ISO 18843:2015

Overview

ISO 18843:2015 establishes a standardized method for determining the flow time of aluminium oxide (alumina) primarily used in aluminium production. This international standard defines the procedure to measure the time required for a specified quantity of smelter-grade alumina to flow by gravity through a precisely constructed, corrosion-resistant funnel with a critical orifice diameter.

Developed by ISO/TC 226, the standard ensures consistent and reliable determination of alumina flow characteristics, which is vital for quality control and process optimization in aluminium manufacturing industries. The method significantly reduces variability in flow time measurements caused by differences in apparatus and test conditions across laboratories.

Key Topics

• Test Principle: The flow time is measured by loading 100 g (±0.1 g) of alumina into a standard funnel and recording the time for the material to flow out under gravity.
• Equipment Specifications:
  • Corrosion-resistant funnel (e.g., brass or aluminium) with an abrasion-resistant insert and a controlled orifice diameter (3.95 to 4.00 mm).
  • Accurate timing device with at least 1-second precision.
  • Sample preparation tools including sieves (300–400 µm aperture) and balances (0.1 g accuracy).
• Sample Preparation: Samples must be conditioned for a minimum of 2 hours at laboratory atmosphere with specific layer thickness before sieving and weighing.
• Testing Procedure:
  • Conduct three determinations per sample.
  • Ensure the funnel is clean and level before each test.
  • Avoid tapping or other disturbances while the alumina flows.
• Precision and Repeatability:
  • Provides within-laboratory repeatability (r) and between-laboratory reproducibility (R) benchmarks to ensure reliable inter-laboratory comparison.
• Reporting Requirements: Test reports must include sample identification, reference to ISO 18843, average flow time, test date, and any factors influencing results.

Applications

• Quality Control in Aluminium Production: Ensures the consistent physical flow properties of oxide feedstock to smelters, impacting efficiency and product quality.
• Material Characterization: Facilitates the classification and quality assurance of smelter-grade alumina, critical in refining processes.
• Inter-laboratory Comparisons: Provides a harmonized method enabling fair comparison of alumina flow characteristics globally, benefiting producers, suppliers, and consumers.
• Research and Development: Assists in studying how alumina particle size, moisture content, and other variables affect flow time for process improvements.

Related Standards

• AS 4538.2 – Guide to sampling of alumina: Preparation of samples for testing.
• AS 2879.9 – Previous Australian Standard on alumina flow time determination, which ISO 18843:2015 builds upon.
• AS 4538.1 – Guide to sampling of alumina: Sampling procedures.
• Other ISO and IEC standards for aluminium materials and testing modalities may complement ISO 18843 for integrated quality management.

By adhering to ISO 18843:2015, stakeholders in the aluminium production supply chain can accurately determine alumina flow characteristics. This ensures smooth processing, reduces equipment wear, and supports superior aluminium quality. Implementing the standard helps achieve consistent results, fostering trust and efficiency across production and testing facilities worldwide.