ISO 8220:1986

Overview

ISO 8220:1986 specifies a laboratory method for determining the fine particle size distribution (less than 60 µm) of aluminium oxide (alumina) primarily used for aluminium production. The method quantitatively separates particles in the 63–16 µm range by wet sieving using electroformed sieves (square- or round-aperture), followed by drying and high-precision weighing of each fraction. This standard supports consistent particle-size reporting for quality control, supplier–purchaser agreements and process control in alumina production.

Key topics and technical requirements

• Scope: determination of alumina particle-size distribution below 60 µm, focusing on sieve apertures 63, 45, 32 and 16 µm.
• Sieves: electroformed sieves (square- or round-aperture). Note: results from square- and round-aperture sieves are not directly correlated - sieve type must be recorded.
• Apparatus and conditions:
  • Agitation device for slow oscillation of sieves (typical operation ~1 Hz, 10 mm amplitude).
  • Electroformed sieves mounted on stainless-steel frames (max. dimensions 75 mm; available Ø 65 mm).
  • Ultrasonic cleaner (max power 100 W) for sieve cleaning.
  • Electric oven controlled at 110 ± 2 °C for drying; weighing to 0.0001 g precision.
  • Vacuum device, polyethylene funnel, glass crystallization vessels (≈125 mm × 65 mm), adjustable supports, desiccator.
• Reagents:
  • Sodium hexametaphosphate dispersant, 1 g/L.
  • Non‑ionic polyethoxyl surface-active agent (saturated solution) for wetting.
  • Use distilled or equivalent purity water and analytical-grade reagents.
• Test portion masses (per ISO 802 sampling guidance):
  • 2 g for 63 µm and 45 µm sieves
  • 1 g for 32 µm sieve
  • 0.4 g for 16 µm sieve
• Procedure highlights:
  • Wet sieving in dispersant solution with repeated solution changes and agitation until no further material passes each sieve.
  • Dry sieves + residues and determine mass differences to express each fraction as a percentage by mass.
  • Sieve cleaning: brush, ultrasonic cleaning (≈2 min), rinse and oven-dry; inspect electroformed membrane microscopically.

Applications and users

• Quality control and acceptance testing for alumina producers, suppliers and purchasers.
• Process control in aluminium smelters and refining operations where particle size affects calcination, reactivity, sintering or feedstock performance.
• Materials testing and research laboratories performing granulometry of fine alumina powders.
• Contract specification and verification between manufacturers and end-users for product consistency.

Related standards

• ISO 862 - Preparation and storage of alumina test samples
• ISO 803 - Determination of loss on ignition / moisture at 300 °C
• ISO 3310-2 - Test sieves: technical requirements
• ISO 802 - Sampling guidance for aluminium oxide

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