ISO 4700:2015

Iron ore pellets for blast furnace and direct reduction feedstocks - Determination of the crushing strength

ISO 4700:2015 specifies a method to provide a measure of the compressive load attained to cause breakage of pellets. This International Standard is applicable to hot bonded pellets.

Boulettes de minerais de fer pour charges de hauts fourneaux et réduction directe — Détermination de la résistance à l'écrasement

General Information

• Status: Published
• Publication Date: 04-Aug-2015
• 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: 9093 - International Standard confirmed
• Start Date: 20-Jan-2021
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 4700:2007 - Iron ore pellets for blast furnace and direct reduction feedstocks - Determination of the crushing strength
• Effective Date: 26-May-2012

Overview

ISO 4700:2015 defines a standardized laboratory method to determine the crushing strength of iron ore pellets used as blast furnace and direct reduction feedstocks. The standard applies to hot bonded pellets and gives a repeatable procedure to measure the compressive load that causes pellet breakage. Results are intended for quality control, contractual specifications and research, enabling consistent comparison between laboratories.

Key topics and requirements

• Scope: Measures the compressive load to cause pellet breakage for hot bonded pellets.
• Sample preparation
  • Pellet size range: −12.5 mm +10.0 mm.
  • Test sample: at least 1 kg (dry basis).
  • Oven-dry to constant mass at 105 °C ± 5 °C, then cool to room temperature.
• Test portion: Random selection of ≥ 60 pellets (minimum), or more where precision demands.
• Apparatus
  • Two surface‑hardened steel, parallel flat platens.
  • Platen speed adjustable 10–20 mm/min (constant speed recommended).
  • Load transmission: load cell or lever; load cell capacity ≥ 10 kN.
  • Load indicator/recorder with suitable response and graduation.
• Procedure
  • Compress single pellets centrally between platens at specified speed.
  • Test ends when either the load drops to ≤ 50% of the maximum recorded or the platen gap reduces to 50% of initial mean pellet diameter.
  • For automatic equipment, exclude individual pellet strength values < 10 daN from result calculations.
• Expression of results: Crushing strength (CS) = arithmetic mean of measured values, reported in decanewtons per pellet to one decimal place.
• Reporting: Test report must reference ISO 4700 and include sample identification, test laboratory, dates, operator signature, CS, standard deviation, pellet size distribution, number tested, platen speed and other test conditions.
• Verification: Regular calibration and checks of plates, load cell/lever, indicators and recording systems; maintain verification records.

Applications and users

ISO 4700:2015 is used to:

• Support quality control at pelletizing plants and steelworks.
• Define contractual acceptance criteria for pellet shipments.
• Provide data for process optimization and research into pellet performance. Primary users:
• Metallurgical laboratories and testing services
• Pellet plant QC teams and production engineers
• Steelmakers (blast furnace and direct reduction operations)
• Raw material procurement and QA personnel
• Research institutions studying pellet properties

Related standards

• ISO 3082 - Sampling and sample preparation procedures for iron ores (normative reference).
• ISO 11323 - Vocabulary for iron ore and direct reduced iron (terms and definitions).

Keywords: ISO 4700:2015, crushing strength, iron ore pellets, pellet testing, blast furnace feedstock, direct reduction feedstock, hot bonded pellets, compressive load, pellet quality control.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4700
Fourth edition
2015-08-01
Iron ore pellets for blast furnace
and direct reduction feedstocks —
Determination of the crushing strength
Boulettes de minerais de fer pour charges de hauts fourneaux et
réduction directe — Détermination de la résistance à l’écrasement
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
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ii © ISO 2015 – 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 Sampling, sample preparation and preparation of test portions .1
5.1 Sampling and sample preparation . 1
5.2 Preparation of test portions . 2
6 Apparatus . 2
7 Procedure. 2
7.1 Number of determinations for the test . 2
7.2 Load application . 3
8 Expression of results . 4
9 Test report . 4
10 Verification . 5
Foreword
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electrotechnical standardization.
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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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The committee responsible for this document is ISO/TC 102, Iron ore and direct reduced iron,
Subcommittee SC 3, Physical testing.
This fourth edition cancels and replaces the third edition (ISO 4700:2007) which has been technically
revised to provide clarification in 7.2 when using automatic equipment.
iv © ISO 2015 – All rights reserved

Introduction
This International Standard concerns one of a number of physical test methods that have been developed
to measure various physical parameters and characteristics 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 and direct reduction processes.
This International Standard 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.
© ISO 2
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