Overview
ISO 2927:1973 specifies practical requirements for taking representative samples of aluminium oxide (alumina) intended for chemical analysis and determination of physical characteristics. The standard applies to alumina during transport, loading/unloading, continuous flow and storage, and remains an interim reference until broader general sampling methods are published. It has also been approved by IUPAC.
Key principles include sampling without reducing particle size, taking increments of constant mass, and keeping the sample in the same physical and chemical state from collection until laboratory examination.
Key Topics
- Scope and purpose: Representative sampling for chemical and physical testing of aluminium oxide used in aluminium production.
- Sampling principle: Remove increments of constant mass manually or mechanically; do not reduce particle size during sampling.
- Sampling during continuous flow: Take increments from the full width of the flow (never from the belt) at regular time intervals (example: increments representing 1/20th of conveyor operating time). Minimum increment sizes and batch requirements are specified.
- Apparatus and handling:
- Use suitable manual or mechanical equipment (e.g., Archimedean screws, inclined chutes).
- Prefer plastic sample vessels and avoid non-rigid sacks.
- Prevent free fall and segregation; transfer samples with screws or inclined chutes.
- Sample sizes:
- A typical laboratory sample of 500 g is sufficient for alumina with particle sizes from a few micrometres up to 300 µm.
- Bulk and laboratory sample increment counts vary by situation; for example, one increment per 10 m3 for containers of specified capacity, and ten to fifteen increments per batch for larger loads.
- Environmental control and storage:
- Store and transport laboratory samples at ambient temperature in closed, airtight containers.
- When measuring physical properties, fill the flask to the brim and stopper to avoid particle displacement and moisture exchange.
- Reporting: The sampling report should include method reference, proportion of the lot sampled, number and characteristics of laboratory samples, unusual observations, and any optional operations performed.
Applications
This standard provides practical guidance for:
- Industrial sampling of alumina during conveyor transport, silo/tank unloading, ship holds and heaps.
- Preparing representative laboratory samples for chemical analysis, quality control and acceptance testing.
- Minimizing errors from segregation, moisture exchange, and particle-size alteration during sampling and transport.
Practical benefits include improved traceability, consistent sampling procedures across operations, and reliable test results for process control in aluminium production.
Related Standards
- ISO standards on sampling of bulk and powdered materials (general sampling methods are under development and will prompt revision of ISO 2927).
- Industry-specific sampling and testing procedures used by aluminium producers and analytical laboratories.
For implementation, follow the detailed procedures in ISO 2927:1973 for apparatus selection, increment frequency and handling to ensure representative, uncontaminated samples for laboratory examination.
