ISO 11257:2022

INTERNATIONAL ISO
STANDARD 11257
Fourth edition
2022-03
Iron ores for shaft direct-reduction
feedstocks — Determination of
the low-temperature reduction-
disintegration index and degree of
metallization
Minerais de fer pour charges utilisées dans les procédés par réduction
directe — Détermination de l'indice de désintégration par réduction à
basse température et du degré de métallisation
Reference number
ISO 11257:2022(E)
© ISO 2022

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ISO 11257:2022(E)
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© ISO 2022
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ISO 11257:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Sampling, sample preparation, and preparation of test portions .2
5.1 Sampling and sample preparation . 2
5.2 Preparation of test portion . 2
6 Apparatus . 2
7 Test conditions .4
7.1 General . 4
7.2 Reducing gas . 4
7.2.1 Composition . 4
7.2.2 Purity . 4
7.2.3 Flow rate . 4
7.3 Heating and cooling gas . 4
7.4 Temperature of the test portion . 4
8 Procedure .4
8.1 Number of determinations for the test . 4
8.2 Reduction . 4
8.3 Sieving . 5
8.4 Chemical analysis . 5
9 Expression of results . 5
9.1 Calculation of the reduction-disintegration index (D ) . 5
DR
9.2 Calculation of the degree of metallization (M) . 6
9.3 Repeatability and acceptance of test results . 6
10 Test report . 6
11 Verification . 7
Annex A (normative) Flowsheet of the procedure for the acceptance of test results .8
Bibliography . 9
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ISO 11257:2022(E)
Foreword
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 3, Physical testing.
This fourth edition cancels and replaces the third edition (ISO 11257:2015), which has been technically
revised to include ISO 16878 as a reference for the metallic iron determination.
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.
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ISO 11257:2022(E)
Introduction
This document concerns one of a number of physical test methods that have been developed to
measure various physical parameters and to evaluate the behaviour of iron ores, including reducibility,
disintegration, crushing strength, apparent density, etc. This method was developed to provide a
uniform procedure, validated by collaborative testing, to facilitate comparisons of tests made in
different laboratories.
The results of this test have to be considered in conjunction with other tests used to evaluate the quality
of iron ores as feedstocks for direct reduction processes.
This document can be used to provide test results as part of a production quality control system, as a
basis of a contract, or as part of a research project.
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INTERNATIONAL STANDARD ISO 11257:2022(E)
Iron ores for shaft direct-reduction feedstocks —
Determination of the low-temperature reduction-
disintegration index and degree of metallization
CAUTION — This document can involve hazardous operations and equipment. document does
not purport to address all of the safety issues associated with its use. It is the responsibility of
the user of this document to establish appropriate safety and health practices and determine
the applicability of regulatory limitations prior to its use.
1 Scope
This document specifies a method to provide a relative measure for evaluating the degree of size
degradation and degree of metallization of iron ores, when reduced under conditions resembling those
prevailing in shaft direct-reduction processes.
This document is applicable to lump ores and hot-bonded pellets.
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 2597-1, Iron ores — Determination of total iron content — Part 1: Titrimetric method after tin(II)
chloride reduction
ISO 2597-2, Iron ores — Determination of total iron content — Part 2: Titrimetric methods after
titanium(III) chloride reduction
ISO 3082, Iron ores — Sampling and sample preparation procedures
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3310-2, Test sieves — Technical requirements and t
...