Overview
ISO 4701:2019 - "Iron ores and direct reduced iron - Determination of size distribution by sieving" specifies standardized methods to determine the particle size distribution (PSD) of iron ore and direct reduced iron (DRI) using sieving. The standard applies to sieves with aperture sizes of 36 µm or larger and expresses size distribution as mass and percentage mass passed or retained on selected sieves. Its primary purpose is to provide a reliable, agreed basis for testing used in the sale, purchase and quality control of iron ore and DRI.
Key technical topics and requirements
- Scope and purpose: Methods for size determination of iron ores and DRI (excluding briquetted iron) for contractual and quality-control use. Parties using results for comparison should agree on detailed methods to avoid disputes.
- Sampling and sample preparation: Procedures for deriving representative test samples, minimum sample masses, drying and division before sieving.
- Sieving methods: Guidance on selection between dry sieving, wet sieving, hand sieving, mechanical batch sieving and continuous machine sieving; includes recommended loading and sieving times and end-point criteria.
- Apparatus and sieves: Specifications for sieve media (aperture shape, size and construction), sieve frames and mechanical sieving equipment. Sieve aperture sizes covered are ≥36 µm.
- Impact of material properties: Consideration of moisture content, degradation, magnetic ores and bulk density on PSD results.
- Verification and quality assurance: Verification of sieves, sieving machines and weighing devices; procedures to check division and repeatability.
- Results and reporting: Calculation and expression of PSD in mass and percentage, repeatability limits, test reports and working logs.
- Annexes and precision: Includes normative and informative annexes (e.g., minimum mass determination, flowsheets, maximum retained mass correction for bulk density, APS calculation, and precision data).
Practical applications and users
ISO 4701:2019 is used by:
- Mining companies and exploration operations for product specification
- Independent and in-plant analytical laboratories for quality control (QC) and batch acceptance
- Traders, ports and logistics teams for contract testing and shipment inspection
- Metallurgists and process engineers for process monitoring and grind/product optimization
- Standards bodies and auditors as a reference method for compliance
Practical benefits include consistent PSD measurement, reduced contractual disputes, improved process control, and traceable test reporting.
Related standards
- ISO 565 - Test sieves - Metal wire cloth (normative reference cited in ISO 4701:2019)
- Work managed by ISO/TC 102 (Iron ore and direct reduced iron), Subcommittee SC 1 (Sampling)
Keywords: ISO 4701:2019, iron ore, direct reduced iron, sieving, size distribution, particle size distribution, PSD, sieve aperture, dry sieving, wet sieving, sample preparation, quality control.
