ISO 7992:2022

Iron ores for blast furnace feedstocks - Determination of reduction under load

This document specifies a method to provide a relative measure for evaluating the structural stability of iron ores when reduced under conditions resembling those prevailing in the reduction zone of a blast furnace. This document is applicable to lump ores and hot-bonded pellets.

Minerais de fer pour charges de hauts fourneaux — Détermination de la réduction sous charge

General Information

• Status: Published
• Publication Date: 11-May-2022
• ICS: 73.060.10 - Iron ores
• Technical Committee: ISO/TC 102/SC 3 - Physical testing
• Drafting Committee: ISO/TC 102/SC 3 - Physical testing
• Current Stage: 6060 - International Standard published
• Start Date: 12-May-2022
• Due Date: 30-Sep-2022
• Completion Date: 12-May-2022

Relations

• Revises: ISO 7992:2015 - Iron ores for blast furnace feedstocks - Determination of reduction under load
• Effective Date: 24-Jul-2021

Overview - ISO 7992:2022 (reduction under load)

ISO 7992:2022 specifies a laboratory method to evaluate the structural stability (reduction under load) of iron ores intended as blast furnace feedstocks. The test simulates conditions in the blast-furnace reduction zone by isothermally reducing a fixed bed of ore at 1 050 °C under a static load, and measuring the mechanical and permeability changes at 80% degree of reduction. It applies to lump ores and hot‑bonded pellets and is intended for quality control, contract specification and research comparisons.

Key topics and technical requirements

• Scope and purpose: Provides a relative measure of ore behaviour under reducing, loaded conditions; results should be used alongside other physical tests (reducibility, disintegration, crushing strength, density).
• Sampling & preparation:
  • Sampling per ISO 3082.
  • Size range: –12.5 mm +10.0 mm.
  • Test sample: ≥ 6.0 kg (dry basis); oven-dry at 105 °C ± 5 °C.
  • Prepare at least five test portions ~1 200 g each.
• Test apparatus:
  • Double‑walled reduction tube (inner Ø 125 mm ± 1 mm), perforated support plates, furnace, loading ram and porcelain balls (10.0–12.5 mm).
  • Measurement devices: differential gas pressure (resolution 0.01 kPa), bed height (resolution 0.1 mm), thermocouples, balance (±1 g).
• Test conditions:
  • Isothermal reduction at 1 050 °C ± 10 °C.
  • Reducing gas composition: CO 40.0% ± 0.5%, H2 2.0% ± 0.5%, N2 58.0% ± 0.5%.
  • Reducing gas impurities limits and flow: flow 83 L/min ± 1 L/min.
  • Static load: 50 kPa ± 2 kPa applied via ram and perforated footplate.
• Measured outcomes:
  • Differential pressure across the bed and change in bed height at 80% reduction - reported as Δp80 and Δh80.
  • Chemical analyses and repeatability/acceptance criteria are specified; test report and verification requirements included.
• Safety: Standard notes hazardous operations - users must establish appropriate safety measures.

Practical applications & who uses it

• Blast-furnace operators: assess feedstock stability and permeability under operating-like reduction.
• Iron ore producers and pelletizers: quality control for product acceptance and contract compliance.
• Metallurgical laboratories & third‑party testing: standardized comparative testing and certification.
• R&D teams: investigate ore behaviour, sintering/pellet bonding effects and process optimization.

Related standards

• ISO 3082 - Sampling and sample preparation procedures
• ISO 2597-1 / 2597-2 - Total iron determination (titrimetric methods)
• ISO 9035 - Acid‑soluble iron(II) determination
• ISO 11323 - Iron ore and DRI vocabulary

Keywords: ISO 7992:2022, reduction under load, iron ores, blast furnace feedstocks, reducibility, Δp80, Δh80, lump ores, hot-bonded pellets.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7992
Fourth edition
2022-05
Iron ores for blast furnace
feedstocks — Determination of
reduction under load
Minerais de fer pour charges de hauts fourneaux — Détermination de
la réduction sous charge
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Sampling, sample preparation and preparation of test portions . 2
5.1 Sampling and sample preparation . 2
5.2 Preparation of test portions . 2
6 Apparatus . 2
7 Test conditions .6
7.1 General . 6
7.2 Reducing gas . 6
7.2.1 Composition . 6
7.2.2 Purity . 6
7.2.3 Flow rate . 6
7.3 Heating and cooling gas . 7
7.4 Temperature of the test portion . 7
7.5 Loading of the test portion . 7
8 Procedure .7
8.1 Number of determinations for the test . 7
8.2 Chemical analysis . 7
8.3 Reduction . 7
9 Expression of results . 8
9.1 Preparation of the reduction curve . 8
9.2 Calculation of the differential pressure at 80 % reduction (Δp80) . 8
9.3 Calculation of the change in the height of the test bed at 80 % reduction (Δh80) . 8
9.4 Repeatability and acceptance of test results . 9
10 Test report . 9
11 Verification . 9
Annex A (normative) Flowsheet of the procedure for the acceptance of test results .11
Annex B (informative) Derivation of equation for reducibility .12
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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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
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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 7992:2015), which has been technically
revised to adjust the apparatus described in the previous edition according to the original text.
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
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 blast furnace 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.
v
INTERNATIONAL STANDARD ISO 7992:2022(E)
Iron ores for blast furnace feedstocks — Determination of
reduction under load
CAUTION — This document can involve hazardous operations and equipment. This 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 structural stability
of iron ores when reduced under conditions resembling those prevailing in the reduction zone of a blast
furnace.
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 9035, Iron ores — Determination of acid-soluble iron(II) content — Titrimetric method
ISO 11323, Iron ore and direct reduced iron — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11323 apply.
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 test portion is isothermally reduced in a fixed bed, at 1 050 °C, under static load, using a reducing
gas consisting of CO, H and N , until a degree of reduction of 80 % is obtained. The differential gas
2 2
pressure across the bed and the change in the test bed height are measured at 80 % reduction.
5 Sampling, sample preparation and preparation of test portions
5.1 Sampling and sample preparation
Sampling of a lot and preparation of a test sample shall be in accordance with ISO 3082.
The size range for pellets and lump ores shall be –12,5 mm +10,0 mm.
A test sample of at least 6,0 kg, on a dry basis, of the sized material shall be obtained.
Oven-dry the test sample to constant mass at 105 °C ± 5 °C and cool it to room temperature before
preparation of the test portions.
NOTE Constant mass is achieved when the difference in mass between two subsequent measurements
becomes less than 0,05 % of the initial mass of the test sample.
5.2 Preparation of test portions
Collect each test portion by taking ore particles at random.
NOTE Manual methods of division recommended in ISO 3082, such as riffling, can be applied to obtain the
test portions.
At least five test portions, each of approximately 1 200 g (±the mass of one particle) shall be prepared
from the test sample: four test portions for testing and one for chemical analysis.
Weigh the test portions to the nearest 1 g and register the mass of each test portion on its recipient
label.
6 Apparatus
The usual laboratory apparatus and, in particular, the following shall be used.
6.1 Ordinary laboratory equipment, such as an oven, hand tools, a time-control device and safety
equipment.
6.2 Reduction tube, with a double wall made of non-scaling, heat-resista
...