 6.7: first line, after “approximately”, insert “10 g”;
— 9.2.4: modify Formula (7) and the relevant descriptions, to harmonize this subclause across all
standards for which ISO/TC 102/SC 2 is responsible.
A list of all parts in the ISO 4689 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
This document was originally published as ISO 4690:1986. Under a policy of rationalization of the
numbering system used in ISO/TC 102, it has been decided to re-designate this document as ISO 4689-2.
It was further decided to introduce a combustion/infrared method, numbered ISO 4689-3.
When next revised, ISO 4689:1986 will be re-designated as ISO 4689-1.
INTERNATIONAL STANDARD ISO 4689-2:2017(E)
Iron ores — Determination of sulfur content —
Part 2:
Combustion/titration method
WARNING — This document may 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 regulatory limitations prior to use.
1 Scope
This document specifies a combustion/titration method for the determination of the sulfur content of
iron ores.
This method is applicable to sulfur contents between 0,002 % (mass fraction) and 0,25 % (mass
fraction) in natural iron ores, iron ore concentrates, and agglomerates, including sinter products. The
results are not affected by the presence of fluoride.
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 385, Laboratory glassware — Burettes
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 7764, Iron ores — Preparation of predried test samples for chemical analysis
ISO Guide 35, Reference materials — General and statistical principles for certification
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 sample is mixed with tungsten(VI) oxide and heated at 1 200 °C in a resistance furnace, using
nitrogen as a carrier gas.
The evolved sulfur dioxide is absorbed in dilute hydrochloric acid solution containing starch and
potassium iodide, and the solution is titrated continuously during evolution with a standard volumetric
solution of potassium iodate.
5 Reagents
During analysis, use only reagents of recognized analytical grade, and only distilled water or water of
equivalent purity.
5.1 Magnesium perchlorate, Mg(ClO ) , anhydrous, free flowing, particle size 0,5 mm to 2 mm.
4 2
5.2 Tungsten(VI) oxide, (WO ).
5.3 Tin(II) chloride, SnCl ·2H O, particle size 0,5 mm to 2 mm.
2 2
5.4 Sodium hydroxide coated silica, particle size 0,5 mm to 2 mm.
5.5 Hydrochloric acid, ρ, 1,16 g/ml to 1,19 g/ml, diluted 1 + 66.
5.6 Potassium iodide, KI, 3 % (mass fraction) solution.
5.7 Starch, 2 % (mass fraction) solution.
Make a suspension of 2,0 g of starch in 10 ml of water, add to 50 ml of boiling water and stir. Cool, dilute
to 100 ml and mix.
Prepare this solution immediately prior to use.
5.8 Potassium iodate, KIO , standard volumetric solution, 0,001 042 mol/l.
The potassium iodate should be previously dried for 2 h at 130 °C.
Weigh, to the nearest 0,000 2 g, 0,223 g of dried potassium iodate and dissolve in water. Cool, transfer
to a 1 l volumetric flask, dilute to volume and mix.
1 ml of this standard volumetric solution is equivalent to 0,10 mg of sulfur.
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, as well as the following. See Figure 1.
6.1 Nitrogen supply.
6.2 Drying tower, containing sodium hydroxide coated silica (5.4) and magnesium perchlorate (5.1).
6.3 Flowmeter, graduated from 0 to 1 l/min.
6.4 Resistance furnace, capable of maintaining a temperature of 1 200 °C ± 25 °C.
6.5 Refractory combustion tube, capable of withstanding a temperature of 1 200 °C ± 25 °C.
2 © ISO 2017 – All rights reserved

6.6 Refractory combustion boat, with loose-fitting lid, or a suitable refractory combustion boat
capable of accommodating a porous cartridge, as shown in Figure 2 a) or b) respectively.
The following dimensions can be used as guidelines.
Combustion boat Cartridge
Length 80 mm Length 50 mm
Width 13 mm Internal diameter 15 mm
Depth 9 mm
6.7 Tin(II) chloride absorption tube, of narrow glass tubing containing approximately 10 g of solid
tin(II) chloride (5.3), suitably plugged with inert wool to prevent the reagent being blown into the
absorption vessel.
A U-tube is suitable. Where necessary, this is inserted in the train at the exit of the combustion tube at
point X in Figure 1.
If the sample is known or thought to contain chloride, e.g. in the form of sodium chloride, chlorapatite,
or scapolite, the chlorine formed during combustion of the sample should be removed by passing the gas
stream through solid tin(II) chloride in a suitable tube or vessel (6.7) prior to absorption and titration.
If numerous samples having chloride contents >1 (mass fraction) are to be analysed, it is advisable to
determine the absorption capacity of the tin(II) chloride in order to be able to judge the most suitable
interval for reagent replacement. In such cases, a larger absorption vessel may be preferred.
The tin(II) chloride absorption tube should also be fitted if the chloride content of the test sample is
unknown.
6.8 Cylinder, 100 ml, tall form, to hold the absorbing solution.
6.9 Bubbler, multi-hole, to reach to the bottom of the cylinder (6.8).
6.10 Burette, conforming to ISO 385, graduated in divisions of 0,05 ml.
For determination of low sulfur contents [<0,005 % (mass fraction)], alternative titration devices such
as a piston burette or a suitable micro-syringe capab
...