Overview
ISO 18842:2015 specifies a laboratory method for determining tapped and untapped bulk density of smelter‑grade aluminium oxide (alumina) used primarily in aluminium production. The standard defines a controlled sample delivery and receiving arrangement that minimizes flow‑rate variations seen in simple “fall into a receptacle” methods. Results are reported on a moisture‑free (300 °C) basis and are suitable for production control, quality assurance and materials specification.
Key topics and requirements
- Scope: Applies to smelter‑grade alumina for aluminium production; minimizes sensitivity to particle flow properties.
- Sample preparation:
- Condition sample in laboratory atmosphere for a minimum of 2 hours in a layer ≤ 5 mm, mix and split according to sampling guide (AS 4538.2).
- Typical test portions: ~300 g for density tests, ~50 g for moisture (loss on ignition at 300 °C).
- Apparatus:
- Sample delivery apparatus with a 5.0 mm orifice and impact plate (abrasion‑resistant materials such as stainless steel, brass or aluminium).
- Receiver: cylindrical container nominally 200 ± 10 ml and a length‑to‑diameter ratio ≈ 6:1; volume precisely determined by temperature‑corrected water mass.
- Balance capable of 0.1 g readability, sieves (300–1 000 µm), straight edge, tapper and brush.
- Procedure:
- Untapped density: allow narrow stream to fill receiver, level with straight edge, weigh.
- Tapped density: compact sample by controlled tapping while adding sample until no further settling; level and weigh.
- Moisture correction using loss of mass at 300 °C (ISO 806).
- Calculations and reporting:
- Densities are calculated on a moisture‑free basis and reported in kg/m3 (rounded to nearest 1 kg/m3).
- Test report must identify sample, reference ISO 18842:2015, provide untapped and tapped densities, test date and any unusual observations.
- Precision:
- Reported repeatability and reproducibility (95% confidence): untapped r = 13 kg/m3, R = 31 kg/m3; tapped r = 14 kg/m3, R = 52 kg/m3.
Applications and users
- Primary users: alumina producers, aluminium smelters, materials testing laboratories and quality control teams.
- Practical uses:
- Incoming inspection of smelter‑grade alumina shipments.
- Process control and specification compliance for aluminium production feedstock.
- Comparative testing for product development, procurement and contract verification.
Related standards
- ISO 806 - Determination of loss of mass at 300 °C and 1 000 °C (moisture correction).
- AS 4538.2 - Guide to sampling of alumina (sample preparation).
- AS 2850 - Interlaboratory precision guidance.
Keywords: ISO 18842:2015, aluminium oxide, alumina, tapped density, untapped density, bulk density, smelter grade, moisture‑free, MOI, aluminium production.