Overview
ISO 23202:2006 specifies a wet‑sieving test method for determining the percentage by mass of particles of smelter‑grade aluminium oxide (alumina) that pass a 20 µm aperture sieve. The procedure is intended for aluminas with a −20 µm content up to 4% and yields a gravimetric result reported on an “as‑received” basis to one decimal place. Key elements include use of an electroformed 20 µm test sieve, acetone as the suspending/washing medium, and drying of retained material at 300 °C.
Key topics and technical requirements
- Scope: Applicable to smelter‑grade alumina (−20 µm content ≤ 4%).
- Principle: Wet‑sieving on a 20 µm electroformed sieve and gravimetric determination after drying.
- Reagents & safety:
- Acetone (analytical grade) - flammable, use in a fume hood.
- Desiccant (e.g., phosphorus pentoxide; note associated hazards).
- Ethanol or methanol for sieve cleaning.
- Apparatus:
- Electroformed 20 µm test sieve meeting ISO 3310‑3 requirements.
- Ultrasonic bath for cleaning, vacuum desiccator with heat sink, platinum crucibles.
- Sample prep & test portions:
- 50 g test sample prepared per ISO 802; 2 g test portions used for the sieve test (nominal).
- Sampling scoop (~0.5 g capacity) and careful tumble mixing to avoid segregation.
- Procedure highlights:
- Inspect sieve for ruptures and aperture blinding (clean if >30% blinded).
- Wet‑sieve with acetone, brush gently for ~10 minutes, ensure ≥400 ml acetone passes through.
- Evaporate acetone, then heat crucibles at (300 ±10) °C (2 h), cool in desiccator and weigh.
- Calculation & precision:
- Percent passing 20 µm is calculated gravimetrically from crucible and sample masses and reported to 0.1%.
- Precision: repeatability r = 0.24% (absolute); reproducibility R = 0.47% (absolute).
Applications and users
ISO 23202:2006 is used by:
- Quality control and analytical laboratories in alumina refineries and aluminium smelters.
- Suppliers and purchasers verifying smelter‑grade alumina particle fineness for process performance.
- Metallurgists and process engineers assessing feedstock particle size effects on reduction cell operation and product quality.
Practical uses include incoming raw‑material inspection, batch quality checks, supplier certification, and process troubleshooting where fines content influences sintering, transport, or electrochemical behaviour.
Related standards
- ISO 3310‑3 - Test sieves (electroformed sheets)
- ISO 802 - Preparation and storage of alumina test samples
- ISO 806 - Determination of loss on mass at elevated temperatures
- AS 2879.2‑2003 - Australian method on which ISO 23202 is based
Keywords: ISO 23202:2006, alumina particle size, 20 µm sieve, wet‑sieving, smelter‑grade alumina, −20 µm content, gravimetric determination, aluminium oxide testing.
Open preview (PDF)Aluminium oxide used for the production of aluminium — Determination of particles passing a 20 micrometre aperture sieve