ISO 9686:2006

Direct reduced iron — Determination of carbon and/or sulfur — High-frequency combustion method with infrared measurement

ISO 9686:2006 specifies a method for the determination of the mass fraction of carbon and/or sulfur in direct reduced iron by infrared measurement after high-frequency combustion. This method is applicable to mass fractions of carbon between 0,05 % and 2,5 %, and/or mass fractions of sulfur between 0,001 % and 0,05 % in direct reduced iron.

Minerais de fer préréduits — Dosage du carbone et/ou du soufre — Méthode par combustion haute fréquence et mesurage par infrarouge

General Information

• Status: Withdrawn
• Publication Date: 26-Apr-2006
• Withdrawal Date: 26-Apr-2006
• 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: 9599 - Withdrawal of International Standard
• Completion Date: 17-May-2017

Relations

• Revised: ISO/TR 9686:2017 - Direct reduced iron — Determination of carbon and/or sulfur — High-frequency combustion method with infrared measurement
• Effective Date: 09-Jul-2016
• Revises: ISO 9686:1992 - Direct reduced iron — Determination of carbon and/or sulfur content — High frequency combustion method with infrared measurement
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 9686
Second edition
2006-05-01

Direct reduced iron — Determination of
carbon and/or sulfur — High-frequency
combustion method with infrared
measurement
Minerais de fer préréduits — Dosage du carbone et/ou du soufre —
Méthode par combustion haute fréquence et mesurage par infrarouge




Reference number
ISO 9686:2006(E)
©
ISO 2006

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ISO 9686:2006(E)
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ISO 9686:2006(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Principle. 1
4 Reagents. 1
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 General operating instructions . 3
7.2 Test portion . 3
7.3 Blank test. 4
7.4 Calibration. 4
7.4.1 Crucible preparation. 4
7.4.2 Combustion . 5
7.5 Determination. 5
8 Expression of results. 6
8.1 Calculation of mass fractions of carbon or sulfur . 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
9 Test report. 8
Annex A (normative) Crucible loading sequence . 9
Annex B (normative) Flowsheet of the procedure for the acceptance of analytical values for test
samples. 10
Annex C (informative) Features of commercial HF combustion/infrared sulfur analysers . 11
Annex D (informative) Derivation of repeatability and permissible tolerance equations . 12
Annex E (informative) Precision data obtained by international analytical trials. 13

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ISO 9686:2006(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 9686 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 9686:1992), 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 9686:2006(E)

Direct reduced iron — Determination of carbon and/or sulfur —
High-frequency combustion method with infrared measurement
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 the mass fraction of carbon and/or
sulfur in direct reduced iron by infrared measurement after high-frequency combustion.
This method is applicable to mass fractions of carbon between 0,05 % and 2,5 %, and/or mass fractions of
sulfur between 0,001 % and 0,05 % in direct reduced iron.
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 1042, Laboratory glassware — One-mark volumetric flasks
ISO 7550, Laboratory glassware — Disposable micropipettes
ISO 7764, Iron ores — Preparation of predried test samples for chemical analysis
ISO 10835, Direct reduced iron — Sampling and sample preparation — Manual methods for reduced pellets
and lump ores
3 Principle
The test portion is combusted in a refractory crucible in a flow of oxygen in the presence of an accelerator, the
crucible being inserted in the combustion tube of a high-frequency (HF) furnace.
The carbon present is converted into carbon dioxide and the sulfur into sulfur dioxide. Each gas is measured
by infrared absorption, with calibration using barium carbonate and potassium sulfate.
4 Reagents
During the analysis, use only reagents of recognized analytical grade and only distilled water or water of
equivalent purity.
4.1 Oxygen, minimum purity 99,5 % (m/m).
The pressure in the furnace should be controlled by a pressure regulator designed specially for the purpose
and complying with the manufacturer's specification.
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ISO 9686:2006(E)
4.2 Magnesium perchlorate, grain size 0,7 mm to 1,2 mm.
4.3 Accelerator, tungsten (granular form) with known low mass fractions of carbon [< 0,002 %] and sulfur
[< 0,000 5 %].
4.4 Pure iron, or iron of known low mass fractions of carbon and sulfur, as in 4.3.
4.5 Tin capsules, of capacity 0,3 ml, diameter 5 mm, length 17 mm.
4.6 Barium carbonate (BaCO ), fine powder.
3
Dry at 105 °C for 3 h and cool in a desiccator.
4.7 Sulfur standard solutions.
Dry potassium sulfate (K SO ) at 105 °C for 1 h and cool in a desiccator.
2 4
Weigh, to the nearest 0,000 2 g, the amounts of potassium sulfate specified in Table 1.
Table 1 — Sulfur standard solutions
Mass of K SO Sulfur concentration
2 4
Sulfur standard solution
g mg/ml
SS 1 0,217 4 0,4
SS 2 0,434 8 0,8
SS 3 0,652 2 1,2
SS 4 0,869 6 1,6
SS 5 2,174 0 4,0

Transfer to five 100 ml one-mark volumetric flasks, dissolve with 50 ml of water, dilute to volume and mix.
4.8 Ascarite, used only for carbon determination.
5 Apparatus
Ordinary laboratory apparatus, including micropipettes and one-mark volumetric flasks complying with the
specifications of ISO 7550 and ISO 1042 respectively, and the following.
5.1 Commercial carbon/sulfur apparatus
The apparatus required for HF combustion of the samples and the subsequent infrared absorption
measurement of evolved carbon dioxide and/or sulfur dioxide may be obtained commercially from a number of
manufacturers. Common features of such systems are discussed in Annex C.
The manufacturer's instruction for the operation of their equipment shall be followed.
5.2 Ceramic combustion crucibles, required for containing the sample and any additions that may be
necessary for the subsequent combustion.
The crucibles shall be of precise dimensions for the system, and shall adapt to the supporting pedestal post,
so that the sample in the crucible will be positioned at the correct height within the induction coil when it is in
the raised position.
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ISO 9686:2006(E)
These crucibles shall be pre-ignited in an oxygen flow, in a furnace, for not less than 2 h at 1 350 °C (or at
1 100 °C if only sulfur is to be determined), and then stored in a desiccator or closed container before use.
For pre-ignition, a resistance furnace may be used.
5.3 Micropipette, of capacity 50 µl.
6 Sampling and samples
6.1 Laboratory sample
For analysis, use a laboratory sample of minus 160 µm particle size, which has been taken and prepared in
accordance with ISO 10835.
6.2 Preparation of predried test samples
Thoroughly mix the laboratory sample using non-magnetic materials. Taking multiple increments with a non-
magnetic spatula, 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 °C ± 2 °C as specified in ISO 7764. (This is the predried test sample.)
7 Procedure
WARNING — The risks related to combustion analysis are mainly hand burns when pre-igniting the
ceramic crucibles, and in the subsequent combustion. Normal precautions for handling oxygen
cylinders should be taken. Oxygen from the combustion process should be removed effectively from
the apparatus and room, since a too high concentration of oxygen in a confined space may present a
fire hazard. HF screening should be effective to avoid radiation hazards.
7.1 General operating instructions
Purify the oxygen supply using tubes packed with ascarite (4.8) and magnesium perchlorate (4.2) and
maintain a quiescent flow rate of about 0,5 l/min whilst on standby.
Maintain a glass-wool filter between the furnace chamber and the analyser and change as necessary. The
furnace chamber, pedestal post and filter trap should be cleaned frequently to remove oxide build-up.
The oxygen flow rate may vary from one instrument to another, but is usually about 2,0 l/min during the
combustion period, according to the nature of the material. The temperature reached
...