ISO 1953:2025

Overview

ISO 1953:2025 - "Coal - Size analysis by sieving" - is an international reference method for determining the particle-size distribution of coal by manual sieving, either dry or wet, using test sieves with apertures from 90 mm down to 45 μm. The standard specifies sampling guidance (Annex A), apparatus, preparation and division of test samples, sieving procedures, result expression and reporting. It applies to all coals (but not to coke) and, for pulverized coal that mostly passes the smallest sieve, specifies determination of the oversize mass fraction only.

Key technical topics and requirements

• Scope and applicability: Manual sieving methods for coals; wet and dry sieving; sieves with aperture sizes between 90 mm and 45 μm. Not applicable to coke.
• Apparatus and sieve series: Recommended sieve series (e.g., 125, 90, 75, 63, 50, 45, 31.5, 22.4 mm … down to 45 μm); sieves ≤ 4 mm should be metal wire cloth; alternatives for square- or round-holed screens per ISO 3310-1/2.
• Sampling and sample preparation: Gross sample taken per ISO 13909‑2 or ISO 18283; minimum gross/test sample masses are defined (see Table 1) to achieve target precisions (1 % or 2 %). Special division procedures for wet coal < 4 mm are given.
• Sieving procedure: Detailed manual and mechanical (vibratory shaker) methods for different maximum particle sizes; wet sieving methods (pressure filtration, Buchner funnel) are included.
• Quality controls: Limits on fraction mass (no fraction should exceed ~30 % of total when a complete analysis is required), guidance on selecting largest/smallest sieves (largest sieve should retain ≤ 5 % and smallest should pass ≤ 5 %), annual sieve inspection per ISO 3310, and checks for holed/worn screens.
• Drying and equilibration: Instructions for drying, air-drying at enhanced temperatures, and equilibration periods for different coal ranks.
• Reporting and presentation: Calculation methods, graphical presentation of size distributions and required test report items are specified.

Practical applications and users

ISO 1953:2025 is used to:

• Verify size specifications for coal shipments (import/export).
• Provide design and performance data for coal preparation and screening plants.
• Assess crushing plant performance and product yields.
• Select coal feeds for specific processes or equipment.

Typical users:

• Coal laboratories, quality control and QA/QC teams
• Coal preparation and processing engineers
• Mining companies, brokers and trading houses
• Equipment manufacturers and test laboratories

Related standards

• ISO 3310‑1 / ISO 3310‑2 (test sieves)
• ISO 13909 series (mechanical sampling, sample preparation)
• ISO 18283 (manual sampling)
• ISO 1213‑1 / ISO 1213‑2 (vocabulary for coal preparation and sampling/testing)

Keywords: ISO 1953:2025, coal size analysis, sieving, wet sieving, dry sieving, test sieves, coal sampling, particle-size distribution, coal preparation.