ISO 23028:2019

Overview

ISO 23028:2019 specifies methods for the preparation and storage of test samples of smelter‑grade aluminium oxide (alumina). The standard covers reduction of a bulk sample (1 kg to 20 kg) to representative portions suitable for chemical and physical analysis. It is intended for dry, free‑flowing aluminium oxide and emphasizes minimizing atmospheric exposure to avoid water absorption that can affect analytical results.

Keywords: ISO 23028:2019, aluminium oxide sample preparation, smelter‑grade aluminium oxide, sample storage, test samples.

Key topics and technical requirements

• Scope and principle
  • Procedures ensure the reduced sample is representative of the initial bulk from one source.
  • Mixing and rotary splitting are the primary methods for homogenization and division.
• Apparatus
  • Rotary splitter (large): stainless steel recommended; minimum of eight receivers; receiver capacity up to 2 kg; design to minimize fall distance and fines loss.
  • Small rotary splitter: receivers up to 250 g; minimum eight receivers; may require vibratory feeder.
  • Laboratory top‑pan balance: capacity ~4 kg with 1 g readability.
  • Airtight sample bottles, brush, powder funnel.
• Fines control
  • If determining particles <20 µm, test work shall ensure no more than 0.2% loss of fines over the division process.
• Procedure highlights
  • Mix by rotary splitting (repeat splits and recombine for blending).
  • Divide to required mass using calculated recombination of receivers (Annex B gives worked example).
  • Transfer quantitatively to containers using funnels; brush and tap receivers to recover adhering material.
  • Typical analytical portions: e.g., 35–50 g (sieve particle size), 50–60 g (attrition index).
  • Identify containers (ID, date) and store in clean, dry conditions; tumble containers before taking analytical portions.
• Sample integrity
  • Minimize contamination and exposure to air, limit handling time, and keep equipment dedicated to alumina where possible.

Applications and users

ISO 23028:2019 is used by:

• Quality control and analytical laboratories in aluminium smelting and refining operations
• Material engineers and metallurgists evaluating feedstock chemistry and physical properties
• Sampling technicians preparing representative test samples for particle size, moisture, attrition, and chemical assays
• Standards and regulatory bodies overseeing alumina testing protocols

Practical benefits include reproducible, representative sampling for accurate laboratory analysis, reduced analytical bias from moisture or fines loss, and standardized sample storage practices.

Related standards

• Prepared by ISO/TC 226 (Materials for the production of primary aluminium).
• The document contains no normative references; users should consult other ISO standards relevant to specific analytical tests (e.g., particle size or chemical assay methods) as needed.